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西北干旱区刺山柑(Capparis spinosa L.)的谱系地理学研究
王茜
学位类型博士
导师尹林克 ; 张明理
2016
学位授予单位中国科学院大学
学位授予地点北京
学位专业植物学
关键词刺山柑 谱系地理学 遗传多样性 西喜马拉雅地区 天山地区 更新世气候变化
摘要刺山柑(Capparis spinosa L.)为多年生藤本小半灌木,系山柑科(Capparaceae)山柑属(Capparis Tourn. ex L.)中的模式种。在干旱区呈单种属的形式分布,是第三纪古地中海的孑遗种,为中国西北部旱生植物的典型代表。本研究从刺山柑的遗传多样性及谱系地理学两个方面深入,以期探讨旱生植物遗传分布格局及其物种进化过程逐步响应古地质、古气候变迁的机制。 1. 刺山柑的遗传多样性研究 遗传多样性的大小是物种长期进化的结果,是其生存发展和适应性进化的基础。为了探讨地理分隔对干旱区植物物种分化格局的影响,对广泛分布于天山及邻近荒漠区域刺山柑的遗传变异性和遗传多样性进行了系统评估。通过两段cpDNA基因间隔(rpS12-rpL20和ndhF)的测序结果,从取样的25个居群300个个体中共得到14个叶绿体单倍型。研究表明,高水平的遗传多样性(HT = 0.859)归因于天山区域广阔的地理分布范围以及数目较多的大规模有效居群。空间分子方差分析根据地理位置和遗传关系的亲疏程度将现有分布区划分为4个地理单元。分子方差分析的结果显示较高比例的遗传变异(66.33%)发生在地域之间;Permut程序的运算结果也表明地域间存在显著的遗传分化(GST = 0.670)和低水平的基因流(Nm = 0.2463)。研究结果揭示了天山区域刺山柑的遗传分化与单倍型的地理分布之间密切相关。区域内复杂的山体屏障和沙漠隔离限制了地理单元间的基因交流,从而导致了地域之间刺山柑居群的高度分化。 2. 刺山柑的谱系地理学研究 西喜马拉雅地区和东部中亚地区的干旱、半干旱成分起源于干旱的古地中海植物区系。复杂的地质运动或多或少影响或改变了植物区系的结构,而第四纪冰期、间冰期的循环交替通常被认为是进一步形成当今温带植物物种间断性遗传分布格局的重要原因。本文以刺山柑为研究对象,目的在于探讨该物种的谱系地理结构,以及探究其对更新世地质与气候变化逐步响应的过程机制。通过3段叶绿体基因间隔区trnL-trnF,rpS12-rpL20和ndhF(329F, 927R)对31个自然居群进行测序的核苷酸变异结果,共检测出24个叶绿体单倍型。SAMOVA将31个居群划分为5个主要的谱系地理组;network与BEAST系统发育树的重建也体现了相似的遗传分歧趋势。AMOVA的结果显示主要的遗传分化存在于谱系地理组之间,组间的基因交流很大程度上受限于地理分隔。分子钟测年的结果表明种内的遗传分歧始于早更新世,这与喜马拉雅、天山山脉强烈隆升的时期相一致;而加剧的遗传分歧发生在中更新世。物种分布模型揭示,在末次盛冰期(LGM)冰川递进所造成的寒冷气候条件影响下,高海拔山区刺山柑的分布范围有一定程度的退缩;位于天山中海拔的峡谷区在此时为物种提供了潜在的冰期生物避难所;而分布于低海拔的荒漠区居群鉴于其较高水平的遗传多样性和遗传距离,几乎未受到冰川作用的影响。该物种异域分化、局部演变、间冰期及冰后期传播的进化过程揭示了更新世时期强烈的山体隆升以及随后发生的冰川作用对第三纪孑遗植物物种复杂而深刻的影响,以期为今后有关旱生植物对第四纪历史事件响应机制的研究提供一定的科学依据。
其他摘要Capparis spinosa L., a perennial creeping subshrub, is a type member of a relatively large genus (Capparis Tourn. ex L.) of the Capparaceae. In arid region of China, there is only one single genus with one single species belonging exclusively to this family. As a Tertiary relic originated from the arid Tethyan Flora, C. spinosa is a typical xerophyte in northwestern region. Here we study the genetic diversity and phylogeography of C. spinosa, in order to explore the genetic pattern and evolution process of desert species in response to paleogeologic and paleoclimatic changes. 1. Genetic diversity of Capparis spinosa Genetic diversity within and among populations is essential for the long-term survival and adaptive evolution of plant species. We systematically assessed the genetic variability and diversity of Capparis spinosa widely distributed in Tianshan Mountains and adjacent desert areas, to explore the influence of vicariance on differentiation pattern of xerophytes in arid regions. A total of 300 individuals from 25 populations were sampled and 14 haplotypes were identified using two chloroplast DNA sequences (rps12-rpl20 and ndhF). A high level of total genetic diversity (HT = 0.859) was detected, attributing to extensive distribution range with numerous large-sized populations. The spatial analysis of molecular variance clustered the 25 populations into 4 major geographic units, according to the geographical distribution and genetic relationship of cpDNA haplotypes in populations. The analyses of molecular variance showed that most of the total genetic variation (66.33%) existed among geographic units. Furthermore, significant genetic differentiation (GST = 0.670) and a low level of gene flow (Nm = 0.2463) were found among populations via Permut procedure. Our results indicated that there was a considerable correlation between genetic divergence and geographic distribution. Complex mountain and desert isolations in Tianshan region limited the gene exchange between disjunct populations, thereby resulting in high genetic differentiation among geographical units. 2. Phylogeography of Capparis spinosa The desert and semi-desert elements of the Western Himalayan and Eastern Central Asian regions have been deemed to have originated from the arid Tethyan Flora. Complex geological movements more or less affected or changed floristic structures, while the alternation of glacials and interglacials in Quaternary is presumed to have further shaped the present discontinuous genetic pattern of temperate plants. Here we consider Capparis spinosa and discuss its phylogeographic structure, and explore how it responded in a stepwise fashion to Pleistocene geologic and climatic changes. In total, 31 natural populations were sampled and 24 haplotypes were identified, based on three cpDNA intergenic spacers, trnL-trnF, rpS12-rpL20, and ndhF (329F, 927R). SAMOVA results suggested that the 31 populations were clustered into 5 major geographical groups; a similar divergence trend was found by constructing a network diagram and a BEAST phylogenetic tree. AMOVA results revealed that the main genetic differentiation existed between groups, gene flow between which might be restricted by vicariance. Molecular clock dating indicated that the intraspecific divergence began in early Pleistocene, consistent with a time of intense uplift of the Himalayas and Tianshan Mountains; and intensified in middle Pleistocene. Species distribution modeling (SDM) suggested range reduction in the high mountains during the Last Glacial Maximum (LGM) as a result of cold climates during glacial advances, while gorges at mid-elevations in the Tianshan range appear to have served as potential refugia. Populations of low-altitude desert regions on the other hand, probably experienced only marginal impacts from glaciation, according to the high levels of genetic diversity and genetic distance. The findings of allopatric divergence, local evolution, and dispersal during interglacial and postglacial periods highlight the complex influence of Pleistocene intense mountain uplift and glaciation occurrence on relic plant species, providing the basis for future studies on how xerophytes gradually responded to Quaternary historic events.
学科领域植物学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14749
专题研究系统_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
王茜. 西北干旱区刺山柑(Capparis spinosa L.)的谱系地理学研究[D]. 北京. 中国科学院大学,2016.
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