Comparisons of genetic diversity in a narrow endemic, Impatiens hypophylla, and in its widespread congener .1. Textori (Balsaminaceae)

Genetic diversity in two species of Impatiens in Korea was investigated using starch gel electrophoresis. Impatiens hypophylla is a rare species endemic to southwestern Japan and southeastern Korea, whereas I. textori is widespread in East Asia. Impatiens textori has considerably higher genetic diversity than I. hypophylla. For example, mean values of genetic diversity within populations (He) of I. textori and I. hypophylla were 0.206 and 0.102, respectively. The high outcrossing rate (mean (t) under bar = 0.89), abundance and widespread distribution, and large population size may be factors responsible for the maintenance of high levels of genetic variation in I. rex tori. Analyss of fixation indices indicated that considerable population substructuring within populations of I. hyophylla, partly resulting from inbreeding and/or genetic drift in small populations coupled with limited gene flow (mean F-IS = 0.699). However, the degree of population divergence observed in I. hypophylla (mean G(ST) = 0.059) was considerably lower than that in other plants with similar life history traits. It is supposed that similar selection at populations of I. hypophylla examined might maintain similar gene frequencies in isolated populations.