Allozyme diversity and population structure in Korean populations of Cymbidium goeringii (Orchidaceae)

Using 14 allozyme loci we investigated levels of genetic diversity and popu lation genetic structure in 16 Korean populations of Cymbidium goeringii (O rchidaceae), Mean observed population heterozygosity (H-OP=0.181), expected heterozygosity (H-eP=0.240), and total genetic diversity (H-T=0.351) were all higher than average values for species with similar life-history charac teristics. A considerable deficit of heterozygotes relative to Hardy-Weinbe rg expectations was detected (77% of fixation indices were positive) with a mean F-IS of 0.278, On average, 90% of the fetal genetic diversity was fou nd within populations (mean G(ST)= 0.098). An indirect estimate of the numb er of migrants per generation (Nm=2.30, calculated from G(ST), Nm=8.48, cal culated from the frequencies of unique alleles) indicated that gene flow ha s been extensive in C. goeringii. Results of a spatial autocorrelation anal ysis based on allele frequencies of 16 populations revealed a trend with re spect to the distance classes (0<63km, six significant positive values; bey ond that distance, 12 significant negative values), It is highly probable t hat C, goeringii has a history of relative large, continuous populations th at had greater chance for gene movement among adjacent populations via larg e numbers of small seeds, following the last Ice Age. Factors contributing to the high levels of genetic diversity found within populations of C. goer ingii include its large and continuous populations, its long-lived perennia l habit, its widespread geographical distribution, and its ability for rela tively long distance seed movement by wind.