Sexual selection in socially-structured, polyandrous populations: Some insights from the fowl

Sexual selection is widely recognized as the evolutionary agent driving male exaggeration and strategies of intrasexual competition over repro- ductive opportunities. Two advances have characterized the development of our understanding of sexual selection in recent years. The first was the realization that sexual selection can extend to post-copulatory episodes whenever females mate with multiple males (polyandry). The second con- cerns the operation of sexual selection in structured population in light of increasing evidence that populations are often non-randomly assem- bled. Populations of domestic fowl (Gallus domesticus) and red jungle- fowl (Gallus gallus), which are typically socially-structured and polyan- drous, have offered a convenient vertebrate model system to study pat- terns and mechanisms of sexual selection, providing a helpful counter- point to studies of socially monogamous systems. Here, we review our understanding of the way sexual selection operates in these populations, with emphasis on recent work focusing on the interrelated implications of polyandry and social structure.