tag:theconversation.com,2011:/au/topics/mating-5845/articlesMating – The Conversation2023-01-05T13:45:39Ztag:theconversation.com,2011:article/1942792023-01-05T13:45:39Z2023-01-05T13:45:39ZGrasshopper sex life is interrupted by noisy humans<figure><img src="https://images.theconversation.com/files/495066/original/file-20221114-22-9w8nzs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A Bullacris unicolor male grasshopper blending in with its leafy surroundings.</span> <span class="attribution"><span class="source">Vanessa Couldridge</span></span></figcaption></figure><p>Grasshoppers have a bad reputation. They’re <a href="https://www.bhg.com/gardening/pests/insects-diseases-weeds/stop-grasshoppers/">not popular with gardeners</a> And locusts, a type of swarming grasshopper, can <a href="https://www.youtube.com/watch?v=6bx5JUGVahk">do huge damage</a> to <a href="https://theconversation.com/explainer-whats-behind-the-locust-swarms-damaging-crops-in-southern-africa-147129">vegetation and crops</a> when they’re in a feeding frenzy.</p>
<p>But more often than not, grasshoppers have more to fear from humans than the other way around. As we increasingly encroach on their habitats, we are making a lasting imprint on the insects. There is even a chance that we may be negatively affecting their behaviours, their reproduction and their very evolution. </p>
<p>This is a problem because of the central role insects play in food webs, as both predators and prey, and in the nutrient cycle. They consume nutrients in the soil and later provide nutrients when they die and decompose. There’s even growing global interest in grasshoppers as a <a href="https://www.bbc.com/future/article/20220720-why-insects-are-the-sustainable-superfood-of-the-future">source of protein for humans</a>. The insects have been eaten for centuries <a href="https://theconversation.com/how-insects-can-help-fight-hunger-in-the-world-104951">in parts of Africa</a>.</p>
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Read more:
<a href="https://theconversation.com/how-insects-can-help-fight-hunger-in-the-world-104951">How insects can help fight hunger in the world</a>
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<p>One way that humans impose on grasshoppers is through noise. It’s long been known that anthropogenic noise – the many sounds generated by humans and all our activities – change the way that <a href="https://repository.si.edu/handle/10088/35188">birds</a>, <a href="https://www.ecologyandsociety.org/vol14/iss1/art25">frogs</a> and mammals communicate with each other. Noise can have widespread negative consequences for animals, such as interfering with their feeding, mating and parental care behaviour, increasing their predation risk and increasing their physiological stress.</p>
<p><a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2013.2683">Grasshoppers</a> have not been spared. A <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2435.12000">small body of research</a> has recorded how grasshoppers have had to, for instance, modulate their <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2435.12215">courtship signals</a> to be heard above the human din. </p>
<p>We wanted to see whether African grasshopper species have similar experiences. So we <a href="https://www.tandfonline.com/doi/abs/10.1080/09524622.2019.1703818?journalCode=tbio20">studied</a> <a href="https://etd.uwc.ac.za/xmlui/bitstream/handle/11394/6119/758-1400-1-RV.pdf?sequence=1&isAllowed=y"><em>Bullacris unicolor</em></a>, a species of bladder grasshopper. Bladder grasshoppers are an ancient group of grasshoppers found only in Africa, predominantly in South Africa’s coastal regions. They are also among the loudest insects in the world: their calls can reach intensities of 98 decibels at one metre, which is about as loud as a hand drill.</p>
<p>We found that as levels of traffic noise increased, grasshoppers reduced their calling effort, becoming less likely to call. At noisier locations they shifted their calling activity to later in the night, presumably to take advantage of relatively quieter conditions. They also altered the structure of the call itself under higher levels of noise.</p>
<p>This is a reminder that the organisms around us are not immune to humans’ ecological footprint. We, the noisy neighbours, are having long-lasting ecological and evolutionary consequences on the species with whom we share the planet – including those we don’t often think about, like grasshoppers.</p>
<h2>Mating calls matter</h2>
<p>The calls that insects make serve many purposes, from indicating aggression to scaring off predators. We focused on <em>Bullacris unicolor’s</em> mating calls since successful mating is key to any species’ ability to survive and thrive. </p>
<p>For instance, it’s been shown that female response rate to male courtship songs in the <a href="https://www.jstor.org/stable/40599636">fruit fly</a> (<em>Drosophila montana</em>) decreased in the presence of background noise. <a href="https://academic.oup.com/beheco/article/22/4/791/301068">Another study</a> found that female grasshoppers were more attracted by the courtship songs of male grasshoppers whose calls were more likely to stand out against the broadband white noise generated by the researchers. Broadband white noise consists of a broad range of sound frequencies (pitches), like static.</p>
<p>When it came to <em>Bullacris unicolor</em>, we wanted to look at how the male grasshoppers respond not only to anthropogenic noise, but also to changing environmental factors like temperature, wind and moisture, all of which could have an impact on their success at mating.</p>
<p><em>Bullacris unicolor</em> is a bladder grasshopper, so called for its inflated abdomen, which allows for amplified sound production. We compared two groups of bladder grasshoppers. The first is found at the <a href="https://www.fynboslife.com/nature-reserves/cape-flats-nature-reserve/">Cape Flats Nature Reserve</a> on the University of the Western Cape campus, next to a major road and a railway line. The second is at the nearby but quieter <a href="https://www.capetown.gov.za/Family%20and%20home/see-all-city-facilities/our-recreational-facilities/Nature%20reserves/Tygerberg%20Nature%20Reserve">Tygerberg Nature Reserve</a>. </p>
<p>Despite the reserves’ proximity to each other – they’re about 15km apart – climate at the two sites differs. We then recorded noises at the two reserves for three consecutive weeks, recording not only the grasshoppers’ calls, but also the levels of anthropogenic noise. We also regularly took humidity, temperature and wind speed readings.</p>
<p>We found that, across the two sites, <em>B. unicolor</em> males adapted their calling behaviours over noisier times. Rather than over-exerting themselves in noisier periods, they increased their call intervals (the periods between successive calls) and decreased call rate (the number of times they call). They also lowered the pitch of their calls. Thus, while there was a clear difference in noise levels between the two sites, overall the grasshoppers responded in similar ways to noise.</p>
<h2>Calling frequencies</h2>
<p>But our findings differed in some regards from those of other studies, which had previously shown that invertebrates produce higher-frequency calls in noisier habitats. Instead we found that grasshoppers at the noisier on-campus site lowered the frequency of their calls more than males at the other, quieter site.</p>
<p>We have to consider that weather conditions may also have a hand in these results. For instance, calls became shorter and more closely spaced under windier conditions, whereas call rate decreased. This suggests that fewer males were active when it was windy, but those that were active produced shorter and more frequent calls.</p>
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Read more:
<a href="https://theconversation.com/what-bush-crickets-are-telling-researchers-via-their-unique-calls-172424">What bush crickets are telling researchers via their unique calls</a>
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<p>In addition, there was a marked difference in the times of night at which the two communities were most active. At the site with less noise, we observed much higher calling activity earlier in the night, with calls dropping off sharply after midnight. In contrast, males at the noisier site were less active earlier at night, and called at higher levels from midnight onwards. This would seem to indicate that males at the noisy site were shifting their activity period to later in the night, to take advantage of relatively quieter conditions.</p>
<h2>More questions</h2>
<p>These and other findings need further unpacking. As this species is highly dependent on acoustic communication for mate location, the reduced calling effort demonstrated by males at both study sites might have a negative impact on mating success. We need to understand how females respond to these changes in the calling behaviour of the males and how population numbers are affected. We plan to study this in the future.</p><img src="https://counter.theconversation.com/content/194279/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vanessa Couldridge receives funding from the National Research Foundation (South Africa). </span></em></p>Humans are ‘noisy neighbours’ whose behaviour has long lasting ecological and evolutionary effects on other species.Vanessa Couldridge, Senior Lecturer, University of the Western CapeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1965532022-12-14T03:29:05Z2022-12-14T03:29:05ZSnakes have clitorises<figure><img src="https://images.theconversation.com/files/500911/original/file-20221214-14-cj88o9.jpeg?ixlib=rb-1.1.0&rect=17%2C0%2C1904%2C1260&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Luke Allen</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Snakes have clitorises – and we have given a full anatomical description of them for the first time.</p>
<p>In <a href="https://doi.org/10.1098/rspb.2022.1702">research</a> published in Proceedings of the Royal Society B, we describe the size and shape of the snake clitoris (or hemiclitores) across nine species. </p>
<p>We also closely studied the cellular makeup of the clitoris in Australian death adders, finding it to be composed of erectile tissue and bundles of nerves.</p>
<p>The discovery of what appears to be a functional clitoris offers a new perspective on snake courtship and mating. </p>
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Read more:
<a href="https://theconversation.com/the-sex-life-aquatic-how-moving-from-land-to-water-led-to-the-surprisingly-touchy-courtship-of-sea-snakes-159431">The sex life aquatic: how moving from land to water led to the surprisingly touchy courtship of sea snakes</a>
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<h2>Finding the snake clitoris</h2>
<p>As part of her PhD research, our student Megan Folwell at the University of Adelaide had been dissecting snake specimens in museums. She came across a heart-shaped structure in the female tail, nestled between two scent glands, that she thought was the clitoris (or the hemiclitores, as it is called in snakes) and showed me.</p>
<p>I wasn’t sure what we were looking at, so we got in touch with Patricia Brennan at Mount Holyoke College in the US, who is an expert in how genitals have evolved in vertebrates. </p>
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<a href="https://images.theconversation.com/files/500876/original/file-20221213-151-bqi4g7.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An animation showing a wireframe drawing of the lower half of a snake's body with the clitoris highlighted." src="https://images.theconversation.com/files/500876/original/file-20221213-151-bqi4g7.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/500876/original/file-20221213-151-bqi4g7.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=323&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500876/original/file-20221213-151-bqi4g7.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=323&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500876/original/file-20221213-151-bqi4g7.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=323&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500876/original/file-20221213-151-bqi4g7.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=406&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500876/original/file-20221213-151-bqi4g7.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=406&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500876/original/file-20221213-151-bqi4g7.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=406&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The snake clitoris is a heart-shaped structure in the tail.</span>
<span class="attribution"><span class="source">Folwell et al</span>, <span class="license">Author provided</span></span>
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<p>On closer inspection, we found it was a structure full of red blood cells and nerve tissue, as we would expect for erectile tissue. This suggests it is indeed the clitoris, and may swell and become stimulated during mating.</p>
<p>We went on to examine nine different species of snakes representing the major branches of snake evolution. All had a clitoris, though their sizes and shapes varied.</p>
<h2>Why didn’t we know about this already?</h2>
<p>Across all species, researchers have given female genitalia <a href="https://pubmed.ncbi.nlm.nih.gov/35353194/">a lot</a> <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001851">less attention</a> compared to its male counterpart. </p>
<p>What’s more, it’s hard to get a good look at snake genitalia. It’s all internal to the snake’s tail, for the most part, though the snake penis (or hemipenes) inflates for mating. </p>
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<a href="https://images.theconversation.com/files/500912/original/file-20221214-13-kq7mqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/500912/original/file-20221214-13-kq7mqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/500912/original/file-20221214-13-kq7mqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=627&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500912/original/file-20221214-13-kq7mqq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=627&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500912/original/file-20221214-13-kq7mqq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=627&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500912/original/file-20221214-13-kq7mqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=788&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500912/original/file-20221214-13-kq7mqq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=788&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500912/original/file-20221214-13-kq7mqq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=788&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The clitoris of an Australian death adder.</span>
<span class="attribution"><span class="source">Folwell et al.</span>, <span class="license">Author provided</span></span>
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<p>There has been quite a bit of research into the snake penis, but the snake clitoris has been missed.</p>
<p>While there are earlier reports, most actually referred to lizards, or mistakenly described the penis or scent glands, or featured only vague descriptions without anatomical references. Studies of species in which intersex individuals are relatively common heightened this confusion.</p>
<p>However, we have shown that the snake clitoris, although it shares its developmental origins with the penis, is very different from the penis – and our detailed anatomical description should help prevent this kind of confusion occurring in future.</p>
<h2>A crucial piece of anatomy</h2>
<p>In other species, we know the clitoris has <a href="https://linkinghub.elsevier.com/retrieve/articleSelectSinglePerm?Redirect=https%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0065345420300012%3Fvia%253Dihub&key=22f7498e0cabf6da1cbf5bbec791b299065c7bd7">important functions</a> in reproduction. </p>
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Read more:
<a href="https://theconversation.com/all-female-mammals-have-a-clitoris-were-starting-to-work-out-what-that-means-for-their-sex-lives-114916">All female mammals have a clitoris – we're starting to work out what that means for their sex lives</a>
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<p>Perhaps because many scientists assumed female snakes had no clitoris, and hence no capacity for arousal, it has generally been assumed that mating in snakes is largely a matter of males coercing females. </p>
<p>But a crucial piece of anatomy was missing from this conversation. Our discovery suggests female arousal – and something more like seduction – may play a role.</p>
<p>We still have a lot to learn. It may turn out that variation in the clitoris between species will be correlated with courtship and mating behaviours, and help us understand how females choose mates.</p><img src="https://counter.theconversation.com/content/196553/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jenna Crowe-Riddell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The first description of the snake clitoris may change what we think we know about mating and courtship among the slithering reptiles.Jenna Crowe-Riddell, Postdoctoral Researcher in Neuroecology, La Trobe UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1947932022-11-21T13:15:49Z2022-11-21T13:15:49ZPeople don’t mate randomly – but the flawed assumption that they do is an essential part of many studies linking genes to diseases and traits<figure><img src="https://images.theconversation.com/files/496010/original/file-20221117-25-slwoe3.jpg?ixlib=rb-1.1.0&rect=110%2C96%2C4690%2C2134&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Statistical pitfalls in GWAS can result in misleading conclusions about whether some traits (like long horns or spotted skin, in the case of dinosaurs) are genetically linked.</span> <span class="attribution"><span class="source">@meanymoo</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>The idea that <a href="https://doi.org/10.1002/0471667196.ess0209.pub2">correlation does not imply causation</a> is a fundamental caveat in epidemiological research. A classic example involves a hypothetical link between ice cream sales and drownings – instead of increased ice cream consumption causing more people to drown, it’s plausible that a third variable, summer weather, is driving up an appetite for ice cream and swimming, and hence opportunities to drown.</p>
<p>But what about correlations involving genes? How can researchers be sure that a particular trait or disease is truly genetically linked, and not caused by something else?</p>
<p>We are <a href="https://www.richardborder.com">statistical</a> <a href="https://scholar.google.com/citations?user=SPXgieEAAAAJ&hl=en">geneticists</a> who study the genetic and nongenetic factors that influence human variation. In our <a href="https://www.science.org/doi/10.1126/science.abo2059">recently published research</a>, we found that the genetic links between traits found in many studies might not be connected by genes at all. Instead, many are a result of how humans mate.</p>
<h2>Genome-wide association studies try to link genes to traits</h2>
<p>Because the genes you inherit from your parents remain unchanged throughout your life, with rare exception, it makes sense to assume that there is a causal relationship between certain traits you have and your genetics.</p>
<p>This logic is the basis for <a href="https://www.genome.gov/about-genomics/fact-sheets/Genome-Wide-Association-Studies-Fact-Sheet">genome-wide association studies, or GWAS</a>. These studies collect DNA from many people to identify positions in the genome that might be correlated with a trait of interest. For example, if you have certain forms of the <a href="https://www.cancer.gov/about-cancer/causes-prevention/genetics/brca-fact-sheet"><em>BRCA1</em> and <em>BRCA2</em> genes</a>, you may have an increased risk for certain types of cancer.</p>
<p>Similarly, there may be gene variants that play a role in whether or not someone has schizophrenia. The hope is to learn something about the complex mechanisms that link variation at the molecular level to individual differences. With a clearer understanding of the genetic basis of different traits, scientists would be better able to determine risk factors for related diseases. </p>
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<figcaption><span class="caption">GWAS studies seek to find genetic associations between individual traits.</span></figcaption>
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<p>Researchers have run <a href="https://doi.org/10.1093/nar/gky1120">thousands of GWAS to date</a>, identifying genetic variants associated with myriad diseases and disease-related traits. In many instances, researchers have identified genetic variants that affect more than one trait. This form of biological overlap, in which the same genes are thought to influence several apparently unrelated traits, is known as <a href="https://doi.org/10.1186/s13073-016-0332-x">pleiotropy</a>. For example, certain variants of the <a href="https://medlineplus.gov/genetics/gene/pah"><em>PAH</em> gene</a> can have <a href="https://medlineplus.gov/genetics/condition/phenylketonuria/">several distinct effects</a>, including altering skin pigmentation and causing seizures.</p>
<p>One way scientists assess pleiotropy is through <a href="https://doi.org/10.1038/ng.3604">genetic correlation analysis</a>. Here, geneticists investigate whether the genes associated with a given trait are associated with other traits or diseases by statistically analyzing large samples of genetic data. Over the past decade, genetic correlation analysis has become the primary method for assessing potential pleiotropy across fields as diverse as <a href="https://doi.org/10.1038/ng.3406">internal medicine</a>, <a href="https://www.thessgac.org">social science</a> and <a href="https://doi.org/10.1017/s0033291717002318">psychiatry</a>. </p>
<p>Scientists use the findings from genetic correlation analyses to figure out the potential shared causes of these traits. For instance, if <a href="https://doi.org/10.1126/science.aap8757">genes associated with bipolar disorders</a> also predict anxiety disorders, perhaps the two conditions may partially involve some of the same neural circuits or respond to similar treatments.</p>
<h2>Assortative mating and genetic correlation</h2>
<p>However, just because a gene is correlated with two or more traits doesn’t necessarily mean it causes them.</p>
<p>Virtually all the statistical methods researchers commonly use to assess genetic correlations <a href="https://doi.org/10.1046/j.1439-0388.2002.00356.x">assume that mating is random</a>. That is, they assume that potential mating partners decide who they will have children with based on a roll of the dice. In reality, many factors likely influence who mates with whom. The simplest example of this is geography – people living in different parts of the world are less likely to end up together than people living nearby.</p>
<p>We wanted to find out how much the assumption of random mating affects the accuracy of genetic correlation analyses. In particular, we focused on the potential confounding effects of <a href="https://doi.org/10.1038/s41562-018-0476-3">assortative mating</a>, or how people tend to mate with those who share similar characteristics with them. Assortative mating is a widely documented phenomenon seen across a broad array of traits, interests, measures and social factors, including <a href="https://doi.org/10.1002/ajhb.22917">height</a>, <a href="https://doi.org/10.2307/2095670">education</a> and <a href="https://doi.org/10.1016/j.biopsych.2019.06.025">psychiatric conditions</a>.</p>
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<figcaption><span class="caption">Humans do not mate randomly – rather, people tend to gravitate toward certain traits.</span></figcaption>
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<p>In <a href="https://doi.org/10.1126/science.abo2059">our study</a> we examined cross-trait assortative mating, whereby people with one trait (for example, being tall) tend to mate with people with a completely different trait (for example, being wealthy). From our database of 413,980 mate pairs in the U.K. and Denmark, we found evidence of cross-trait assortative mating for many traits – for instance, an individual’s time spent in formal schooling was correlated not only with their mate’s educational attainment, but also with many other characteristics, including height, smoking behaviors and risk for different diseases.</p>
<p>We found that taking into consideration the similarities across mates could strongly predict which traits would be considered genetically linked. In other words, just based on how many characteristics a pair of mates shared, we could identify around 75% of the presumed genetic links between these traits – all without sampling any DNA.</p>
<h2>Genetic correlation does not imply causation</h2>
<p>Cross-trait assortative mating shapes the genome. If people with one heritable trait tend to mate with people with another heritable trait, then these two distinct characteristics will become genetically correlated to each other in subsequent generations. This will happen regardless of whether or not these traits are truly genetically linked to each other.</p>
<p>Cross-trait assortative mating means that the genes you inherit from one parent will be correlated with those you inherit from the other. How people mate is not random, violating the key assumption behind genetic correlation analyses. This inflates the genetic association between traits that aren’t truly linked together by genes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of dinosaurs with and without long horns or spiked backs." src="https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/495756/original/file-20221116-21-hyom6p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">If dinosaurs with long horns preferentially mate with dinosaurs with spiked backs, genes for both of these traits can become associated with each other in subsequent generations even though the same gene doesn’t code for them.</span>
<span class="attribution"><span class="source">Aaqilah M</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Recent studies corroborate our findings. Earlier this year, researchers computed genetic correlations using a method that examines the association between the <a href="https://doi.org/10.1038/s41588-022-01062-7">traits and genes of siblings</a>. The genetic links between traits influenced by cross-trait assortative mating were substantially weakened.</p>
<p>But without accounting for cross-trait assortative mating, using genetic correlation estimates to study the biological pathways causing disease can be misleading. Genes that affect only one trait will appear to influence multiple different conditions. For example, a genetic test designed to assess the risk for one disease may incorrectly detect vulnerability for a broad number of unrelated conditions.</p>
<p>The ability to measure variation across individuals at the genetic and molecular level is truly a feat of modern science. However, genetic epidemiology is still an observational enterprise, subject to the same caveats and challenges facing other forms of nonexperimental research. Though our findings don’t discount all genetic epidemiology research, understanding what genetic studies are truly measuring will be essential to translate research findings into new ways to treat and assess disease.</p><img src="https://counter.theconversation.com/content/194793/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Border receives funding from the National Institutes of Health.</span></em></p><p class="fine-print"><em><span>Noah Zaitlen receives funding from the NIH, NSF, DoD, and CZI. </span></em></p>People don’t randomly select who they have children with. And that means an underlying assumption in research that tries to link particular genes to certain diseases or traits is wrong.Richard Border, Postdoctoral Researcher in Statistical Genetics, University of California, Los AngelesNoah Zaitlen, Professor of Neurology and Human Genetics, University of California, Los AngelesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1840112022-05-31T23:08:06Z2022-05-31T23:08:06ZIn the animal kingdom, mating calls and pheromones can attract a mate – or a canny predator<figure><img src="https://images.theconversation.com/files/466206/original/file-20220531-16-nwa3my.jpeg?ixlib=rb-1.1.0&rect=132%2C224%2C3702%2C1931&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Reproduction is the ultimate goal in life for most animals, but securing a mate is hard work. You must not only find a potential suitor, but hold their attention, identify yourself, and advertise your quality. </p>
<p>To achieve this, animals use “sexual signals”. These conspicuous displays or ornaments help beat out the competition in the contest for mates. And some of the most beautiful aspects of the animal world have evolved for this purpose.</p>
<p>Sexual signals are costly, though, and not just in terms of the energy it takes to sing or dance. One seemingly obvious and profound cost is predation. The idea is simple. Just as your private phone call may be overheard by nosy passersby, so too may the bright colours and loud calls of sexual displays catch the eyes and ears of predators seeking a meal. </p>
<p>From the shimmering wings of butterflies, to the sweet songs of birds, we admire these signals in other species daily – even though they’re not meant for us. So how often are they intercepted by predators? And is the risk equal across all kinds of signals? </p>
<p>My colleagues and I sought to answer these questions in <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2022.0444">a recent publication</a>. We found the dangers to signallers are real, although much more varied than we once thought.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/465900/original/file-20220530-12-x5hnjw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/465900/original/file-20220530-12-x5hnjw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=296&fit=crop&dpr=1 600w, https://images.theconversation.com/files/465900/original/file-20220530-12-x5hnjw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=296&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/465900/original/file-20220530-12-x5hnjw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=296&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/465900/original/file-20220530-12-x5hnjw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=372&fit=crop&dpr=1 754w, https://images.theconversation.com/files/465900/original/file-20220530-12-x5hnjw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=372&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/465900/original/file-20220530-12-x5hnjw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=372&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Animals use colours, calls, and smells to attract mates, but do they also attract predators? Pictured: <em>Anolis sagre</em> (left), <em>Pseudacris crucifer</em> (right)</span>
<span class="attribution"><span class="source">Ryan Hagerty/USFWS</span></span>
</figcaption>
</figure>
<h2>Eavesdropping on private conversations</h2>
<p>Biologists describe the illicit interception of sexual signals as “eavesdropping”, and it has been formally studied since at least Charles Darwin. The Tungara frogs of Central and South America are a classic example; their loud <a href="https://doi.org/10.1093/beheco/arl003">mating calls attract</a> the unwanted attention of parasitic flies in search of a blood meal. </p>
<p>To make sense of the wealth of work available on this topic we scoured the literature for every published study of predatory eavesdropping, and found 78 in total. Most were similar in design, in that they placed fake models of animals or their signals out in the wild and recorded how often these were attacked by predators. </p>
<p>After statistically combining the results of these studies we found that, as expected, communicating with mates does increase the risk of being predated. Animals bearing sexual signals were roughly five times more likely to be attacked than those that were not actively signalling.</p>
<p>Digging deeper, however, we discovered the risk of being eaten depends on <em>how</em> the animals are communicating with each other. Those that use calls or pheromones to attract mates are in far greater danger than those using visual displays, which surprisingly experience no increased risk at all.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/465940/original/file-20220530-16-mz0nql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two colourful butterflies sit on leaves, facing away from one another." src="https://images.theconversation.com/files/465940/original/file-20220530-16-mz0nql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/465940/original/file-20220530-16-mz0nql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/465940/original/file-20220530-16-mz0nql.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/465940/original/file-20220530-16-mz0nql.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/465940/original/file-20220530-16-mz0nql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/465940/original/file-20220530-16-mz0nql.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/465940/original/file-20220530-16-mz0nql.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">There are a few possible reasons for why visual displays to attract mates do not increase predation risk as much as some other signals.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/heres-how-we-proved-that-tropical-birds-are-more-colourful-and-why-colour-helps-them-survive-180357">Here's how we proved that tropical birds are more colourful – and why colour helps them survive</a>
</strong>
</em>
</p>
<hr>
<h2>Not-so-risky business</h2>
<p>The dangers of booming calls or strong pheromones are intuitive enough, but why do bold colours not raise the risk of being eaten? We suspect there are two related reasons. </p>
<p>One is that most predators are fussy eaters. Even those with broad diets such as insect-eating birds and lizards prefer to eat familiar prey, and only rarely try new things. Since most animals present their sexual displays intermittently, colourful ornaments may be unfamiliar to predators, who will then avoid them out of caution. </p>
<p>The other possible reason is that many animals use vivid colours as warning signals. Consider the striking black and red abdomens of redback spiders, which advertise the fact that they are <a href="https://doi.org/10.1093/beheco/arw014">dangerous and well defended</a>. Predators may be generally wary of conspicuous patterns, then, since the animals bearing them are often more trouble than they’re worth. </p>
<p>So what do these results tell us about the evolution of communication? For one, we might expect visual displays to be more conspicuous and elaborate than other types of signals such as calls or pheromones, given predators pose little threat in the face of extravagance. </p>
<p>And in populations where predation is a persistent threat, we should expect to find that adaptive evolution favours the use of less risky signals, such as colour or motion (or the abandonment of signalling altogether). We can see this take place among the Pacific field crickets of Hawaii, where males have lost the ability to sing in response to intense <a href="https://doi.org/10.3389/fevo.2019.00255">predation by parasitic flies</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/tug-of-war-between-survival-and-reproductive-fitness-how-chameleons-become-brighter-without-predators-around-182427">Tug of war between survival and reproductive fitness: how chameleons become brighter without predators around</a>
</strong>
</em>
</p>
<hr>
<h2>Weaponizing the language of sex</h2>
<p>Predators aren’t the only ones interested in eavesdropping on prey; humans are too. Pests such as aphids and grasshoppers are not only a nuisance in our gardens, but also wreak havoc on Australian crops to the tune of <a href="https://doi.org/10.1111/aen.12017">hundreds of millions of dollars</a> each year. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/466203/original/file-20220531-14-uq2ner.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dozens of tiny green aphids are seen sitting on a holey leaf." src="https://images.theconversation.com/files/466203/original/file-20220531-14-uq2ner.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/466203/original/file-20220531-14-uq2ner.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=349&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466203/original/file-20220531-14-uq2ner.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=349&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466203/original/file-20220531-14-uq2ner.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=349&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466203/original/file-20220531-14-uq2ner.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=438&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466203/original/file-20220531-14-uq2ner.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=438&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466203/original/file-20220531-14-uq2ner.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=438&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Aphids cause hundreds of millions of dollars’ worth of damage to Aussie crops each year.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Enterprising researchers have shown we can hijack the sexual signals of these pests to combat them in two ways. One is by using said signals to attract and trap the pests themselves, as in the case of artificial acoustic signals mimicking <a href="https://dx.doi.org/10.1079/PAVSNNR20127001">field crickets and grasshoppers</a>.</p>
<p>Or we can tap into the existing interests of predators to lure them toward pests in greater numbers. This has proven effective in managing aphids, for example, where we now commercially synthesise the sex pheromones of females. This attracts predatory wasps which <a href="https://dx.doi.org/10.1002/ps.550">lay their eggs inside the aphids</a>, and ultimately kill them.</p>
<p>Of course, our study only offers a brief guide to bio-inspired pest management. More generally, it shines new light on what was thought to be a fundamental cost of sex, and shows that while attracting mates can be a dangerous game, it depends entirely on how you play.</p><img src="https://counter.theconversation.com/content/184011/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thomas White receives funding from the Hermon Slade foundation and the Australian Research Council. </span></em></p>We wanted to understand the ways in which predatory animals eavesdrop on the sexual ‘conversations’ of their prey.Thomas White, Senior lecturer, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1777922022-03-07T13:19:48Z2022-03-07T13:19:48ZDeer have antlers, walruses have tusks – here’s why so few birds have weapons of their own<figure><img src="https://images.theconversation.com/files/449869/original/file-20220303-19-1qu7tlv.jpg?ixlib=rb-1.1.0&rect=10%2C0%2C3551%2C2499&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's plenty of aggression in the bird world, but little armed violence.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/MXPaqo">Velvet Shearer, USFWS/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Mating season in the animal kingdom can be dramatic, and sometimes violent. As an example, take <a href="https://youtu.be/dg4VeesS6_I">deer clashing their antlers</a> during the rut – nostrils flaring, hooves hammering the ground, grass flying everywhere, and that eerie silence before the thunderous collision. The winning buck gets access to the harem, while the loser must find other females to fight for. </p>
<p>Many other animals also have formidable weapons. They range from <a href="https://youtu.be/kOg2TGoVYoE">rhinoceros beetles’ pointy horns</a> to <a href="https://youtu.be/bMlogVug_vs">fiddler crabs’ proportionally gigantic claws</a> and the long tusks of <a href="https://youtu.be/sxMc-INN-GA">walruses</a> and narwhals.</p>
<p>Birds also need to compete for their mates, which often involves fiercely defending a territory. But most birds don’t sport impressive weapons; we know them better for their colors, dances and songs. As evolutionary biologists primarily interested in <a href="https://jocateme.webnode.com">birds</a> and <a href="http://www.alexandrevpalaoro.eco.br">weapons</a>, respectively, we couldn’t help but wonder: Why do most birds lack their own version of antlers? The answer, which we present in a <a href="https://doi.org/10.1111/ele.13964">recent study</a>, likely lies in a trade-off between flying and fighting.</p>
<h2>It’s all about weight</h2>
<p>For anything that flies, whether it’s a bird or an airplane (or even Superman), flight demands more energy – in the form of burned fat or fuel – than <a href="https://doi.org/10.1093/icb/42.5.1060">moving on the ground or in the water</a>. And the amount of energy required <a href="https://doi.org/10.1016/j.cbpa.2019.06.003">increases with weight</a>.</p>
<p>How stark is this trade-off? Several years ago, United Airlines started <a href="https://www.latimes.com/business/la-fi-travel-briefcase-united-inflight-magazine-20180120-story.html">printing its inflight magazine on lighter paper</a> to reduce the weight of a typical flight by about 11 pounds, or <a href="https://en.wikipedia.org/wiki/Boeing_737">0.01% of an airplane’s empty weight</a>. Through this tiny decrease, the company cut its annual fuel use by 170,000 gallons, saving US$290,000 yearly. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/449871/original/file-20220303-27-6ys4qa.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Black-capped seabird perches on a fence post near the ocean" src="https://images.theconversation.com/files/449871/original/file-20220303-27-6ys4qa.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/449871/original/file-20220303-27-6ys4qa.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/449871/original/file-20220303-27-6ys4qa.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/449871/original/file-20220303-27-6ys4qa.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/449871/original/file-20220303-27-6ys4qa.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/449871/original/file-20220303-27-6ys4qa.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/449871/original/file-20220303-27-6ys4qa.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Arctic terns fly more than 40,000 miles each year, the longest migration in the animal kingdom. Their long, pointed wings – in scientific terms, a high hand-wing index – and forked tails make them fast, maneuverable flyers.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Arctic_tern">Jamumiwa/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>If you fly a lot, like an airline that operates 4,500 daily flights or a swift that <a href="https://doi.org/10.1016/j.cub.2016.09.014">flies 10 months out of every year</a>, every reduced ounce counts. And consequences are harsher for the swift. Animals can’t buy energy in the form of fuel – they have to find food and consume it, which itself requires energy.</p>
<p>On the other hand, if you are a rooster that only barely flies, you might be able to afford a bit of extra weight in the form of a weapon. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/449893/original/file-20220303-15-110566j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Legs of a walking turkey with pointed spurs protruding backward" src="https://images.theconversation.com/files/449893/original/file-20220303-15-110566j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/449893/original/file-20220303-15-110566j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=533&fit=crop&dpr=1 600w, https://images.theconversation.com/files/449893/original/file-20220303-15-110566j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=533&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/449893/original/file-20220303-15-110566j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=533&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/449893/original/file-20220303-15-110566j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=670&fit=crop&dpr=1 754w, https://images.theconversation.com/files/449893/original/file-20220303-15-110566j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=670&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/449893/original/file-20220303-15-110566j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=670&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Leg spurs on a male wild turkey.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/ruH73u">Paul VanDerWerf/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>In other words, given the cost of flying, it makes sense that birds should be able to afford weapons only if they don’t depend too much on flight. This trade-off is supported by <a href="https://www.elsevier.com/books/modelling-the-flying-bird/pennycuick/978-0-12-374299-5">mathematical flight models</a> and measurements of <a href="https://doi.org/10.1016/j.cbpa.2019.06.003">the cost of flight in real birds</a>, which show that carrying avian weapons such as leg or wing spurs in flight costs more “fuel” the more a bird flies and the lighter the rest of its body is.</p>
<h2>Avian spurs</h2>
<p>To be sure, some birds do have weapons specialized for fighting – just not very many species. And the weapons that birds do carry aren’t as big, heavy or flashy as in other animals. <a href="https://flic.kr/p/q5r9T5">Rooster spurs</a>, a classic example, are about as antlerlike as bird weapons get. </p>
<p>About 170 species – less than 2% of all existing avian species – possess spurs on their legs or wings. Spurred legs are only found on <a href="https://eol.org/pages/7589">landfowl</a> – birds that mostly feed on the ground – including <a href="https://flic.kr/p/6hZkVD">turkeys</a>, <a href="https://flic.kr/p/253kEaW">pheasants</a>, <a href="https://flic.kr/p/c7pJyw">peacocks</a> and many of their <a href="https://flic.kr/p/o9R2pa">relatives</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/UqlRAe_DODg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Two roosters fight for territory in Kauai, Hawaii, using their leg spurs to strike each other.</span></figcaption>
</figure>
<p>Wing spurs are less common and more dispersed across bird species. Examples include <a href="https://flic.kr/p/diN41a">lapwings</a>, <a href="https://flic.kr/p/qCyHz5">jacanas</a>, <a href="https://flic.kr/p/23vmNCt">sheathbills</a> and some ducks, <a href="https://flic.kr/p/NYw2SJ">geese</a> and doves. Wing spurs are typically located on the bird’s wrists and vary in form from <a href="https://flic.kr/p/hd4qtg">blunt knobs</a> to <a href="https://flic.kr/p/bGoUix">sharp spikes</a>.</p>
<p>For the purpose of testing the fight-or-flight idea, it’s good news that some species carry weapons. This allows us to analyze our expectation that spurs should be found more often in species that depend less on flight than on those that fly frequently. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/450111/original/file-20220304-23-9yaro9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two grey and white tropical birds with yellow wing spurs." src="https://images.theconversation.com/files/450111/original/file-20220304-23-9yaro9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/450111/original/file-20220304-23-9yaro9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=513&fit=crop&dpr=1 600w, https://images.theconversation.com/files/450111/original/file-20220304-23-9yaro9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=513&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/450111/original/file-20220304-23-9yaro9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=513&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/450111/original/file-20220304-23-9yaro9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=645&fit=crop&dpr=1 754w, https://images.theconversation.com/files/450111/original/file-20220304-23-9yaro9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=645&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/450111/original/file-20220304-23-9yaro9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=645&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Masked lapwings have yellow spurs on the carpal joints of their wings.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/e4Azz7">Heather Paul/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Luckily, we were able to draw on a global data set of the hand-wing index – a metric of wing shape that scientists use to quantify how well various bird species are adapted for flight and hence, presumably, how much they depend on it. This information was recently made available for <a href="https://doi.org/10.1038/s41467-020-16313-6">every living bird species</a>.</p>
<p>Our findings showed clear connections across bird species between the presence of spurs and flight behavior. On average, species that depend more on flight have fewer or no spurs. Among species that do have spurs, longer spurs tend to appear in larger-sized species. </p>
<p>Using <a href="https://doi.org/10.1098/rspb.1994.0006">evolutionary models</a>, we also looked back at the historical process that led to this current fight-or-flight situation. We found that species that depended more on flight were more likely to lose spurs over time than species that flew only occasionally. In other words, the absence of spurs on most birds today is likely the result of species that were frequent flyers losing spurs, not occasional flyers gaining them.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/nPhVOZiPokA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Many bird species rely on some combination of plumage, songs and dances to attract mates rather than fighting.</span></figcaption>
</figure>
<h2>To fight or not to fight</h2>
<p>Our findings show that flight is a very good explanation for why birds don’t impress much in the weaponry department. But that doesn’t necessarily translate to peace and love. For example, <a href="https://www.youtube.com/watch?v=WUV81ukrsHc">hawks use their talons as weapons in violent fights</a>, and <a href="http://revbrasilornitol.com.br/BJO/article/view/270301">toucans do the same with their bills</a>. </p>
<p>[<em>Over 150,000 readers rely on The Conversation’s newsletters to understand the world.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-150ksignup">Sign up today</a>.]</p>
<p>We shouldn’t expect these cases to be the rule, though. That’s because claws and bills are essential for other tasks like foraging, feeding, thermoregulating, preening and anchoring. In contrast, spurs’ and antlers’ only function is to fight. Using claws and bills in combat can mean compromising other essential functions. For example, in 2017, Chinese engineers designed a titanium alloy bill for a captive crane that broke its bill during a fight and consequently <a href="https://doi.org/10.1016/j.matdes.2016.11.092">lost the ability to feed without human help</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/449878/original/file-20220303-19-gt4qcm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A songbird waves its wings and cries at another bird to drive it away from a bird feeder." src="https://images.theconversation.com/files/449878/original/file-20220303-19-gt4qcm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/449878/original/file-20220303-19-gt4qcm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/449878/original/file-20220303-19-gt4qcm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/449878/original/file-20220303-19-gt4qcm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/449878/original/file-20220303-19-gt4qcm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/449878/original/file-20220303-19-gt4qcm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/449878/original/file-20220303-19-gt4qcm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Competition for space at feeders doesn’t usually involve actual combat.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/9uTVbY">Holly Occhipinti/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>If most birds can neither bear spurs because they compromise flight nor risk features such as their bills because they are essential for other tasks, the solution may be to avoid physical combat as much as possible. Indeed, many birds defend territories primarily by singing or showing off ornaments. Flight preventing the evolution of weapons may thus help explain the striking colors, dances and songs that we find across birds.</p>
<p>The next time you’re outdoors and hear two birds <a href="https://youtu.be/dvK-DujvpSY">screaming their lungs out</a> at each other instead of fighting, remember that peace might be the only option evolution gave them.</p>
<p><em>This article has been updated to clarify that deer have antlers, not horns.</em></p><img src="https://counter.theconversation.com/content/177792/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexandre V. Palaoro receives funding from NSF, grant number IOS-2042937.</span></em></p><p class="fine-print"><em><span>João C. T. Menezes receives funding from the University of Massachusetts Amherst. </span></em></p>Birds will shriek and dive at each other over food, territory or mates, but only a small number of species sport actual weapons. The reason: Flying matters more for their survival than fighting.Alexandre V. Palaoro, Post-doctoral Fellow in Materials Sciences & Engineering, Clemson UniversityJoão C. T. Menezes, PhD Student in Organismic and Evolutionary Biology, UMass AmherstLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1594312021-06-07T04:20:05Z2021-06-07T04:20:05ZThe sex life aquatic: how moving from land to water led to the surprisingly touchy courtship of sea snakes<figure><img src="https://images.theconversation.com/files/403537/original/file-20210531-27-1xf8j0d.JPG?ixlib=rb-1.1.0&rect=19%2C19%2C4294%2C2851&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Claire Goiran</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Although sea snakes aren’t usually associated with intimate interactions, our new research is revealing their “sensitive” side.</p>
<p>In a study <a href="https://academic.oup.com/biolinnean/article-lookup/doi/10.1093/biolinnean/blab069">published today</a> in the Biological Journal of the Linnaean Society, my colleagues and I detail the enlarged touch receptors which evolved in the male turtle-headed sea snake (<em>Emydocephalus annulatus</em>). </p>
<p>We suspect these curious sensory organs help the males keep up with their female counterparts underwater.</p>
<h2>As I headed to sea</h2>
<p>The sun rises over the calm water of Baies des Citrons in Nouméa, New Caledonia. I don my wetsuit and snorkel out in search of turtle-headed sea snakes. </p>
<p>Once I slip into the water it doesn’t take long to spot one; a yellow and black banded male swims with purpose along the rocky reef. It’s the winter breeding season.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Xsnm6XmE86k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A banded male turtle-headed sea snake swims along the reef, looking for females.</span></figcaption>
</figure>
<p>During mating season, a male will search frantically for females and approach nearly everything that moves, including my flippers! </p>
<p>When he does find a female, he begins a curious courtship behaviour — undulating his body over hers, while repeatedly prodding his head into her back. </p>
<p>The female swims to the surface to breathe as the smaller-bodied male rushes to keep up. As she dives back down, he becomes disorientated and swims in the opposite direction. Realising he has lost her, the male erratically circles their last place of contact. She may be metres away, but he’ll probably never find her again. </p>
<p>This is a common story for this species. <a href="https://link.springer.com/article/10.1007/s00265-004-0897-z">One study</a> found up to 60% of males will lose contact with females they encounter. </p>
<h2>Sea sense: how do sea snakes find their mates?</h2>
<p>On land, snakes use tongue-flicking to sense and follow sex pheromones left by other snakes. In the water, however, these chemicals are diluted. </p>
<p>Turtle-headed sea snakes also can’t see very clearly underwater and have been known to court anything long and dark, including sea cucumbers. To make matters worse, once a female is found, the male must overcome buoyancy force so he doesn’t float away from his potential mate. </p>
<p>Given the challenges of living underwater, my colleagues and I hypothesised male turtle-headed sea snakes might have an enhanced sense of touch, to maintain contact with females during close courtship. </p>
<h2>Underwater tactile foreplay</h2>
<p>Most snakes have a dusting of thousands of touch receptors that look like freckles all over their face. These touch receptors are much larger in sea snakes, potentially so they can sense vibrations made by swimming prey and predators.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403539/original/file-20210531-19-1y3w99i.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A comparison of scale receptors in a land snake (<em>Pseudonaja textilis</em>) and sea snake (<em>Hydrophis schistosus</em>).</span>
<span class="attribution"><span class="source">xx</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>One of the largest touch receptors on any snake is found on turtle-headed sea snakes. And when we took a closer look at museum specimens, we discovered males have larger touch receptors than females overall. </p>
<p>We also found mature males have enlarged scale structures on their snout, chin and their cloaca (which is an all-purpose hole used for reproduction and excretion). The positioning of these enlarged receptors over the body hints at the role they play in sea snake courtship.</p>
<p>The touch receptors on the chin of males (referred to as “genial knobs”) have the same specialised cells as those on the face, but the outer bump is four times larger. </p>
<p>Their position on the underside of the head gives sensory feedback to the male as he swims above females, helping him orient towards the direction of her swimming. </p>
<p>The touch receptors on his anal scales (or “anal knobs”) provide feedback to align both snakes’ cloacae, which is necessary for sex. Genital alignment may seem like a trivial task, but for tube-shaped limbless snakes, touch receptors on the cloaca are essential. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=292&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=292&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=292&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=367&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=367&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403542/original/file-20210531-17-16n7e7n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=367&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Comparison of male and female turtle-headed sea snakes. Males have rostral spines (RS) and enlarged genial knobs (GK) and anal knobs (AK). Males also have larger scale receptors (SS). H = hemipene, which is a male reproductive organ.</span>
<span class="attribution"><span class="source">Chris Jolly</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Males also have a tapered scale on their snout known as the “rostral spine”. While courting the female, the male will prod the female’s back with this hardened scale. </p>
<p>We investigated the micro-structure of the rostral spine and found it is made of thickened layers of skin with no specialised sensory cells. As such, we think it may play a role in stimulating female interest in mating. </p>
<p>However, it provides relatively less feedback for the male, especially compared to the touch receptors on his chin and cloaca.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=567&fit=crop&dpr=1 600w, https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=567&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=567&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=713&fit=crop&dpr=1 754w, https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=713&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/403544/original/file-20210531-19-1163v4w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=713&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Positioning of the scale structures on a male turtle-headed sea snake. RS = rostral spine and GK = genial knob.</span>
<span class="attribution"><span class="source">Photo of full snake by Max Jackson; photos of tactile receptors by Chris Jolly</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>A similar form of “tactile foreplay” has been observed in species of boas and pythons. These snakes have hard claws known as pelvic spurs near their cloaca, which are vestigial remnants of legs lost through evolution! </p>
<p>During courtship, males will scratch and pry at the female’s scales during mating. Such sinuous courtship can stimulate beneficial hormonal changes and receptive behaviours in females, such as “cloacal gaping” which increase mating success for both sexes.</p>
<p>Could the rostral spine in turtle-headed sea snakes play a similar role in stimulating females? </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/1ygIGg6XMQA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The mating begins.</span></figcaption>
</figure>
<h2>Evolutionary transitions</h2>
<p>Sea snakes <a href="https://doi.org/10.1098/rsob.160054">evolved from land snakes</a> some 20 million years ago. Most live their entire lives at sea. </p>
<p>Decades of research have revealed their remarkable morphological adaptations to aquatic life, including paddle-shaped tails, salt-excreting glands and the ability to breathe through their skin. Now, our research is beginning to uncover the importance of touch for social behaviours in sea snakes.</p>
<p>While sea snakes are not typically appreciated for their sensitive side, our discovery suggests an enhanced sense of touch evolved to improve communication within members of a species. This is especially crucial in aquatic environments, where other sensory signals such as vision and pheromones are diminished.</p>
<p>As our work continues, sea snakes are becoming a fantastic example of how evolution can create opportunity from constraint.</p><img src="https://counter.theconversation.com/content/159431/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jenna Crowe-Riddell received funding for this study from an Australian Government Research Training Program Scholarship and a New Caledonia University Scientific Exchange Program Grant. </span></em></p>During mating season, a male turtle-headed sea snake will often lose sight of the female before mating can happen. The female may be metres away, but the male won’t ever find her again.Jenna Crowe-Riddell, Postdoctoral research fellow, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1610812021-05-19T19:57:31Z2021-05-19T19:57:31ZMen are from Mars, women are from… Mars? How people choose partners is surprisingly similar (but depends on age)<figure><img src="https://images.theconversation.com/files/401542/original/file-20210519-19-1psbexl.jpg?ixlib=rb-1.1.0&rect=41%2C17%2C3952%2C1479&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>As behavioural scientists, we have a keen interest in how people make decisions, and particularly how these decisions incorporate a range of emotional, cognitive and psychological factors.</p>
<p>Choosing a life partner is arguably one of the most important decisions a person can make. And <a href="https://www.abc.net.au/news/2019-11-26/australia-talks-national-survey-where-to-find-a-partner/11692170">research</a> <a href="https://news.stanford.edu/2019/08/21/online-dating-popular-way-u-s-couples-meet/">has shown</a> the most common way to do this these days is to go online.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=951&fit=crop&dpr=1 600w, https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=951&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=951&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1195&fit=crop&dpr=1 754w, https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1195&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/401526/original/file-20210519-21-kk0ghq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1195&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">John Gray’s famous 1992 book purports that men and women have innately different natures.</span>
<span class="attribution"><span class="source">Wiki</span></span>
</figcaption>
</figure>
<p>As increasing numbers of people wade cautiously through the digital dating market, many still subscribe to stereotypical ideas about what men and women find attractive in a partner.</p>
<p>Our latest research, <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0250151">published</a> today in PLOS One shows the truth, as ever, is more nuanced. </p>
<p>Using survey data from 7,325 heterosexual users of dating websites, aged 18 to 65, we show there is no absolute difference between the preferences of men and women when it comes to choosing a mate. Both essentially desire the same qualities, but prioritise them slightly differently.</p>
<h2>The democratisation of dating?</h2>
<p>Dating in the 21st century is <a href="https://theconversation.com/sex-bots-virtual-friends-vr-lovers-tech-is-changing-the-way-we-interact-and-not-always-for-the-better-159427">a truly unique experience</a>. For millennia, the human search for companionship had been constrained by access, distance and resources. Most people had to find a partner through close or extended family, or religious, cultural or social organisations.</p>
<p>Today, online dating allows seemingly unrestrained and “<a href="https://www.cs.ubc.ca/%7Ekevinlb/teaching/cs322%20-%202005-6/Lectures/lect32.pdf">nonsequential</a>” decision-making.</p>
<p>Imagine if you met someone at a bar and told them to wait around for two hours, just in case you managed to find someone better. It sounds bizarre, but that’s what <a href="https://medium.com/@therealnair/tinder-and-cognitive-overload-5c7650f5fe00">online dating allows</a>. You can search through thousands of people and never have to make a decision. </p>
<p>This is good news for researchers of human behaviour. With such a vast and growing pool of data, we can study mating choices in a way we never could before.</p>
<h2>Pressure to play the evolutionary game</h2>
<p>Obviously, a huge part of sexual attraction comes down to personal preference regarding what makes someone “sexy”. That said, there are many stereotypes relating to what heterosexual men and women find sexy. </p>
<p>It’s often assumed women favour more emotional, personality, intelligence and commitment-based traits in men, while men are often said to prefer physical attractiveness. </p>
<p>From an evolutionary psychology angle, these stereotypes aren’t unfounded. In the game of life, the main aim is to pass on your genes — and once you do, to ensure your offspring achieve the same success. </p>
<p>Naturally, men and women play different roles in the reproduction process. From an evolutionary standpoint, it makes sense for women to seek a man with traits that will benefit her offspring in both the short and long term, as women bear a bigger reproductive cost than men. </p>
<p>They have internal gestation for nine months and then must successfully give birth, all while facing discomfort and risk. They will then continue to nurse and care for the child. </p>
<figure class="align-center ">
<img alt="Mother and child place their hands atop each other's" src="https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/401522/original/file-20210519-21-1bi2qzi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Throughout the evolution of our species, mothers on average have had a far greater parenting responsibility across their offspring’s lives.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Men, at its simplest, need only to invest time into copulation to have offspring. Theoretically, then, the specific selection pressures on men and women to pass on their genes should be observable in the characteristics of the mates they choose.</p>
<p>Many of these assumptions fall under a school of thought called “<a href="https://www.sciencedirect.com/topics/neuroscience/parental-investment">parental investment theory</a>”, developed in the early 1970s by evolutionary biologist Robert Trivers. </p>
<p>More recent theories in gender studies and social and evolutionary psychology have countered the notion of absolute differences. They demonstrate men and women are far more similar in their preferences than previously thought.</p>
<p>Our research reinforces one such theory, referred to as “<a href="https://www.pnas.org/content/106/Supplement_1/10001">mutual mate choice</a>”. We found both men and women essentially desire the same qualities in a partner, differing only in the relative emphasis placed on each trait at different life stages.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/should-i-stay-or-should-i-go-here-are-the-relationship-factors-people-ponder-when-deciding-whether-to-break-up-153707">Should I stay or should I go? Here are the relationship factors people ponder when deciding whether to break up</a>
</strong>
</em>
</p>
<hr>
<h2>If men are from Mars, women are too</h2>
<p>We asked survey participants to rate from 0 to 100 the importance they placed on nine traits when looking for a mate. They fell into three categories: </p>
<ul>
<li><strong>aesthetics</strong>, such as age, attractiveness and physical features</li>
<li><strong>resources</strong>, such as intelligence, education and income</li>
<li>and <strong>personality</strong>, such as trust, openness and emotional connection.</li>
</ul>
<p>Both genders rated aesthetics as highly important, along with all three personality traits, while income was much less important. </p>
<hr>
<p><iframe id="ScLiU" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/ScLiU/2/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<hr>
<p>Women, however, rated factors including age, education, intelligence, income, trust and emotional connection about 9 to 14 points higher than men. Men placed relatively more emphasis on attractiveness and physical build.</p>
<p>Importantly, the way both genders prioritised traits changed with age. Both cared less about physical attractiveness as they got older, whereas emphasis on personality increased. This makes sense, considering we require different things from a partner at different life stages. </p>
<p>Our findings reinforce that both men and women tend to give similar emphasis to certain traits, depending on their individual needs at a particular stage in life.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Older couple" src="https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/401520/original/file-20210519-13-ebp1j4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">On dating apps, users can at times be spoilt for choice. This may result in us not placing as much emphasis on the actual search for a partner that older generations historically did.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Men and women can both be very picky</h2>
<p>One interesting revelation came when we grouped participants’ preference data together. </p>
<p>Of those individuals who said one specific trait was very important to them, it turned out the majority of traits were very important to them. On the other hand were respondents who said they didn’t have a strong preference for any particular trait at all. </p>
<p>So while some people were happy to go with the flow, many of the participants actually cared <em>a lot</em> about <em>a lot</em> of different factors. For men, the likelihood of having such stringent preferences was most common between ages 20 and 40. Among women it was more likely between the ages of 35 and 50. </p>
<h2>Personal circumstance and preference is key</h2>
<p>The bottom line is there is no single unified theory of mate choice. Attractiveness matters to everyone to some extent. Resources and intelligence matter to everyone to some extent. </p>
<p>Beyond human biology and evolution, it’s likely our individual personal constraints — such as employment, education, family and social circle — still have a huge impact on how we choose a mate, even if we are dating online.</p>
<p>While dating apps and websites may come with an element of “cognitive overload”, they are ultimately just conduits for human communication. They let people search far and wide for a mate who will help them achieve their own relationship goals.</p>
<p>And our relationship goals, just as is the case with the importance we place on our preferences, change over time.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-one-could-dna-tests-find-our-soulmate-we-study-sex-and-sexuality-and-think-the-idea-is-ridiculous-158533">The One: could DNA tests find our soulmate? We study sex and sexuality — and think the idea is ridiculous</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/161081/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rob Brooks receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Benno Torgler, Ho Fai Chan, and Stephen Whyte do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Each year, more and more people are looking to dating apps to find a partner. And a trove of data from these users is finally revealing what men and women really want.Stephen Whyte, Deputy Director, Centre for Behavioural Economics, Society and Technology, Queensland University of TechnologyBenno Torgler, Professor, Business School, Queensland University of TechnologyHo Fai Chan, Postdoctoral Research Fellow, Queensland University of TechnologyRob Brooks, Scientia Professor of Evolutionary Ecology; Academic Lead of UNSW's Grand Challenges Program, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1517272021-01-12T19:00:30Z2021-01-12T19:00:30ZBirds sniff out potential mates who are genetically different<figure><img src="https://images.theconversation.com/files/377856/original/file-20210108-15-tbqm61.jpg?ixlib=rb-1.1.0&rect=15%2C22%2C5097%2C3380&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scent plays an important role in how birds choose their mates.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>I’ll never forget the heady scent of Cindy, my first major crush. Sometimes, I catch a whiff of her Hawaiian Ginger Body Mist perfume and I’m transported 15 years back in time and straight into a darkened club. <a href="https://www.youtube.com/watch?v=8yjGPgs0_S0">Calgon, take me away</a>.</p>
<p>Many of us have experienced the power of a <a href="https://www.bustle.com/p/why-some-smells-make-you-feel-nostalgic-according-to-science-7685224">nostalgic scent</a> triggering our memories. Of course, our sense of smell doesn’t only serve to remind us of our long-lost loves. Smell can inform us of the presence of enticing food nearby, or it can warn us of dangerous toxins in the environment. We can even <a href="https://www.nationalgeographic.com/news/2018/01/smell-sickness-parkinsons-disease-health-science">smell when our companions are ill</a>. </p>
<p>Our body odour is affected by many factors. The <a href="https://doi.org/10.1016/j.appet.2015.11.001">food we eat</a>, our <a href="https://doi.org/10.1007/s10646-020-02171-x">stress levels</a>, if we are healthy <a href="https://doi.org/10.1093/jb/mvr090">or sick</a>, the <a href="https://doi.org/10.1098/rstb.2019.0269">bacteria</a> and fungi that naturally live on our bodies and even our <a href="https://doi.org/10.1098/rspb.2012.2889">genetic makeup</a> can all affect the way we smell.</p>
<h2>Avian body scent</h2>
<p>But what does this have to do with birds?</p>
<p>Much like the phrase “blind as a bat” (<a href="https://www.livescience.com/55986-are-bats-really-blind.html">bats can see quite well, thank you</a>), there is a persistent myth that birds can’t smell. In the 1820s, <a href="https://www.smithsonianmag.com/science-nature/john-james-audubon-americas-rare-bird-97819781/">artist and ornithologist John James Audubon</a> wrongly claimed that <a href="https://baynature.org/article/comes-smell-turkey-vulture-stands-nearly-alone/">vultures use sight over smell to find food</a>. Audubon’s <a href="https://doi.org/10.1093/icb/7.3.415">conclusions were flawed</a>, but the myth lingers on.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of two vultures with the head of a calf." src="https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377809/original/file-20210108-23-fb64yi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ornithologist John James Audubon’s illustration of two black vultures. Audubon conducted experiments that falsely indicated that vultures relied on sight rather than smell.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Illustration_from_Birds_of_America_(1827)_by_John_James_Audubon,_digitally_enhanced_by_rawpixel-com_106.jpg">(National Gallery of Art)</a></span>
</figcaption>
</figure>
<p>Researchers have shown that birds use smell to do all sorts of things, like <a href="https://www.audubon.org/magazine/january-february-2014/birds-can-smell-and-one-scientist">find food</a>, <a href="https://doi.org/10.1111/j.1365-2435.2007.01361.x">avoid predators</a>, <a href="https://doi.org/10.1007/s00442-009-1418-6">protect their nests</a>, <a href="https://doi.org/10.1016/j.anbehav.2012.06.014">distinguish relatives from nonrelatives</a> and <a href="https://doi.org/10.1038/s41598-017-13110-y">identify their parents</a>.</p>
<p>Our feathered friends have a special preen gland at the base of their tail. When birds rub the gland with their beak, it releases preen oil, which they groom themselves with. Preen oil helps waterproof and protect feathers from damage, but it is also a major source of bird body odour. </p>
<p>Does a bird’s body odour have a purpose? I wanted to know whether birds feel attracted to each other because of how they smell, like I did with Cindy’s perfume. </p>
<p>By gently squeezing the preen gland, I collected preen oil from a common North American bird called the song sparrow (<em>Melospiza melodia melodia</em>), brought them in to captivity, and gave them a choice between preen oil from males and females. Males spent more time with preen oil from females, and females spent more time with preen oil from males, suggesting that <a href="https://doi.org/10.1016/j.anbehav.2019.06.035">birds prefer the smell of the opposite sex</a>. This is probably because the sparrows were looking for mates to start a family with.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A sparrow preening on a beach" src="https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377852/original/file-20210108-15-9z7ae0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Birds groom themselves by rubbing preen oil over their feathers with their beaks.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Smell the difference</h2>
<p>Birds, like humans, are more likely to raise a healthy family if their mate is genetically unrelated to them. But how can we assess whether a potential partner is a good genetic match? </p>
<p>Our B.O. may hold the key. </p>
<p>Believe it or not, in the 1990s, researchers convinced a group of women to rate their preferences for the smell of men’s dirty shirts. This “<a href="https://www.nytimes.com/1998/06/09/science/studies-explore-love-and-the-sweaty-t-shirt.html">sweaty t-shirt experiment</a>” showed that women prefer the B.O. of men who are genetically different from themselves. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-smelly-truth-about-romantic-relationships-and-health-131171">The smelly truth about romantic relationships and health</a>
</strong>
</em>
</p>
<hr>
<p>More recently, researchers showed that there is a <a href="https://doi.org/10.1098/rspb.2016.1966">link between bird scent and bird genes</a>, suggesting that genetically dissimilar birds smell different than genetically similar birds. </p>
<p>I wanted to know whether birds, like humans, prefer the odour of genetically dissimilar partners, so I designed my own sweaty t-shirt experiment. I gave female song sparrows a choice between preen oil from males who were more or less genetically similar to themselves. Just like in the human study, <a href="https://doi.org/10.1016/j.anbehav.2019.10.005">female birds preferred the smell of genetically dissimilar males</a>. </p>
<p>What’s more, I gave male birds the same test and got the same result: males preferred the smell of genetically dissimilar females. </p>
<p>Birds and humans both prefer the scent of a genetically different partner. This can help us ensure our offspring are healthy and able to fight off harmful pathogens.</p><img src="https://counter.theconversation.com/content/151727/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Leanne Grieves receives funding from the Natural Sciences and Engineering Research Council of Canada (NSERC). </span></em></p>Birds use body odour to smell out potential mates, and partners who are genetically unrelated to them smell more attractive.Leanne Grieves, McCall MacBain Postdoctoral Fellow, Dept. of Psychology, Neuroscience & Behaviour, McMaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1388932020-06-16T09:14:20Z2020-06-16T09:14:20ZHow will dating change after coronavirus? Psychology offers some clues<figure><img src="https://images.theconversation.com/files/340384/original/file-20200608-176550-zre8ux.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-asian-couple-using-telephone-call-727198444">Shutterstock/Sushiman</a></span></figcaption></figure><p>The dating scene could be a confusing place in world where at least some social distancing seems likely for the foreseeable future. And while many people will have maintained or begun contact with romantic partners online during lockdown, video chats and text messages are clearly not a long-term substitute for intimate (or even non-intimate) physical contact.</p>
<p>When it comes to online dating, science gives us some insight into how people normally behave. <a href="https://dictionary.apa.org/parental-investment-theory">Parental investment theory</a>, for example, predicts that in humans (and other animals), it is the sex investing more heavily in their offspring who will be more choosy or selective in securing a mate. Male reproduction requires relatively little investment over and above a few minutes of sexual contact, whereas female reproductive effort requires nine months or longer. </p>
<p>To see how these sex differences were evident in online opposite-sex dating, we conducted <a href="https://pure.southwales.ac.uk/en/publications/tinder-and-location-based-dating(f8575f28-e99b-4485-9a18-a5524868e4aa)/export.html">a study</a> in which participants viewed and responded to photographs of potential dates in a simulated online dating environment. The number of people they chose to date and the time it took them to make each choice was recorded. The photographs used were prejudged for level of attractiveness and categorised as being of high or low attractiveness. </p>
<p>In keeping with parental investment theory, we found that men chose a greater number of potential dates overall compared to women and did so regardless of the level of attractiveness of the photos they viewed. </p>
<p>When presented with attractive faces and less attractive faces, women chose more of the attractive ones. Men chose an almost equal number of attractive as unattractive photos. Therefore women were more selective. On measuring the time it took them to make choices, both men and women took more time to consider the attractive photos compared to the unattractive ones.</p>
<p>In summary, the findings suggested that men take more time to make less prudent decisions in online dating compared to women. </p>
<p>But how might all of this change in a time of pandemic? <a href="https://psycnet.apa.org/record/2012-03617-001">Research has shown</a> that the threat of disease leads us to avoid contact with people who compromise our well-being and pose a risk of infecting us. Yet romantic behaviour is generally characterised by a need for physical intimacy and bodily contact which is very much at odds with behaviour motivated to remain free of disease. Dating behaviour could clearly be altered while concerns of an infectious disease continue to affect the way we live.</p>
<p><a href="https://journals.sagepub.com/doi/abs/10.1177/0146167217736046">One interesting study suggests</a> a way this may happen. Researchers set up an online dating scenario in which participants judged pictures of prospective opposite-sex dating partners on aspects of “dateability”. The researchers also assessed participants’ individual concerns about infection using a measure called “<a href="https://www2.psych.ubc.ca/%7Eschaller/DuncanSchallerPark2009.pdf">perceived vulnerability to disease</a>” (PVD). This tests our emotional responses to the threat of germs in our surroundings and our beliefs about being susceptible to them.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/340388/original/file-20200608-176560-1mz9hhf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/340388/original/file-20200608-176560-1mz9hhf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/340388/original/file-20200608-176560-1mz9hhf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/340388/original/file-20200608-176560-1mz9hhf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/340388/original/file-20200608-176560-1mz9hhf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/340388/original/file-20200608-176560-1mz9hhf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/340388/original/file-20200608-176560-1mz9hhf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Taking precautions.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-man-woman-kissing-surgical-face-1701088090">Shutterstock/22Images Studio</a></span>
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</figure>
<p>The researchers found that participants with high PVD scores displayed lower levels of interest in prospective online-dating partners. This was the case even when the dating partners were highly attractive. </p>
<p>Also, those with high PVD scores were choosier overall compared to those with low PVD scores. It seems the threat of disease has an understandable power to lower our interest in prospective online-dating partners. </p>
<h2>More partners</h2>
<p>But the perception of a threat of disease has another effect on our dating and mating behaviour. Women who reproduce with several men at different times can increase the genetic variability of their children. The advantage of having a genetically diverse group of offspring is that at least some may possess the necessary characteristics to survive in environments with a prevailing threat of disease. </p>
<p>In this sense, such diverse mating behaviour may be advantageous to women. A <a href="https://europepmc.org/article/med/26030057">series of experiments in 2015</a> found that the threat of serious disease (no particular one was specified) did indeed influence women’s mating strategies in terms of their desire for a greater number of sexual partners. Given this finding, we might ask whether coronavirus will increase the desire for sexual diversity by women engaged in online dating.</p>
<p>Overall then, it seems there are some distinct gender differences in online dating behaviour, although these may vary at times when disease poses a particular threat – especially in those who have a higher perception of vulnerability. </p>
<p>Also, however, some women may seek greater sexual variety in order to increase the survival chances of their offspring. Of course, it is also possible that those who feel less bothered by the risk of infection from others might just continue to date as normal.</p>
<p>The pandemic also potentially provides a little more time for daters to improve their profiles and hone their online communication skills. And to perhaps spend time reflecting on what they are looking for in a partner when the time finally comes to get up close and personal.</p><img src="https://counter.theconversation.com/content/138893/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martin Graff does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Love in a time of corona.Martin Graff, Senior Lecturer in Psychology of Relationships, University of South WalesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1299102020-02-03T02:55:56Z2020-02-03T02:55:56ZDeep impact: grey seals clap underwater to communicate<figure><img src="https://images.theconversation.com/files/310810/original/file-20200120-118319-yw3uzm.jpg?ixlib=rb-1.1.0&rect=2%2C8%2C1914%2C850&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Ben Burville</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Have you ever clapped your hands to get someone’s attention? The resulting “crack!” sound is hard to ignore, rising above and penetrating through any background noise. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/310797/original/file-20200120-118319-1bumfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/310797/original/file-20200120-118319-1bumfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=454&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310797/original/file-20200120-118319-1bumfo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=454&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310797/original/file-20200120-118319-1bumfo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=454&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310797/original/file-20200120-118319-1bumfo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=571&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310797/original/file-20200120-118319-1bumfo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=571&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310797/original/file-20200120-118319-1bumfo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=571&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p>Now imagine trying to do it underwater – you would be unlikely to achieve quite the same impact.</p>
<p>Amazingly, new footage released this week in the journal <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/mms.12666">Marine Mammal Science</a> shows breeding grey seals doing just that: they clap at each other to warn off competitors and attract potential mates. </p>
<figure>
<iframe src="https://player.vimeo.com/video/385880959" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Grey seal clapping underwater. Filmed by Ben Burville as part of Project Grypus.</span></figcaption>
</figure>
<h2>Why is this unusual?</h2>
<p>Like their land-living relatives, marine mammals primarily communicate vocally - think of dolphin whistles or the famous song of humpback whales. Grey seals are no exception, and in fact can be surprisingly versatile. </p>
<p>Besides the bizarre “rup” and “rupe” calls these seals normally make in the wild (see the video below), some captive animals have even been trained to perform the <a href="https://www.newscientist.com/article/2207264-seals-have-been-trained-to-sing-the-star-wars-theme-have-a-listen/">Star Wars theme tune</a>!</p>
<p>But vocals are only half the story. Many marine mammals also produce percussive sounds, such as by slapping the water with their flippers or tails. Normally this happens at the surface, and only involves one flipper at a time. </p>
<p>What makes grey seals different is that - like humans - they literally clap their forelimbs together, and they do it entirely underwater.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sharp-claws-helped-ancient-seals-conquer-the-oceans-92828">Sharp claws helped ancient seals conquer the oceans</a>
</strong>
</em>
</p>
<hr>
<h2>The behaviour that took 17 years to film</h2>
<p>Recording the claps was far from easy, and took no less than 17 years of scuba diving by “seal diver” and marine biologist <a href="https://twitter.com/Sealdiver">Ben Burville</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/310796/original/file-20200120-118352-q7q5en.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/310796/original/file-20200120-118352-q7q5en.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/310796/original/file-20200120-118352-q7q5en.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=357&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310796/original/file-20200120-118352-q7q5en.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=357&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310796/original/file-20200120-118352-q7q5en.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=357&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310796/original/file-20200120-118352-q7q5en.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=448&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310796/original/file-20200120-118352-q7q5en.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=448&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310796/original/file-20200120-118352-q7q5en.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=448&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Seal diver Ben Burville with one of his dive buddies - a wild grey seal off the Farne Islands, UK.</span>
<span class="attribution"><span class="source">Photo provided by Ben Burville.</span></span>
</figcaption>
</figure>
<p>Ben was no stranger to the clapping sound itself. For years, he had heard it when diving with grey seals during their breeding season. Similar noises had also been detected by researchers using underwater microphones, but had been mistaken for a vocal signal. </p>
<p>It wasn’t until he actually saw a big male clapping together its paw-like flippers that Ben finally identified the true source of the sound. Yet the claps were quick and difficult to film; by the time he pointed his camera, things had usually moved on.</p>
<p>Years passed until finally, in October 2017, Ben caught the behaviour on film while diving near the Farne Islands, UK. A male grey seal performed seven claps right in front of him while his camera was rolling.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/310836/original/file-20200120-69559-1pe6c4k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/310836/original/file-20200120-69559-1pe6c4k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/310836/original/file-20200120-69559-1pe6c4k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=289&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310836/original/file-20200120-69559-1pe6c4k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=289&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310836/original/file-20200120-69559-1pe6c4k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=289&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310836/original/file-20200120-69559-1pe6c4k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=363&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310836/original/file-20200120-69559-1pe6c4k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=363&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310836/original/file-20200120-69559-1pe6c4k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=363&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Grey seals use their short paw-like forelimbs to make loud clapping sounds underwater.</span>
<span class="attribution"><span class="source">Filmed by Ben Burville. Illustrations by David Hocking.</span></span>
</figcaption>
</figure>
<h2>Why do grey seals clap?</h2>
<p>At first, the discovery might not seem that surprising. After all, seals are famous for performing this behaviour in zoos and aquaria. However, there is a crucial difference: whereas captive animals (usually fur seals or sea lions) have been trained to clap for our entertainment, grey seals do so in the wild and of their own accord. </p>
<p>So why do they do it?</p>
<p>Imagine being in a noisy room, with everyone around you chatting away. Getting attention can be difficult, unless you make a statement. That’s exactly what a clap is: a sharp, loud noise that rises above the background chatter. </p>
<p>Usually it’s males that do the clapping - sometimes by themselves, and sometimes at each other. Depending on the context, the claps may help ward off competitors and/or attract potential mates. </p>
<p>Similar functions underlie display behaviour in many other species. Think of a chest-beating male gorilla, for example. Like seal claps, those chest beats carry two messages: “I am strong, stay away”, and “I am strong, my genes are good.”</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/EAkxix31aJI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Male gorillas beat their chest as a show of strength to competitors and potential mates.</span></figcaption>
</figure>
<h2>Do other marine mammals clap?</h2>
<p>The short answer seems to be no, or at least not as far as we know. Clapping seems to be a genuinely novel behaviour that evolved in seals only once. Perhaps larger species such as sea lions are prevented from doing it by increased water resistance.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/310821/original/file-20200120-118347-halxbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/310821/original/file-20200120-118347-halxbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/310821/original/file-20200120-118347-halxbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310821/original/file-20200120-118347-halxbk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310821/original/file-20200120-118347-halxbk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310821/original/file-20200120-118347-halxbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310821/original/file-20200120-118347-halxbk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310821/original/file-20200120-118347-halxbk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Australian sea lions have long flipper-like forelimbs that may create too much drag to clap effectively underwater.</span>
<span class="attribution"><span class="source">Photo by David Hocking</span></span>
</figcaption>
</figure>
<p>Of course, it is also possible that some other species also clap, but haven’t done so in front of a camera. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/when-mammals-took-to-water-they-needed-a-few-tricks-to-eat-their-underwater-prey-73770">When mammals took to water they needed a few tricks to eat their underwater prey</a>
</strong>
</em>
</p>
<hr>
<p>Even if clapping were unique to grey seals, it seems the sharp signal it generates is important for many marine mammals. Several dolphins, whales and seals produce similar sounds via tail or flipper slaps, or even gunshot-like vocalisations. The oceans are a noisy place, after all, and it can be important to stand out in a crowd. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Vo31hoY1NUA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Wild harbour seal slapping the water to create a loud noise - possibly to scare fish out of hiding so that they can be caught.</span></figcaption>
</figure>
<h2>What should we learn from this?</h2>
<p>Clapping seals show us just how much we still don’t know about the remarkable mammals in our oceans. Clapping seems to be an important social behaviour, hence anything that disturbs it may impact breeding success and survival. </p>
<p>Human noise pollution is known to interfere with other forms of marine mammal communication, including <a href="https://thewire.in/the-sciences/how-noise-pollution-is-silencing-whale-songs-and-why-thats-a-problem">whale song</a>. Loud industrial noises could conceivably disturb grey seals (and other species that rely on acoustic signals) in similar ways. </p>
<p>But if we do not know a behaviour exists, we cannot easily act to protect it. </p>
<p>Understanding the animals around us better can therefore help us to protect them and their way of life.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/311034/original/file-20200121-144971-wloh9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/311034/original/file-20200121-144971-wloh9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/311034/original/file-20200121-144971-wloh9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=342&fit=crop&dpr=1 600w, https://images.theconversation.com/files/311034/original/file-20200121-144971-wloh9g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=342&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/311034/original/file-20200121-144971-wloh9g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=342&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/311034/original/file-20200121-144971-wloh9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=430&fit=crop&dpr=1 754w, https://images.theconversation.com/files/311034/original/file-20200121-144971-wloh9g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=430&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/311034/original/file-20200121-144971-wloh9g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=430&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption"></span>
<span class="attribution"><span class="source">Photo by Ben Burville</span></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/129910/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Hocking receives funding from from Monash University and the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Felix Georg Marx received funding from from the Australian Research Council (DECRA fellowship DE190101052). </span></em></p><p class="fine-print"><em><span>Ben Burville does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Clapping underwater takes real strength. But wild grey seals can do it, to warn off competitors and attract potential mates.David Hocking, Postdoctoral fellow, Monash UniversityBen Burville, Visiting Researcher - Marine Biology, Newcastle UniversityFelix Georg Marx, Curator Vertebrates, Te Papa TongarewaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1280012020-01-01T05:04:46Z2020-01-01T05:04:46ZI spy on real turtles having sex with 3D-printed turtle sex dolls<figure><img src="https://images.theconversation.com/files/306449/original/file-20191211-95111-yo99y.jpg?ixlib=rb-1.1.0&rect=12%2C0%2C2774%2C1873&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The northern map turtle is listed as a species at risk in Canada. Little is known about its reproductive behaviour as it spends most of its life underwater. </span> <span class="attribution"><span class="source">G. Bulté</span>, <span class="license">Author provided</span></span></figcaption></figure><p>I am a turtle voyeur. I record the private lives of turtles with hidden cameras and have gone as far as posting online some of the zesty bits. This peculiar penchant is part of my work as a <a href="https://ucmp.berkeley.edu/anapsids/testudines/chelonia.html">chelonian behavioural ecologist</a>. </p>
<p>I spy on turtles to document and understand how they make more turtles. This may seem straightforward given the notorious sluggishness of the subjects. How hard can it be to spy on turtles? </p>
<p>It’s harder than it sounds, but also much more exciting. And thanks to affordable gadgets such as action cameras and 3D printers, it is getting easier — and more fun. </p>
<h2>Turtle preoccupations</h2>
<p>In documentaries and popular media, turtles are often shown doing one of two things: lazily basking away summer days on a log or heart wrenchingly dodging cars to reach a safe place to bury their eggs. These noticeable behaviours are crucial to the baby-making business of turtles and we know a fair bit about both. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/306249/original/file-20191211-95120-ca0n6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/306249/original/file-20191211-95120-ca0n6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306249/original/file-20191211-95120-ca0n6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306249/original/file-20191211-95120-ca0n6i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306249/original/file-20191211-95120-ca0n6i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306249/original/file-20191211-95120-ca0n6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306249/original/file-20191211-95120-ca0n6i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306249/original/file-20191211-95120-ca0n6i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Contrary to what popular nature documentaries can portray, turtles spend most of their lives underwater.</span>
<span class="attribution"><span class="source">G. Bulté</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>What we know less about are the intricacies of mating and courtship: what happens below the murky surface of lakes, rivers, ponds, swamps, marshes and other watery environments.</p>
<p>Cheap, submersible action cameras are changing the game. Animal ecologists have embraced these toys because <a href="https://fisheries.org/2015/11/action-cameras-bringing-aquatic-and-fisheries-research-into-view/">they allow them to take prolonged peeks below the surface while minimally disturbing their favourite study subjects</a>. </p>
<p>Three-dimensional printing is also opening <a href="https://doi.org/10.1186/s12898-018-0190-z">exciting avenues for the study of animal behaviour in the field</a>. We are now able to inexpensively and rapidly produce anatomically accurate animal decoys.</p>
<h2>Watching northern map turtles</h2>
<p>We adopted these emerging tools to shed some light on the mating habits of the <a href="https://wildlife-species.canada.ca/species-risk-registry/species/speciesDetails_e.cfm?sid=712">northern map turtle</a>: a federally listed <a href="https://www.canada.ca/en/environment-climate-change/services/environmental-enforcement/acts-regulations/about-species-at-risk-act.html">species at risk</a> in Canada.</p>
<p>Most striking about map turtles is the huge difference in size between males and females. A large adult female can exceed 3,000 grams. A hunky male, on the other hand, will be lucky to tip the scale at 350 grams. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/306208/original/file-20191210-95135-1th374i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/306208/original/file-20191210-95135-1th374i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/306208/original/file-20191210-95135-1th374i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306208/original/file-20191210-95135-1th374i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306208/original/file-20191210-95135-1th374i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306208/original/file-20191210-95135-1th374i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306208/original/file-20191210-95135-1th374i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306208/original/file-20191210-95135-1th374i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Two adult northern map turtles from Ontario showing the extreme size difference between males and females. The male is the smaller one.</span>
<span class="attribution"><span class="source">(G. Bulté)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This asymmetry of size is the outcome of two facts. First, male map turtles don’t fight with one another, the key behaviour driving male burliness in animals. With many animals, when two males simultaneously encounter a receptive female, things get ugly if not lethally bloody. The bigger male typically comes out on top and passes his large male genes to the next generation. Not so in map turtles. The diminutive males can’t be bothered by same sex rivals. </p>
<p>The second fact is the correlation between a mom’s size and the size of her offspring. Large moms lay large eggs. Large eggs hatch large babies. Large babies have better odds of making it through the first few days of life than small ones. Natural selection has thus favoured large size in females. </p>
<h2>Mate choice</h2>
<p>Whether males were aware of this was something we set to find out with action cams and 3D-printed turtle sex dolls of various sizes. Our prediction was straightforward. If a typical male encounters many females of varying sizes, which happens because of the unusual overwintering habits of this species, and cannot possibly mate with all of them, he should prefer to mate with the larger ones. </p>
<p>Every fall, map turtles gather at specific spots of lakes and rivers where they spend their winter days quietly sitting at the bottom. These overwintering grounds also serve as mating grounds. Turtles mate when they arrive at these communal sites in the fall and afterwards, they take a five-month long winter snooze (<a href="https://www.youtube.com/watch?v=fdgeJ2b_U1k">it looks like this</a>). </p>
<p>When spring finally arrives, they mate again before taking off for the summer. Hundreds of turtles can use these communal grounds, making it inconceivable for any male to mate with all the females present. For a brief period, we have a bunch of libidinous turtles concentrated in one spot. This is a dream come true for a chelonian behavioural ecologist like myself. </p>
<p>To test our prediction, we 3D-printed decoys of female map turtles and placed them in pairs at two of these special meeting spots. The decoys were identical in every respect except for their size. One was about the size of an average female, and the second was slightly smaller than the largest female on record for our study population. </p>
<p>The incongruous pair was mounted on a rig fitted with an action camera. The whole assembly was dropped at bottom of the lake early in the morning and recovered at the end of the day. This was repeated for nine days with two pairs of decoys. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/306228/original/file-20191211-95153-1hp507d.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/306228/original/file-20191211-95153-1hp507d.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306228/original/file-20191211-95153-1hp507d.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306228/original/file-20191211-95153-1hp507d.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306228/original/file-20191211-95153-1hp507d.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306228/original/file-20191211-95153-1hp507d.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306228/original/file-20191211-95153-1hp507d.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306228/original/file-20191211-95153-1hp507d.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A 3D-printed decoy used to study the mating habits of northern map turtles.</span>
<span class="attribution"><span class="source">(S. Dobson)</span></span>
</figcaption>
</figure>
<h2>Big findings</h2>
<p>The response of wild males was clear: <a href="https://doi.org/10.1016/j.anbehav.2018.02.018">they preferred the larger female</a>. The large decoys received nearly twice the number of male visits and five times more mating attempts than the smaller ones. </p>
<p>The video below shows what a mating attempt looks like — this video is played at eight times the speed, and with musical accompaniment. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/MagFMhLjelw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A captured mating attempt of a male northern map turtle on a female decoy.</span></figcaption>
</figure>
<h2>Changing the turtle-watching game</h2>
<p>Action cameras offer a window into the private, underwater lives of animals. With these devices and other technologies like 3D scanners and printers, we are able to not only test hypotheses and predictions, but we can also simply observe what animals do. </p>
<p>As we were sifting through videos from our experiments, we witnessed a number of phenomena we did not know were possible, including a female map turtle seemingly squeaking at a female decoy and <a href="https://youtu.be/IPFvrFvt35E">a loon attacking a male decoy</a>. These may just be anecdotes for now, but perhaps there is more to them. </p>
<p>The ubiquity and affordability of action cameras will surely yield many insightful observations about aquatic animals including turtles. Some may influence how we think about animal behaviour, others may just be intriguing tidbits of a world largely unexplored.</p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/ca/newsletters?utm_source=TCCA&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/128001/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Grégory Bulté does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New technologies are revealing more about the secret lives of underwater turtles. Using underwater cameras and 3D printing, researchers are learning more than ever before.Grégory Bulté, Instructor, Ecology and Evolutionary Biology, Carleton UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1282842019-12-11T12:44:19Z2019-12-11T12:44:19ZLeopard slugs mate in the most beautifully bizarre way – and nobody knows why<figure><img src="https://images.theconversation.com/files/306088/original/file-20191210-95125-sj2zwu.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C4710%2C2987&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Beautifully bizarre.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/mating-leopard-slugs-limax-maximus-australia-1435271348">Ken Griffiths/Shutterstock</a></span></figcaption></figure><p>Under the cover of night, two large leopard slugs begin to court, circling each other, before climbing single-file up a tree or onto a rock. They lower themselves on a mucus rope, while entwining their bodies in a strictly anti-clockwise fashion.</p>
<p>Both slugs then push out and entwine two overly-sized penises from openings on the side of their head, before exchanging sperm that may later fertilise each of their eggs. Or, perhaps be eaten. Eventually, one slug crawls off and the other follows, eating the mucus trapeze as it goes.</p>
<p>The astonishing sex lives of leopard slugs, or <em>Limax maximus</em>, have long been recognised by naturalists and frequently feature in <a href="https://youtu.be/wG9qpZ89qzc">wildlife documentaries</a>. But while their carnal dance has mesmerised millions, nobody knows why they mate in this most bizarre way.</p>
<p>This is because slug sex science has rarely attracted anything other than observational study. Fortunately for our curiosity, there are a few <a href="http://www.scholarpedia.org/article/Gastropod_reproductive_behavior">noble individuals</a> who have taken time to understand the mating habits of snails and slugs, and <a href="http://www.joriskoene.com/">whose research</a> can give us some valuable clues.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Zxow0-hZia4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>It’s well known that leopard slugs, like the majority of land-based snails and slugs, are hermaphrodites – meaning that both sexual organs are contained in the same individual. Yet, self-fertilisation is generally not the <a href="https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1017/S0952836905007648">preferred option</a>. This is likely because natural selection favours mating with another individual to avoid the loss of health, fertility and fitness associated with <a href="https://www.sciencedirect.com/science/article/pii/S0169534716301586">inbreeding</a>.</p>
<p>Even though they can choose whether to mate as male or female, most slugs and snails mate as male and female at the same time. They can also <a href="http://www.scholarpedia.org/article/Gastropod_reproductive_behavior">store sperm</a> for months and even years, and so don’t always need to receive sperm if they have previously mated with a better partner. They can have the best of both worlds by choosing to eat and digest most of the sperm, while retaining just enough to fertilise their eggs.</p>
<p>We also know why leopard slugs turn anti-clockwise when mating. Just like human hearts are <a href="https://www.theguardian.com/science/blog/2016/sep/08/situs-inversus-and-my-through-the-looking-glass-body">nearly always</a> to the left hand side in our bodies, a slug’s body is also asymmetric. This is most obvious during mating, when the genitals emerge from the right side of the head. This asymmetry makes leopard slugs turn anti-clockwise in synchrony during courting and mating – and is also what made rare left-coiling snail Jeremy <a href="https://web.archive.org/web/20171020222103/http://www.bbc.co.uk/bbcthree/item/249e54d9-7c5c-451e-940c-7826f6dd2a14">a media sensation</a> in his/her <a href="https://www.npr.org/sections/thetwo-way/2017/05/17/528796939/tragic-love-triangle-is-sad-for-lonely-rare-snail-still-good-for-science">search for love</a>.</p>
<h2>The rest is mystery</h2>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/306207/original/file-20191210-95138-q0ny8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/306207/original/file-20191210-95138-q0ny8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=903&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306207/original/file-20191210-95138-q0ny8k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=903&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306207/original/file-20191210-95138-q0ny8k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=903&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306207/original/file-20191210-95138-q0ny8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1135&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306207/original/file-20191210-95138-q0ny8k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1135&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306207/original/file-20191210-95138-q0ny8k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1135&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">It’s a long way up from there.</span>
<span class="attribution"><a class="source" href="https://flickr.com/photos/kongniffe/48904576193/">Inge Knoff/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>The rest of their elaborate mating behaviour is less well understood. It might be that that <a href="https://www.youtube.com/watch?v=UOcLaI44TXA">communication and cooperation</a> are important aspects of sexual behaviour in the mollusc world, beginning with the head-to-tail <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12023">trail-following</a>. The long mucus trapeze could be an example of sexual evolution going into overdrive to signify commitment to what’s to come, making sure that any mating efforts won’t be wasted. The spiral entwinement between mating slugs may also facilitate close physical contact and commitment, minimising the risk of sudden withdrawal.</p>
<p>But this behaviour is also more sinister than it first appears. Some slugs and snails engage in hormone warfare or sexual conflict to increase their chances of fertilising their mate. For example, as artistically interpreted by <a href="https://www.youtube.com/watch?v=BckqviVaWl0">Isabella Rossellini</a>, many snails (including the common garden variety) <a href="https://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-5-25">stab each</a> with <a href="https://en.wikipedia.org/wiki/Love_dart">love-darts</a>, transferring hormones to improve the chances that sperm are used for fertilisation. The field slug <em>Deroceras</em>, seen below, <a href="https://youtu.be/b70CGCdeP3I?t=180">flicks and strokes</a> its partner with what looks like a <a href="https://bioone.org/journals/american-malacological-bulletin/volume-23/issue-1/0740-2783-23.1.137/A-review-of-mating-behavior-in-slugs-of-the-genus/10.4003/0740-2783-23.1.137.short">sticky slug blanket</a> for the same reason.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/b70CGCdeP3I?wmode=transparent&start=210" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>The leopard slug’s beautiful entwinement could be another manifestation of this sexual coercion, maximising surface area for hormone transfer. The long penises – which can be <a href="http://www.scholarpedia.org/article/Gastropod_reproductive_behavior">60 to 90cm</a> long in one <a href="http://www.scholarpedia.org/article/File:Limax_Long_Penes.jpg">Italian version</a> of the leopard slug – may also be another extreme result of an evolutionary arms race to improve the prospects of fertilisation.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/306350/original/file-20191211-95159-bxkp7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/306350/original/file-20191211-95159-bxkp7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1067&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306350/original/file-20191211-95159-bxkp7.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1067&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306350/original/file-20191211-95159-bxkp7.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1067&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306350/original/file-20191211-95159-bxkp7.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1341&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306350/original/file-20191211-95159-bxkp7.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1341&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306350/original/file-20191211-95159-bxkp7.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1341&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Yes, that’s all penis.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Accoppiamento_fra_lumache_2.JPG">Viktor Volkov/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Why they intertwine so intricately is another matter. It could be that the beautiful complexity makes it more difficult for one slug to “cheat” by giving sperm and then not receiving some in return.</p>
<p>In the absence of direct study, the above explanations can only be considered speculation. The truth is that science doesn’t yet have a firm handle on the fascinating sex rituals of leopard slugs.</p>
<h2>More than voyeurism</h2>
<p>Scientists are not just being voyeuristic when we say we’d like to unravel the mysteries of slug sex. Aside from just understanding the wonder and beauty of the behaviour, there are potential benefits.</p>
<p>Some species of slugs are <a href="https://www.rhs.org.uk/advice/profile?pid=228">farm and garden pests</a>, eating holes in leaves, stems, flowers, tubers and bulbs and causing particular damage to new growth. With the pending ban of key pesticides for agricultural use in some countries, including the active ingredient in <a href="https://www.gardenorganic.org.uk/news/metaldehyde-slug-pellets-ban-overturned">slug pellets</a>, there is growing pressure to find other ways to control their spread. One way could be to identify otherwise harmless chemicals that interfere with their sex lives. A contraceptive sheath for slugs, so to speak.</p>
<p>Another approach could be to question why some of the slugs that cause the most agricultural nuisance forgo sex completely, especially in northern latitudes. Lack of sex reduces genetic variation, which causes crops such as potatoes and bananas to suffer from disease outbreaks. Studying the self-contained reproductive habits of slugs may reveal a similar vulnerability that could be exploited to control their numbers.</p>
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<p>There may of course also be benefits which we can’t anticipate. So just as people champion trees, bees and butterflies, we need more slug enthusiasts of <a href="https://www.bbc.co.uk/news/entertainment-arts-46399187">all kinds</a> to help unravel their mucosal mysteries, including backyard explorers who can contribute to <a href="https://www.rhs.org.uk/slugssurvey">citizen science</a> studies. </p>
<p>Of course, if you are already a convert, then how about a leopard slug sex ornament for the <a href="http://www.furaffinity.net/view/25744884/">Christmas tree</a>?</p><img src="https://counter.theconversation.com/content/128284/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Angus Davison received funding from the Biotechnology and Biological Sciences Research Council</span></em></p>Scientists don’t just want to unravel the mysteries of slug sex for voyeurism.Angus Davison, Associate Professor and Reader in Evolutionary Genetics, University of NottinghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1210722019-07-29T15:48:33Z2019-07-29T15:48:33ZBelligerent beetles show that fighting for mates could help animals survive habitat loss<figure><img src="https://images.theconversation.com/files/286026/original/file-20190729-43145-1p8sarc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">En garde!</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rhinoceros-beetle-on-wood-forest-243404500?src=x3wJuQTOXK6isXUv-_Gwog-1-1&studio=1">BaLL LunLa/Shutterstock</a></span></figcaption></figure><p>Animals around the world are seeing their environments change. <a href="https://theconversation.com/animals-will-struggle-to-adapt-fast-enough-to-cope-with-climate-change-study-finds-120857">Climate change</a> is causing heating and changes to weather patterns, the oceans are becoming <a href="https://theconversation.com/the-worlds-shellfish-are-under-threat-as-our-oceans-become-more-acidic-103868">more acidic</a>, and previously undisturbed habitats are being <a href="https://theconversation.com/habitat-loss-doesnt-just-affect-species-it-impacts-networks-of-ecological-relationships-117687">altered and degraded</a> by human activities.</p>
<p>If we want to understand how these changes will affect animals around the world, we need a better understanding of how their biology might determine how well they survive these changes. My colleagues and I have just <a href="https://doi.org/10.1111/ele.13358">published research</a> that demonstrates how important an animal’s mating system is to this. We found that species whose males compete for mates are more likely to survive damaging changes to their environment.</p>
<p>In many species, males try to woo females <a href="https://theconversation.com/strut-your-stuff-how-rockstars-and-peacocks-attract-the-ladies-29045">with signals</a> like calls, colouration or long tails, or they try to monopolise access to females by fighting other males with weaponry like horns or antlers. This competition for mates helps drive the evolution of these species, in a process called <a href="https://theconversation.com/why-men-are-not-biologically-useless-after-all-42012">sexual selection</a>. The most attractive or most aggressive mates are more likely to pass on their genes to the next generation and produce more offspring with their attractive features or aggressive nature. </p>
<p>There are many reasons to think competitive mating could affect the resilience of a species to environmental change. First, the signals and weapons that often evolve in those species where competition is more intensive are costly to grow and to carry. They can make animals more conspicuous to predators, and both contests with rival males and extravagant displays to females can use enormous amounts of energy. So these strongly sexually selected species could be less able to cope with environmental change because of these costs.</p>
<p>On the flip side, strong competition between males for mates means that only a few particularly strong, healthy or energetic males “win” and father the majority of the next generation. If the environment is changing, then males that are genetically best suited to the new environment are likely to be in the best condition. If these males end up as the winners in the competition for mating then their well-adapted genes will spread very rapidly. So strong sexual selection could make animal populations <a href="https://mast.queensu.ca/%7Etday/pdf/Lorchetal03.pdf">adapt faster to new environments</a>, making them more resilient in the face of it changing.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Peacocking is a costly mating strategy.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/indian-male-peacock-1147396844?src=8jEkBHVkTbTf6jxsFJXBGw-1-4&studio=1">Kandarp/Shutterstock</a></span>
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<p>So which process is more important in influencing species survival? A <a href="https://www.nature.com/articles/s41467-019-10074-7">series of lab studies</a> have consistently found that strong sexual selection improves outcomes for animal species when the environment shifts from their optimum. But studies of animals in the field have often found either no effect of sexual selection or the opposite. For example, when birds have been introduced to islands <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1046/j.1365-2656.1998.00199.x">such as New Zealand</a>, then the species that are more sexually selected are less likely to become established.</p>
<p>One possible reason for this disparity is that the field studies have often concentrated on very small populations of animals. It’s possible that the effects of sexual selection on a population’s resilience vary with its size. </p>
<p>Very small populations living in a certain location might not have enough genetic variety to produce individuals that are very well adapted to its particular environment. In which case, the costs of sexual selection could make them more likely to go extinct. Whereas large populations are more likely to have the genetic variety that will produce “winning” males even when the environment is unfriendly.</p>
<p>What was needed was a field study of sexual selection and persistence in larger populations. To that end, my colleagues and I conducted a study, published in <a href="https://doi.org/10.1111/ele.13358">Ecology Letters</a>, of how dung beetles respond to environmental change in the rainforest of Sabah in Malaysian Borneo.</p>
<h2>Horny beetles</h2>
<p>Dung beetles are fascinating animals for many reasons, one of which is the diversity of their sex lives. Males from the familiar ball-rolling species do compete for matings. But there are also many species of dung beetle that don’t roll, instead burying dung directly under where they find it, and these species show much greater variability. Some species have <a href="https://www.sciencenewsforstudents.org/article/little-beetle-big-horns">males with horns</a>, which they use in <a href="http://hs.umt.edu/dbs/labs/emlen/documents/Emlen%20Publications/BRCLososEmlenFINALlowres.pdf">fights with other males</a>, whereas others are less strongly sexually selected, with hornless males who are less aggressive in their pursuit of mates.</p>
<p>Using an existing large-scale study called the <a href="https://www.safeproject.net/">SAFE Project</a>, we followed 34 species of beetle found in untouched “old growth” forest. We looked at how they fared in lightly-logged and heavily logged forest and then oilpalm plantation where the original forest was largely removed. </p>
<p>We found that those species with horns were more likely to survive in all these cases. Strikingly, all 11 remaining species in the most disturbed plantation environment carried horns. </p>
<p>We also compared species with relatively small horns against those with big horns for their size. We found that beetle species with big horns are not only more likely to survive in disturbed environments, but they also tend to have larger remaining population sizes.</p>
<p>This tells us that – in some particular cases at least – we should think about sexual selection as well as other aspects of an animal’s biology if we want to predict or to manage population sizes in the face of environmental change. Sexual selection is a ubiquitous and powerful force driving evolution in the animal kingdom and has been intensively studied by behavioural and evolutionary biologists. Maybe now it’s time ecologists and wildlife management specialists started to think about it as well.</p><img src="https://counter.theconversation.com/content/121072/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rob Knell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New evidence boosts the idea that species with males who compete for mates adapt faster to changing circumstances.Rob Knell, Reader in Evolutionary Ecology, Queen Mary University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1004782019-06-20T13:43:50Z2019-06-20T13:43:50ZSix amazing facts you need to know about ants<figure><img src="https://images.theconversation.com/files/280292/original/file-20190619-171183-p0runh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Black_Garden_Ant_tending_Citrus_Mealybug_(15876770928).jpg">Katja Schulz</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Have you have seen ants this year? In Britain, they were probably black garden ants, known as <em>Lasius niger</em> – Europe’s most common ant. One of somewhere between <a href="http://science.sciencemag.org/content/312/5770/101">12,000 and 20,000 species</a>, they are the scourge of gardeners – but also fascinating. </p>
<p>The small, black, wingless workers run around the pavements, crawl up your plants tending aphids or collect tasty morsels from your kitchen. And the <a href="https://theconversation.com/the-amazing-secrets-behind-flying-ant-day-79686">flying ants</a> that occasionally appear on a warm summer’s evening are actually the reproductive siblings of these non-winged workers. Here’s what else you need to know:</p>
<h2>1. Most ants you see are female</h2>
<p>Ants have a <a href="https://www.youtube.com/watch?v=t-2BpBjId1c">caste system</a>, where responsibilities are divided. The queen is the founder of the colony, and her role is to lay eggs. Worker ants are all female, and this sisterhood is responsible for the harmonious operation of the colony. </p>
<p>Their tasks range from caring for the queen and the young, foraging, policing conflicts in the colony, and waste disposal. Workers will most likely never have their own offspring. The vast majority of eggs develop as workers, but once the colony is ready the queen produces the next generation of reproductives which will go on to start own colonies.</p>
<p>A female ant’s fate to become a worker or queen is mainly <a href="https://www.journals.uchicago.edu/doi/10.1086/590961">determined by diet</a>, not genetics. Any female ant larva can become the queen – those that do receive diets richer in protein. The other larvae receive less protein, which causes them to <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/een.12337">develop as workers</a>.</p>
<h2>2. Male ants are pretty much just flying sperm</h2>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/280287/original/file-20190619-171271-5dtywo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/280287/original/file-20190619-171271-5dtywo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=819&fit=crop&dpr=1 600w, https://images.theconversation.com/files/280287/original/file-20190619-171271-5dtywo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=819&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/280287/original/file-20190619-171271-5dtywo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=819&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/280287/original/file-20190619-171271-5dtywo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1029&fit=crop&dpr=1 754w, https://images.theconversation.com/files/280287/original/file-20190619-171271-5dtywo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1029&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/280287/original/file-20190619-171271-5dtywo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1029&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Male ants have a mother but no father.</span>
<span class="attribution"><span class="license">Author provided</span></span>
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<p>Unlike humans, with X and Y chromosomes, an ant’s sex is determined by the <a href="https://frontiersinzoology.biomedcentral.com/articles/10.1186/1742-9994-3-1">number of genome copies it possesses</a>. Male ants develop from unfertilised eggs so receive no genome from a father. This means that male ants don’t have a father and cannot have sons, but they do have grandfathers and can have grandsons. Female ants, in comparison, develop from fertilised eggs and have two genome copies – one from their father and one from their mother.</p>
<p>Male ants function like flying sperm. Only having one genome copy means every one of their sperm is genetically identical to themselves. And their job is over quickly, dying soon after mating, although their sperm live on, <a href="https://jeb.biologists.org/content/jexbio/221/6/jeb173435.full.pdf">perhaps for years</a>.
– essentially their only job is to reproduce. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/280045/original/file-20190618-118543-13mbljf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/280045/original/file-20190618-118543-13mbljf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/280045/original/file-20190618-118543-13mbljf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/280045/original/file-20190618-118543-13mbljf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/280045/original/file-20190618-118543-13mbljf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/280045/original/file-20190618-118543-13mbljf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/280045/original/file-20190618-118543-13mbljf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Let them eat cake.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<h2>3. After sex queens don’t eat for weeks</h2>
<p>When the conditions are warm and humid, the winged virgin queens and males leave their nests in search of mates. This is the behaviour seen on “<a href="https://www.independent.co.uk/news/science/fly-ant-day-when-is-what-why-explained-nuptial-flight-uk-london-a8431871.html">flying ant day</a>”. In <em>L. niger</em>, mating takes place on the wing, often hundreds of meters up (hence the need for good weather). Afterwards, queens drop to the ground and shed their wings, while males quickly die. Mated queens choose a nest site and burrow into the soil, made softer from recent rain. </p>
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<strong>
Read more:
<a href="https://theconversation.com/the-amazing-secrets-behind-flying-ant-day-79686">The amazing secrets behind 'flying ant day'</a>
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<p>Once underground, the queens will not eat for weeks – until they have produced their own daughter workers. They use energy from their fat stores and redundant flight muscles to lay their first batch of eggs, which they fertilise using sperm stored from their nuptial flight. It is the same stock of sperm acquired from long dead males that allows a queen to continue laying fertilised eggs for her entire life. Queens never mate again.</p>
<h2>4. Home-making the ant way: cooperation, death and slavery</h2>
<p>Sometimes two <em>L. niger</em> queens unite to found a nest. This initially cooperative association – which increases the chance of establishing a colony – dissolves once new adult workers emerge and then the queens fight to the death. More sinister still, <em>L. niger</em> colonies sometimes steal brood from their neighbours, putting them to work as slaves. </p>
<p>Slave-making has evolved in a number of ant species, but they also display cooperation at extraordinary levels. An extreme example of this is a “supercolony” of Argentine ants (<em>Linepithema humile</em>) which extends over 6,000km of European coastline from Italy to north-west Spain, and is composed of literally <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC122904/">billions of workers from millions of cooperating nests</a>.</p>
<h2>5. Queen ants can live for decades, males for a week</h2>
<p>After establishing her colony, the queen’s work is not done and she has many years of egg-laying ahead of her. In the laboratory, <em>L. niger</em> queens have lived for <a href="http://entnemdept.ufl.edu/walker/ufbir/chapters/chapter_34.shtml">nearly 30 years</a>. Workers live for about a year, males little more than a week (although their sperm live longer). These extraordinary differences in longevity are purely due to the way their genes are switched on and off.</p>
<h2>6. Ants can help humans and the environment</h2>
<p>Ants have a major influence in ecosystems worldwide and their roles are diverse. While some ants are considered pests, others act as <a href="https://www.annualreviews.org/doi/pdf/10.1146/annurev.en.37.010192.002403">biological-control agents</a>. Ants benefit ecosystems by <a href="https://www.jstor.org/stable/24996901?seq=1#page_scan_tab_contents">dispersing seeds</a>, <a href="https://brill.com/abstract/journals/tar/4/2/article-p157_4.xml">pollinating plants and improving the quality of soil</a>. Ants might also benefit our health, as a potential source of new medicines such as <a href="https://theconversation.com/antibiotic-resistance-fight-could-get-a-little-help-from-ants-91412">antibiotics</a>. </p>
<p>So when you next see an ant, before you think to kill her, consider how fascinating she really is.</p><img src="https://counter.theconversation.com/content/100478/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charlie Durant receives funding from the Biotechnology and Biological Sciences Research Council (BBSRC).</span></em></p><p class="fine-print"><em><span>Max John receives funding from the Biotechnology and Biological Sciences Research Council (BBSRC), and the Genetics Society. </span></em></p><p class="fine-print"><em><span>Rob Hammond receives funding from NERC, BBSRC, The Genetics Society.</span></em></p>They might be a hated household pest, but ants actually live fascinating and complex lives.Charlie Durant, PhD Candidate, Department of Genetics and Genome Biology, University of LeicesterMax John, PhD Candidate, Department of Genetics and Genome Biology, University of Leicester, University of LeicesterRob Hammond, Lecturer, Department of Genetics and Genome Biology, University of LeicesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1185862019-06-12T06:09:58Z2019-06-12T06:09:58ZA parasite attack on Darwin’s finches means they’re losing their lovesong<figure><img src="https://images.theconversation.com/files/278820/original/file-20190611-32351-1hoo5hb.jpg?ixlib=rb-1.1.0&rect=29%2C196%2C2710%2C1683&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A Small Tree Finch from the Galápagos Islands with an enlarged nostril caused by a parasite.</span> <span class="attribution"><span class="source">Katharina J Peters</span>, <span class="license">Author provided</span></span></figcaption></figure><p>A parasite known to infect beaks in some iconic Darwin finches on the Galapagos Islands is changing the mating song of male birds.</p>
<p>Our research, <a href="http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2019.0461" title="Introduced parasite changes host phenotype, mating signal and hybridisation risk: Philornis downsi effects on Darwin’s finch song">published today in Proceedings of the Royal Society B</a>, reveals how the parasite deforms the beak. This has the effect of weakening the male bird’s mating call, and making it no longer clearly distinguishable from that of other closely related species.</p>
<p>A changed song can have an important effect on the male finch’s ability to find a mate. </p>
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<strong>
Read more:
<a href="https://theconversation.com/simply-returning-rescued-wildlife-back-to-the-wild-may-not-be-in-their-best-interest-118521">Simply returning rescued wildlife back to the wild may not be in their best interest</a>
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<p>It’s another factor that could contribute to declining numbers of these already threatened birds on the Pacific archipelago, about 1,000km off the coast of South America.</p>
<h2>A family song to impress</h2>
<p>A male finch learns the mating song from his father, and produces the same song for the <a href="https://www.pnas.org/content/107/47/20156/tab-article-info" title="Songs of Darwin's finches diverge when a new species enters the community">rest of his life</a>.</p>
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<p>It’s a simple tune consisting of one syllable repeated 3 to 15 times, depending on what species of finch he belongs to. Larger-bodied finch species produce a slower song with few syllable repeats, and smaller-bodied finch species produce faster song with <a href="https://www.cambridge.org/core/journals/bird-conservation-international/article/avian-population-trends-in-scalesia-forest-on-floreana-island-20042013-acoustical-surveys-cannot-detect-hybrids-of-darwins-tree-finches-camarhynchus-spp/7FE5D763A26BC9C0398398DE336CB778">many syllable repeats</a>.</p>
<p>Whatever species of finch you belong to, hitting the high notes is important – because females prefer males who can produce such vocally challenging songs. </p>
<p>In the case of the <a href="https://link.springer.com/article/10.1007/s10531-009-9740-1">Medium Tree Finch</a> (<em>Camarhynchus pauper</em>), a critically endangered species that only occurs on Floreana Island of the Galapagos Islands, its species-typical song has a bright resonance that rings across the forest canopy.</p>
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Medium Tree Finch.
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<p>An accomplished male singer that can hit the high notes is quickly swooped up by a female looking to pair with a proficient singer. </p>
<h2>The ‘Vampire’ parasite</h2>
<p>The Vampire Fly – a <a href="https://twitter.com/CStenoien/status/1110602027275571200">suggested name</a> for the parasite <em>Philornis downsi</em> given its blood feeding habits from dusk until dawn – was <a href="https://onlinelibrary.wiley.com/doi/full/10.1046/j.1474-919X.2002.00076.x" title="Philornis downsi– a recently discovered parasite on the Galápagos archipelago – a threat for Darwin's finches?">first discovered in a Darwin’s finch nest in 1997</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279035/original/file-20190612-32317-1tai1zv.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The parasitic <em>Philornis</em> larvae in a finch nest.</span>
<span class="attribution"><span class="source">Sonia Kleindorfer</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Since then, the devastating impacts of its larval feeding habits on nestling birds have been <a href="https://www.cambridge.org/core/journals/parasitology/article/lifecycle-of-philornis-downsi-diptera-muscidae-parasitizing-darwins-finches-and-its-impacts-on-nestling-survival/597D469905598A7105BBE59990009B32">coming to light</a>. The adult fly is vegetarian, but the females lay their eggs into bird nests and their <a href="https://bmczool.biomedcentral.com/articles/10.1186/s40850-016-0003-9" title="Host-parasite ecology, behavior and genetics: a review of the introduced fly parasite Philornis downsi and its Darwin’s finch hosts">larvae feed on nestling bird beaks from the inside out</a>. </p>
<p>Many Darwin’s finch species now have beaks with massively enlarged nostrils because of damage the feeding fly larvae have caused <a href="https://www.sciencedirect.com/science/article/pii/S2351989416300336?via%3Dihub" title="Naris deformation in Darwin’s finches: Experimental and historical evidence for a post-1960s arrival of the parasite Philornis downsi">during the nestling stage</a>. We discovered that a changed beak apparatus measurably affects the song of Darwin’s tree finches with consequences for pairing success. </p>
<p>A Medium Tree Finch male with extremely enlarged nostrils is unable to hit the high notes.</p>
<p><audio preload="metadata" controls="controls" data-duration="2" data-image="" data-title="Medium Tree Finch with enlarged nostrils" data-size="33017" data-source="" data-source-url="" data-license="Author provided" data-license-url="">
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Medium Tree Finch with enlarged nostrils.
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<p>We found the same pattern in Small Tree Finches (<em>C. parvulus</em>) with enlarged nostrils. </p>
<p>Male finches that produce song with a narrower frequency bandwidth, because their song has a lower maximum frequency, have poor quality song. These males are less likely to be chosen by females, a pattern we documented in both the Medium Tree Finch and the Small Tree Finch.</p>
<p>Also, the song of Medium Tree Finches with enlarged nostrils sounds like the song of the Small Tree Finch.</p>
<p><audio preload="metadata" controls="controls" data-duration="1" data-image="" data-title="Small Tree Finches" data-size="29674" data-source="" data-source-url="" data-license="Author provided" data-license-url="">
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Small Tree Finches.
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<h2>When species merge</h2>
<p>But confusion among the species and their mating songs may not necessarily be a bad thing for the future survival of individual finches – though it could herald the collapse of species lineages.</p>
<p>Previously, we discovered evidence of <a href="https://www.ncbi.nlm.nih.gov/pubmed/24561597" title="Species collapse via hybridization in Darwin's tree finches">hybridisation in Darwin finches</a>. This is where two separate species of finch breed which could potentially produce a new species, phase out one of the species, or cause the collapse of the two existing species into one.</p>
<p>We observed hybridisation driven by <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/jeb.13167" title="Females drive asymmetrical introgression from rare to common species in Darwin's tree finches">female Medium Tree Finches</a> pairing with male Small Tree Finches. </p>
<p>When a female Medium Tree Finch inspects male Small Tree Finches in the forest, she pairs with one who produces high quality song, even if that male is from another species.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/279048/original/file-20190612-32361-ve8cs4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A Tree Finch with a normal beak and nostril size, so no infection from the parasite.</span>
<span class="attribution"><span class="source">Katharina J Peters</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This female choice seems to be paying dividends, because hybrid pairs with greater genetic diversity also sustained <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.181616" title="Genetic admixture predicts parasite intensity: evidence for increased hybrid performance in Darwin's tree finches">fewer of the parasitic larvae in the nest</a>. And that could lead to fewer birds with infected beaks.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/galapagos-species-are-threatened-by-the-very-tourists-who-flock-to-see-them-86392">Galapagos species are threatened by the very tourists who flock to see them</a>
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</em>
</p>
<hr>
<p>There are concerted efforts underway to develop control and eradication methods for <em>P. downsi</em> on the Galapagos Islands, building on a collaborative relationship between the Charles Darwin Foundation and the Galapagos National Parks. The <a href="https://www.darwinfoundation.org/en/research/projects/philornis-downsi"><em>Philornis downsi</em> Action Group</a> is an international consortium of concerned scientists working to develop biological control methods.</p>
<p>Our new research is an important step towards understanding how this invasive fly may be changing the evolutionary pathway of Darwin’s finches by literally changing the beak of the finch.</p><img src="https://counter.theconversation.com/content/118586/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>For this project the authors received funding from the Australian Research Council, the Max Planck Institute for Ornithology, the Mohamed bin Zayed Species Conservation Fund, the Ecological Society of Australia, Earthwatch Institute, Club300 Bird Protection, Rufford Small Grants Foundation, the Winifred Violet Scott Trust, the American Bird Conservancy, the Conservation International, the Australian Federation for University Women, and the Royal Society for the Protection of Birds/Birdfair. TAME airlines provided reduced airfares.
Katharina J. Peters is affiliated with Flinders University, Adelaide, Australia, and Massey University, Albany, New Zealand. </span></em></p><p class="fine-print"><em><span>Sonia Kleindorfer does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>An infestation as a chick leads to enlarged nostrils in the beak of Darwin finches, and that affects their mating call.Katharina J. Peters, Postdoctoral fellow, Flinders UniversitySonia Kleindorfer, Professor of Animal Behaviour, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1162712019-05-06T05:09:26Z2019-05-06T05:09:26ZSexual aggression key to spread of deadly tumours in Tasmanian devils<figure><img src="https://images.theconversation.com/files/272146/original/file-20190502-117604-2lcbwp.jpg?ixlib=rb-1.1.0&rect=111%2C298%2C2859%2C1540&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Both male and female Tasmanian devils can become very violent during sexual interactions. </span> <span class="attribution"><span class="source">Shutterstock/PARFENOV</span></span></figcaption></figure><p>Tasmanian devils have a reputation as a fearsome animal – most of the time this is undeserved. When it comes to the mating season, however, it’s a fair judgement. Between February and April, mating can be incredibly aggressive, with male and female devils prone to biting one another both during and after the act.</p>
<p>That could be deadly for the devils, according to <a href="https://academic.oup.com/beheco/advance-article/doi/10.1093/beheco/arz054/5479352" title="Rate of intersexual interactions affects injury likelihood in Tasmanian devil contact networks">new research published online in the journal Behavioral Ecology</a>.</p>
<p>Unfortunately, biting <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1111/j.1365-2656.2012.02025.x" title="Biting injuries and transmission of Tasmanian devil facial tumour disease">drives the spread of devil facial tumour disease</a> (<a href="https://dpipwe.tas.gov.au/wildlife-management/save-the-tasmanian-devil-program/about-dftd">DFTD</a>) a transmissible cancer that has been afflicting the species since the mid-1990s.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/survival-of-the-fittest-perhaps-not-if-youre-a-tasmanian-devil-76402">Survival of the fittest? Perhaps not if you're a Tasmanian devil</a>
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<p>DFTD is highly unusual for a cancer because it can <a href="https://theconversation.com/tassie-devil-facial-tumour-is-a-transmissible-cancer-34312">transfer between individual devils and grow in its new host</a>.</p>
<p>The fact that devils regularly bite one another around the mouth means tumour cells can easily transfer from an infected devil to an open wound on a healthy devil. This makes the buildup of wounds in devils extremely important to our understanding of this disease.</p>
<h2>When devils mate</h2>
<p>In our <a href="https://academic.oup.com/beheco/advance-article/doi/10.1093/beheco/arz054/5479352" title="Rate of intersexual interactions affects injury likelihood in Tasmanian devil contact networks">study</a>, we examined the accumulation of bite wounds in a population of wild devils in northwest Tasmania.</p>
<p>We found males were much more likely than females to pick up high numbers of bite wounds. But these wounds appear to be related to the amount of time males spent in mating season interactions with females, as opposed to fights with other males (as we had previously thought).</p>
<p>In the mating season, after male devils have mated with females, they spend an extended period either confining the female in a den, or closely following her to make sure other males are unable to mate with her. </p>
<p>During our study we found this behaviour could go on for up to two weeks in the wild. The process is known as “<a href="https://www.sciencedirect.com/topics/neuroscience/mate-guarding">mate guarding</a>” and is relatively common in the animal kingdom.</p>
<p>We found the longer males spent engaging in mate guarding behaviour, the more bite wounds they received. This would seem to put successful males, who mate with a high number of females, in the firing line when it comes to acquiring DFTD.</p>
<p>But <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.13088" title="Density trends and demographic signals uncover the long‐term impact of transmissible cancer in Tasmanian devils">no pattern of sex bias in DFTD prevalence</a> has ever been observed in the wild.</p>
<p>So how does this fit with our study on the increased vulnerability in males?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/272155/original/file-20190502-103068-ecwq5j.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/272155/original/file-20190502-103068-ecwq5j.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272155/original/file-20190502-103068-ecwq5j.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272155/original/file-20190502-103068-ecwq5j.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272155/original/file-20190502-103068-ecwq5j.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272155/original/file-20190502-103068-ecwq5j.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272155/original/file-20190502-103068-ecwq5j.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272155/original/file-20190502-103068-ecwq5j.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A Tasmanian devil with the Devil Facial Tumour Disease.</span>
<span class="attribution"><a class="source" href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0040342">Menna Jones/PLOS ONE</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Disease transfer</h2>
<p>A crucial unknown in the DFTD transmission process involves directionality – which way the deadly disease is passed on by a devil. There are two possibilities:</p>
<ol>
<li><p>an infected devil bites an uninfected animal, transferring tumour cells (from its teeth or saliva) directly into the wound it causes</p></li>
<li><p>an uninfected devil bites into tumours on an infected animal, and cells transfer into an open wound inside the biter’s mouth. </p></li>
</ol>
<p>The reality is likely to involve a combination of the two.</p>
<p>Our results indicate that most disease transmission occurs during extended mating season interactions, when females appear to be causing high numbers of wounds to their mates.</p>
<p>If DFTD can transfer in either direction during these encounters, then both the males receiving the wounds and the females causing them would be equally at risk of acquiring the disease.</p>
<h2>Future of the devil</h2>
<p>We have highlighted mating season encounters between the sexes as crucial transmission points for the spread of DFTD. The behaviour of male devils appears to be driving patterns that support transmission of the disease.</p>
<p>This information is important for potential disease management options, as it pinpoints males in good condition – who are likely to be reproductively successful – as targets for management interventions, such as vaccinations. </p>
<p>Most importantly, these results add one more piece to the puzzle of rapid evolution in the Tasmanian devil, in response to the strong evolutionary pressure DFTD is placing on this iconic species. With almost 100% mortality once devils reach breeding age, any advantage an individual devil might have to survive a little longer and reproduce should – over time – spread through the population. </p>
<p>The species has already shown remarkably rapid shifts in their <a href="https://www.pnas.org/content/105/29/10023.short" title="Life-history change in disease-ravaged Tasmanian devil populations">life history</a> and <a href="https://www.nature.com/articles/ncomms12684" title="Rapid evolutionary response to a transmissible cancer in Tasmanian devils">genome</a>, while some are able to mount an <a href="https://royalsocietypublishing.org/doi/full/10.1098/rsbl.2016.0553">immune response and recover from the tumours</a>.</p>
<p>DFTD is spread through biting so we can expect strong evolutionary pressure for devils to become less aggressive towards each other over time. </p>
<p>With these new results, we can now pinpoint for the first time <em>who</em> (healthy, successful males) and <em>when</em> (guarding females after mating) the intense selection pressure on aggressive behaviour in devils will operate.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/could-tassie-devils-help-control-feral-cats-on-the-mainland-fossils-say-yes-63120">Could Tassie devils help control feral cats on the mainland? Fossils say yes</a>
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</em>
</p>
<hr>
<p>Ultimately, devils will solve the DFTD problem themselves by evolving resistance, tolerance and changing their behaviour. One of the best things we can do is let evolution take its course, giving a helping hand along the way via well guided management actions.</p><img src="https://counter.theconversation.com/content/116271/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Hamilton receives funding from the Holsworth Wildlife Research Endowment. </span></em></p><p class="fine-print"><em><span>Elissa Cameron receives funding from Australian Research Council, the Holsworth Wildlife Trust, Marsden Fund. </span></em></p><p class="fine-print"><em><span>Menna Elizabeth Jones receives funding from the Australian Research Council, the Ian Potter Foundation, the US National Institute of Health, the US National Science Foundation, the Holsworth Wildlife Trust, the University of Tasmania Foundation Dr Eric Guiler grants. </span></em></p><p class="fine-print"><em><span>Rodrigo Hamede receives funding from Australian Research Council. </span></em></p>Tasmanian Devils can be incredibly aggressive during mating season and their biting can have fatal consequences.David Hamilton, PhD Candidate in Zoology, University of TasmaniaElissa Cameron, Professor of Wildlife Ecology, University of TasmaniaMenna Elizabeth Jones, Associate Professor in Zoology, University of TasmaniaRodrigo Hamede, Post Doctoral Research Fellow, Conservation Biology and Wildlife Management, University of TasmaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1010672018-09-19T10:40:27Z2018-09-19T10:40:27ZWhy women – including feminists – are still attracted to ‘benevolently sexist’ men<figure><img src="https://images.theconversation.com/files/236684/original/file-20180917-158225-3ekt0f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What sort of signal does holding a door for a woman send?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/man-opens-door-girl-interpersonal-relationships-795778363?src=rN7GvTSI6HXl85L0eNHN4Q-1-0">KOLOTAILO LIDIIA</a></span></figcaption></figure><p>If a man offers to help a woman with her heavy suitcase or to parallel park her car, what should she make of the offer? </p>
<p>Is it an innocuous act of courtesy? Or is it a sexist insult to her strength and competence? </p>
<p>Social psychologists who describe this behavior as “<a href="http://psycnet.apa.org/buy/1996-03014-006">benevolent sexism</a>” firmly favor the latter view. </p>
<p>But researchers have also revealed a paradox: <a href="http://psycnet.apa.org/record/2010-09720-015">Women prefer men</a> who behave in ways that could be described as benevolently sexist over those who don’t. </p>
<p>How could this be? </p>
<p>Some say that women simply fail to see the ways benevolent sexism undermines them because they’re misled by the flattering tone of this brand of kindness. Psychologists have even suggested that benevolent sexism <a href="https://www.sciencedaily.com/releases/2015/03/150309093214.htm">is more harmful than overtly hostile sexism</a> because it is insidious, acting like “a wolf in sheep’s clothing.” </p>
<p>As social psychologists, we had reservations about these conclusions. Aren’t women sophisticated enough to be able to tell when a man is being patronizing? </p>
<p>Surprisingly no previous research had tested whether women do, in fact, fail to recognize that benevolent sexism can be patronizing and undermining. And given our backgrounds in evolutionary theory, we also wondered if these behaviors were nonetheless attractive because they signaled a potential mate’s willingness to invest resources in a woman and her offspring. </p>
<p>So we conducted a series of studies to further explore women’s attraction to benevolently sexist men.</p>
<h2>What does benevolent sexism really signal?</h2>
<p>The concept of benevolent sexism was first developed in 1996. The idea’s creators argued that sexism is not always openly hostile. To them, attitudes like “women should be cherished and protected by men” or behaviors like opening car doors for women cast them as less competent and always in need of help. In this way, they argued, benevolent sexism subtly undermines gender equality.</p>
<p>Since then, social psychologists have been busy documenting the pernicious effects that benevolent sexism has on women. </p>
<p>According to studies, women who acquiesce to this behavior tend to become <a href="https://www.ncbi.nlm.nih.gov/pubmed/26461798">increasingly dependent on men for help</a>. They’re more willing <a href="http://journals.sagepub.com/doi/abs/10.1177/0146167207304790">to allow men to tell them what they can and can’t do</a>, are more ambivalent about <a href="http://journals.sagepub.com/doi/10.1177/0146167203258825">thinking for themselves</a>, are <a href="http://journals.sagepub.com/doi/abs/10.1177/0146167203256906">less ambitious</a> and don’t perform as well <a href="http://psycnet.apa.org/record/2007-15390-005">at work and on cognitive tests</a>.</p>
<p>Given these documented downsides, why are women still attracted to this behavior? </p>
<p>The answer could lie in what evolutionary biologists call “<a href="http://roberttrivers.com/Robert_Trivers/Publications_files/Trivers%201972.pdf">parental investment theory</a>.”</p>
<p>Whereas men can successfully reproduce by providing a few sex cells, a woman’s reproductive success must be tied to her ability to complete months of gestation and lactation. </p>
<p>During much of human history, a woman’s ability to choose a mate who was able and willing to assist in this process – by providing food or protection from aggressors – would have increased <a href="https://www.sciencedirect.com/science/article/pii/S109051380300014X">her reproductive success</a>. </p>
<p>Evolution, therefore, shaped female psychology to attend to – and prefer – mates whose characteristics and behaviors reveal the willingness to invest. A prospective mate’s muscular physique (and, today, his big wallet) certainly indicate that he possesses this ability. But opening a car door or offering his coat are signs that he may have the desired disposition.</p>
<h2>Women weigh in</h2>
<p><a href="http://journals.sagepub.com/doi/full/10.1177/0146167218781000">In our recently published research</a>, we asked over 700 women, ages ranging from 18 to 73, in five experiments, to read profiles of men who either expressed attitudes or engaged in behaviors that could be described as benevolently sexist, like giving a coat or offering to help with carrying heavy boxes. </p>
<p>We then had the participants rate the man’s attractiveness; willingness to protect, provide and commit; and his likelihood of being patronizing.</p>
<p>Our findings confirmed that women do perceive benevolently sexist men to be more patronizing and more likely to undermine their partners. </p>
<p>But we also found that the women in our studies perceived these men as more attractive, despite the potential pitfalls. </p>
<p>So what made them more attractive to our participants? In their responses, the women in our study rated them as more likely to protect, provide and commit.</p>
<p>We then wondered whether these findings could only really be applied to women who are simply OK with old-fashioned gender roles.</p>
<p>To exclude this possibility, we studied participants’ degree of feminism <a href="https://www.sciencedirect.com/science/article/pii/S1090513804000546">with a widely used survey</a> that measures feminist attitudes. We had them indicate their level of agreement with statements such as “a woman should not let bearing and rearing children stand in the way of a career if she wants it.”</p>
<p>We found that strong feminists rated men as more patronizing and undermining than traditional women did. But like the other women, they still found these men more attractive; the drawbacks were outweighed by the men’s willingness to invest. It seems that even staunch feminists may prefer a chivalrous mate who picks up the check on a first date or walks closer to the curb on a sidewalk.</p>
<p><a href="https://www.huffingtonpost.com/2011/06/27/men-dont-recognize-benevolent-sexism_n_885430.html">In this time of fraught gender relations</a>, our findings may provide reassurance for women who are confused about how to feel towards a man who acts chivalrous, and well-meaning men who wonder whether they should change their behavior towards women.</p>
<p>But several interesting questions remain. Does benevolent sexism always undermine women? It might depend on context. A male being overly helpful to a female co-worker in a patronizing way might hurt her ability to project professional competence. On the other hand, it’s tough to see the harm in helping a woman move heavy furniture in the home.</p>
<p>Understanding these nuances may allow us to reduce the negative effects of benevolent sexism without requiring women to reject the actual good things that can arise from this behavior.</p><img src="https://counter.theconversation.com/content/101067/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Social psychologists have been busy documenting the harmful effects that this brand of chivalry has on women. But are they missing something?Pelin Gül, Post-doctoral Research Fellow, Iowa State UniversityTom R. Kupfer, Marie Curie Research Fellow, Vrije Universiteit AmsterdamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/980292018-06-20T11:29:30Z2018-06-20T11:29:30ZWhy homosexual behaviour in insects may be a case of mistaken identity<figure><img src="https://images.theconversation.com/files/223626/original/file-20180618-85863-oxij9q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="source">Iain Barr</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Sex is costly for insects. It uses up resources such as water, energy and time. Some species, like bush crickets, can ejaculate as much as <a href="https://www.ncbi.nlm.nih.gov/pubmed/17834586">a quarter</a> of their body weight. In others, like one species of fruit fly, their sperm is <a href="https://www.sciencedirect.com/science/article/pii/S0960982203002756">actually longer</a> than their body.</p>
<p>Just as for humans, insect sex also carries risks such as the transfer of infections (nearly <a href="https://www.ncbi.nlm.nih.gov/pubmed/15366763">100 insect STIs</a> are known), and injury from mating trauma (like <a href="http://rspb.royalsocietypublishing.org/content/266/1424/1183">from spiny</a> or <a href="https://www.sciencedirect.com/science/article/pii/S0003347209004485">needle-like</a>- penises), as well as increased vulnerability to attack from <a href="https://www.sciencedirect.com/science/article/pii/016953479190210O">predators</a>. </p>
<p>Yet despite this, homosexuality in insects – which carries all of the risks of sex without the evolutionary benefit of passing on genes – has been seen in <a href="https://link.springer.com/article/10.1007/s00265-013-1610-x">more than 100</a> species. In some studies, over half of matings were male on male.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/223572/original/file-20180618-85825-1dgi9c3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/223572/original/file-20180618-85825-1dgi9c3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=488&fit=crop&dpr=1 600w, https://images.theconversation.com/files/223572/original/file-20180618-85825-1dgi9c3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=488&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/223572/original/file-20180618-85825-1dgi9c3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=488&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/223572/original/file-20180618-85825-1dgi9c3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=614&fit=crop&dpr=1 754w, https://images.theconversation.com/files/223572/original/file-20180618-85825-1dgi9c3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=614&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/223572/original/file-20180618-85825-1dgi9c3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=614&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Bed bugs: traumatic insemination.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Traumatic_insemination#/media/File:Traumatic_insemination_1_edit1.jpg">Rickard Ignell</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>No real consensus has been reached on why insect homosexuality is so common, with different studies supporting or refuting particular ideas <a href="https://link.springer.com/article/10.1007/s10905-015-9498-0">even within</a> the <a href="https://www.ncbi.nlm.nih.gov/pubmed/19120811">same species</a>. But my colleagues and I have produced <a href="https://doi.org/10.1016/j.anbehav.2018.03.004">new evidence</a> that supports the idea that male insects that mate with other males are simply making a mistake.</p>
<p>There are dozens of ideas used to explain homosexual behaviour in insects, which broadly fall into two categories. Either they suggest insect homosexuality has evolved because it actually helps males have more offspring, or that it is not an evolutionary adaptation and instead occurs when males simply don’t recognise potential mates.</p>
<p>In the former category, scientists have suggested male homosexual activities may reduce mating competition <a href="https://www.ncbi.nlm.nih.gov/pubmed/17790854">by distracting</a> <a href="http://science.sciencemag.org/content/197/4298/81">or injuring</a> other males, or establishing <a href="https://bit.ly/2JQx9tU">social alliances with them</a> or <a href="https://www.sciencedirect.com/science/article/pii/S0003347216000087">dominance over them</a>. It could also improve heterosexual performance by keeping the <a href="https://link.springer.com/article/10.1007/s10905-015-9498-0">ejaculate primed</a> with fresh, younger sperm, or help males <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1558-5646.1988.tb02528.x">practise courtship</a> to improve sexual performance. It could even potentially <a href="https://www.ncbi.nlm.nih.gov/pubmed/19120811">fertilise females indirectly</a> by loading sperm onto male rivals who unwittingly transfer it in subsequent matings.</p>
<p>On the other hand, homosexual behaviour in insects may provide no evolutionary advantage and instead be due to confusion caused by environmental factors (as when fruit flies <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0001391">consume alcohol</a> in rotting fruit). Or it may be because they <a href="http://www.genetics.org/content/121/4/773">fail to recognise</a> potential mates, possibly because their social conditioning has been different, as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3085551/">has been shown</a> to be important in other, more complex animals. It could also be <a href="http://rspb.royalsocietypublishing.org/content/282/1809/20150429">a by-product</a> of genes that have other beneficial effects elsewhere (a phenomenon known as pleiotropy).</p>
<h2>Mistaken behaviour</h2>
<p>To try to gather more evidence on this question, my colleagues and I have been studying the red flour beetle (<em>Tribolium castaneum</em>). Because they can complete a lifecycle within a month and are pretty hardy, these insects are ideal for studying how evolution progresses through several generations. Beetles account for 25% of all insect species, and they are also <a href="https://www.nature.com/articles/nature06784">a good model</a> from which to draw more general conclusions about insects.</p>
<p>Homosexuality is widely reported in <a href="https://link.springer.com/article/10.1007/s00265-013-1610-x">many beetle species</a>. But we had noticed that male flour beetles aren’t very fussy at all, mounting females, males, dead beetles and even oats. This suggests they may simply not be very good at recognising potential mates.</p>
<p>To test our theory and see whether or not this behaviour really does give the beetles any kind of evolutionary advantage, we compared two groups of flour beetles, one with more males and the other with more females. The males in the male-biased group had more competition so any that successfully fertilised a female should be <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1558-5646.2010.01174.x">better at mating</a>. This means any traits consistently displayed across the generations by males in this group should represent an evolutionary advantage.</p>
<p>In <a href="https://www.sciencedirect.com/science/article/pii/S0003347218300836">our experiment</a>, we placed males from each group in an arena and gave them the choice of mating with a male or a female. We then watched nearly 300 males mating. Because of the environment we had to create for the beetles to live in, this equated to over 50 hours of watching beetles trying to have sex at 30°C and 60% humidity.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/223583/original/file-20180618-85863-1fw25kh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/223583/original/file-20180618-85863-1fw25kh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=442&fit=crop&dpr=1 600w, https://images.theconversation.com/files/223583/original/file-20180618-85863-1fw25kh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=442&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/223583/original/file-20180618-85863-1fw25kh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=442&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/223583/original/file-20180618-85863-1fw25kh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=555&fit=crop&dpr=1 754w, https://images.theconversation.com/files/223583/original/file-20180618-85863-1fw25kh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=555&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/223583/original/file-20180618-85863-1fw25kh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=555&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Results of our experiment.</span>
<span class="attribution"><span class="source">Kriss Sales</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We found that the males from the two groups were equally motivated to mate. The beetles from the female-biased group weren’t picky, spending equal time trying to mate with the male as with the female. But those from the male-biased group were more likely to mate the female first, mate her more frequently and spend a greater amount of time mating her. So those beetles who came from a group with greater sexual competition were less likely to show homosexual behaviour. </p>
<p>This suggests the competitive males were more efficient at recognising females. This makes sense because males who aren’t as good at recognising potential mates in a group with more competition are less likely to pass on their genes. So, over multiple generations, a strong ability to recognise mates becomes more common. In the less competitive female-biased group, meanwhile, there’s less of a cost to mistakenly having sex with a male because there are more chances to mate with females and no pressure to improve the mate-spotting ability.</p>
<p>The implication is that homosexual behaviour in insects, especially in these beetles, isn’t an evolutionary adaptation because, where there is the pressure of sexual competition, it becomes less common over time. If it gave insects an evolutionary advantage then we’d expect it to become more common in this situation.</p>
<p>Instead, our research adds to the <a href="https://link.springer.com/article/10.1007/s00265-013-1610-x">weight of evidence</a> suggesting insect homosexuality is the result of poor mate-spotting abilities, although we still don’t know exactly why this occurs. To my knowledge, this is also the first time long-term experimental evolution has been used to study the paradox of same-sex behaviour in insects.</p>
<p>The results also suggest that the ability to recognise mates may require a costly amount of energy, otherwise the males in the female-biased group wouldn’t have shed this ability once they were faced with less competition and so had less need of it.</p>
<p>It’s also worth noting that our results were relevant to flour beetles specifically and probably to invertebrates generally. But our conclusions cannot be generalised to explain the behaviour of animals with more complex cognitive function and social structures like birds and mammals, which probably have very different reasons for same-sex mating.</p><img src="https://counter.theconversation.com/content/98029/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kris Sales is currently on an EnvEast DTP PhD studentship. His research was partially funded by ASAB summer studentships.</span></em></p>Up to half of insect sex can involve two males but our study suggests it’s probably less design and more a case of mistaken identity.Kris Sales, PhD Candidate in Ecology, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/921842018-03-11T09:02:16Z2018-03-11T09:02:16ZSex: birds do it, bees do it - and fungi do it too. Here’s how, and why it matters<figure><img src="https://images.theconversation.com/files/209695/original/file-20180309-30958-1w7hmly.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The sweet-smelling, fluffy white fungus, _Huntiella moniliformis_, engaging in sexual reproduction in the lab.</span> <span class="attribution"><span class="source">Author supplied</span></span></figcaption></figure><p>Sex is an essential part of life. You, me and almost every other living organism on this planet are only here because two individuals got together at some point in the past to have their genes represented in the next generation. </p>
<p>For many species on earth – especially humans – that’s a pretty inflexible process. There are strict requirements: for instance, having two partners of the opposite sex tends to be indispensable for the production of offspring. </p>
<p>But there are a number of exceptions to this rigidity. Some of the most beautiful and interesting are exemplified by certain species of fungi.</p>
<p>Fungi play a variety of roles in our lives. Some are food sources, like button mushrooms; some are used in the production of cheese, wine, beer and bread. Others have provided humans with antibiotics for almost a century. And still others can cause great harm, wiping out trees by the hectare – or even killing humans.</p>
<p>And of course, like most species, fungi have sex lives. I study the sexual behaviour of <em>Huntiella moniliformis</em>, a sweet-smelling and fluffy white fungus that’s found in plantations all over the world. It’s fairly unique in that it’s unisexual – able to reproduce completely alone. </p>
<p>This makes it potentially very dangerous: even if it’s the only fungus in, say, an entire forest, it can keep mating and reproducing. It gets all the evolutionary benefits of sex, without having to go through all the trouble of finding a mating partner. </p>
<p>If we understand its sex life, we can come up with ways to control, manage or even stop it. That’s important in the case of species like <em>Huntiella moniliformis</em>, because they can infect damaged trees and cause disease. </p>
<h2>Fungal mating strategies</h2>
<p>In humans and most other mammals there is only one way to produce sexual offspring: sexual intercourse between a male and a female. Reptiles and birds often also reproduce heterosexually. </p>
<p>Fungi, meanwhile, can utilise one or more of six different sexual strategies. These range from the fungal equivalent of heterosexuality to changing their mating type as necessary.</p>
<p><strong><a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.1949.tb00582.x/pdf">Heterothallism</a></strong>: is like heterosexuality in humans and requires two partners. In humans, having two X chromosomes makes you female; having an X and a Y chromosome makes you male. Some fungi use a similar system but instead of a whole chromosome they use single genes. A fungus with the <em>MAT1</em> gene is of the MAT1 mating type; having the <em>MAT2</em> gene means its mating type is MAT2. </p>
<p>For sex to take place, MAT1 and MAT2 partners need to get together. This means that out of everyone you meet, only half are sexually compatible with you. This severely limits the number of successful partners a fungus can meet in its search for a mate.</p>
<p>So how do they find each other? Smell. Or, at least, something similar: pheromones. These are small molecules that let a MAT1 individual know that a MAT2 individual is close, and vice versa. This ensures that no one wastes time and energy slowly growing towards an incompatible partner. </p>
<p><strong>Primary homothallism:</strong> is when a single fungus has sex completely alone. Instead of having either the <em>MAT1</em> or the <em>MAT2</em> gene, they have both. In this way a single individual can make both pheromones and recognise itself as a partner. There are other forms of self-sex too. Two of these include the ability to change mating type. These systems mimic those of some fish that can switch between male and female, depending on what partners are available. The third relies on having two genomes and is functionally very similar to heterothallism. </p>
<p>The fourth lonely sexual strategy completely changed the way we think about sex in fungi. <strong>Unisexuality</strong> occurs in individuals we would classically have thought to be either MAT1 or MAT2. We would have expected them to need a partner, but they don’t.</p>
<p>My PhD research at the <a href="https://www.fabinet.up.ac.za/">Forestry and Agricultural Biotechnology Institute</a> in South Africa has revealed that unisexual reproduction is possible in <em>H. moniliformis</em>. My supervisors and I have recently <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0192517">shown</a> that MAT2 individuals are able to secrete both pheromones, despite the absence of the <em>MAT1</em> gene. </p>
<p>This means that a single mating type can recognise itself as a compatible partner and respond appropriately. We are currently working on understanding how this system evolved and whether related species could be manipulated to employ the same strategy.</p>
<h2>Why does this matter?</h2>
<p>There are obvious evolutionary benefits to species having sex. The most obvious is because it ensures a species’ longevity. But there are downsides – not for <em>H. moniliformis</em>, in this case, but for forestry plantations. </p>
<p>Sex combines genes from different individuals and produces genetically unique offspring. In disease causing fungi this has been shown to enable host jumping – the movement from a susceptible host species such as a Pine tree in a plantation, to a previously resistant species, like an indigenous tree in a natural forest. </p>
<p>This means that hosts previously thought to be immune to infection could get infected in the future, and can cause serious disease outbreaks that are difficult to control. </p>
<p>The other downside to sex in fungi like <em>H. moniliformis</em> is that it produces easily dispersible spores. These are often the agent that enhances fungal spread and infection. </p>
<p>Understanding these processes, and the sex lives of fungi like <em>H. moniliformis</em>, can help us find answers to how to control the spread of diseases. This will ultimately mean keeping plantations – and humans – safer.</p><img src="https://counter.theconversation.com/content/92184/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andi Wilson receives funding from the National Research Foundation (NRF). </span></em></p>Understanding the sex lives of fungi can help in finding answers about disease control.Andi Wilson, PhD: Genetics Candidate, University of PretoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/907642018-02-14T13:13:45Z2018-02-14T13:13:45ZKamikaze sperm and four-headed penises – the hidden ways animals win the mating game<figure><img src="https://images.theconversation.com/files/206154/original/file-20180213-44651-1j0cpnw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The echidna has a four-headed penis.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/success?src=5Mt7Ua1T_g5mVPXvneA1VA-1-1">Shutterstock</a></span></figcaption></figure><p>We all know that individuals fight over potential love interests. Just think of Daniel Cleaver (Hugh Grant) and Mark Darcy (Colin Firth) scuffling – rather impotently – <a href="https://www.youtube.com/watch?v=iapVomK4eFA">over Bridget Jones in a fountain</a>. But you might be surprised to hear that the fierce rivalry continues behind the scenes – in the form of <a href="https://www.youtube.com/watch?v=WnxuCiwVc-4">sperm competition</a>. This is when the sperm of two or more males compete inside the reproductive tract of a female, to fertilise the eggs, something that is widespread in the animal kingdom. </p>
<p>It is generally assumed that the sperm in a female’s reproductive tract around the time of fertilisation will belong to one male. But <a href="http://onlinelibrary.wiley.com/doi/10.1046/j.1365-294X.2002.01613.x/full">DNA fingerprinting</a> has revealed that even “monogamous” bird species that form exclusive pair bonds are not as exclusive as was once thought.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/206155/original/file-20180213-44627-a8hy6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/206155/original/file-20180213-44627-a8hy6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=484&fit=crop&dpr=1 600w, https://images.theconversation.com/files/206155/original/file-20180213-44627-a8hy6b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=484&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/206155/original/file-20180213-44627-a8hy6b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=484&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/206155/original/file-20180213-44627-a8hy6b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=608&fit=crop&dpr=1 754w, https://images.theconversation.com/files/206155/original/file-20180213-44627-a8hy6b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=608&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/206155/original/file-20180213-44627-a8hy6b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=608&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">‘Are you sure they’re all mine?’</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/success?src=fx_yzW7nlC1MYKZ-_nhGLQ-1-12">Shutterstock</a></span>
</figcaption>
</figure>
<p>In fact, extra-pair young (those fathered by another male) are found in around 90% of bird species, and extra-pair copulations (matings with a different male) result typically in 11% of all young. In fact, the percentage of extra-pair young can be as high as 76% in species such as the <a href="https://changingtheclimateblog.wordpress.com/2017/04/07/the-promiscuous-life-of-the-superb-fairy-wren/">superb fairy wren</a>.</p>
<p>Fertilising an egg is often likened to winning a lottery – the more tickets you possess, the higher your chances of winning. Consequently, the more sperm a male manages to get to the egg, the greater his chances of fathering offspring. This has led to huge variation in copulatory behaviour and sperm morphology.</p>
<p>Here are five elaborate methods that have evolved to increase the chance that an individual male’s sperm is the winner:</p>
<h2>1. When big is best</h2>
<p>The obvious way to increase the chance of fertilising an egg is to increase the number of sperm that are produced. Males have been found to make the most sperm in species where individuals
are most promiscuous. For example, the <a href="https://www.nature.com/articles/293055a0">testes</a> of gorillas – a monogamous species – are 30g, whereas testes of chimpanzees – <a href="https://theconversation.com/why-did-humans-evolve-big-penises-but-small-testicles-71652">a promiscuous species with multiple mates</a> – are a whopping 120g. To put this in context, human testes are around 50g, and chimps are around two thirds our body size, making chimp testes, relatively speaking, almost four times the size of human ones.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/206156/original/file-20180213-44647-1d35qfc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/206156/original/file-20180213-44647-1d35qfc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/206156/original/file-20180213-44647-1d35qfc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/206156/original/file-20180213-44647-1d35qfc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/206156/original/file-20180213-44647-1d35qfc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/206156/original/file-20180213-44647-1d35qfc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/206156/original/file-20180213-44647-1d35qfc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Chimps have big testes. Relative to body size, they are four times bigger than humans’.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/success?src=fx_yzW7nlC1MYKZ-_nhGLQ-1-12">Shutterstock</a></span>
</figcaption>
</figure>
<h2>2. Sperm ‘trains’</h2>
<p>In general, larger sperm (specifically, those that are longer) are more successful because they have a greater swimming velocity. So, sperm length is longer in more promiscuous species. One species that has truly taken advantage of this is the <a href="http://www.nature.com/news/2002/020711/full/news020708-10.html">wood mouse</a>, where the sperm possess hooks to attach to each other. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/206157/original/file-20180213-44636-skmaks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/206157/original/file-20180213-44636-skmaks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/206157/original/file-20180213-44636-skmaks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/206157/original/file-20180213-44636-skmaks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/206157/original/file-20180213-44636-skmaks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/206157/original/file-20180213-44636-skmaks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/206157/original/file-20180213-44636-skmaks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The wood mouse: a canny mater.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/306247235?src=A6OuqlgE5HWoqaj3XmnT1w-1-1&size=medium_jpg">Shutterstock</a></span>
</figcaption>
</figure>
<p>This means they can form aggregations, or mobile “trains”, of hundreds or thousands of sperm cells, greatly increasing sperm motility.</p>
<h2>3. Kamikaze sperm</h2>
<p>Around 20% of sperm are abnormal – possessing two heads, no heads or two tails, for example. These <a href="https://www.psychologytoday.com/blog/how-we-do-it/201310/kamikaze-sperms-or-flawed-products">“kamikaze” sperm </a> are incapable of fertilising eggs but it is thought that they might be able to prevent sperm from rival males reaching the egg, either by killing them with enzymes or simply by blocking them. Although there is little evidence of kamikaze sperm in non-humans, some <a href="https://www.sciencedirect.com/science/article/pii/S0968432897000644?via%3Dihub">snails</a> possess abnormal sperm that contain enzymes capable of degrading sperm.</p>
<h2>4. Preventative behaviour</h2>
<p>Many males cement up the genital opening of the female with a copulatory plug, producing an obstacle to prevent other males from further copulations. For example, male <a href="http://www.nature.com/news/spider-mating-plugs-become-better-with-age-1.15407">European dwarf spiders</a> produce a plug which starts as a liquid secreted by a specialised gland and then hardens to become an obstacle. What’s more, the longer the copulation, the larger the plug left behind. Smaller, fresher plugs are relatively easy for other males to remove. But males are unlikely to try to remove larger plugs, benefiting those that have invested more time in the female.</p>
<h2>5. Brushes and whips</h2>
<p>If females mate with multiple males, each suitor generally will father more offspring than the previous one. Therefore, males compete by trying to ensure their sperm is the one to fertilise the egg. </p>
<p>This has led to the evolution of some bizarre penises. The <a href="http://news.softpedia.com/news/Why-Do-Echidnas-Have-Four-Headed-Penises-69334.shtml">echidna</a> (a spiny, egg-laying mammal) for example, has a four-headed penis – although only two heads ejaculate at once. </p>
<p>In some species, penises are specifically shaped to pack sperm tightly into the corners of the female reproductive tract, whereas others are armed with spines, brushes, barbs or hooks to scrape out the sperm of previous males, or stimulate the females to release sperm. The most <a href="http://www.sciencephoto.com/media/368301/view">elaborate</a> are the <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.567.2582&rep=rep1&type=pdf">penises of odonata</a>, insects such as dragonflies. Some even possess whip-like flagella to remove rival sperm. </p>
<p>These removal methods are quite successful as even the <a href="http://news.bbc.co.uk/1/hi/health/3128753.stm">human penis</a> is able to remove 90% of sperm from a reproductive tract.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/206158/original/file-20180213-44639-h93isn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/206158/original/file-20180213-44639-h93isn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/206158/original/file-20180213-44639-h93isn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/206158/original/file-20180213-44639-h93isn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/206158/original/file-20180213-44639-h93isn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/206158/original/file-20180213-44639-h93isn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/206158/original/file-20180213-44639-h93isn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">‘Are you looking at my claspers?’</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/306247235?src=A6OuqlgE5HWoqaj3XmnT1w-1-1&size=medium_jpg">Shutterstock</a></span>
</figcaption>
</figure>
<p>Many reptiles, rays and sharks actually possess two “penises”. In <a href="http://www.arkive.org/epaulette-shark/hemiscyllium-ocellatum/image-G116530.html">sharks</a> these are known as <a href="https://www.youtube.com/watch?v=JHUm6cgLbYY">claspers</a>, and either one can be used to inseminate the female. These claspers not only possess small hooks to anchor them in place, but they are also linked to siphon sacs filled with seawater that spray the sperm into the female reproductive tract under pressure. It has even been theorised that one of the claspers could act as a “<a href="http://www.science.fau.edu/sharklab/courses/elasmobiology/readings/whitney%20et%20al.pdf">jet wash</a>”, cleaning out the sperm of previous males, although there is little evidence for this as shark matings are rarely observed.</p>
<p>Whatever the reason, it is clear that animals have evolved some extraordinary ways of ensuring that they win the competition for fertilisation.</p><img src="https://counter.theconversation.com/content/90764/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Louise Gentle works for Nottingham Trent University</span></em></p>The competition to father young is often most intense behind the scenes.Louise Gentle, Senior Lecturer in Behavioural Ecology, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/912522018-02-07T14:01:39Z2018-02-07T14:01:39ZWhy some fireflies become femme fatales in their race for survival<figure><img src="https://images.theconversation.com/files/205040/original/file-20180206-14083-tcllf7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">"Hello there, handsome..."</span> <span class="attribution"><span class="source">knoelle44/flickr</span></span></figcaption></figure><p>Fireflies are the flashy stars of the insect world. At night, you can see them coming because each little bug shines like a lamp – and, appropriately, they belong to the beetle family <a href="https://bugguide.net/node/view/85">Lampyridae</a>. </p>
<p>The “lamplight” of fireflies is generated by an enzyme inside the bugs’ abdomens called luciferase, which reacts with other elements and compounds to produce a cold light. This turns each individual firefly into a <a href="https://www.scientificamerican.com/article/how-and-why-do-fireflies/">bioluminescent</a> beauty.</p>
<p>Their glow is also used for courtship. Males of different firefly species use different <a href="http://science.sciencemag.org/content/187/4175/452">flash patterns</a> to <a href="http://www.annualreviews.org/doi/abs/10.1146/annurev.ento.53.103106.093346">attract potential mates</a>. A male firefly will flash in a certain pattern for a particular length of time; he knows whether the female he’s spotted is interested based on how long it takes her to “flash” in reply.</p>
<p>This all sounds very romantic and beautiful. But there’s a dark secret lurking behind the facade: some female fireflies dupe the males with false flash patterns – then, when their amorous would-be partners approach, they attack and eat them. The <a href="http://www.pnas.org/content/94/18/9723.short">femme fatales</a> aren’t doing this from malice or hunger: they’re trying to ingest a toxin that will keep them safe from predators.</p>
<h2>“Come closer…”</h2>
<p>This lethal mating ritual happens in two genera of fireflies, <a href="http://animaldiversity.org/accounts/Photinus_pyralis/"><em>Photinus</em></a> and <a href="http://animaldiversity.org/accounts/Photuris_versicolor/"><em>Photuris</em></a>. Both of the fireflies are native to North America.</p>
<p>The <em>Photuris</em> female is able to mimic <em>Photinus’</em> flashing patterns; with this deception, she answers the flash patterns of a <em>Photinus</em> male. He comes closer, hoping to consummate their new relationship. Instead, she captures and eats him.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/yJp0cXChsFM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Predation in fireflies: <em>Photuris versicolor</em> preys on <em>Photinus pyralis</em></span></figcaption>
</figure>
<p>Why? Because, as the saying goes, “You are what you eat.” In this case, the <em>Photuris</em> female eats the <em>Photinus</em> male to get chemical defences that are present in his blood. The toxins can be used to fight off <a href="https://www.hindawi.com/journals/psyche/2012/634027/">predators</a> like birds, spiders, ants and others.</p>
<p>When the <em>Photinus</em> male is under attack, the toxins are released as tiny droplets. By eating the male, the <em>Photuris</em> female absorbs that toxic power and makes herself safer from predation. The powerful toxins are called <a href="http://www.pnas.org/content/75/2/905.short">lucibufagins</a>, which are steroids similar to the heart poison generated from the <a href="https://www.aaas.org/blog/scientia/digitalis-flower-drug-poison">foxglove plant</a>, <em>Digitalis</em>. </p>
<p>When a firefly is attacked its outer skin, called the <a href="http://bugs.bio.usyd.edu.au/learning/resources/Entomology/internalAnatomy/cuticle.html">cuticle</a>, ruptures and bitter tasting blood loaded with lucibufagins oozes out. Predators release the firefly because they can’t stand the taste.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205082/original/file-20180206-14072-dr5h4f.JPEG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A firefly (<em>Photuris</em>) exuding the poisonous fluid from its body when disturbed.</span>
<span class="attribution"><span class="source">Thomas Eisner, 1997</span></span>
</figcaption>
</figure>
<h2>Avoidance tactics</h2>
<p>When a female <em>Photuris</em> eats a <em>Photinus</em> male and absorbs his lucibufagins, she is also protecting her young. The females are able to pass on this toxic defence mechanism <a href="http://www.pnas.org/content/94/18/9723.short">to their offspring</a>.</p>
<p>The <em>Photinus</em> males try to protect themselves from being eaten by <em>Photuris</em> females. They take their time looking for the real thing: a female of their own species. One study, in a laboratory <a href="https://books.google.com.np/books?hl=en&lr=&id=eHV_8YC_NL0C&oi=fnd&pg=PA113&dq=photinus+males+attempt+to+land+further+away+from+the+female+to+make+sure+that+she+is+of+the+same+species&ots=78t3MceGkQ&sig=Y4DrDTo6eL0-KtF9pZ6In9pZrCY&redir_esc=y#v=onepage&q&f=false">showed</a> that <em>Photinus</em> males took more than seven nights to find a female of its own species, while a <em>Photinus</em> female of the same species took less than six minutes to attract a male for mating. </p>
<p>The <em>Photinus</em> males also change their light emitting patterns in a bid to mislead their nemesis or – if they’re quick enough – simply fly away as soon as they are realise they’ve been drawn into a trap.</p><img src="https://counter.theconversation.com/content/91252/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Prayan Pokharel does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Beneath their beautiful, flashing facade some female fireflies are ruthless predators.Prayan Pokharel, Doctoral Student at the Institute for Insect Biotechnology, University of GiessenLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/894532017-12-27T20:46:51Z2017-12-27T20:46:51ZYou might be Christmassed out, but these Australian birds are festive all year<figure><img src="https://images.theconversation.com/files/200136/original/file-20171220-4980-p0x1gw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">You might dress like this once a year, but for eclectus parrots it's a way of life.</span> <span class="attribution"><span class="source">Doug Janson/Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>With partridges in pear trees, robins, and of course turkeys, you might think birds of the northern hemisphere have a monopoly on Christmas. But if you look closely, many Australian native birds embody the Christmas spirit with as much gusto as their northern counterparts.</p>
<p>And while you might be ready to call it a day rather than face yet another turkey sandwich, these festive birds keep the Christmas spirit going all year round.</p>
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Read more:
<a href="https://theconversation.com/is-it-really-so-wrong-to-care-for-an-introduced-bird-species-78557">Is it really so wrong to care for an introduced bird species?</a>
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</p>
<hr>
<h2>The carollers</h2>
<p>At any local candlelit carol service, dads can be heard enthusiastically belting out Joy to the World.</p>
<p>While it is not clear if their vocal acrobatics impress anyone, male lyrebirds rely on their complex melodious calls to attract mates. These species have an extensive repertoire, and will often mimic the sounds they hear around them. In Sir David Attenborough’s classic <a href="http://www.bbc.co.uk/programmes/b007qn69">The Life of Birds</a>, the <a href="http://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon:4da712ae-427c-4fee-8f40-c8e2ec1e7d6e">superb lyrebird</a> imitates kookaburras, whipbirds and even chainsaws, camera shutters and car alarms!</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/mSB71jNq-yQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Lyrebird call.</span></figcaption>
</figure>
<h2>Underneath the mistletoe</h2>
<p>The Christmas traditions around the evergreen mistletoe originate in the northern hemisphere, but did you know there are <a href="https://www.anbg.gov.au/mistletoe/">more than 90 species of mistletoe</a> that are native to Australia? </p>
<p>Mistletoes are aerial parasitic plants that attach to tree branches, and their seeds are dispersed by birds. The aptly named <a href="http://www.birdlife.org.au/bird-profile/mistletoebird">mistletoebird</a> eats the mistletoe berries and excretes the seed a short time later. With a wiggle and a twist, the mistletoebird then wipes the seed onto the branch of a suitable host tree. A sticky substance around the seed then glues it in place. </p>
<p>By dispersing mistletoe seeds with such care, the mistletoebird ensures a reliable source of its favourite food throughout the year.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/of72tj-CxKc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Mistletoebirds.</span></figcaption>
</figure>
<h2>The gift-givers</h2>
<p>At Christmas time, excellent gift-giving skills may help win over a discerning love interest. In the avian world, bowerbirds take gift selection and presentation very seriously. </p>
<p>Male bowerbirds construct a bower (two parallel walls of sticks) in which they display a selection of items designed to tempt females. These gifts can include leaves, shells, feathers and flowers and bits of glass and plastic. </p>
<p><a href="http://www.birdsinbackyards.net/species/Ptilonorhynchus-violaceus">Satin bowerbirds</a> collect bright blue items, whereas <a href="http://www.iucnredlist.org/details/22703694/0">great bowerbirds</a> go for the (arguably more Christmassy) green and white. </p>
<p>Once the female is suitably interested in a male bowerbird’s collection, the males will perform a wing-flapping, head-bobbing dance with accompanying sounds. While this approach works well for the bowerbird, human results may vary.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/200420/original/file-20171221-15907-1bombwl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/200420/original/file-20171221-15907-1bombwl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/200420/original/file-20171221-15907-1bombwl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/200420/original/file-20171221-15907-1bombwl.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/200420/original/file-20171221-15907-1bombwl.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/200420/original/file-20171221-15907-1bombwl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/200420/original/file-20171221-15907-1bombwl.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/200420/original/file-20171221-15907-1bombwl.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A satin bowerbird with his blue collection.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/w/index.php?curid=61962784">Joseph C. Boone</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Our native turkeys</h2>
<p>While I am not suggesting you swap your turkey roast for a native alternative, there are several types of “bush turkeys” that have been a valued food source for Aboriginal Australians for millennia.</p>
<p>The <a href="http://www.birdsinbackyards.net/species/Ardeotis-australis">Australian bustard</a> – the heaviest flying bird in Australia, weighing up to 14.5kg – was once described by Captain James Cook as “an excellent bird, far the best … that we have eat [sic] since we left England”. </p>
<p>The bustard’s range and population have <a href="https://doi.org/10.1016/0006-3207(86)90066-2">greatly declined</a> since Cook’s time, as a result of increased hunting, the introduction of feral predators, and changes in land use that have destroyed large tracts of its habitat.</p>
<figure>
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<figcaption><span class="caption">Australian bustard.</span></figcaption>
</figure>
<h2>Red and green all over</h2>
<p>You might have decided, justifiably enough, that once a year is enough when it comes to dressing from head to toe in red and green. But some of our native birds wear their Christmas colours all year round. </p>
<p>The male and female <a href="https://australianmuseum.net.au/eclectus-parrot-eclectus-roratus">eclectus parrot</a> make a striking pair. This species is known for their pronounced differences in plumage: males are mostly bright green, whereas females are almost entirely bright red. </p>
<p>This has been <a href="https://doi.org/10.1017/S0952836902003138">attributed to the mating strategy of the species</a>. Both males and females breed with multiple partners. The bright red females are conspicuous as they sit at the entrance to their nesting hollow, warding off rival females and attracting males. The bright green males, meanwhile, are camouflaged as they forage for food to deliver to multiple females at their nesting sites.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/EcGfK7uceok?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Eclectus parrots.</span></figcaption>
</figure>
<p><em><strong>Read more</strong>: <a href="https://theconversation.com/why-we-hate-certain-birds-and-why-their-behaviour-might-be-our-fault-54404">Why we ‘hate’ certain birds, and why their behaviour might be our fault</a></em></p>
<hr>
<h2>Santa’s spies?</h2>
<p>How does Santa manage to collect so much information on Australian children’s behaviour without leaving the North Pole? One theory (suggested by no less a scientific authority than my five-year-old daughter) holds that he does it with the help of the migratory waterbirds that every year make an astonishing trip from Australian shores to the Arctic Circle and back.</p>
<p><a href="http://birdlife.org.au/bird-profile/bar-tailed-godwit">Bar-tailed godwits</a> arrive in Australia in August, having flown from their northern hemisphere breeding grounds. Over the Australian summer they use their long bills to scour mudflats, mangroves and beaches for food.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/oUltxW8rZBo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Bar-tailed godwits.</span></figcaption>
</figure>
<p>Most of them leave Australia in April with full bellies (and valuable intel?) and head back to their Arctic breeding grounds. The distances travelled during migration are mind-blowing: a bar-tailed godwit was <a href="http://rspb.royalsocietypublishing.org/content/276/1656/447.short">tracked flying more 11,000km</a>, non-stop, in nine days. Beat that, Santa.</p><img src="https://counter.theconversation.com/content/89453/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Heather Neilly does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>From mistletoebirds, to bush turkeys, to the festively plumaged eclectus parrot, Australian birds can more than hold their own when it comes to embracing the Christmas spirit.Heather Neilly, PhD Candidate, Centre for Tropical Biodiversity and Climate Change Navigation, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/863712017-11-02T23:38:41Z2017-11-02T23:38:41ZIt’s mostly mothers who pass on mitochondria – and a new theory says it’s due to the first sexual conflict<figure><img src="https://images.theconversation.com/files/193092/original/file-20171102-26478-lwqk5w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Is this how we got the sperm and the egg?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sperm-egg-1762515">Sebastian Kaulitzki/Shutterstock</a></span></figcaption></figure><p>Evolutionary interests of males and females do not always coincide. This is known as sexual conflict: male innovations that allow them to reproduce more sometimes hurt females, and vice versa.</p>
<p>Male fruit flies, for instance, inject their partners with <a href="http://www.nytimes.com/1995/01/24/science/sex-and-the-fruit-fly-price-of-promiscuity-is-premature-death.html">toxic chemicals</a> during sex. These toxins destroy sperm of the female’s previous mates, improving his own chances for becoming the sole father of her offspring. But the toxins also make female flies sick and reduce their lifespan. Females, in turn, have evolved defenses to counter the chemicals, sometimes at the expense of males’ success. </p>
<p>Biologists believe that sexual conflicts are rooted in the <a href="http://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(02)00004-6">size and number of reproductive cells</a> – eggs and sperm. Males typically produce large numbers of sperm that can fertilize multiple eggs. Females, on the other hand, produce a small number of large reproductive cells, and so invest more energy and resources in each. </p>
<p><a href="http://www.ucl.ac.uk/%7Eucbhpom/people.html">My team</a> of evolutionary biologists at University College London <a href="https://doi.org/10.1186/s12915-017-0437-8">has now identified a different kind of sexual conflict</a>, dating back to the days when the most complex organisms were made of single cells, possibly as far as 1.5 billion years ago. This ancient sexual conflict – before the two sexes even existed – had to do with whose mitochondria would be passed on to offspring.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=544&fit=crop&dpr=1 600w, https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=544&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=544&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=684&fit=crop&dpr=1 754w, https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=684&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/192858/original/file-20171101-19894-1jdkw1c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=684&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Eukaryotic cells have a nucleus (blue) and numerous mitochondria (green).</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nihgov/20495441928">Dylan Burnette and Jennifer Lippincott-Schwartz, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>Whose mitochondria will be passed on?</h2>
<p>We studied inheritance of genes located in <a href="https://www.livescience.com/50679-mitochondria.html">mitochondria</a> – the structures inside our cells that breathe and produce energy. In many animals and plants, when the egg is fertilized, only the mother’s mitochondrial genes survive, while the father’s mitochondria are lost.</p>
<p>This is not by accident: Females have evolved many mechanisms to recognize a partner’s mitochondria entering the egg. Once detected, an army of enzymes is sent to digest them. Previous research has shown that <a href="https://doi.org/10.1098/rspb.2013.1920">getting rid of male mitochondria</a> is a way to keep descendents’ mitochondrial genes mutation-free. In the long run, inheritance of healthy maternal mitochondria is good news for the offspring.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=511&fit=crop&dpr=1 600w, https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=511&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=511&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=642&fit=crop&dpr=1 754w, https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=642&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/192864/original/file-20171101-19845-1rugssj.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=642&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">For the most part mitochondria come from the mother’s line. But there are exceptions.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Mitochondrial_DNA_versus_Nuclear_DNA.gif">University of California Museum of Paleontology and the National Center for Science Education</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>But there are many exceptions that remain unexplained. In some species, <a href="https://doi.org/10.1038/hdy.2012.60">paternal mitochondria remain undigested</a>, as if the father had found a way to protect them from being detected. Stranger still, in organisms such as fruit flies and many plants, it is the father that destroys most of his own mitochondria during production of sperm.</p>
<p>If maternal inheritance is as beneficial as previous research shows, why are there so many exceptions?</p>
<h2>Taking the long or the short view</h2>
<p>In our new study, we show that these exceptions arise because of a <a href="https://doi.org/10.1186/s12915-017-0437-8">sexual conflict over the control of mitochondrial inheritance</a>.</p>
<p>Using mathematical modeling, we found that evolution in females tends to focus on long-term effects. Destroying paternal mitochondria makes it easier to weed out harmful mutations in the future, but this effect unfolds over many generations. This strategy works well in females, because the same healthy set of maternal mitochondria is passed down the female line over and over again. </p>
<p>But males don’t have a long evolutionary time horizon to deal with in this case. Since most of their mitochondria are replaced by maternal ones at the start of every generation, evolution cannot detect long-term benefits from males’ mitochondrial genes. Because there’s no long-term link, they can benefit only in the immediate future, and that often means passing on some of their mitochondria right now. Males therefore seek to improve the fitness of their offspring in the short-term, even if the long-term effects are harmful.</p>
<p>It’s these different interests of males and females that can lead to an evolutionary arms race, as selection in the two sexes acts in opposite directions. Evolution in females strives to keep the future generations free of male mitochondria, while males make every effort to get some of theirs into the mix.</p>
<p>“Over and over again, males have come up with ways to subvert female destruction of their mitochondria,” said my co-author, geneticist <a href="http://www.ucl.ac.uk/%7Eucbhpom/">Andrew Pomiankowski</a>. “So females had to develop new ways to block male mitochondria. Our model explains nicely why there are so many different mechanisms used to exclude male mitochondria, and why males sometimes do it themselves.”</p>
<p>It’s all about the control of mitochondrial inheritance – and for males it’s better to be in the driver’s seat to decide how many mitochondria they contribute to the mix than be completely excluded.</p>
<h2>A sexual conflict that led to the sexes</h2>
<p>There is evidence that this conflict dates back to the days when all organisms were made of single cells. Male and female sexes did not exist, because all reproductive cells were of the same size. </p>
<p>“One of the strategies an organism can use to win in this conflict is to simply have more mitochondria than their partner, for example, by increasing the size of their sex cells,” Andrew Pomiankowski said. “Strikingly, this might have been the impetus to evolve two sexes in the first place.” Larger sex cells – the future eggs – garnered an advantage in the battle over mitochondrial inheritance, simply by swamping smaller sex cells – the forerunners of sperm – that had fewer mitochondria to contribute.</p>
<p>Most biologists currently think that <a href="https://doi.org/10.1098/rspb.2002.2161">two sexes evolved through division of labor</a> – a so-called “disruptive selection” theory. Large female sex cells can survive longer but cannot move much, while smaller sperm are fragile but move faster and can find more mating partners.</p>
<p>Our hypothesis on the origin of sexes, if true, adds a new angle to this origins story, tracing it back to an ancient conflict over mitochondrial inheritance. Females may have won this ancient battle by simply producing larger sex cells packed with mitochondria, ensuring that mitochondrial transmission is effectively one-sided (and reaping the long-term fitness benefits). But ultimately, as with all scientific hypotheses, this one will have to stand the test of thorough experimental verification.</p><img src="https://counter.theconversation.com/content/86371/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arunas L Radzvilavicius receives funding from David and Lucille Packard Foundation.</span></em></p>An ancient sexual conflict over mitochondrial inheritance may be responsible for the evolution of the two sexes as we know them.Arunas L. Radzvilavicius, Postdoctoral Researcher of Evolutionary Biology, University of PennsylvaniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/841792017-10-31T16:07:36Z2017-10-31T16:07:36ZSynthetic sex in yeast promises safer medicines for people<figure><img src="https://images.theconversation.com/files/192654/original/file-20171031-18720-13bi7tz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What can mating yeast tell us about new drugs?</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/conchur/13316830914">Conor Lawless</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Our old friend <em>Saccharomyces cerevisiae</em> – the yeast that’s helped people bake bread and brew beer <a href="https://doi.org/10.1073/pnas.0407921102">for millennia</a> – has just had its sex life upgraded.</p>
<p>Bioengineers at the University of Washington have <a href="https://doi.org/10.1073/pnas.1705867114">reprogrammed the mating habits</a> of this single-celled organism, letting the fungus get it on like never before. The result? A sexual revolution that could lead scientists to safer future medicines.</p>
<h2>Yeast as lab guinea pig</h2>
<p>We already rely on yeast for a lot more than just fermented food. Much of our modern understanding of genetics and cell biology has come from careful study and manipulation of the fungus.</p>
<p>Scientists and drug designers love <a href="http://doi.org/10.1038/nrc1372">working with yeast</a> because of its rapid cell cycle (a new generation is born every 90 minutes) and the relative ease with which its genes can be tweaked. Even human genes and genes encoding protein-based drugs can be spliced in, allowing researchers to study them in the lab in detail. Anti-cancer drugs <a href="http://dx.doi.org/10.1038/nri1837">have been optimized</a> this way. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=512&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=512&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186279/original/file-20170917-8076-cg1xmj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=512&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Our species’ relationship with yeast predates our use of gold, horses and writing.</span>
<span class="attribution"><span class="source">Ian Haydon</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>One of the most popular techniques for this type of biomolecular research is known as <a href="https://doi.org/10.1038/nbt0697-553">yeast surface display</a>. Using this method, a gene can be added to yeast and the protein that results will appear on the easily accessible outer surface of the cell. With a new protein displayed on the surface, researchers can easily determine what other biomolecules the protein interacts with.</p>
<p>This method, pioneered in the laboratory of <a href="http://kdw-lab.mit.edu/">Dane Wittrup</a>, exploits aspects of the fungus’ sexual machinery.</p>
<p>Yes, even single-cell microbes can have sex. But as is often the case outside the animal kingdom, the way DNA gets swapped can seem unusual to human observers.</p>
<h2>Fungal fornication</h2>
<p>The terms “male” and “female” don’t really apply to budding yeast. Instead of forming sperm or eggs, the sex cells of yeast all look the same – like tiny, single-cell blobs. What makes two yeast blobs able to sexually reproduce are their so-called mating types.</p>
<p>The proteins that decorate the outside of a yeast sex cell, or gamete, determine that cell’s mating type. Put on copies of one protein and you’re one mating type; swap them out for a different protein and you’re the other. Agglutination (the unsexy term for yeast sex) only happens when the surface proteins of yeast gametes from opposite mating types interact.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=387&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=387&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=387&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186262/original/file-20170916-8121-vevpb8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Single-celled yeast as seen under a scanning electron microscope.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Saccharomyces_cerevisiae_SEM.jpg">Mogana Das Murtey and Patchamuthu Ramasamy</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Inspired by this molecular precision, a team of synthetic biologists led by University of Washington graduate student David Younger realized they could convert the natural yeast mating system into a new tool that would let them precisely measure molecular interactions at a much larger scale. </p>
<p>Though tiny and difficult to measure, molecular interactions are a big deal in drug design. Virtually every drug works via specific interactions with its target, and drugs that bind where they shouldn’t can be lethal.</p>
<p>Some experts blame off-target interactions for last year’s failed phase III clinical trial of Alnylam Pharmaceuticals’ revusiran, an RNA drug designed to treat a rare heart disease. <a href="https://doi.org/10.1038/nbt1216-1213">Nineteen people died</a> before the trial was called off, and the company’s stock took a <a href="https://www.businessinsider.com.au/alnylam-stock-down-after-drug-trial-discontinued-2016-10">US$3 billion hit</a>.</p>
<p>Figuring out whether a new drug binds what it’s supposed to is relatively easy; figuring out whether it binds anything else in our cells is tough. Established laboratory techniques like yeast surface display have helped scientists screen new drugs for potentially dangerous off-target interactions before they make it to clinical trials, but that technique lets you look for off-target interactions only one at a time. Younger’s team envisioned a way to test hundreds of drugs against thousands of potential targets, all by redesigning yeast sex.</p>
<h2>Redesigning yeast sex with multiple mating types</h2>
<p>To start, Younger needed a way to precisely measure mating efficiency in lab-grown yeast. Perfect efficiency would mean every cell that could fuse would do so. The more efficient the mating, the better matched the two mating types.</p>
<p>The team linked genetically encoded fluorescent markers – one blue, one red – to each of the natural yeast mating types. That made it simple to measure mating efficiency for a whole yeast population: They could just count the cells that stayed blue or red (unmated) versus those that turned purple (mated). It turns out for typical yeast grown in the lab, mating efficiency is around 60 percent.</p>
<figure class="align-right zoomable">
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<span class="caption">Example of fluorescent-tagged yeast, in this case red and green. Together the markers look yellow.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Yeast_membrane_proteins.jpg">Masur</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>The team then deleted the natural agglutination proteins and replaced them with a pair of foreign proteins known to interact weakly. The mating efficiency dropped tenfold to 5.7 percent. They swapped in another pair and saw it rise to 19 percent. When they tried a third pair of proteins known to interact with much higher affinity, mating efficiency rose to 51.6 percent – close to what was seen in natural agglutination.</p>
<p>Just by tracking mating efficiency, the team could tell how strongly any two protein molecules interact. When they checked a pair of proteins that shouldn’t interact at all, mating efficiency was a meager 0.2 percent.</p>
<p>Now, instead of just the two natural mating types, <a href="https://doi.org/10.1073/pnas.1705867114">scientists can quickly engineer thousands of “sexes”</a> by coaxing individual yeast to decorate the outside of their cells with new, human-specified proteins. If a pair of new mating types are sexually compatible – meaning the proteins decorating their cell surfaces interact – their offspring will rise in number. By tallying up each genetically distinct offspring in a tube not much bigger than a thimble, thousands of potential molecular interactions can be quantified.</p>
<h2>Improving drug safety</h2>
<p>To show that their new tool could aid in drug development, the team generated 1,400 distinct variants of an emerging anti-cancer drug known as <a href="https://doi.org/10.7554/eLife.20352">XCDP07</a>. The drug is supposed to disrupt the unrestrained growth of cancer cells by binding specific cellular targets, but as with every drug, significant off-target interactions could render it useless. By mixing yeast displaying different versions of the drug with other yeast displaying human proteins, the team was able to identify versions of XCDP07 which only bound to the intended target.</p>
<p>Younger is working to get his new tool into the hands of more scientists. He’s already gifted his engineered yeast strains to eager researchers at Stanford, Yale, UCSD and beyond. Concerns over the cost and safety of emerging drugs have motivated him to start a company – funded by scientific grants, not investors – to turn his results into the next generation of medicines. Younger says the goal is to provide “comprehensive preclinical drug screening, rather than the current practice of screening a very small subset of possible off-target interactions.”</p>
<p>The next blockbuster drugs may owe a debt to yeast and their mating practices. Who says you can’t teach an old fungus new tricks?</p><img src="https://counter.theconversation.com/content/84179/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Haydon is a researcher at the Institute for Protein Design at the University of Washington.</span></em></p>By exploiting the way yeast cells mate, researchers have figured out a quicker, easier way to identify on- and off-target drug interactions.Ian Haydon, Doctoral Student in Biochemistry, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/719032017-01-27T13:00:38Z2017-01-27T13:00:38ZFish show cheating can be better than playing by the rules in the mating game<figure><img src="https://images.theconversation.com/files/154546/original/image-20170127-30394-514ou6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The males of some species go to extraordinary lengths to attract females – but some simply cheat. Take African cichlid fish. Many males build underwater “sandcastle” structures that the females use to judge the quality of their potential mates. But, as my colleagues and I found out during a <a href="http://www.nature.com/articles/srep41128">recent study</a>, some males don’t bother with this show of construction prowess, and instead are able to father offspring by engaging in “sneaky mating”.</p>
<p>There are hundreds of species of colourful cichlid fish in Lake Malawi, Africa, and about two hundred of these build pit- or volcano-shaped structures known as “bowers” out of sand. Each species builds a slightly different type of sand bower, and they function as a signal of male quality, both to <a href="https://www.researchgate.net/profile/Martin_Genner/publication/228646881_A_role_for_male_bower_size_as_an_intrasexual_signal_in_a_Lake_Malawi_cichlid_fish/links/55846dbc08ae7bc2f4483742.pdf">other males</a>, and <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1558-5646.2010.00984.x/full">to females</a>.</p>
<p>The females are what are known as <a href="http://www.cichlid-forum.com/articles/mouthbrooders.php">mouthbrooders</a>. After courtship with their male partners, which takes place on top of the bower, the females lay eggs and pick them up in their mouths. The males then fertilise the eggs while they are still in the females’ mouths.</p>
<p>The females then carry the eggs for about three weeks until they hatch into baby fish known as “fry”. The male contributes no parental care, nothing but his genetic material. So the females need to ensure they choose high quality males, and they use the shape of his bower to do this.</p>
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<p>The males even help the females to do this by congregating in breeding arenas <a href="https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=0ahUKEwiWjoysm-LRAhXMDMAKHVWuAw8QFggxMAI&url=http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%2FBF00005175&usg=AFQjCNGuqsCgnrKZR42iP-5xSTQK5BGnaw">called “leks”</a>. The females can then visit a lek and judge a large number of males at once, usually laying only a handful of eggs with each chosen male. The ability to build and defend a bower in this hotbed of male activity is thought to demonstrate the quality of the male to the females. It takes two to three weeks for each male to build his bower and he has to work hard to maintain it over a breeding season of several weeks.</p>
<h2>No bower needed</h2>
<p>But we wondered whether there was another way that male cichlids could father offspring without building a bower. Trying to find this out in the wild would be very difficult, so we recreated a mini-version of their habitat for a breeding population of fish in <a href="http://www2.hull.ac.uk/science/biologicalbiomedicalenvironmen/facilities/aquaria.aspx">our aquarium system in Hull</a>. We then implanted tiny tracking microchips into the fish, similar to those often implanted into pets, and allowed the males to form a lek in a large tropical pond.</p>
<p>We also put microchip readers on to the bowers as they were built so we would know which males had built and were defending a bower and which weren’t. We then waited until a number of females were brooding and then DNA paternity-tested their offspring to find out which males had been most successful.</p>
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<img alt="" src="https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/154539/original/image-20170127-30416-hcy0t1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Mine’s the biggest.</span>
<span class="attribution"><span class="license">Author provided</span></span>
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<p>We found that bower-owning males were considerably more successful than non-bower owning ones, which makes evolutionary sense given the considerable effort and investment it requires. But a small number of non-bower holding males still fathered offspring, showing that an alternative strategy can be successful. Male cichlids spend a lot of time chasing away rivals. This suggests that some non-territorial males attempt to sneak past the bower holders and distract the females, persuading them to hedge their bets and mate again. </p>
<p>There’s still a lot we don’t know about these fish. How did so many species evolve in such a short evolutionary <a href="http://news.stanford.edu/news/2014/september/fish-genome-fernald-092214.html">time scale</a>? What is the genetic basis for their behaviour? What determines female preference and why? How do changes in the environment affect their ability to attract mates?</p>
<p>Studying these questions provides a wider insight into the evolution of complex behaviours and the way that female choice can shape evolution. Males who build impressive sandcastles are favoured by females, and this has driven their evolution. But it’s possible that being sneaky could also be a viable strategy for evolutionary success.</p><img src="https://counter.theconversation.com/content/71903/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Domino Joyce has received funding from the Leverhulme Trust, and NERC. </span></em></p>Some fish build sandcastles to attract a mate but others just use sneaky tactics.Domino Joyce, Senior Lecturer in evolutionary biology, University of HullLicensed as Creative Commons – attribution, no derivatives.