Genetic structure and mating system of northernArbutus menziesii(Ericaceae) populations

Abstract

Arbutus ( Arbutus menziesii Pursh. (Ericaceae)) is the only broadleaved evergreen tree native to Canada. It occurs in three red-listed (endangered) plant communities in British Columbia (BC), threatened by urban encroachment, fire suppression, grazing, and exotic invasive species. Its growth is sensitive to environmental changes: more severe summer drought caused by climate change could further threaten this species. Amplified fragment length polymorphisms (AFLPs) were assayed in 10 populations in BC and 1 in Washington to obtain baseline population genetic and mating system data. We found that genetic diversity within populations was low (mean H = 0.094) for a woody perennial. Genetic variation among populations (FST= 0.15) was comparable to woody perennials on average (0.19). Pairwise kinship coefficients were significantly associated with distance (p < 0.01). The multilocus outcrossing rate for one BC island population was high (tm= 0.97), but inbreeding due to consanguineous matings was also quite high (tm– ts= 0.10). These data can be used to guide conservation strategies and future research priorities for arbutus.