When it comes to the mating game, it’s true that size does matter for North American male dance flies, who are most attracted to mates who display the largest inflatable abdominal sacs, says Rosalind Murray, a post-doctoral researcher in biology at the University of Toronto.
Murray’s research, published last week in Proceedings of the Royal Society B, focuses on one of the rare insect species (Rhamphomyia longicauda) in which the female partner displays sexual ornamentation to attract mates to fertilize her eggs. It is much more for common for males to display ornamentation, because doing so requires energy. The female generally devotes this energy to producing eggs and parenting.
Murray and researchers from U of T Mississauga and the University of Stirling in Scotland explored the attractiveness of two sexual ornaments common among North American female dance flies: inflatable abdominal sacs and leg scales. She and her colleagues demonstrated that larger, inflated abdominal sacs are the most alluring to the males of the species. Leg scales are important to mates only if the female in question has a small abdomen – and among this population, the males prefer females with larger leg scales.
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Image via University of Toronto.