Abstract

Most theoretical works predict that selfing should reduce the level of additive genetic variance available for quantitative traitswithin natural populations. Despite a growing number of quantitative genetic studies undertaken during the last two decades,this prediction is still not well supported empirically. To resolve this issue and confirm or reject theoretical predictions, we reviewedquantitative trait heritability estimates from natural plant populations with different rates of self-fertilization and carried out ameta-analysis. In accordance with models of polygenic traits under stabilizing selection, we found that the fraction of additivegenetic variance is negatively correlated with the selfing rate. Although the mating system explains a moderate fraction of thevariance, the mean reduction of narrow-sense heritability values between strictly allogamous and predominantly selfing popu-lations is strong, around 60%. Because some nonadditive components of genetic variance become selectable under inbreeding,we determine whether self-fertilization affects the relative contribution of these components to genetic variance by comparingnarrow-sense heritability estimates from outcrossing populations with broad-sense heritability estimated in autogamous popula-tions. Results suggest that these nonadditive components of variance may restore some genetic variance in predominantly selfingpopulations; it remains, however, uncertain how these nonadditive components will contribute to adaptation.