【摘要】 采用空间自相关分析方法对巴东木莲目前残留的两个最大居群, 小溪居群的40个个体和桑植居群的28个个体等位酶遗传变异的空间结构进行了研究, 以揭示两居群遗传变异的空间模式, 并探讨其形成机制及与巴东木莲致濒原因、过程之间的关系。根据检测出来的8个酶系统的19个酶位点, 选择基因频率大于0 1小于0 9的等位基因, 运用等样本频率和等地理距离间隔两种方法分别计算两居群不同距离等级下的Moran’sI空间自相关系数。结果表明: 小尺度的小溪居群等位基因的遗传变异缺乏空间结构, 为随机分布模式。巴东木莲生境片断化的桑植居群则是相反的结果, 遗传变异存在明显的空间结构, 遗传变异空间分布为斑块状。造成这种差别的原因可能是桑植居群片断化和地理隔离造成的基因流的限制。上述结果为进一步制定有效的巴东木莲的保育措施提供科学的理论依据。更多还原

【Abstract】 Spatial autocorrelation analysis on allozyeme genetic variability was used to explore the patterns of genetic structure in two biggest remnant M.patungensis populations.A total of 40 and 28 individual trees were sampled from the two remnant populations and subjected to spatial analysis in two approaches of equal gene frequency correlograms with five classes and equal distance interval correlograms with ten classes,respectively.Moran’s I correlograms revealed no significant spatial structure in Xiaoxi population indicating that genetic variations of the most polymorphic loci in this population were randomly distributed.In Sangzhi population,the result revealed large positive values at short distances (<1-2?km),then autocorrelations decrease,and at the distance of 6-7?km they become significantly negative.Within the distance range of 17-21?km,positive values prevail again.However,in the distance class of 24?km,almost all Moran’s indices are negative.These fluctuations indicate a patchy genetic structure within this population.Limited gene flow due to habitat fragmentation and isolation by distance may account for the genetic clustering.These results have provided theoretical information for drawing up a conservation strategy of this species.更多还原