The endangered herb Kirengeshoma palmata, from eastern Asia, has had its population severely reduced in number through habitat loss and fragmentation. All of the individuals within five subgroups at Mt. Baek-un-san, in the southern part of Korea, were genetically surveyed by allozyme analysis. Genetic diversity levels within subgroups were relatively high, and a consistently high outcrossing rate as well as a negligible biparental mating rate were confirmed by this study. Several groups of visibly connected ramets were observed in a clustered distribution which suggested cloning. Absence of mating partner rather than pollinators decreased seed production in small mating groups. The present genetic structure of the five subgroups was probably the result of local extinction of intervening populations. Because K. palmata may be a self-incompatible species, populations with few genets face lowered seed set due to mate scarcity. Thus, this type of population may be at an increased risk of extinction as a result of inbreeding depression, loss of genetic variability, and reduced sexual reproduction. The small, genetically depauperate subgroups may need an input of seeds or plants from other populations in China or Japan in order to regenerate, but the possibility of outcrossing depression leads us to recommend outbreeding among the local subgroups of Mt. Baek-un-san to restore genetic variability.

Patterns of variation at 27 allozyme loci were investigated in the endangered endemic plant Megaleranthis saniculifo. lia. Levels of allozyme variation (A = 1.47, P = 40%, He = 0.088) were also compared with other endemic plant species. Genetic divergence between populations was very high (Gsr = 0.271), with moderate to high interpopulation differentiation, which probably arose through historical bottlenecks in a landscape of habitat fragmentation and/or human influence. The percentage of polymorphic loci, heterozygosity, and mean number of alleles per locus were positively related to population size, probably due to the stochastic loss of rare alleles in the smaller populations. Individuals in the small and marginal populations (TB, KD, and CJ) showed higher proportions of fixed loci. These ecologically marginal populations were typically more distant from the nearest neighboring population and were more genetically distinct from one another. The genetic structure of the current population of M. saniculifolia is probably the result of local extinctions of intervening populations. This, in turn, is due to the Pleistocene climatic change and increased habitat destruction. A positive association appears to exist between genetic diversity and population size. Although these small population sizes are more sensitive to stochastic events, securing a certain number of individuals from the three larger populations (SB, JB, and TG) could be accomplished as part of a conservation strategy. In addition, it is important to prioritize populations in different regions in order to limit population declines caused by large-scale environmental catastrophes.

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