Allozyme variation of Cyclobalanopsis championii (Fagaceae), a narrowly distributed species in southern Taiwan

Allozyme genetic variability in five natural populations of Cyclobalanopsis championii (Fagaceae) in Taiwan was investigated using 12 loci from 9 enzy me systems. The average values of parameters describing within-population v ariation, expected heterozygosity (H-e = 0.151), the percentage of polymorp hic loci per individual (P = 50%), the average number of alleles per locus (A = 1.7), effective number of alleles per locus (A(e) = 1.25), and the ave rage number of alleles per polymorphic loci (AP = 2.2) are comparable to th ose of other long-lived woody plants. The overall fixation index (F-is = 0. 208) indicates a significant deficiency of heterozygotes at the population level. Allelic frequency deviation from Hardy-Weinberg equilibrium was foun d for different loci in different populations. An exact test for population differentiation using the Tools for Population Genetic Analyses program al so indicates that allelic frequencies among populations are significantly d ifferent (P < .001). Among-population variation, G(st), accounted for 9.2% of the total heterozygosity, The population at Shouchia and the southernmos t population Nanjenshan had higher inbreeding coefficients (0.177 and 0.153 , respectively) than did the northern populations. Genetic drift is support ed by the observations of the variance components of linkage disequilibrium and a large proportion of loci in Nanjenshan and Shouchia that show pairwi se locus disequilibrium. We believe continuous genetic drift in the souther n populations will increase genetic divergence among populations of C. cham pionii in Taiwan. Significant correlation was found between elevation and e xpected heterozygosity. We therefore inferred that temperature is the most important ecological factor to influence the genetic diversity of C. champi onii.