Sex-specific assumptions and their importance in models of sexual selection

Sexual selection is a field coloured by tension and contrasting views. One contested claim is the causal link from the definition of the sexes (anisogamy) to divergent selection on the sexes. Does theory truly engage with this claim? We survey the extent to which theory makes sex-specific assumptions and engages with anisogamy, and discuss these issues in a broader context. The majority of theory in sexual selection makes sex-specific assumptions and does not engage with the definition of the sexes. While this does not invalidate existing results, debates and criticisms regarding sexual selection force us to think deeper about its logical foundations. We discuss ways to strengthen the foundations of sexual selection theory by relaxing central assumptions.