ALLOZYME GENETIC AND CLONAL DIVERSITY WITHIN POPULATIONS OF CHIMAPHILA JAPONICA AND PYROLA JAPONICA (PYROLACEAE)

Chimapliila japonica Miq., a rhizomatous evergreen subshrub, and Pyrola japonica Klenze, an evergreen herbaceous perennial, occur mainly in conifer forests in East Asia. The levels of genetic variability within populations of C. japonica are fairly low, whereas those of P. japonica are less so. Mean percentage of polymorphic loci within populations (P p), mean number of alleles per locus across populations (A p), and mean population genetic diversity (He p) were 14.8%, 1.15, and 0.030 for C. japonica and 18.4%, 1.35, and 0.087 for P. japonica. The degree of population differentiation observed in C. japonica (mean G ST = 0.028) and P. japonica (mean G ST = 0.147) was lower than that in other plants with similar life history traits. Considering the habit and pollen and seed dispersal mechanisms, it is suggested that the low G ST of C. japonica is caused by unifying selection. For C. japonica, the mean number of multilocus genotypes per population sample (G/N = 0.19) and mean genotypic diversity index (DG = 0.69) were relatively low. On the other hand, relatively high values of clonal diversity were observed in P. japonica (G/N = 0.39 and DG = 0.93). For C. japonica and P. japonica, 14% (3/21) and 6% (5/81) of multilocus genotypes were “widespread genotypes” (genotypes occurring in more than 75% of the populations), whereas the proportions of “local genotypes” (genotypes occurring in only one population) were 33% (7/21) and 40% (22/81). About 50% and 20% of the total samples examined were homozygous multilocus-genotypes for C. japonica and P. japonica, respectively. Relatively high numbers of these genotypes and low levels of clonal diversity in C. japonica are responsible for the low levels of expected heterozygosity within populations of the species. The results indicate that, for C. japonica, clonal reproduction may act as an enhancer of genetic drift by reducing the effective size of local populations.