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Dryad

Data from: Stalk-eyed flies carrying a driving X chromosome compensate by increasing fight intensity

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Sep 12, 2024 version files 137.75 KB

Abstract

Exaggerated ornaments provide opportunities for understanding how selection can operate at different levels to shape the evolution of a trait. While these features aid their bearer in attracting mates or fending off competitors, they can also be costly and influenced by the environment and genetic variation. Eyestalks of the stalk-eyed fly, Teleopsis dalmanni, are of interest because eyestalk length is the target of both intra-and intersexual selection and is also reduced by loci on a highly-diverged sex ratio X chromosome (XSR), a meiotic driver accounting for up to 30% of wild X chromosomes. Male stalk-eyed flies fight to control access to females and over food using a combination of low intensity displays and high intensity physical fights. We staged, filmed and scored contests among eyespan-matched male pairs to evaluate whether X chromosome type impacts the behavior and outcome of aggressive interactions. While our results broadly match expectations from previous studies, we find that XSR males used more high intensity behaviors than males carrying a non-driving, standard X chromosome (XST), in particular when their eyestalks were of similar size or smaller than their opponents. Additionally, we find that when XSR males use high intensity behaviors they win more bouts than when they use low intensity behaviors. Taken together these results suggest that XSR impacts male aggressive behavior to compensate for the shorter eyestalks of XSR males, and may help to explain how this selfish chromosome is maintained.