The ecology of sexual conflict: Temperature variation in the social environment can drastically modulate male harm to females

Sexual conflict is a fundamental driver of male/female adaptations, an engine of biodiversity and a crucial determinant of population viability. Sexual conflict frequently leads to behavioural adaptations that allow males to displace their rivals, but in doing so harm those same females they are competing to access, which can decrease population viability and facilitate extinction. We are far from understanding what factors modulate the intensity of sexual conflict and particularly the role of ecology in mediating underlying behavioural adaptations. In this study, we show that, in Drosophila melanogaster, variations in environmental temperature of +/- 4 degrees C decrease male harm impact on female fitness by between 45% and 73%. Rate-sensitive fitness estimates indicate that such modulation results in an average rescue of population productivity of 7% at colder temperatures and 23% at hotter temperatures. Our results: (a) show that the thermal ecology of social interactions can drastically modulate male harm via behavioural plasticity, (b) identify a potentially crucial ecological factor to understand how sexual conflict operates in nature and (c), along with recent studies, suggest that behaviourally plastic responses can lessen the negative effect of sexual conflict on population viability in the face of rapid environmental temperature changes.