Contrasting levels of genetic diversity between the common, self-compatible Liparis kumokiri and rare, self-incompatible Liparis makinoana (Orchidaceae) in South Korea

Abstract

Levels of allozyme variation and intrapopulation spatial genetic structure of the two terrestrial clonal orchids Liparis kumokiri, a self-compatible relatively common species, and L. makinoana, a self-incompatible rare species, were examined for 17 (N = 1875) and four (N = 425) populations, respectively, in South Korea. Populations of L. makinoana harboured high levels of genetic variation (He = 0.319) across 15 loci. In contrast, L. kumokiri exhibited a complete lack of allozyme variation (He = 0.000). Considering the lack of genetic variability, it is suggested that current populations of L. kumokiri in South Korea originated from a genetically depauperate ancestral population. For L. makinoana, a significant deficit of heterozygosity (mean FIS = 0.198) was found in population samples excluding clonal ramets, suggesting that pollen dispersal is localized, generating biparental inbreeding. The significant fine-scale genetic structuring (≤ 2 m) found in a previous study, in addition to the moderate levels of population differentiation (FST = 0.107) and the significant relationship between genetic and geographical distances (r = 0.680) found here, suggests a leptokurtic distribution of seed dispersal for L. makinoana. Although populations of L. makinoana harbour high levels of genetic variation, they are affected by a recent genetic bottleneck. This information suggests that genetic drift and limited gene flow could be the main evolutionary forces for speciation of a species-rich genus such as Liparis. © 2007 The Linnean Society of London.