物种形成一直是进化生物学和生态学研究的核心之一。近年来，物种形成研究多集中在探索现有邻域分布近缘物种的形成历史，而对现异域分布姊妹物种的群体遗传历史研究相对较少。异域物种形成过程中的适应性报道也较少。本项目拟以分布于青藏高原、且存间断分布的两对柏木属姊妹群（岷江柏木的两个地理宗和干香柏-巨柏姊妹种）为研究对象，在群体水平上研究多套核基因座位的序列多态性变异，检验各基因位点是否受到选择，并利用溯祖分析模拟物种分化过程中的群体动态历史和环境候选基因可能受到的自然选择作用。我们的研究结果一方面为揭示两个姊妹群的物种分化机制、特别是阐明地理隔离下环境适应对物种形成的作用提供重要依据；另一方面也对保护与利用这些生长在青藏高原极端环境下的林木遗传资源也具有重要意义。

The mechanisms underlie speciation is one central aim of evolutionary and ecological studies. In recent years, most researches have focused on the genetic patterns of parapatrically distributed species, relatively few similar studies were conducted on allopatrically distributed ones. In this study, we will focus on two pairs of sister groups respectively with allopatric distributions, two local races of Cupressus chengiana, and one pair of sister species C. duclouxiana and C. gigantea, in the eastern Qinghai-Tibetan Plateau. We will use population genetic data from multiple nuclear loci to screen sequence variation at each locus for two sister groups. We will test whether these nuclear loci had undergone past natural selection during their allopatric speciation. In addition, we will model and test the speciation hypotheses for these two pairs of sister group by coalescent and other analyses. Our results will improve our understanding on speciation mechanisms under these two pairs of sister groups as well as the conservation and exploitation of the genetic diversity resources of these forest trees that survived under extreme environments on the Qinghai-Tibetan Plateau.