Thermal environment during and outside courtship jointly determine female remating rate in Drosophila melanogaster

Abstract

The behaviour of animals, particularly ectotherms, occurs in the context of daily and seasonal fluctuations in temperature and year-on-year increases in temperature associated with global climate change. Despite the importance of mating rate as a determinant of the intensity of male/female conflict over reproduction, the effects of ecological factors such as thermal environment on this process are poorly understood. We examined how temperature affects female remating rate in Drosophila melanogaster. The mating behaviour of D. melanogaster shows a circadian rhythm, and we partitioned thermal environment effects into those experienced at the point of courtship and those experienced outside courtship bouts. Temperature during and outside courtship both affected female remating rate, and did so in an approximately additive fashion. We found that female remating rate was more sensitive to thermal environment at the point of courtship than that encountered outside courtship periods. Elevation of temperature during courtship increased male courtship intensity, and we hypothesize that this directly increased a female's likelihood of remating. Our results highlight the importance of thermal conditions during and after courtship in determining mating rate in Drosophila and we discuss its implication for rates of polyandry in natural populations in terms of daily, seasonal and spatial variation, and changes that may be associated with climate change.