Protein deprivation decreases male survival and the intensity of sexual antagonism in southern field crickets Gryllus bimaculatus.

Abstract

Recent theory predicts that the magnitude of sexual antagonism should depend on how well populations are adapted to their environment. We tested this idea experimentally by comparing intersexual genetic correlations for adult survival in pedigreed populations of southern field crickets (Gryllus bimaculatus) raised on naturally balanced (free-choice) vs. imbalanced (protein-deprived) diets. We tested for (1) sex differences in nutritional intake and preference, (2) sex-specific effects of protein deprivation on survival and (3) diet dependence of the level of sexual antagonism. Adult males and females consumed a similar amount of protein, but protein deprivation decreased male survival but not female survival. Protein deprivation appeared to decrease the degree of sexual antagonism as intersexual genetic correlations were significantly lower than 1 only for the complementary free-choice diet group but close to 1 for the protein-deficient diet group. Our findings thereby implied that variation in nutritional environments can alter the magnitude of sexual antagonism. This research represents an important step towards understanding the relationship between sexual antagonism and adaptation in heterogeneous environments.