Fly with Me

Flies, like other animals, go to great lengths to secure a mate. But rather than ripping the head off a passing antelope as a gift (or perhaps just buying flowers) the fruit fly Drosophila have evolved a different trick. These male flies produce sperm that are up to 20 times as long at their bodies (pictured surrounding the fly on the right) – that’s 1000 times longer than human sperm. Longer sperm settle better in the female fly’s coiled reproductive tract, displacing smaller sperm from other sexual encounters. Whereas some species evolve attractive antlers, tails or horns, this example of post-copulatory sexual selection uses simple anatomy, and not female recognition, to settle competition between the males – possibly suggesting hidden depths to sexual selection in other species.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Image from work by Stefan Lüpold and colleagues
• Center for Reproductive Evolution, Department of Biology, Syracuse University, NY, USA
• Image copyright held by Nature Publishing Group 2016
• Published in Nature, May 2016