New research dissects how a single genetic switch helps butterflies mimic wing patterns of other species to protect themselves from predators.
Many butterflies develop wing patterns that mimic other species to protect themselves from predators.
While growing complex body parts like wings involves many genes, the difference between two versions of the same thing-like wings in different colors-is frequently enough controlled by variation in one genetic location.
The new study in PNAS dissects the inner workings of one such “supergene” called doublesex that helps a species of swallowtail butterfly (Papilio alphenor) mimic the wing patterns of other, distantly related species that are toxic to predators.
Using modern genomic sequencing techniques and experimental tools like CRISPR to study the evolution and functions of doublesex, researchers showed how the supergene gained its ability to control wing patterns by becoming linked with other genetic elements that regulate its own expression.
“Males and females of these butterflies can have totally different color patterns with pretty much the same genome-but somehow one piece of DNA encodes those different phenotypes,” says Nicholas VanKuren, a research scientist in the ecology and evolution department at University of Chicago and lead author of the new study.
“WhatS great about this study is that we identified not onyl the differences between the two versions of that gene,” he says, “but also how those differences affected how the gene functions and turns these wing patterns on or off.”
A supergene is usually a group of neighboring genes on a chromosome that are inherited together as they function to control complex traits, such as color patterns and mating behaviors.They are often made up of tens or hundreds of individual genes linked together.
In swallowtail butterflies, however, the doublesex supergene comprises just one gene. Only females in this species develop alternate wing patterns, adding orange spots to their array of white patches to mimic other species-males k