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Butterflies show how patterns evolve on the wing

Posted on 1 July 2014

A handful of highly specific genetic “switches” can control a kaleidoscopic diversity of colours and wing patterns in butterflies, scientists will demonstrate at this year’s Royal Society Summer Science Exhibition.

Photo: Heliconius erato erato, Credit: C. Jiggins

The research, which is based on recent studies in the jungles of Central and South America, has focused on variants of Heliconius, or passion vine, butterflies, and shows that the wide range of patterns found in their wings depends on where and when particular genes are turned on or off in the wings.

The process by which these switches change is known as “regulatory evolution”, and according to scientists, appears to be one of the most important processes responsible for generating the huge diversity of animal life on Earth.

The findings will be presented by a research team from Cambridge, Sheffield and York at the exhibition in central London, which begins on July 1.

“Over recent years, the Heliconius butterflies have become a great system for studying how genes control the diversity of animal forms that we see in the natural world,” Dr Chris Jiggins, from St John’s College, Cambridge, said.

Heliconius butterflies are brightly coloured to advertise their toxic defensive chemicals. Decades of genetic experiments have shown that the amazing diversity of these bright wing patterns is controlled by just a few genes.

Dr Richard Wallbank, also at the University of Cambridge, said: “One example is a gene called optix, which is switched on in the wings of the butterfly pupa. Wherever optix is switched on, the wings will become red.”

Switches in the DNA control when and where optix is turned on. In this way the same shared gene, optix, can produce a wide variety of dazzling wing pattern forms.

Although the research has focused on butterflies, its implications are much wider. Despite the range of animals on earth, most share a surprisingly similar set of genes. A major problem in biology is explaining the great diversity of shapes and forms seen among animals, while accounting for this similarity.

Many Heliconius butterfly species have very similar wing colour patterns, a phenomenon known as mimicry. “We have found that one butterfly species can gain its protective colour pattern genes ready-made from a different species by hybridizing (or interbreeding) with it. A much faster process than having to evolve one’s colour patterns from scratch,” said Dr Kanchon Dasmahapatra from the Department of Biology at the University of York.

‘Our work is important for understanding the fundamental basis of evolution – how this happens at the level of the DNA sequence. It just so happens we can do this while studying beautiful animals like butterflies that live in exotic places like the Amazon,’ said Dr Nicola Nadeau, of the University of Sheffield.

Regulatory evolution is one explanation, and in all likelihood a principal cause. “This research is part of a much bigger picture of understanding how the great diversity of animal life that we see on earth today has evolved,” Dr Jiggins added.

The research was funded by the Biotechnology and Biological Sciences Research Council, the Natural Environment Research Council and the Leverhulme Trust. 

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