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题名	木蓼属的谱系地理格局及进化历史研究
作者	徐喆
学位类别	硕士
答辩日期	2015
授予单位	中国科学院大学
授予地点	北京
导师	张明理
关键词	木蓼属，谱系地理学，气候变化，沙漠化，分化
学位专业	工程硕士
中文摘要	为了研究中国北方干旱区植物空间遗传格局以及对第四纪环境变化（例如冰期循环、沙漠扩张）的响应，我们选择木蓼属（Atraphaxis）以及属下的木蓼（Atraphaxis frutescens）在属和种的水平对其谱系地理格局进行了研究。在木蓼的谱系地理研究中，我们共采集了木蓼33个自然居群的272个样本。通过对psbK-psbI以及psbB-psbH两个叶绿体基因间隔区测序，共确定了10个单倍型。对其居群的遗传结构进行分析，结果发现木蓼的总遗传多样性(HT=0.858)较高，而居群内遗传多样性(HS=0.092)比较低。分子方差分析结果认为其居群遗传变异主要发生在地理组之间。BEAST分子钟分析结果认为单倍型之间的遗传变异主要发生在更新世中晚期，我们推断其遗传分化主要是由居群隔离以及干旱化扩张等因素引起。古尔班通古特沙漠以及库姆塔格沙漠的扩张促使了木蓼在西部、中部、东部居群的遗传分化。另外，两个可能的避难所被确定，包括伊犁河谷以及准噶尔盆地北缘。另外，早全新世之后，气候逐渐变暖以及适宜栖息地的扩张促使了木蓼的近期扩张。在对木蓼属的研究中，我们总共采集了木蓼属在中国分布的11个种72个居群总共564份样本。我们分析了木蓼属的种内谱系地理格局、祖先栖息地以及可能隔离/迁移事件。结果表明木蓼属除一些广布种以及同域分布的单倍型外，其它单倍型都是每个物种独有的。我们检测到木蓼属较高的总遗传多样性(hT=0.919)。BEAST分析认为木蓼属的主要分歧时间发生在更新世早期至更新世晚期（2.31-0.05 Ma），与中国北方沙漠的形成时间趋于一致。我们认为腾格里沙漠的扩张催生了沙木蓼这一物种。S-DIVA分析结果认为木蓼属的祖先栖息地包括伊犁河谷、准噶尔盆地、塔里木盆地以及黄土高原的大部分地区。
英文摘要	In order to investigate the spatial genetic diversity and response to environmental changes (glacial cycles, arid expansion) of climate oscillations on evolutionary processes of organisms in northern China, Atraphaxis and Atraphaxis frutescens were selected to examine the phylogeographical structure in genus and species levels. In the phylogeographical study of Atraphaxis frutescens, two cpDNA regions (psbK-psbI, psbB-psbH) were sequenced in 272 individuals from 33 natural populations across the range of this shrub, and 10 haplotypes were identified. It was found to contain high levels of total gene diversity (HT=0.858), and low levels of within-population diversity (HS=0.092). Analysis of molecular variance (AMOVA) indicated that genetic differentiation primarily occurs among groups of populations. Based on BEAST analysis, it was suggested that intraspecific differentiation of the species, resulting from isolated populations, accompanied enhanced desertification during the middle and late Pleistocene. The expansion of the Gurbantunggut and Kumtag deserts in this area appeared to have triggered divergence among populations of the western, central and eastern portions of the region and shaped genetic differentiation among them. Two possible independent glacial refugia including Ili Valley and northern Junggar Basin were predicted. Extensive development of arid habitats (desert margin and arid piedmont grassland) coupled with a more equable climate since the early Holocene might be the key factors that generated recent expansion of A. frutescens. In the study of Atraphaxis, the species-level phylogeographical patterns of Atraphaxis species, as well as the origin and vicariance/dispersal events in China were totally investigated. The plastid spacers psbK-psbI and psbB-psbH from 72 populations and 564 individuals across the distribution ranges of 11 species of the genus were sequenced. The results showed that most chloroplast haplotypes were species-specific, except for some haplotypes in widespread species and overlapping distributions. High levels of total genetic diversity (hT=0.919) was detected. The phylogeny of Atraphaxis was reconstructed, and an estimated BEAST analysis suggested the main divergence events occurred during the early Pleistocene and late Pleistocene (2.31-0.05 Ma), and likely coinciding with the formation of deserts in Northern China. It was suggested that the expansion of Tengger Desert lead to the origin of the A. bracteata. The statistical dispersal-vicariance analysis (S-DIVA) results suggested that complex ancestral areas included the the Ili valley, Junggar basin, Tarim Basin and Loess plateau.
语种	中文
学科主题	生物工程
内容类型	学位论文
源URL	[http://ir.xjlas.org/handle/365004/14987]
专题	新疆生态与地理研究所_研究系统_荒漠环境研究室
作者单位	中科院新疆生态与地理研究所
推荐引用方式 GB/T 7714	徐喆. 木蓼属的谱系地理格局及进化历史研究[D]. 北京. 中国科学院大学. 2015.

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