藏羚遗传多样性、遗传结构与种群历史动态———线粒体DNA D-loop序列的分析

NWIPB OpenIR

	藏羚遗传多样性、遗传结构与种群历史动态———线粒体DNA D-loop序列的分析
其他题名	Genetic diversity, genetic structure and population history of Chiru (Pantholops hodgsoni): inferred from partial mtDNA D-loop sequences
	都玉蓉
学位类型	博士
导师	苏建平
	2008-06-05
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	藏羚羊线粒体dna D-loop 遗传多样性遗传分化基因流种群历史动态
摘要	藏羚（Pantholops hodgsoni）是青藏高原特有种，主要分布于我国的青海省、新疆自治区、西藏自治区、四川省海拔3 700～5 500米的高山荒漠草原，为国家一级保护动物，世界濒危野生动物物种，被列入《濒危动植物种国际贸易公约》。近几十年来，藏羚羊面临栖息地毁坏、惨遭猎杀等严重威胁，致使其生境破碎化、种群数量急剧下降，其生存状况已引起国际社会的极大关注。本研究采用DNA测序技术对藏羚mtDNA D-loop区部分序列进行测序，通过分析我国青海、西藏、新疆三省（区）6个藏羚种群（PA、PB、PC、PD、XJ、XZ）共312个样本（35条序列从GenBank获得）的序列变异，分析和探讨了我国藏羚羊的遗传多样性水平、基因流、遗传分化、种群历史动态及历史成因。主要研究结果如下： 1.在所测的藏羚羊（n=312）385 bp的mtDNA D-loop片段中共检测到110个变异位点，包括43个单突变位点和67个简约信息位点。基于上述突变位点，共检测到232种单倍型；而单倍型多样性、核苷酸多样性分别高达0.9970±0.0007和0.02653±0.01343，以上表明藏羚羊具有丰富的mtDNA遗传多样性。 2.由藏羚羊单倍型网络关系图可以看出，各种群的单倍型交错分布于整个网络关系中，表明藏羚羊种群不存在显著的地理结构，且种群间存在一定程度的基因流。 3.藏羚羊各种群间存在较强的基因流。除PA—>PD、XJ—>PD、PD—>PC的基因流较小外（分别为0.52头/世代、0.13头/世代和0.41头/世代），其余各种群对相互间基因流（迁入与迁出）均大于1，与藏羚羊迁徙产仔的生活习性相符；且自1百万年以来，藏羚羊种群间基因交流频次随时间呈逐步上升趋势。 4.AMOVA结果显示，种群内遗传变异占96.61%，而种群间的变异仅为3.39%，说明地理分化不大；但依据单倍型频率计算的固定指数却表明藏羚羊种群的地理分化已达到显著水平（P<0.01） 5.藏羚羊种群在过去100万年期间，种群规模总体上呈增长趋势，约增长了31.72倍。在这一时间段内，藏羚羊种群规模的变化并不表现为持续增长，而是经历了一个缓慢增长 —> 快速增长 —> 种群减少的波动过程。 6.藏羚羊在1 My BP～0.18 My BP期间种群规模呈稳定增长趋势；而在0.18 My BP～42.95 ka BP期间以较快速度增长，这与近百万年来青藏高原的气候事件存在较好的相关；在42.95 ka BP～10.74 ka BP期间，藏羚羊种群急剧增长，表明该时期青藏高原气候特征、植被等适合藏羚羊生存、繁殖。 7.近1万年以来，藏羚羊总体数量呈下降趋势。藏羚羊种群的下降可能与全新世以来青藏高原人类活动加剧密切相关。
其他摘要	Tibetan antelope, Pantholops hodgsoni, world endangered wildlife, a species listed on Category I of the List of Chinese State Key Protected Wild Animals, and CITES appendix I, is endemic to Qinghai-Tibetan Plateau (QTP) and mainly distribute on the desert steppe of 3700-5500 meters above sea level in Qinghai, Xinjiang, Tibet and Sichuan province of China. In the past several decades, the population of P. hodgsoni decreased dramatically, which due to the habitat destroyed, poaching and habitat fragmentation. These situations were aroused widespread concern in the international community. To investigate the genetic diversity, genetic differentiation, gene flow and demographic history of P. hodgsoni, we presented genetic variation analysis of partial mitochondrial(mt) DNA control region (CR) for 312 samples from 6 populations(PA, PB, PC, PD, XJ, and XZ) across Qinghai, Sinkiang, and Tibetan. The results provided scientific information for formulating effective management strategies. The results are as follows: i) 110 variable sites were detected in partial mtDNA D-loop sequences of P. hodgsoni. The aligned length of mtDNA D-loop is 385 bp, which includ 43 single mutational sites and 67 parsimony sites. A total of 232 haplotypes were indentified in 312 individuals. The value of haplotype diversity and nucleotide diversity reached 0.9970±0.0007 and 0.026530±0.013436, respectively. Our results showed that the P. hodgsoni had a high genetic diversity. ii) The network relationship of the haplotype showed that the haplotype of P. hodgsoni staggerly distributed into the network, which implied that certain gene flow but no geographic structure existed in P. hodgsoni. iii) The strong gene flow among the populations of P. hodgsoni was observed. The value of gene flow (immigration and migration) for pairwise populations exceeded 1 except that of PA→PD、XJ→PD、PD→PC, with the value were 0.52, 0.13 and 0.41, respectively. Furthermore, we found that the gene flow of pariwise populations kept increasing since 1 million years(My) before present(BP). iv) The population structure of P. hodgsoni is investigated here by subdividing the total molecular variance. Accounting for 3.39 percnets of total variance, the variance component of intra-populations was 0.17492, which showed that little geographic structure existed among population of P. hodgsoni. However, a significant genetic differentiation among populations was observed(P<0.01) by using non-parametric permutation procedures. v) The population scales of P. hodgsoni increased 31.72 times during the past one million years. However, the population sizes of P. hodgsoni did not increase continuously, but undergo the fluctuant process of slow increase → fast increase → the decrease. vi) Using bayesian coalescent simulation, a steady but slow population expansion of P. hodgsoni was observed during 1 My BP to 0.18 My BP. Hovever, a faster population expansion of P. hodgsoni was observed during 0.18 My BP to 42.95 thousands years(ky) BP. Those were well correlated with the climatic incident since approximate 1 million years before present. During the period of 42.95 ky BP to 10.74 ky BP, the population started to increas dramatically, which suggested that the climatic and vegetation characteristics provided favorable conditions for their survival and reproduction during that period. vii) Bayesian coalescent simulation provided compelling evidence for a short-term population decline since circa 10 ky BP in P. hodgsoni, which may well correlated with the increasing human activity in the Qing-Tibetan Plateau since the Holocene Epoch.
页数	102
语种	中文
文献类型	学位论文
条目标识符	http://210.75.249.4/handle/363003/3030
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	都玉蓉. 藏羚遗传多样性、遗传结构与种群历史动态———线粒体DNA D-loop序列的分析[D]. 西北高原生物研究所. 中国科学院西北高原生物研究所,2008.