甜槠种群在不同演替阶段森林群落中的遗传多样性

Genetic diversity of Castanopsis eyrei populations in three forest communities with different succession stage

利用RAPD技术对甜槠种群在浙江省天台山不同演替阶段森林群落（针叶林、针阔混交林、常绿阔叶林）中的遗传多样性和遗传分化进行了分析．3个甜槠种群平均多态位点百分率为67．98％，总多态位点百分率为92．13％．Shannon信息指数估算的3个种群的遗传多样性以常绿阔叶林种群最高，平均为0．4188；其次是针阔混交林种群，平均为0．3873；最低的是针叶林种群，为0．3613．在总的遗传变异中，种群内占75．00％，种群闾占25．00％．Nel指数计算的3个种群的基因多样性大小也是常绿阔叶林种群（0．2858）〉针阔混交林种群（0．2642）〉针叶林种群（0．2434）．种群间的遗传分化系数为0．2473，基因流为1．5542．3个种群间的遗传距离在0．1757～0．2134之间．通过聚类分析，常绿阔叶林种群与针阔混交林种群先聚合，再与针叶林种群聚在一起．

RAPD （Random amplified polymorphie DNA） was used to detect the genetic diversity of Castanopsis eyrei populations in three forest communities at different succession stages in Tiantai mountain Zhejiang Province, namely, needle-leaved forest, needle/broad-leaved mixed forest and evergreen broad-leaved forest. The total percentage of polymorphic loci of Castanopsis eyrei was 92.13% with an average of 67.98%. The highest genetic diversity as estimated by Shannon index was shown to exist in evergreen broad-leaved forest community with a 0.4188 average index. Next in degree of diversity was the needle/broad leaved mixed forest community, and the average index of which was 0.3873. The last genetic diversity was shown to exist in needle-leaved forest community with an average of 0.3613. Of the total genetic diversity, 75% was ascribed to the differentiation among populations while 54.41% resided within populations. Judged from the so-called Nei＇s index, however, genetic diversity of evergreen board-leaved forest community ranked first and was 0.2858, followed by needle, broad-leaved mixed forest community （0.2642） and, then, needle-leaved forest community （0.2434）. The coefficient of gene differentiation （Gst） was 0.2473 and the gene flow estimated from Gst was only 1.5542. Genetic distances as defined by Nei between every two populations were also calculated, which ranged from 0.1757 to 0.2134. The clustering analysis showed that the evergreen broad-leaved forest community gathered initially with the needle/broad-leaved mixed forest community, and later with the needle-leaved forest community.