Behavioral studies of sexual selection tend to focus on events that lead up to copulation and the transfer of sperm. Not surprisingly, we know most about how the selective forces prior to copulation act on female choice and male--male competition. The playground for postcopulatory processes is the female genital tract where we expect male and female adaptations to control fertilization. Because postcopulatory processes are hidden away within the female reproductive tract, there are only few systems (e.g., some birds and insects) where they are well understood. In spiders, studies have revealed an astonishing diversity in precopulatory selection processes with female choice and male--male competition the focus of investigations. Recent work on sperm morphology, seminal fluids, and the fertilization process in spiders has highlighted an astonishing and clearly underappreciated diversity. The aim of this "Ideas" paper is to bring together recent advances in sperm and genital morphology with behavioral studies of sexual selection in spiders. By combining these 2 fields, we aim to identify patterns linking pre and postcopulatory process and highlight the power of combining morphological and behavioral studies. Copyright 2011, Oxford University Press.
