Geography, assortative mating, and the effects of sexual selection on speciation with gene flow

Abstract

Theoretical and empirical research on the evolution of reproductive isolation have both indicated that the effects of sexual selection on speciation with gene flow are quite complex. As part of this special issue on the contributions of women to basic and applied evolutionary biology, I discuss my work on this question in the context of a broader assessment of the patterns of sexual selection that lead to, versus inhibit, the speciation process, as derived from theoretical research. In particular, I focus on how two factors, the geographic context of speciation and the mechanism leading to assortative mating, interact to alter the effect that sexual selection through mate choice has on speciation. I concentrate on two geographic contexts: sympatry and secondary contact between two geographically separated populations that are exchanging migrants and two mechanisms of assortative mating: phenotype matching and separate preferences and traits. I show that both of these factors must be considered for the effects of sexual selection on speciation to be inferred.

Dissolved organic carbon and unimodal variation in sexual signal coloration in mosquitofish: a role for light limitation?

“…This suggests that adaptive divergence in sexual signals along environmental gradients may not necessarily favour reproductive isolation due to assortative mating by signal phenotype, a common phenomenon in fishes [56], and a hypothetically important mechanism in models of speciation with gene flow (e.g. [57,58]). …”

Women in evolution – highlighting the changing face of evolutionary biology

“…The research they describe reflects the strength and diversity of evolutionary biology today, regardless of gender. The articles in this special issue span the breadth of areas in evolutionary biology and touch upon many of the hottest topics, including sex chromosome evolution (Charlesworth ), sexual selection (Servedio ; Wellenreuther and Sánchez‐Guillén ), behavioural evolution (Aubin‐Horth ; Charmantier et al. ), evolution of cooperation (Aktipis ), diversification and speciation (Charmantier et al.…”

“…; Johannesson ; Qvarnström et al. ; Servedio ; Wellenreuther and Sánchez‐Guillén ), host–parasite interactions (Leftwich et al. ; Myers and Cory ), evolutionary change accompanying invasion (Aktipis ; Gillespie ; Haig et al.…”

“…(), for example, investigate the possibility that adaptation to different climates may drive speciation, even if this divergence is difficult to detect morphologically. Servedio (), in her recent theoretical work, has explored the interplay between sexual selection and speciation, yielding many counterintuitive results that challenge our understanding of these processes (e.g. finding that stronger sexual selection can hinder rather than promote divergence between populations and that mating preferences can reduce local adaptation of traits).…”

Insights into the genetic architecture of sexual dimorphism from an interspecific cross between two diverging Silene (Caryophyllaceae) species

“…In dioecious species, a balance between sexual conflict and natural selection will play a role in the evolution and maintenance of sexual dimorphism (Chenoweth, Rundle, & Blows, ; Lande, ). While sexual conflict will favour the evolution of sex differences, a match in floral traits within populations or species, including phenology and pollinator attraction between sexes, will favour assortative mating within species (Connallon, ; Delph & Meagher, ; Servedio, ). Consequently, the evolution of sexual dimorphism may be constrained such that assortative mating within populations is maintained.…”