Allozyme Diversity in Populations of Cymbidium goeringii (Orchidaceae)

Abstract

: Using 14 allozyme loci, we investigated levels of genetic diversity within populations, and degree of genetic divergence among 24 populations of Cymbidium goeringii (Orchidaceae) in Korea and Japan. Cymbidium goeringii maintains high levels of genetic diversity both at population (mean expected heterozygosity, He = 0.238) and species levels (0.260). Means of He found in 24 populations were not significantly different from each other. About 90 % of the total variation in the species is common to all populations (mean GST = 0.108). No unique allele was found in any population. The indirect estimate of gene flow based on the mean GST was high (Nm = 2.06). Nei's genetic identities for pairs of populations had high values (mean = 0.974 [SD = 0.013]). The Mantel-Z test showed a significant correlation between genetic distance and geographic distance. However, the mean GST value between 17 populations in Korea and seven Japanese populations was relatively low (0.029), even though the land connection between the southern Korean peninsula and southern Japanese archipelagos has not existed since the middle Pleistocene. Large numbers of small seeds of C. goeringii might travel long distances by wind from populations to populations both in Korea and Japan, increasing genetic diversity within populations and maintaining low genetic differentiation among populations.