The Genetic Structure of a Gynodioecious Plant: Nuclear and Cytoplasmic Genes

Sex expression in gynodioecious plants is often determined by an interaction between biparentally and maternally inherited genes. Their relative rates of gene flow should be considered when modeling the evolution of the sex ratio in structured populations. In order to understand patterns of gene flow in Silene vulgaris, a gynodioecious plant, genetic structure was estimated from biparentally inherited genetic markers (allozymes) and a maternally inherited marker (chloroplast DNA) using Wright's Fst. Based on data from 16 local populations, chloroplast DNA showed considerably more genetic structure than did allozymes (Fst values of 0.62 and 0.22, respectively). This suggests that the rate of gene flow is about three times greater for nuclear genes.