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Fly with Me
08 September 2016

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

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BPoD stands for Biomedical Picture of the Day. Managed by the MRC Laboratory of Medical Sciences until Jul 2023, it is now run independently by a dedicated team of scientists and writers. The website aims to engage everyone, young and old, in the wonders of biology, and its influence on medicine. The ever-growing archive of more than 4000 research images documents over a decade of progress. Explore the collection and see what you discover. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.

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