Butterfly species a master of disguise

Supergene allows butterfly to mimic several species

The tasty Heliconius numata butterfly evades predators by copying the wing patterns of foul-tasting Melinaea butterflies. H. numata, also known as the passion-vine butterfly, has to get the pattern exactly right or a sharp-eyed bird will spot the fake and gobble it up.

Tasty Heliconius numata butterflies (right) mimic the wing patterns of foul-tasting Melinaea butterflies (left) to avoid getting eaten. Genetic tricks using a supergene allow the butterflies to faithfully masquerade as other species. © Mathieu Joron

Born mimics, members of the species lock in wing patterns with flipped-around bits of DNA, Richard ffrench-Constant of the University of Exeter in England and colleagues report online August 14 in Nature.

The flipped DNA causes six or more genes — on a section of a chromosome important in setting wing patterns in butterflies and peppered moths — to be inherited as a single unit, a supergene. Different versions of the super­gene allow H. numata to adopt seven different wing patterns reminiscent of several bad-tasting species.

Other Heliconius butterflies mimic only one nonpalatable species. Researchers aren’t sure if other butterfly species use DNA flipping to determine their patterns. 

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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