Genetic Structure and Conservation Considerations of Rare Endemic Abeliophyllum distichum Nakai (Oleaceae) in Korea

Abeliophyllum distichum

, was assessed using starch gel electrophoresis. Although A. distichum maintained relatively high genetic diversity probably due to floral heteromorphism and preferred outcrossing, their genetic variation, where small effective size of population and genetic drift are of utmost importance, was lower than the other outbreeding plants. The calculated G_sT indicated a high level of genetic differentiation among populations, suggesting that gene flow was limited. The dendrogram based on Nei's genetic distance showed that the Pu-an and the Koe-san populations fell into two distinct groups, which were consistent with geographic distance and distribution. It was probable that in the populations of A. distichum sexually reproduced individuals rarely become established within the populations. From observations, Lassioglossum bee was found to be the most effective pollinator of A. distichum. Artificial crossing experiment indicated that pollinators contributed considerably to natural population and that pollinator limitation could potentially reduce fitness of A. distichum in wild populations. The management of rare plant species should include improvement of genetic exchanges among populations by artificial gene flow. From each of the four subpopulations, fresh twigs from 20 trees should be collected and propagated as the cutting for ex situ conservation.