Allozyme and clonal diversity in Korean populations of Ardisia japonica and Ardisia crenata (Myrsinaceae)

Using allozymes as genetic markers, genetic and genotypic diversity of Kore an populations of Ardisia japonica and A. crenata, insect-pollinated and se lf-compatible subshrubs. were investigated to infer the establishment histo ry of populations. Populations of the two species maintained low levels of allozyme diversity (expected heterozygosity = 0.061 for A. japonica and 0.0 48 for A. crenata). The average genotypic diversity index for the two Ardis ia species is also low, and the degree of population differentiation observ ed in A. japonica was high. It is suggested that populations are establishe d (colonized) from only a few seeds via long-distance seed dispersal by bir ds. The resulting adult populations would consist of only a few reproductiv e adults (founders) and the population will experience a genetic bottleneck coupled with limited migration. The process results in lower genetic diver sity within populations and increased genetic diversity among populations f ound in A. japonica. Genotypic diversity among populations of A. japonica w as large, and no 'widespread genotypes" were observed. These findings sugge st that the present populations of A. japonica might have been founded from sexually produced seed rather than asexually by fragmentation and dispersa l of preexisting clones. For A, crenata. however, one widespread genotype o ccurred at a high frequency due to extensively clonal spread in populations , resulting in the low genetic differentiation among populations (G(ST)). T hus, allozyme data suggest that the pattern of colonization and clonal repr oduction rather than gene flow are important factors in shaping population genetic structure in Ardisia species.