Sexually antagonistic polymorphism in simultaneous hermaphrodites

Abstract

In hermaphrodites, pleiotropic genetic tradeoffs between female and male reproductive functions can lead to sexually antagonistic (SA) selection, where individual alleles have conflicting fitness effects on each sex function. While an extensive theory of SA selection exists for dioecious species, these results have not been generalized to hermaphrodites. We develop population genetic models of SA selection in simultaneous hermaphrodites, and evaluate effects of dominance, selection on each sex function, self-fertilization, and population size, on the maintenance of polymorphism. Under obligate outcrossing, hermaphrodite model predictions converge exactly with those of dioecious populations. Self-fertilization in hermaphrodites generates three points of divergence with dioecious theory. First, opportunities for stable polymorphism decline sharply and become less sensitive to dominance with increased selfing. Second, selfing introduces an asymmetry in the relative importance of selection through male versus female reproductive functions, expands the parameter space favorable for the evolutionary invasion of female-beneficial alleles, and restricts invasion criteria for male-beneficial alleles. Finally, contrary to models of unconditionally beneficial alleles, selfing decreases genetic hitchhiking effects of invading SA alleles, and should therefore decrease these population genetic signals of SA polymorphisms. We discuss implications of SA selection in hermaphrodites, including its potential role in the evolution of “selfing syndromes”.

Selection for pollen competitive ability in mixed-mating systems

“…As is visualized in Figures and , invasion conditions and equilibrium allele frequencies under both selfing modes assuming haploid control of pollen competitiveness are qualitatively similar to those derived using models provided in Jordan and Connallon (), where competitiveness is under paternal genotype control (for derivation of analytical results, see Supporting Information; for models and discussion of analytical solutions, see Appendix ). They also found selfing and dominance restrict potential for stable polymorphism and ultimately diminish selection through male function.…”

“…By comparing invasion conditions and equilibrium allele frequencies under haploid and diploid control (as seen in Jordan and Connallon ) of pollen ability (Figs. and ), we demonstrate that the form of genetic control overseeing competitive ability has important implications for the fate of an allele conferring an advantage to pollen ability.…”

Sex‐biased gene expression, sexual antagonism and levels of genetic diversity in the collared flycatcher (Ficedula albicollis) genome

“…One factor that could potentially contribute to maintenance of genetic diversity is sexual conflict. Here, opposing directions of selection in males and females for sexually antagonistic alleles (intralocus sexual conflict) should increase the fixation time for positively selected mutation and act towards stable maintenance of segregating variation (Connallon & Clark, , ; Jordan & Connallon, ), that is, one form of balancing selection. Loci experiencing balancing selection are expected to show an excess of intermediate frequency variants, elevated diversity and longer coalescence times than under neutrality (Charlesworth, ; Hudson & Kaplan, ; Turelli & Barton, ).…”

Fruit shape and reproductive self and cross compatibility for the performance of fruit set in an andromonoecious species: Xanthoceras sorbifolium Bunge

“…Theoretical sexual selection studies in plants have predicted the presence of conflict between attributes affecting individual or both male and female functions (Bedhomme et al 2009;Jordan and Connallon 2014); thus, floral traits evolution is expected to mirror the balance between male and female selection forces (Runquist et al 2017). The allocation of resources between male and female dictates their respective fitness (known as "Bateman's principle" (Bateman 1948)).…”