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Published on: December 2, 2022
Experimental evolution of reduced sex ratio adjustment under local mate competition
Emilie Macke1, Sara Magalhães, Fabien Bach
1Institut des Sciences de l'Evolution, UMR 5554, Université Montpellier 2, Place Eugène Bataillon, Montpellier cedex 05, France. emilie.macke@univ-montp2.fr
Abstract:
Theory predicts that local mate competition (LMC) favors the evolution of female-biased sex ratios. Empirical support of this prediction is indirect and comes from comparative studies or from studies showing that individuals can adjust their offspring sex ratio in response to varying LMC intensities. Replicate lines from a population of the spider mite Tetranychus urticae were selected under three LMC intensities for up to 54 generations. Within each selection regime, the final sex ratio matched theoretical predictions. Furthermore, the ability of individuals to adjust their offspring sex ratio diminished in females evolving under strict LMC, but not in females evolving under relaxed LMC levels. These results provide direct experimental evidence for the evolutionary process by which LMC modifies sex-allocation strategies and suggest that evolution under strict and constant LMC may lead to a loss of phenotypic plasticity.
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