A Measure of the Various Modes of Inbreeding in Kalmia latifolia

Inbreeding can occur in several ways. For a given species, analysing overall inbreeding down to its component parts can be useful in explaining how and why inbreeding is maintained in a population. Kalmia latifolia , a long-lived evergreen shrub, was chosen for this study for two reasons: its unique floral morphology suggested that it was specially adapted to assure reproduction in the delayed mode of self-fertilization, and previous studies had suggested that populations that were more limited by pollinators showed higher rates of within-flower self-fertilization when pollinators were excluded. Floral manipulations, controlled pollinations, and paternity analysis were performed to determine the most common form of inbreeding within a flower, among flowers of one individual, or among related individuals. Although plants are capable of setting seed within a flower, the overall rate of inbreeding was low. Among the modes of inbreeding within one individual, a negligible selfing rate among emasculated flowers suggests that selfing is more prevalent within a flower than among flowers on the same plant. In addition, as the multi-locus estimate of inbreeding was less than the single-locus estimate, inbreeding among related individuals also contributes to the natural level of inbreeding.