Intralocus sexual conflict over optimal nutrient intake and the evolution of sex differences in lifespan and reproduction

Despite widespread variation in lifespan across species, three clear patterns exist: sex differences in lifespan are ubiquitous, lifespan is commonly traded against reproduction, and nutrition has a major influence on these traits and how they trade-off. One process that potentially unites these patterns is Intralocus Sexual Conflict (IASC) over the optimal intake of nutrients for lifespan and reproduction. If nutrient intake has sex-specific effects on lifespan and reproduction and nutrient choice is genetically linked across the sexes, IASC will occur and may prevent one or both sexes from feeding to their nutritional optima. Here we determine whether this process is operating in the cricket Gryllodes sigillatus. We show that protein and carbohydrate intake have contrasting effects on lifespan and reproduction in the sexes and that there are strong positive intersexual genetic correlations for the intake of these nutrients under dietary choice. This divergence in nutrient effects, com...