AUTOGAMY AND INBREEDING DEPRESSION IN MOUNTAIN-LAUREL, KALMIA-LATIFOLIA (ERICACEAE)

We compared breeding systems, inbreeding depression, and pollination limitation between two populations of Kalmia latifolia in Virginia and Rhode Island. Plants were autogamous in Virginia but not Rhode Island. Although autogamy with selfing is hypothesized to reduce levels of inbreeding depression, both populations showed similarly high inbreeding depression manifested as reduced fruit set. Autogamy may be uncorrelated with selfing rate because autogamy is not obligate and because geitonogamy is likely. Autogamy in the Virginia population seems most likely to have evolved for reproductive assurance under competition for pollinator service. Fruit set was pollination limited in the Virginia population apparently because bumblebee pollinators were more attracted to a coflowering species, Vaccinium erythrocarpum.