Allozyme variation and population structure of Carex humilis var. nana (Cyperaceae) in Korea

Abstract

Genetic diversity and population structure of 22 Carex humilis var. nana Ohwi (Cyperaceae) populations in Korea were determined using genetic variation at 23 allozyme loci. This is a long-lived herbaceous species with a widespread distribution in eastern Asia. The 12 enzymes revealed 23 putative loci, of which 11 were polymorphic (47.8%). Genetic diversity at the varietal level and at the population level was 0.131 and 0.118, respectively. Total genetic diversity (HT = 0.274) and within population genetic diversity (HS = 0.256) were high, whereas the extent of the population divergence was relatively low (GST = 0.068). An indirect estimate of the number of migrants per generation (Nm = 3.42) indicated that gene flow was high among Korean populations. Wide geographic ranges, perennial herbaceous nature, and the persistence of multiple generations are associated with the high level of genetic variation. A distinct difference between Asian and North American Carex is shown in the proportion of genetic variation (GST) (p < 0.001). The mean GST of Asian Carex was estimated as 0.056; thus, only 5.6% of genetic variability was distributed among populations, whereas the mean GST of North American Carex was estimated as 19.5% (3.5 times higher). It is probable that the geographical distance between population pairs and presence or absence of glacial history may play roles in the substantial difference between both groups.Key words: Carex humilis var. nana, genetic diversity, population structure.