title: Recent selection for self-compatibility in a population of Leavenworthia alabamica.
abstract: The evolution of self-compatibility (SC) is the first step in the evolutionary transition in plants from outcrossing enforced by self-incompatibility (SI) to self-fertilization. In the Brassicaceae, SI is controlled by alleles of two tightly linked genes at the S-locus. Despite permitting inbreeding, mutations at the S-locus leading to SC may be selected if they provide reproductive assurance and/or gain a transmission advantage in a population when SC plants self- and outcross. Positive selection can leave a genomic signature in the regions physically linked to the focus of selection when selection has occurred recently. From an SC population of Leavenworthia alabamica with a known nonfunctional mutation at the S-locus, we collected sequence data from a ∼690 Kb region surrounding the S-locus, as well as from regions not linked to the S-locus. To test for recent positive selection acting at the S-locus, we examined polymorphism and the site-frequency spectra. Using forward simulations, we demonstrate that recent selection of the strength expected for SC at a locus formerly under balancing selection can generate patterns similar to those seen in our empirical data.
authors.affiliation: Department of Biology, McGill University, Montreal, Quebec, H3A 1B1, Canada. aherman@umn.edu.|Current Address: Department of Plant Biology, University of Minnesota, St. Paul, Minnesota, 55108. aherman@umn.edu.
authors.forename: Adam C
authors.initials: AC
authors.lastname: Herman
authors.affiliation: Department of Biology, McGill University, Montreal, Quebec, H3A 1B1, Canada.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Schoen
mesh_terms: D000407:Alabama; D019607:Brassicaceae / Q000502:physiology*; D054817:Pollination; D012098:Reproduction; D057945:Self-Fertilization
keywords: Leavenworthia; S-locus; positive selection; selective sweep; self-compatibility