"These females are definitely committed to being 'stay-at-home-moms' because they're basically a huge sac of eggs," said Sara Lewis, professor of biology at Tufts and co-author of the paper. By giving up wings, such flightless females can devote all their energy to churning out eggs and so gain an advantage over their winged cousins.
"Since wingless females would already enjoy high reproductive output, we thought males might no longer need to support their partners' reproduction with added nutrients," explained Tufts doctoral candidate Adam South, the lead author on the paper.
Working with firefly experts from around the world, the Tufts biologists studied the reproductive structures of 32 different species. They confirmed that in those with flying females, males did bestow nuptial gifts. In most species with flightless females, however, the males did not do so.
Looking Back at the First Fireflies
The researchers also peered back in time to the first fireflies.
In collaboration with colleagues in Georgia and Taiwan, the Tufts biologists used existing knowledge of the evolutionary relationships among different firefly species to examine how flight and nuptial gifts have changed over time.
In very early fireflies, the biologists discovered, females sported normal wings and accepted nuptial gifts from their male suitors. But the evolutionary tree also showed that nearly every time females stopped flying around, their partners retreated to transferring only sperm, revealing a surprising evolutionary correlation between these male and female traits.
So just like people, firefly couples also adjust how much effort each one will devote to work -- flight in this case -- or to family. With stay-at-home moms investing more in reproduction, some firefly males apparently decid
|Contact: Kim Thurler|