How the Butterflies Got Their Spots

By SCIENCEDAILY
Added: Sat, 06 Feb 2010 00:00:00 UTC

http://www.sciencedaily.com/releases/2010/02/100205213102.htm

How two butterfly species have evolved exactly the same striking wing colour and pattern has intrigued biologists since Darwin's day. Now, scientists at Cambridge have found "hotspots" in the butterflies' genes that they believe will explain one of the most extraordinary examples of mimicry in the natural world.

Heliconius, or passion-vine butterflies, live in the Americas -- from the southern United States to southern South America. Although they cannot interbreed, H. melpomene and H. erato have evolved to mimic one another perfectly.

These delicate butterflies have splashes of red and yellow on their black wings, signaling to birds that they contain toxins and are extremely unpalatable. They mimic one another's colour and pattern to reinforce these warning signals.

Scientists have studied these butterflies since the 1860s as a classic case of evolution in action, but only now is modern sequencing technology unlocking the underlying genetics.

The Cambridge-led team of researchers from UK and US universities, which has been breeding the butterflies in Panama for the past decade, has been searching for the genes responsible for the butterflies' wing patterns and the answer to the question of whether the same genes in two different species are responsible for the mimicry.

According to Dr Chris Jiggins of the Department of Zoology at the University of Cambridge, one of the authors of the study: "The mimicry is remarkable. The two species that we study -- erato and melpomene -- are quite distantly related, yet you can't tell them apart until you get them in your hand. The similarity is incredible -- even down to the spots on the body and the minute details of the wing pattern."
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http://www.sciencedaily.com/releases/2010/02/100205213102.htm