Abstract:

In this study， a total of 73 plant samples from four natural populations,in Alihe， Huzhong， Aihui and Wuyiling of China, representing all the taxa in Larix gmelinii were used for evaluating the allozymic genetic diversity. Allozyme data for sixteen loci of ten different enzymes were obtained using a starch gel electrophoresis system. Our results revealed high levels of genetic variation in populations. The percentage of polymorphic loci (P) was 43.8%～62.5%， the average number of alleles per locus (A) was 1.8～2.0， and the mean expected heterozygosity (H_e) was 0.187～0.257. Additionally， the values of all indexes related to gene abundance were decreasing from the north to the south populations， suggesting that the species might move in the direction from north to south. The analysis on population genetic structure indicated that the variation mainly existed within a population， and the value of F_ST is 0.111. The level of genetic differentiation was higher than that of gymnosperm on the average. The fixation index (F) of population was > 0， indicating that heterozygote was insufficient in populations. Outcrossing rate (t)(20.8%) was lower. Genetic identity(I) cluster analysis result indicated that the genetic variation in the populations was influenced by geographical isolation， and changed along with latitude.

Key words: Larix gmelinii, allozyme, genetic variation, population differentiation