Speciation by sexual selection: 20 years of progress

Twenty years ago, a seminal paper summarized the role of sexual selection in speciation as the coordinated evolution of (male) courtship signals and (female) preferences leading to prezygotic (behavioral) isolation between divergent lineages. Here, we discuss areas of progress that inspire an updated perspective. First, research has identified multiple mechanisms of sexual selection, in addition to female mate choice, that drive the origin and maintenance of species. Second, reviews and empirical data now conclude that sexual selection alone will rarely lead to reproductive isolation without ecological divergence, and we discuss the assumptions and possible exceptions underlying that conclusion. Finally, we consider the variable ways in which sexual selection contributes to divergence according to the spatial, temporal, social, ecological, and genomic context of speciation. We revisit a seminal paper on sexual selection and speciation published two decades ago by Panhuis et al. in TREE.Our understanding of the role of sexual selection in speciation has expanded over the past 20 years.Several different mechanisms of sexual selection beyond female choice contribute to speciation.Sexual selection and its interactions with ecological, temporal, spatial, social, and genomic context have important and varying roles in speciation.