title: Evolutionary dynamics of sporophytic self-incompatibility alleles in plants.
abstract: The stationary frequency distribution and allelic dynamics in finite populations are analyzed through stochastic simulations in three models of single-locus, multi-allelic sporophytic self-incompatibility. The models differ in the dominance relationships among alleles. In one model, alleles act codominantly in both pollen and style (SSIcod), in the second, alleles form a dominance hierarchy in pollen and style (SSIdom). In the third model, alleles interact codominantly in the style and form a dominance hierarchy in the pollen (SSIdomcod). The SSIcod model behaves similarly to the model of gametophytic self-incompatibility, but the selection intensity is stronger. With dominance, dominant alleles invade the population more easily than recessive alleles and have a lower frequency at equilibrium. In the SSIdom model, recessive alleles have both a higher allele frequency and higher expected life span. In the SSIdomcod model, however, loss due to drift occurs more easily for pollen-recessive than for pollen-dominant alleles, and therefore, dominant alleles have a higher expected life span than the more recessive alleles. The process of allelic turnover in the SSIdomcod and SSIdom models is closely approximated by a random walk on a dominance ladder. Implications of the results for experimental studies of sporophytic self-incompatibility in natural populations are discussed.
authors.affiliation: Department of Ecology and Genetics, University of Aarhus, Denmark. mheide@pop.bio.aau.dk
authors.forename: M H
authors.initials: MH
authors.lastname: Schierup
authors.forename: X
authors.initials: X
authors.lastname: Vekemans
authors.forename: F B
authors.initials: FB
authors.lastname: Christiansen
mesh_terms: D000483:Alleles; D005075:Biological Evolution; D005787:Gene Frequency; D008957:Models, Genetic; D010944:Plants / Q000235:genetics*; D012098:Reproduction