Little evidence for intralocus sexual conflict over the optimal intake of nutrients for lifespan and reproduction in the black field cricket Teleogryllus commodus

Abstract

There is often large divergence in the effects of key nutrients on lifespan and reproduction in the sexes, yet nutrient intake is regulated in the same way in males and females given dietary choice. This suggests that the sexes are constrained from feeding to their sex-specific nutritional optima for these traits. Here we examine the potential for intralocus sexual conflict (IASC) over optimal protein and carbohydrate intake for lifespan and reproduction to constrain the evolution of sex-specific nutrient regulation in the field cricket, Teleogryllus commodus. We show clear sex differences in the effects of protein and carbohydrate intake on lifespan and reproduction and strong positive genetic correlations between the sexes for the regulated intake of these nutrients. However, the between-sex additive genetic covariance matrix had very little effect on the predicted evolutionary response of nutrient regulation in the sexes. Thus, IASC appears unlikely to act as an evolutionary constraint on sex-specific nutrient regulation in T.commodus. This finding is supported by clear sexual dimorphism in the regulated intake of these nutrients under dietary choice. However, nutrient regulation did not coincide with the nutritional optima for lifespan or reproduction in either sex suggesting that IASC is not completely resolved in T. commodus.