COMPARISON OF THE ALLOZYME DIVERSITY IN SEVERAL POPULATIONS OF CHAMAECYPARIS-FORMOSENSIS AND CHAMAECYPARIS-TAIWANENSIS

Genetic diversity within and genetic differentiation among three popul ations of Chamaecyparis formosensis Matsum. and two populations of Cha mnecyparis taiwanensis Masam. and Suzuki were investigated using one-y ear-old seedlings collected from central and northern Taiwan. For C. f ormosensis 330 seedlings from 33 seed trees were used, while for C. ta iwanensis 260 seedlings from 26 seed trees were used. Eleven enzyme sy stems were investigated. In C. formosensis, 5 of the 21 loci examined were polymorphic. The average percentage of polymorphic loci per popul ation was 20.6% at the 99% criterion for polymorphism. Mean expected h eterozygosity ranged from 0.079 to 0.100 in the different populations. On average, there were 6.6 to 9.2% heterozygous loci per individual a nd 1.24 to 1.29 alleles per locus; the effective number of alleles per locus ranged from 1.09 to 1.11. In C. taiwanensis, 7 of the 20 loci e xamined were polymorphic and the average percentage of polymorphic loc i per population was 22.5%. Mean expected heterozygosity ranged from 0 .044 to 0.060. On average there were 4.5 to 5.6% heterozygous loci per individual and 1.45 alleles per locus; the effective number of allele s per locus ranged from 1.05 to 1.08. The surprisingly low expected he terozygosity and percentage of polymorphic loci compared with other co nifer probably reflects the insular nature of these species. Partition ing the genetic variability into within- and among-population componen ts with F-statistics led to an estimate of within-population variation of 95% of the total variation in both C. formosensis and C. taiwanens is. Chamaecyparis formosensis had a positive fixation index (0.109) th at was significantly different from zero at the 5% level, indicating t hat most loci have slightly higher frequencies of homozygotes. Chamaec yparis taiwanensis, however, had a fixation index close to zero (0.036 ), which suggests that most loci are in Hardy-Weinberg equilibrium. Th e genetic distance between C. formosensis and C. taiwanensis was 0.70, which clearly separates these two species.