Mixing a genetic paint box leads to new butterfly wing patterns

Friday, 22 January 2016

New research involving the University of Adelaide has revealed how different butterfly species in the Amazon rainforest came to mimic one another and share identical brightly coloured patterns on their wings.

Published in the journal PLoS Biology, the team of researchers from the University of Adelaide and the University of Cambridge, sequenced the genes of 142 butterflies from 17 species to learn how mimicry can occur.

“These butterfly species are Mϋllerian mimics. That means multiple species of Heliconius butterflies copy one another’s wing pattern to deter predators,” says Dr Simon Baxter, from the University of Adelaide’s School of Biological Sciences.

"These butterflies are all toxic to predators, so by sharing the same red patterns on their wings, birds quickly learn to avoid all butterflies with the same pattern,” he says.

Analysis of the butterflies’ genes revealed a small sequence controlling the red colour patterns in Heliconius butterflies. When they looked at the fine detail, researchers discovered two regulatory elements: one controlling red stripes on the hindwing and the other controlling the red patches on the forewing.

“We traced back the evolution of the two red patterns and found that each pattern evolved in a different species, some two million years ago. Subsequently, hybridisation between different species brought these two red elements together and created the pattern we see today,” says Dr Baxter.

“This insight provides a better understanding into these insects and it appears hybridisation plays a big role in mimicry,” he says.

It has been known for some time that exchange of genes between species can be important for evolution.

This new study is the first to show such mixing of genetic material can produce entirely new wing patterns in butterflies and allow different species to share common warning signs that ward off predators.

“Heliconius butterflies with this red wing pattern are found across the Amazon rainforest, yet moving towards coastal regions of South America, their wing patterns change – the same species of butterfly has a completely different pattern in one part of South America compared to another,” says Dr Baxter.

"It’s like switching on a tiny piece of the gene's DNA to produce one wing pattern or another – like a genetic paint box," says Dr Richard Wallbank from the University of Cambridge.

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