Different levels of inbreeding depression between outcrossing and selfing Serapias species (Orchidaceae)

We quantified inbreeding depression for fruit production, embryo vitality and seed germination in three deceptiveorchids, Serapias vomeracea, S. cordigera and S. parviflora, which do not provide any reward to their pollinators, andare predicted to experience high outcrossing. Of the three species examined only S. parviflora was autonomouslyselfing. Both S. vomeracea and S. cordigera showed highly significant differences in fitness between selfed andoutcrossed progenies, resulting in high levels of inbreeding depression, which increased in magnitude from seed set toseed germination. Inbreeding depression may promote outcrossing in Serapias by acting as a post-pollination barrier toselfing. Cumulative inbreeding depression across three stages in S. parviflora was lower that in both outcrossingspecies. The large difference in germination between selfed and outcrossed seeds is an important issue in conservationbiology.