Towards an evolutionary ecology of sexual traits.

Empirical studies of sexual traits continue to generate conflicting results, leading to a growing awareness that the current understanding of this topic is limited. Here we argue that this is because studies of sexual traits fail to encompass three important features of evolution. First, sexual traits evolve via natural selection of which sexual selection is just one part. Second, selection on sexual traits fluctuates in strength, direction and form due to spatial and temporal environmental heterogeneity. Third, phenotypic plasticity is ubiquitous and generates selection and responses to selection within and across generations. A move from purely gene-focused theories of sexual selection towards research that explicitly integrates development, ecology and evolution is necessary to break the stasis in research on sexual traits.