Low genetic variation reduces cross-compatibility and offspring fitness in populations of a narrow endemic plant with a self-incompatibility system

摘要: Genetic variation was shown earlier to bereduced in smaller populations of the narrowendemic putatively self-incompatible Cochlearia bavarica. To test whether thisnegatively affects plant fitness by reducedavailability compatible mates and byinbreeding depression, we studied effects ofpopulation size pollination treatments oncross-compatibility offspring 16isolated this plant. After openpollination, compatibility crosses (i.e.,whether at least one fruit developed per markedflower), set crosses, andcumulative (number plants permaternal ovule) after 14 months a commongarden were lower for from smallerpopulations. Throughout study, cumulativefitness hand withpollen donor than open pollination(finally 73.4% lower), suggesting that severalpollen donors or single pollen higherquality are involved pollination.Moreover, cumulative afterhand selfing outcrossing(finally 69.4% indicating bothinbreeding depression reduced compatibilityafter selfing. High self-compatibility(40.6%), dry stigmas, differences thecompatibility 11 33 experimentalreciprocal between pairsconfirmed C. bavarica has asporophytic self-incompatibility system, as iscommon Brassicaceae. Our studydemonstrates, smallerpopulations species with sporophyticself-incompatibility system can experiencetwofold reductions associated withreduced genetic variability, i.e., twofoldgenetic Allee effects: via reducedcross-compatibility offspringfitness.