中文摘要：

为研究青藏高原海拔变化与藏川杨遗传多样性和群体遗传结构的关系,以青藏高原东南部色季拉山分布的藏川杨群体为材料,用24对微卫星标记对其进行遗传分析。在469个个体中共检测到126个等位基因,每个位点的平均等位基因数（Na）为5.25；多态性位点百分率（PPL）为100%,期望杂合度（He）在高、低海拔的群体中都处于较高水平,分别为0.48和0.49；分子方差分析（AMOVA）的结果表明,种群间分化占总变异的6.38%,遗传变异主要集中在群体内不同个体之间；基因分化系数（FST）为0.02,也证实群体分化处于较低水平,而检测到群体间的基因流动（Nm）处于较高水平,为9.89。上述结果表明,海拔因素未对生长在色季拉山高低海拔的藏川杨群体造成地理隔离,从而产生种群分化；在此地区藏川杨遗传背景一致,藏川杨种质资源的保存无需考虑海拔的差异。本研究结果为研究高海拔适应机制材料的选择提供了很大的便利,并为藏川杨的可持续利用与保护提供了一定的理论依据。

英文摘要：

In order to study the relationship between elevation and populations of Populus szechuanica var. tibetica located on the Qinghai-Tibet Plateau,24 pairs of SSR primers were used to study genetic diversity and structure of populations in Sejila Mountain of the southeastern plateau. A total of 126 alleles was detected from 469 individuals,with an average of 5. 25 alleles per locus,a PPL（ polymorphism percentage level） of 100%,and a relatively high expected heterozygosity（ He） for populations at high and low altitudes of 0.48 and 0.49,respectively. Analysis of molecular variance（ AMOVA） showed that differentiation among populations accounted for 6. 38% of the total and most variation existed among the individuals within a population. A differentiation coefficient（ FST） of 0.02 and the value of gene flow（ Nm） was 9.89 at a very high level also supported the conclusion that the differentiation among populations was at a low level. In conclusion,no geographical separation and differentiation of populations along the altitude of Sejila Mountain were observed. As a result,conservation and utilization of Tibetan poplar facilitated on the basis of understanding of differentiation and distribution patterns of the species and study on mechanism of adaptation to a high altitude could be proceed smoothly.