Australia’s first supermodel … no, not that one

Could the zebra finch’s growing popularity ruffle The Body’s feathers? Tracey Nearmy/AAPIMAGE

Long before Elle Macpherson staked her claim to the title, indeed by the end of the 1890s, Australia had inadvertently exported a model to the northern hemisphere that has become internationally famous, the focus of multi-million dollar projects, and the subject of hundreds of articles.

As with some of the more recent antipodean stars such as Kylie, this model is well-known, in the right circles, for its singing and appearance.

Introducing the Zebra finch, Taeniopygia guttata, a bird familiar to many as a childhood pet.

Over the past few decades, this little Aussie has become one of the most important model systems in modern biology and is now the most studied bird in the world.

The crowning glory for this 10-gram finch was that it became just the second bird for which the entire genome was sequenced, following work by a 20-institution team in the US and Europe and funded by government research funds in those countries.

That publicly accessible genome now provides a very rich resource for understanding how a bird’s genes are arranged and control every aspect of its development, morphology and behaviour.

Most of that work lies in the future and the sequenced genome of the zebra finch provides a framework that will ensure this Australian species plays a central role in the next generation of biological research.

Simon Griffith

In the past half-century, modern biology has developed and utilised a number of famous “animal models” such as the fruit fly, Drosophila melanogaster, a roundworm Caenorhabditis elegans, the zebra fish Danio rerio and the laboratory mouse Mus musculus.

The benefits of concentrating research effort on a few species is considerable. Every new incremental finding can be better interpreted and placed in context against the huge background of other detailed information about that particular organism.

That, in turn, helps develop a deep understanding of animal evolution, genetics, development, physiology and behaviour.

Logistically, it’s also far easier to work on a species for which generations of earlier workers have perfected methods of holding, breeding and raising in captivity, and that, to a large degree, have adapted to laboratory conditions.

While most of the research conducted on these animal models may seem quite arcane to most people, such model systems have a profound effect on our ability to understand biological systems at a fundamental level, contributing to diverse fields such as medicine, cognitive science, and the effort to conserve biodiversity.

The zebra finch has become a particularly important model in the study of neuroscience, and specifically how a brain can support the higher mental processes of language development.

Dreams from my father

The song of the male zebra finch (see above) is learned from his father during adolescence by listening and copying in a process that reflects the acquisition of language in a human infant, as they progress from babbling to the formation of words.

It is hoped that eventually work currently being done by research teams in the US will identify genes that will in turn lead to treatments for speech disabilities related to autism and strokes.

The animal models that are used today are selected because they are easy to work with and represent different elements of the tree of life.

The zebra finch is a great model system as a product of the landscape in which it evolved over millions of years – the Australian outback: one of the toughest and most unpredictable environments in the world.

The zebra finch has evolved to overcome the challenge of this environment by ranging around the desert in small social groups. When good conditions are found in this land of boom and bust individuals rapidly nest and produce youngsters.

Remarkably they will breed at any time of the year and for as long as the conditions allow, before the desert dries out once again and the opportunity is lost.

They have the fastest developmental rate of any bird, with the young able to fly within two weeks of hatching, becoming sexually mature and breeding at just over two months of age.

All of these characteristics have made them the perfect bird to study in the laboratory, particularly for evolutionary studies where it is quite possible to work on several generations in the space of a short-term research grant.

Being socially monogamous and having life-long pair bonds, the social and mating system of the zebra finch is actually far more similar to ours than any of the mammals on which behavioural research is typically conducted, none of which are socially monogamous.

The zebra finch also provides an excellent opportunity to investigate, through experiments and cross-generational studies, the evolutionary dynamics of gender roles and strategies in a social system that fundamentally is very similar to our own.

Simon Griffith

Bird brain

If the questions addressed are appropriate and taken in the right context, it is reasonable to learn about ourselves from a bird because evolution is a fundamental process and the mechanisms through which Darwinian selection will act apply equally to modern humans as to a bird in the desert or the laboratory.

The zebra finch has been used to experimentally examine the dynamics of conflict between male and female partners over the level of investment in their offspring.

That conflict exists because each individual has the potential to increase its own fitness at the expense of its partner by investing in alternative strategies.

These alternatives differ between males and females in similar ways across sexually reproducing animals.

In organisms with internal fertilisation and social pair bonds, female behaviour and investment in offspring is underscored by a confidence that the offspring are genetically hers.

Males can never be as confident because it is possible that other males may have copulated with their female partner, and this results in a different set of selective pressures on male behaviour and investment.

The specifics of parental care in zebra finches and humans are obviously very different but the fundamentals guiding selection on male and female investment strategies are similar.

The evolutionary dynamics can be demonstrated through experimental manipulation in a bird model in a way that is not ethically or logistically possible in a human.

Preventing a male bird from seeing his partner for a few hours during her fertile period may subsequently change the effort he makes in parental care weeks later.

The guiding principle when deciding when it would be appropriate to extrapolate from one animal to another (humans included) is whether there is a common fundamental biological process in play.

As such, the zebra finch is more comparable to all other birds than it is to humans, and intensive studies of this model in the laboratory have provided important insight into many areas of avian biology.

Ultimately, by understanding how birds work through detailed studies of common and abundant birds such as the zebra finch, we will be better placed to manage and conserve those birds that are at a higher risk of extinction.

So next time you hear the distinctive “meep meep” of a $5 zebra finch in a pet shop, don’t underestimate what this iconic species can tell us about the ourselves and the biological systems that are so important to the future health of the planet.

As for Elle Macpherson … she’s done not too badly at all.

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