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.