【作者】 彭晓莉；

【导师】 刘建全；

【作者基本信息】 兰州大学 ， 生态学， 2008， 博士

【摘要】 第四纪全球气候波动,不仅影响植物种类分布区的改变和相应的遗传结构,而且还可能导致生物物种的适应性进化以及新物种的起源。青藏高原是气候变迁的敏感区。为研究该地区气候变迁对物种分布格局与物种形成的影响,本论文以丽江云杉复合体及其近缘种青扦和紫果云杉为研究对象,进行了分子谱系地理学和物种形成的研究。松科植物线粒体DNA为母系遗传,叶绿体DNA为父系遗传;二者相互结合对于阐述基于种子和花粉介导的基因流、物种分化与杂交渗入具有重要优势。一共对3种5个分类群67个种群678个体进行了形态鉴定和5套序列的测序。形态学鉴定表明,青扦和紫果云杉之间不存在形态上混合生长的种群。丽江云杉3个变种(丽江云杉、川西云杉和林芝云杉)在异域分布的地区存在大量的纯和种群;但是这3个分类群与紫果云杉在邻近分布区存在两个或者多个分类群的形态混合种群。叶绿体DNA片段(trnS-trnG,trnL-trnF和ndhK/C)排序后共检测到7种单倍型,分成明显的两支:其中一支主要分布在青扦和紫果云杉内。线粒体nad1和nad5片段共检测到了11种单倍型,分成三支:其中分化较早的一支也是主要分布在青扦和紫果云杉内。典型的青扦和紫果云杉种群之间没有单倍型分化,都固定同一种叶绿体或者线粒体单倍型。但是,丽江云杉每个变种内都发现有两种或者两种以上的叶绿体或者线粒体单倍型。通过比较单倍型的进化关系以及地理分布结构,得到如下结论:(1)青扦和紫果云杉是较早分化出来的分支,但它们二者之间的分化较晚或者基因流过于频繁,阻止了二者之间的遗传分化;(2)林芝云杉变种代表了一个独立的物种,它的起源是通过三个谱系杂交而成的,包括丽江云杉变种、川西云杉变种和青扦-紫果云杉谱系;(3)分类群之间存在广泛的杂交;与过去认为花粉更容易在分类群之间杂交渗入的理论相反,研究结果发现种子携带的基因组更容易渗入到邻近分类群中;(4)两个变种丽江云杉和川西云杉的冰期避难所有多个。此外,对丽江云杉物种RAPD研究也证实存在多个避难所。更多还原

【Abstract】 The climatic oscillations during the Quaternary,not only resulted in the change of distribution range of all species,but also promoted adaptive evolution and origin of new species.The Qinghai-Tibetan Plateau is sensitive to the climatic oscillations due to its complex topology with the high altitude.In order to reveal how this oscillation affected the distribution range and speciation of plants occurring there,the present dissertation studied the phylogeography and possible speciation pattern of Picea likiangensis complex and closely related species.The mitochondrial(mt)genomes are inherited matemally while chloroplast(cp)genomes are inherited paternally in Pinaceae,and their respective variations are important for detecting gene flows mediated respectively by seeds and pollens,and having the great advantages of elucidating species divergence and following hybridization introgression.A total of 678 individuals of 67 populations,representing five taxa of three assumed species were collected and their morphological variations were illustrated.A total of five fragments from mt and cpDNA were sequenced for all individuals.No mixed population was found for P.wilsonii and P.purpurea.A few populations are morphologically pure for each of three varieties of P likiangensis (var.likiangensis,var.rubescens and Var.linzhiensis)in their allopatric distribution regions.However,these three taxa and Picea purpurea were morphologically mixed in many populations with two and/or more taxa within their parapatric distribution regions.Three cpDNA fragments(trnS-trnG,trnL-trnF and ndhK/C)identified seven chlorotypes and they clustered into two clades with one mainly occurring in the P. wilsonii-P,purpurea lineage.Two mtDNA fragments(nadl and nad5)identified 11 mitotypes and they grouped into three tentative clades.The earliest diverged one was mainly found in the P.wilsonii-P,purpurea lineage.All typical populations of both P. willsonii and P.purpurea fixed the same mitotype and chlorotype.However,each of three varieties of P.likiangensis contained two or more chlorotypes and mitotypes. According to the evolutionary relationships of haplotypes and their distributions, the following conclusions were drawn.(1)P.wilsonii-P,purpurea lineage diverged early and no differentiation was found between them possibly due to the late divergence between them or too frequent gene flow,which stopped the inter-specific mt and cpDNA differentiation although their morphological differentiation is distinct. (2)Var.linzhiensis should be recognized as a distinct species and its origin was involved three lineage through hybridization,including var.likiangensis,var. rubescens and P.wilsonii-P,purpurea lineage.(3)Frequent hybridizations were detected between most taxa.In contrast to the previous expectation that the long-dispersed pollens may result in the introgression,the present results suggested that the seed-mediated gene flow are more likely to result in the introgression of mtDNA genomes between closely related taxa.(4)Multiple refugia were retained for both var.likiangensis and var.rubescens during the glacial ages.Additionally,the final suggestion was also confirmed by the RAPD result.更多还原