Strong sexual selection in males against a mutation load that reduces offspring production in seed beetles

Theory predicts that sexual reproduction can increase population viability relative to asexual reproduction by allowing sexual selection in males to remove deleterious mutations from the population without large demographic costs. This requires that selection acts more strongly in males than females and that mutations affecting male reproductive success have pleiotropic effects on population productivity, but empirical support for these assumptions is mixed. We used the seed beetle Callosobruchus maculatus to implement a three-generation breeding design where we induced mutations via ionizing radiation (IR) in the F0 generation, measured mutational effects (relative to non-irradiated controls) on an estimate of population productivity in the F1, and effects on sex-specific competitive lifetime reproductive success (LRS) in the F2. Regardless of whether mutations were induced via F0 males or females, they had strong negative effects on male LRS, but a non-significant influence on female ...