Diet quality impairs male and female reproductive performance and affects the opportunity for selection in an insect model

Environmental factors can have profound effects on the strength and direction of selection and recent studies suggest that such environment-dependent selection can be sex-specific. Sexual selection theory predicts that male fitness is more condition dependent compared to female fitness, suggesting that male fitness is more sensitive to environmental stress. However, our knowledge about the effect of environmental factors on sex-specific reproductive performance and on sex differences in the opportunity for selection is still very limited. In the present study, we investigated the sex-specific effects of diet quality (yeast deprivation and flour type) in the red flour beetle Tribolium castaneum. Specifically, we manipulated yeast supplementation in wheat and whole-wheat flour in competition assays allowing to test for sex-specific effects of food quality (i) on reproductive success and (ii) on the opportunity for selection. Our data show that yeast deprivation in wheat flour had signific...