Effect of developmental temperature on sexual and reproductive traits of inbred and outbred female guppies (Poecilia reticulata)
Description
Global temperatures are rising and inbreeding is increasingly common in populations of wild animals as habitat becomes fragmented and local population sizes shrink. There is extensive research on how inbreeding and temperature stress affect animal performance, but little is known about how these two factors interact to affect sexually selected behavior and reproductive traits. We therefore ran a 2x2 experiment to investigate how developmental temperature (26°C or 30°C) and inbreeding (outbreeding or full-sibling mating) affect the performance of female guppies (Poecilia reticulata). We reciprocally cross-bred full-siblings to create inbred and outbred fish. We measured female sexual attractiveness (via male mate choice trial), female fecundity, egg diameter and total egg mass for ~120 females. Female attractiveness was significantly affected by an interaction between breeding status and temperature. For fish reared at 26°C, outbred females were preferred over inbred females as well as inbred and outbred females raised at 30°C. Further, there was no detectable male preference for outbred females when fish developed at 30°C. Inbreeding and an elevated developmental temperature independently reduced egg diameter, indicating that both factors had a significant negative effect on offspring provisioning. Neither inbreeding nor developmental temperature affected fecundity or total egg mass. However, larger and older females produced significantly more eggs, and larger females had significantly heavier clutches. Our results show that the fitness effects of inbreeding depend on developmental temperature: developing at higher temperature can magnify some harmful effects of inbreeding. Climate warming will likely intensify these genotype–environment interactions thereby increasing the costs of inbreeding, and potentially reducing the efficacy of sexual selection if males are less likely to pursue outbred females as temperatures rise.