Evaluation of the extent of among-family variation in inbreeding depression in the perennial herb Scabiosa columbaria (Dipsacaceae)

Significantly different maternal line responses to inbreeding provide a mechanism for the invasion of a selfing variant into a population. The goal of this study was to examine the extent of family-level variation in inbreeding depression in the mixed-mating, perennial herb Scabiosa columbaria. Plants from one population were raised, and hand-pollinated to produce selfed and outcrossed progeny, and the effects of inbreeding depression on life-cycle traits were analyzed. Inbreeding depression significantly affected early life cycle traits. The pollination treatment by family interaction was significant for almost all traits, indicating a high family-level variation in inbreeding depression. The correlations between inbreeding depression values (e.g., percentage germination and flowering date, and flowering date and aboveground biomass) exhibited alternate signs, illustrating the type of association between inbreeding depression loci for different traits across the life cycle. Overall, it is concluded that the extent of among-family variation in inbreeding depression might allow a selfing variant of S. columbaria to invade an outcrossing population, though the pattern of correlations between inbreeding depression values might prevent effective purging of the deleterious genetic load.