A ‘Male Organ’ for Flies Reveals How Evolution Invents New Body Parts
The Drosophila Sex Comb Shows How New Structures Can Emerge – Without New Genes
A male fruit fly aspiring to mate faces steep odds. First, he must spend up to 20 minutes maniacally buzzing and dancing. Even then, his success or failure hinges on a single split-second maneuver, when he vaults onto the female, parts her wings, and connects his abdomen to hers. If the gymnastics go awry, the female delivers a powerful mule-kick — sending him tumbling away.
Some species of fruit flies have met this challenge by evolving a strange new body part – a entomological male member, of sorts – resembling a hair comb. It juts off his front legs, helping him grab his mate-to-be more precisely. The evolutionary origin of this ‘sex comb’ represents a tantalizing mystery.
“It’s one thing to evolve longer legs or a different color, but for complex new structures that evolve out of nowhere — we’re still not sure how that happens,” says Ben Hopkins, who recently finished a post-doctoral fellowship in the Department of Evolution and Ecology.
New research by Hopkins and Artyom Kopp, a professor and chair of evolution and ecology, shows how one new body part – the sex comb – sprouted and bloomed with surprising ease.
“You don’t need new genes to make new structures,” says Kopp. Instead, the sex comb evolved when a handful of cells sped up their metabolism for a few hours.