Abstract

Abstract Maintenance of genetic variance in secondary sexual traits, including bizarre ornaments and elaborated courtship displays, is a central problem of sexual selection theory. Despite theoretical arguments predicting that strong sexual selection leads to a depletion of additive genetic variance, traits associated with mating success show rela-tively high heritability. Here we argue that because of trade-offs associated with the production of costly epi-gamic traits, sexual selection is likely to lead to an increase, rather than a depletion, of genetic variance in those traits. Such trade-offs can also be expected to con-tribute to the maintenance of genetic variation in ecologi-cally relevant traits with important implications for evolutionary processes, e.g. adaptation to novel environ-ments or ecological speciation. However, if trade-offs are an important source of genetic variation in sexual traits, the magnitude of genetic variation may have little relevance for the possible genetic benefits of mate choice.