青藏高原两种高山植物条纹狭蕊龙胆和菊叶红景天的分子亲缘地理学研究

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	青藏高原两种高山植物条纹狭蕊龙胆和菊叶红景天的分子亲缘地理学研究
其他题名	Molecular Phylogeography of two alpine species Metagentana striata and Rhodiola chrysanthemifolia on the Qinghai-Tibet Plateau
	陈生云
学位类型	博士
导师	陈世龙
	2007-12-08
学位授予单位	中国科学院西北高原生物研究所
学位授予地点	西北高原生物研究所
关键词	高山植物叶绿体dna片断冰期避难所条纹狭蕊龙胆分子亲缘地理学菊叶红景天青藏高原
摘要	分子亲缘地理学研究对于阐述物种居群的进化历史及过去气候变迁过程中的响应提供了一种新的途径，通过运用叶绿体DNA（cpDNA）非编码区片段的序列变异进行分析，不仅能揭示植物居群遗传结构、第四纪冰期时的避难所、间冰期或冰后期的迁移路线以及当前分布格局的历史成因，而且也可为一些植物的保护提供科学依据。该领域工作在国外方兴未艾，而在国内研究甚少，特别是以青藏高原特征植物类群为代表的研究工作相对更少，而且对该地区为数不多的研究中几乎都是以木本植物为研究对象，但到目前为止对草本植物的研究却几乎是空白。然而，草本植物由于较短的生活周期以及对环境变化的敏感性，可能会更好地揭示第四纪冰期以来植物居群变化的历史过程。因此，本论文选择了分布在青藏高原及邻近地区的一年生草本植物条纹狭蕊龙胆Metagentiana striata和高原特有的多年生草本植物菊叶红景天Rhodiola chrysanthemifolia为研究对象，通过检测这两种高山植物居群的cpDNA非编码区片断（trnS-trnG和trnH-psbA基因间区）序列变异来分别进行分子亲缘地理学研究。 1、对条纹狭蕊龙胆M. striata进行两套cpDNA非编码区片断的研究得出如下主要结论： 1)对整个分布区14个居群的232个个体进行trnS-trnG片断序列分析，共检测到10种单倍型，青藏高原东北部及东部居群只拥有原始单倍型HapA，遗传多样度和核苷酸多样性都为零，而在高原东南部横断山地区单倍型分布非常集中，特有单倍型数量最多，而且遗传多样度和核苷酸多样性普遍较高；物种水平上的遗传多样度较高（Hd = 0.620），而核苷酸多样性很低（π = 0.014）；整个分布区居群间遗传分化程度很高（GST = 0.746, NST = 0.774），并且有明显的亲缘地理学结构出现（NST > GST; P<0.05）；分子变异分析（AMOVA）结果表明遗传变异绝大部分存在于居群间（76.18%），且具有显著高的居群分化水平（FST＝0.762; P<0.001）和很低的居群间平均基因流（Nm = 0.156）。 2)对整个分布区13个居群的155个个体进行trnH-psbA片断序列分析，共发现7种单倍型，青藏高原东北部居群仅拥有新近分化的单倍型HapA，高原东部居群基本上只固定了单倍型HapB，这两个地区的居群遗传多样度和核苷酸多样性几乎都为零，而在高原东南部横断山地区单倍型分布也非常集中，并且特有单倍型数量最多，居群遗传多样度和核苷酸多样性普遍较高；物种水平上的遗传多样度较高（Hd = 0.756），而核苷酸多样性很低（π = 0.046）；整个分布区的居群间遗传分化程度非常高（GST = 0.805, NST = 0.859），且有明显的亲缘地理学结构出现（NST > GST; P<0.05）；AMOVA结果表明，居群间遗传变异占绝大部分（73.05%），而且居群分化水平显著高（FST＝0.731; P<0.001）以及居群间平均基因流很低（Nm = 0.184）。从两套cpDNA片断的分析结果看出，单倍型间的序列分化水平都较低，青藏高原东北部、东部及邻近地区居群的单倍型分布都非常单一，遗传多样度和核苷酸多样性普遍极低；而高原东南部横断山区居群普遍具有丰富的单倍型，特有单倍型数量最多，遗传多样度和核苷酸多样性普遍较高。结合巢式支系法分析（NCA）研究结果推测，居群9、10、12和14（14是在trnS-trnG片断分析中的居群编号，而在trnH-psbA片断中的编号是居群13）所在的青藏高原东南部横断山区一带是第四纪冰期时该植物的可能避难所，表明了存在多个避难所；在间冰期或冰后期从居群12所在的避难所一带发生范围扩张形成高原东北部及东部的居群，而在避难所的居群之间出现片断化现象，从而塑造了该植物当前单倍型及居群的分布格局。 2、对藏药植物菊叶红景天R. chrysanthemifolia进行trnS-trnG片断分析得出的主要结论如下： 1)对整个分布区17个居群的258个个体进行序列分析，共检测到22种单倍型，单倍型间的序列分化水平比较高。就整个分区来说，单倍型Hap1和Hap8的分布最广，物种水平上具有很高的遗传多样度（Hd = 0.907）和极低的核苷酸多样性（π = 0.009），居群间遗传分化程度较高（GST = 0.571, NST = 0.562）；在两个地理分区中，东喜马拉雅组居群普遍拥有较多的单倍型数量，遗传多样度和核苷酸多样性普遍较高，特有单倍型分布较少，居群间遗传分化程度较低（GST = 0.366, NST = 0.340）；而横断山组居群大部分拥有较单一的单倍型，遗传多样度和核苷酸多样性相对较低，特有单倍型分布最多，居群间遗传分化程度很高（GST = 0.725, NST = 0.846），而且只在这一分区有着显著的亲缘地理学结构（NST > GST; 0.01
其他摘要	Molecular phylogeography has provided a new approach to elucidate the evolutionary history and response of the species populations to past climatic oscillations. Based on the analysis of sequence variations of chloroplast DNA (cpDNA) noncoding fragments, this approach has been successfully implemented to examine genetic structure of plant populations, to identify the refugia during the glaciation and interglacial or postglacial colonization routes, as well as to explain the historical causes of the present spatial distribution pattern. In addition, such phylogeographical information also provides scientific background to design conservation strategies of the studied species. Molecular phylogeographical studies in plants have so far focus on the other countries. Yet, there is limited information available to address these questions for Chinese plant species. Especially, the studies of the Qinghai-Tibet Plateau plant are rare and only several tree species had been studied. Up to now, the herbaceous plants that have a short life cycle and are sensitivity to environmental changes are poorly detected in the Qinghai-Tibet Plateau. These plants might be very suitable to indicate the historical processes of plant populations since Quaternary glaciation. In this paper, two alpine plants of the species Metagentiana striata that is an annual herbaceous plant endemic to the east of Qinghai-Tibet Plateau and the adjacent areas, and Rhodiola chrysanthemifolia that is a perennial herbaceous plant endemic to the Qinghai-Tibet Plateau were chosen. Molecular phylogeographical analyses have been respectively performed by surveying sequence variations of cpDNA noncoding fragments (trnS-trnG and trnH-psbA intergenic spacers) in all individuals of their populations. 1. The results of investigating two cpDNA noncoding fragments of M. striata were as follows: 1)Ten haplotypes were identified by analyzing trnS-trnG fragment sequences of 232 individuals of 14 populations from the entire distributional range. The populations in the northeast and east of Qinghai-Tibet Plateau only held an ancestral haplotype A (Hd = 0; π = 0), while haplotypes were concentrated in the Hengduan Mountains region of southeastern Plateau and the populations had the high uniqueness of haplotypes, genetic diversities and nucleotide diversities. In the species level, the genetic diverity was high (Hd = 0.620) and the nucleotide diversity was quite low (π = 0.014). The estimates of interpopulation differentiation were very high (GST = 0.746, NST = 0.774) and an obviously phylogeographic structure was presented (NST > GST; P<0.05) in the entire distributional region. An analysis of molecular variance (AMOVA) showed that the genetic variation mainly resided among populations (76.18%), the level of population differentiation was significantly high (FST＝0.762; P<0.001) and the average gene flow among populations was very low (Nm = 0.156). 2)Seven haplotypes were detected by examining trnH-psbA fragment sequences of 155 individuals of 13 populations covering the entire distributional range. The populations of the northeastern Qinghai-Tibet Plateau solely fixed a recently derived haplotype A and the populations of the eastern Plateau only had haplotype B on the whole, the genetic diversities and nucleotide diversities of these populations were almost equal to naught. The populations from the Hengduan Mountains region of southeastern Plateau had the most haplotypes including uniqueness, and the genetic diversities and nucleotide diversities were widely high. In the species level, the genetic diversity was quite high (Hd = 0.756) and the nucleotide diversity was very low (π = 0.046). The degree of differentiation among populations was quite high (GST = 0.805, NST = 0.859) and a significantly phylogeographic structure was existed (NST > GST; P<0.05) in the entire distributional region. AMOVA indicated that genetic variation among populations occupied 73.05% and the population differentiation was significantly high (FST＝0.731; P<0.001), while the average gene flow among populations was very low (Nm = 0.184). Based on the analyses of two cpDNA fragments for M. striata, the results showed that the most of the populations held very single haplotypes, and the genetic diversities and nucleotide diversities were extremely low in the northeastern, eastern Qinghai-Tibet Plateau and adjacent region. Whereas, the populations held more haplotypes and the most uniqueness of haplotypes, as well as high genetic diversities and nucleotide diversities in the Hengduan Mountains region of the southeastern Plateau. Based on the nested clade analysis (NCA), our results suggested that the Hengduan Mountains regions of the southeastern Plateau including populations 9, 10, 12 and 14 (14 is population code as analysis of trnS-trnG fragment, while code should be 13 as analysis of trnH-psbA fragment) were the potential refugia of this species during Quaternary glaciation, it suggested multiple refugia of this species; and the populations of the northeastern and eastern Plateau were recolonized from refugia area of population 12 during the interglaciation or postglaciation due to the range expansion, but the fragmentation events were occurred among populations of the refugia to shape the current spatial distribution patterns of haplotypes and populations of the species M. striata. 2. The results of surveying trnS-trnG fragment of Tibetan medicine R. chrysanthemifolia were as follows: 1)Twenty-two haplotypes were discovered by analyzing 258 individuals of 17 populations from the entire distributional range. As far as the entire distributional region, haplotypes 1 and 8 were most common and widespread, and the genetic diversity was very high (Hd = 0.907) but the nucleotide diversity was quite low (π = 0.009) in the species level, and the degree of interpopulation differentiation was high (GST = 0.571, NST = 0.562). In two geographical groups, the populations of the East Himalayan (EH) group widely had more haplotypes, the high diversities and nucleotide diversities and less uniqueness of haplotypes and the interpopulation differentiation was low (GST = 0.366, NST = 0.340). In the Hengduan Mountains (HM) group, the most of the populations held a single haplotype and the most uniqueness of haplotypes, the genetic and nucleotide diversities were low, the differentiation among populations (GST = 0.725, NST = 0.846) was very high and a significantly phylogeographic structure (NST > GST; 0.01
页数	171
语种	中文
文献类型	学位论文
条目标识符	http://210.75.249.4/handle/363003/3142
专题	中国科学院西北高原生物研究所
推荐引用方式 GB/T 7714	陈生云. 青藏高原两种高山植物条纹狭蕊龙胆和菊叶红景天的分子亲缘地理学研究[D]. 西北高原生物研究所. 中国科学院西北高原生物研究所,2007.