Phenotypic Fitness Differs by Mating System in Clarkia xantiana Species
A change in plant mating system from outcrossing to selfing is a common evolutionary shift. Sometimes this shift is accompanied by species divergence: even as both species are still able to reproduce both ways, each subspecies tends to one system of mating. Selfing is associated with lower genetic diversity and higher incidence of passing on deleterious alleles, which can result in fitness, reproductive and otherwise. Here, we analyze second generation Clarkia xantiana plants that are either the offspring of selfing or outcrossing for several fitness-related phenotypes. The rate of seed fertilization was significantly associated with mating system, but germination rate and plant dry mass were not. Differences in fertilization rate by mating system were largely driven by a few individual plants, possibly indicating that over time, differences in fertilization rate between mating system become more pronounced. Further research could investigate genomic links between lower fitness and recessive allele frequency, varied by mating system.