Calystegia soldanella(L.) Roem. et Schutt. is a herbaceous perennial vine with both sexual and asexual modes of reproduction. It grows only on the sand dunes and beaches of East Asia, Europe, and the Pacific. Allozyme study was conducted on leaves collected from 425 plants in 13 Korean populations. In addition, two populations ofIpomoea stolonifera(Cyrillo) Poiret., a beach dune plant species in the southeastern United States, were included in this study. The levels of genetic variability within populations ofC. soldanellaandI. stoloniferaare lower than average values for species with similar life history and ecological traits. Mean percentage of polymorphic loci within populations (Pp), mean number of alleles per locus across populations (Ap), mean effective number of alleles (Aep), and mean population genetic diversity (Hep) were: 28.2, 1.44, 1.19, and 0.100 forC. soldanellaand 15, 1.15, 1.12, and 0.066 forI. stolonifera.ForC. soldanella, the mean number of multilocus genotypes per population (G= 20) and mean genotypic diversity index (DG= 0.88) were relatively high. Analysis of fixation indices indicated considerable population substructuring within populations ofC. soldanella, partly resulting from inbreeding (meanFIS= 0.442) and/or artifacts of founder effect and clonal growth. About 85 of the total variation inC. soldanellais common to all populations. Significant differences in allele frequencies among populations were found in all but one locus (p 0.05) and average genetic identity for all pairs of populations was 0.958. Indirect estimate of the number of migrant (Nm= 1.46, calculated fromFST) indicates that the level of gene flow is moderate among Korean populations probably via seed dispersal by water. Based on available data, several factors such as wide geographic distribution, high levels of clonal diversity, moderate levels of gene flow, restricted ecological distribution, inbreeding, and founder effect may have played roles in shaping genetic structuring ofC. soldanella.
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