Do Longevity and Fecundity Change by Selection on Mating Success at Elevated Temperature?: Correlated Selection Responses in Drosophila buzzatii

Abstract

Adaptation to environmental temperature depends on both direct and correlated responses to selection for reproduction and survival at elevated temperature. Sexual selection is one of the most powerful of all evolutionary forces and we tested both fecundity and longevity for their correlated responses to sexual selection on the ability to mate (mating success) at high temperature. Replicated lines selected for 15 generations of mating at 33 °C (S lines) were compared to their respective controls (C lines) in D. buzzatii in three thermal regimes: 25 °C, 30 °C and a cyclic thermal regime for longevity from 17 to 32 °C. Previous work showed that S lines successfully responded for the trait selected and the present results show a trade-off in males between mating success at elevated temperature and longevity in all three thermal regimes tested. In addition, inter-sexual relationships of trade-offs were apparent between male longevity and female fecundity as correlated selection responses. In this sex-specific association of trade off, S females exhibited higher fecundity than C females at 30 °C only if females were exposed to a limited social environment of a single male. Overall, selection for mating at high temperature increases female fecundity at high temperature but decreases longevity in males. This sex-specific and negative impact on longevity in males could be the result of a genetic correlation between mating success at high temperature and reduced longevity in this sex.