Sexual selection and novel mutations: Empirical tests for good genes indirect benefits and variable search effort

Abstract

In this thesis, I use 10 populations of Drosophila melanogaster, each fixed for a different visible recessive mutation to investigate two outstanding issues in sexual selection research. First, to quantifty indirect benefits of female mate choice and explore the nature of genotype x environment interactions for different fitness components, I estimated the effects of these mutations on male sexual fitness and productivity in the population's ancestral laboratory environment, as well as a novel food environment. Indirect benefits in the ancestral environment were lacking, suggesting that a good genes process is not acting. Cross-environment correlations were not conducive to indirect benefits following colonization of a novel environment. Second, to investigate the contribution of variable search effort to variance among males in mating success, I conducted mate choice trials to compare the relative mating success of mutant males in small vs. large arenas. Sexual selection against mutant males was stronger when search effort was included than when it was excluded, indicating that varying ability to find mates may increase the strength of selection against deleterious alleles.