Ageing via perception costs of reproduction magnifies sexual selection

Abstract

Understanding what factors modulate sexual selection intensity is crucial to a wide variety of evolutionary processes. Recent studies show that perception of sex pheromones can severely impact male mortality when it is not followed by mating (perception costs of reproduction). Here, we examine the idea that this may magnify sexual selection by further decreasing the fitness of males with inherently low mating success, hence increasing the opportunity for sexual selection. We use mathematical modelling to show that even modest mortality perception costs can significantly increase variability in male reproductive success under a wide range of demographic conditions. We then conduct a series of assays suggesting that, in Drosophila melanogaster, failure to reproduce early in life may, via perception costs of reproduction, significantly reduces the subsequent fitness of males (ca 25%), due mostly to increased reproductive ageing. Altogether, our results strongly suggest that perception costs of reproduction can magnify sexual selection in a biologically significant way. Finally, we estimate that around 29% of available studies quantify sexual selection based on short-term fitness estimates that may fail to capture these effects (if they were present in their subject species), and suggest addressing the existence and impact of perception costs of reproduction across taxa should thus be a priority.