Sexual selection shapes development and maturation rates in Drosophila

Explanations for the evolution of delayed maturity usually invoke trade-offs mediated by growth, but processes of reproductive maturation often continue long after growth has ceased. Here, we tested whether sexual selection shapes the rate of post-eclosion maturation in the fruit fly Drosophila melanogaster. We found that populations maintained for more than 100 generations under a short generation time and polygamous mating system evolved faster post-eclosion maturation and faster egg-to-adult development of males, when compared to populations kept under short generations and randomized monogamy that eliminated sexual selection. An independent assay demonstrated that more mature males have higher fitness under polygamy, but this advantage disappears under monogamy. In contrast, for females greater maturity was equally advantageous under polygamy and monogamy. Furthermore, monogamous populations evolved faster development and maturation of females relative to polygamous populations, wit...