基于RAPD数据探讨中华蓑藓(Macromitrium cavaleriei Card.& Thér.)形态变异的遗传基础

中华蓑藓(Macromitrium cavaleriei Card.&;Thér.)的形态变异强烈,为了解形态变异是否具有遗传学背景,本研究以采自浙南凤阳山、浙中金华北山、浙西北的天目山和江西庐山4个种群的中华蓑藓为材料,运用随机扩增多态性DNA(RAPD)探讨了中华蓑藓的遗传多样性。从100条随机引物中筛选出了15条有效引物,利用它们共获得183个条带,其中多态性条带占79.69%,中华蓑藓各种群间的Dice遗传距离为0.0732~0.1514。POPGENE32软件分析得到种的Nei基因多样性指数(H)为0.3378,Shannon指数(I)为0.5126,遗传分化系数(G_st)为0.1670;基因流(N_m)为2.4947;种群内遗传多样性指数为0.4055,占种群总的遗传多样性的79.11%,反映出研究区域内的中华蓑藓遗传变异大多数存在于种群内,中华蓑藓形态变异并没有多少遗传背景,很可能是生态环境因素引起的可塑性变异。聚类分析表明,中华蓑藓种群遗传距离与地理距离之间无直接相关关系,遗传多样性水平与物种特性和所处不同群落有关。虽然4个种群内的形态变异丰富,但是属于同一物种的范围。

Genetic Background of Morphological Variation in Macromitrium cavaleriei Card. & Thér.Based on RAPD

Individuals of Macromitrium cavaleriei Card.& Thér.vary in morphological traits.To know whether such morphological variation of the species has a genetic background,we applied random polymorphic DNA(RAPD)markers to detect genetic diversity using four different Macromitrium cavaleriei populations collected from Fengyangshan(Southern Zhejiang),Jinhua Beishan(Middle Zhejiang),Xitianmushan(Northwestern Zhejiang)and Lushan of Jiangxi.We screened 15 effective primers from 100 random primers,and found 183 amplification sites,which included 145 polymorphic sites,accounting for 79.69% polymorphic loci.We found that:(1)genetic distances among the four populations varied from 0.0732 to 0.1514,Nei’s gene diversity(H)was 0.3378,Shannon’s diversity index(I)was 0.5126,and genetic differentiation coefficient(G_st)was 0.2521,and gene flow among populations(N_m)was 2.4947;and(2) the genetic diversity within populations was 0.4055 on average,accounting for 79.11% of the total genetic diversity of the four populations.The above results showed that Macromitrium cavaleriei had lower genetic diversity,more genetic variations existed within populations than among populations,and the morphological variation of M.cavaleriei had little genetic background,which is mainly caused by ecological factors.Cluster analysis showed that there was no direct correlation between genetic distance and geographic distance.The genetic diversity was related to species traits and habitats.Although rich morphological variations existed within populations,they belonged to the same species.