In distylous plant species, skewed morph ratios are not uncommon and may arise from a range of factors such as demographic stochasticity and leakage of the heteromorphic incompatibility system. Meeus et al. study microsatellite variation among 27 Belgian populations of Pulmonaria officinalis (Boraginaceae), and find that, for all genetic measures used, morph bias is more important in explaining patterns of genetic diversity than population size. Significant deviations from equal morph ratios thus not only affect plant reproductive success, but also population genetic diversity of heterostylous plant species.
