东南石栎种群在演替系列群落中的遗传多样性

Genetic diversity of Lithocarpus harlandii populations in three forest communities with different succession stage

在浙江省天台山,利用RAPD技术对东南石栎种群演替系列群落针叶林、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研究。结果表明,12个随机引物在60株个体中共检测到173个可重复位点,其中多态位点152个,总多态位点百分率为87.86%,3个种群平均多态位点百分率为65.32%。采用Shannon信息指数计算的3个种群总的遗传多样性为0.4529,平均为0.3458。采用Nei指数计算的3个种群总的基因多样性为0.3004,平均为0.2320。3个种群的多态位点百分率、Shannon信息指数、Nei指数大小顺序均为针叶林种群>针阔混交林种群>常绿阔叶林种群。AMOVA分子变异显示,72.85%变异来源于种群内,27.15%变异来源于种群间。种群间的遗传分化系数为0.2277,基因流为1.6949。东南石栎这种遗传结构是其本身生物学特性的反映,同时也与群落的微环境密切相关。3个东南石栎种群间的遗传相似度平均为0.8662,遗传距离平均为0.1442。针阔混交林种群与常绿阔叶林种群的遗传相似度最高,常绿阔叶林种群与针叶林种群最低。根据Nei的遗传距离对不同种群进行非加权成组配对法(UPGMA)聚类表明,针阔混交林种群与常绿阔叶林种群先聚合,再与针叶林种群聚在一起。

By using random amplified polymorphic DNA （RAPD） technique, this paper studied the genetic diversity and genetic differentiation of Lithocarpus harlandii populations in three forest communities （coniferous forest, coniferous and broad-leaved mixed forest, and evergreen broadleaved forest） with different succession stage in Tiantai Mountain of Zhejiang Province. The resuits showed that a total of 173 repetitive loci were produced in 60 individuals of L. harlandii by 12 random primers, among which, 152 loci were polymorphic, and the total percentage of polymorphic loci was 87.86%. The average percentage of polymorphic loci of the populations was 65.32% , and their total genetic diversity estimated by Shannon information index was 0. 4529, with an average of 0. 3458, while that judged from Nei index was 0.3004, with an average of 0. 2320. The percentages of polymorphic loci, Shannon information index, and Nei index of the populations were in the sequence of coniferous forest community 〉 coniferous and broad-leaved mixed forest community 〉 evergreen broad-leaved forest community. Analysis of molecular variance （AMOVA） showed that 72.85% of genetic variance was found within the populations, and 27. 15% of genetic variance resided among the populations. The coefficient of gene differentiation was 0. 2277, and the gene flow was 1. 6949. The genetic structure of L. harlandii was influenced not only by the biological characteristics of this species, but also by the microenvironment of different communities. The mean of genetic identity among 3 populations of L. harlandii was 0. 8662,and the mean of their genetic distance was 0. 1442. The genetic similarity between coniferous and broad-leaved mixed forest community and evergreen broad-leaved forest community was the highest, while that between evergreen broad-leaved forest community and coniferous forest community was the lowest. The unweighted pair group method with arithmeticmean （UPGMA） cluster analysis based on Nei＇s genetic distance showed that coniferous and broad-leaved mixed forest community first gathered with evergreen broad-leaved forest community, and then with coniferous forest community.