GENETIC-VARIATION AND POPULATION-STRUCTURE IN KOREAN ENDEMIC SPECIES .4. HEMEROCALLIS HAKUUNENSIS (LILIACEAE)

Hemerocallis hakuunensis, a Korean endemic species, maintains consider ably higher levels of allozyme variation within populations (mean He=0 .253) and substantially lower levels of allozyme divergence among popu lations (mean G(ST)=0.077) than average values reported for other inse ct-pollinated, outcrossing herbs. Indirect estimates of the number of migrants per generation (Nm=3.00, calculated from G(ST); Nm=3.57, calc ulated from the frequency of nine alleles unique to single populations ) indicate that gene flow has been extensive in H. hakuunensis, This i s somewhat surprising when we consider the fact that no specialized se ed dispersal mechanism is known, flowers are visited by bees, and the present-day populations of the species are discontinous and isolated. Results of a spatial autocorrelation analysis based on mean allele fre quencies of 19 populations reveal that only 13% (95/720 cases) of Mora n's / values for the ten interpopulational distance classes are signif icantly different from the expected values and no distinct trend with respect to the distance classes is detected. Although it is unclear ho w the populations are genetically homogenous, it is highly probable th at H. hakuunensis might have a history of relatively large, continuous populations that had more chance for gene movement among adjacent pop ulations after the last Ice Age. In addition, occasional hybridization with H. thunbergii in areas of sympatry in the central and southweste rn Korean Peninsula may be one factor contributing the present-day hig h allozyme variation observed in H. hakuunensis.