How copycat butterflies stay safe from predators

These two different species (Heliconius numata on top and co-mimic Melinaea mneme on the bottom)both taste unpleasant to predators and have developed similar markings to hammer home the message to predators: we taste foul. (c) Mathieu Chouteau

Want to avoid getting eaten? If you’re a butterfly, it seems it pays to team up with another foul-tasting species and copy each others markings.

Scientists have unlocked the genetic mechanism by which butterflies can evolve to mimic each others wing markings, observing that by forming mimicking co-pairs, two different species that both taste unpleasant can develop similar decorations to hammer home the “we taste foul” message.

“Birds in different localities prefer not to eat certain wing types. So across different places the butterflies form mimicking pairs,” said Dr Siu Fai Lee from the Department of Genetics and Bio21 Institute at the University of Melbourne, who was part of the research team that studied the genetic co-pairing.

“Both species taste bad and if they look like one another, then it is reinforcing the message. It’s in both species interests,” he said.

The study, which was published in the journal Nature, examined the Amazonian butterfly Heliconius numata and its mimicking pairs.

The researchers isolated a “supergene” that controls mimicking and observed how different versions of this gene can be switched on or off to ensure the best wing pattern is reproduced.

“This mechanism is quite neat because it prevents mistakes from happening. Those mistakes that do happen will get purged and killed quite readily,” said Dr Lee.

“People had been wondering for a long time how this is happening and how it is maintained in nature. This provides a straightforward solution.”

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