不同演替阶段臭柏种群的遗传多样性

Genetic diversity of Sabina vulgaris populations at different succession stages.

为了阐明分子变异与演替阶段或生态过渡带的联系，应用随机扩增多态性DNA（random amplifled polymorphic DNA，RAPD）标记方法对毛乌素沙地图克境内4个不同演替阶段的臭柏种群进行了分子生态学研究．用17个随机引物扩增出190条清晰谱带，其中173条为多态性谱带，并利用POPGENE 3．2 Version 1．31软件对数据进行处理．结果表明，臭柏种群的遗传多样性较丰富，各种群多态位点百分比在64．21％-74．63％，以演替早期的半固定沙地油蒿＋臭柏种群最高（74．63％），演替亚顶极时期的固定沙地臭柏种群最低（64．21％）；臭柏种群问分化较小，种群间遗传分化系数Gst=0．1761，82．39％的遗传变异存在于种群内；聚类分析显示，演替阶段相近的种群聚集到一起，反映了臭柏种群的遗传分化和演替阶段密切相关．利用Nei指数统计RAPD数据，各种群基因多样度在0．2163-0．2564之间，也证实了大部分的遗传变异存在于种群内．

By means of random amplified polymorphic DNA markers, a molecular ecological study was made with Sabina vulgaris populations at 4 succession stages in Maowusu sandy grassland, aimed to reveal the relationships between molecular variation and succession stages. A total of 17 random primers were selected for amplification, and 190 repetitive loci were produced, of which, 173 were polymorphic. The data were analyzed by POPGENE 3.2 Version 1.31. The results showed that the genetic diversity of S. vulgaris populations was high, and changed with succession stages. The percentage of polymorphic loci in each S. vulgaris population ranged from 64.21% to 74. 63 %, with the highest in early succession stage Artemisia ordosica ＋ S. vulgaris on semi-fixed sand dunes, and the lowest in sub-climax stage S. vulgaris on fixed dunes. The genetic differentiation among the populations was small （Gst =0. 1761 ）, and 82. 39% of it was within the populations. Cluster analysis demonstrated that the populations at similar succession stage clustered together, suggesting that the genetic differentiation was closely related to succession stage. The genetic diversity indicated by Nei index ranged in 0. 2163 - 0. 2564, and the gene flow （Nm ＊ ） was 2. 7972, indicating that more gene exchange occurred within the populations, which prevented the genetic differentiation among the populations at different succession stages.