Multiple mating rescues offspring sex ratio but not productivity in a haplodiploid exposed to developmental heat stress

Abstract

AbstractReproduction is generally more sensitive to high temperatures than survival and arguably a better predictor of the response of populations to climate change than survival estimates. Still, how temperature simultaneously impacts male and female reproductive success, the mating system and the operational sex ratio remains an open question.Here, we addressed how a sublethal high temperature affects the reproductive system of the haplodiploid spider miteTetranychus urticae. Males and females maintained at 25 or 36°C during development were paired and the fertility of both sexes, their mating and remating eagerness, and the paternity of the offspring of females with different mating histories were measured.Female and male fertility decreased at 36°C compared to 25°C, resulting in lower offspring production and a more male‐biased sex ratio, respectively, because of haplodiploidy. However, when either heat‐stressed females or females that mated with heat‐stressed males remated, there was a shift in paternity share, with more than one male contributing to the offspring. This was accompanied by reduced mating eagerness in pairs with partially sterile males and increased remating eagerness in pairs in which at least one sex was partially sterile in the first mating.The observed temperature‐induced changes in female remating eagerness and sperm use allowed restoring the offspring sex ratio, by increasing the proportion of fertilized offspring, but did not lead to the recovery of offspring number.The temperature‐induced changes in the mating behaviour and mating system should alter the interactions within and between the sexes, and with it the strength of sexual selection and sexual conflict in this species. Whether such changes are sufficient to prevent population extinction, despite the inability to recover offspring number, remains an open question.Read the freePlain Language Summaryfor this article on the Journal blog.