灰背栎遗传多样性、遗传结构及生物地理学研究所
其他题名Genetic Variation、Genetic Structure and Biogeography of Quercus senescens Hand. -Hazz.
王淑霞
学位类型硕士
导师胡运乾
2004
学位授予单位中国科学院昆明植物研究所
学位授予地点中国科学院昆明植物研究所
学位专业植物学
关键词灰背栎 遗传多样性 居群遗传结构 生物地理学
摘要本文通过对灰背栎(如Quercus senescens Hand.-Mazz.)9个居群、共155个个体的AFLP指纹分析对灰背栎的遗传多样性、遗传结构进行了探讨。并根据实验结果结合地质历史及化石资料对灰背栎生物地理学进行论述。得到以下研究结果:1.遗传多样性两对引物组合产生125个位点,94个为多态位点,多态百分率为75.20k。不同居群多态百分比从32.8%(西山居群)到55.2%(篙明居群),平均多态位点百分比为42.0%;无偏差基因杂合度从He=0.1237(宣威居群)到He=0.1847(篙明居群),整体为0.2150;平均观测等位基因数从1.3280(西山居群)到1.5520(篙明居群);有效等位基因数从Ne=1.1854(西山居群)到Ne=1.2979(篙明居群)。与栋属其他物种遗传多样性的研究相比灰背栎的遗传多样性水平偏低,这种现象可能是由于灰背栎分布区地形复杂以及生境片断化等原因所致。分析结果同时表明随着海拔升高灰背栎遗传多样性水平有下降的趋势,与李进[1],对高山栋组川滇高山栎遗传多样性与海拔关系的研究结果类似。但是由于灰背栎本身垂直分布跨度不是很大,并且采样没有覆盖其垂直分布范围,也不是集中在同一山体采样以及生境片断化影响,所以此结果亦难排除巧合的可能性。2.遗传结构AMOVA分析结果揭示30.41%的遗传变异存在于居群间,69.59%的遗传变异存在于居群内部,这一结果高于33种栎属植物等位酶研究结果统计的基因分化度的上限(Gst=0.01-0.17),但与Richard和Nasser[2]采用AFLP方法对加利福尼亚4种红橡树遗传结构的AMOVA分析结果(平均φst=0.218)更有比较性。分析灰背栎居群间高水平分化可能是历史地理以及由复杂地理地形、生境片断化原因导致遗传上隔离居群之间基因流困难所致。同时分析由于生境片断化导致的小居群会引起遗传漂变和近交,进而使适应性和遗传多样性的进一步下降,最终导致显著的居群间分化。另外适应性的差异同样会加强这一结果。3.生物地理学通过AFLP分析结合地质历史资料对灰背栎的现代分布格局成因进行探讨,认为灰背栎中新世(或者更早)起源于喜马拉雅山脉和横断山脉地区,在第四纪初冰期小规模冰川作用的影响下,灰背栋从喜马拉雅地区东撤,向横断山脉地区集中,随着中更新世暖期的到来,灰背栎一部分沿着横断山脉向滇中地区扩散,另一部分向北高纬度地区扩散,由此形成了现代的分布格局。同时以两对引物组合得到的聚类图为基础进行祖先分布区重建,对灰背栎的现代分布格局的形成过程进行分析,其结果与上面推测的结果基本一致。
其他摘要The population genetic variation and structure of 115 plants representing 9 populations of Quercus senescens Hand.-Mazz. Were investigated by amplification fragment length polymorphism (AFLP) analysis. The biogeography of Q. senescens was discussed in this paper Based on experiment results, geological development and fossil information. The main results are summarized as follows: 1. Genetic variation Total 125 markers was detected from 2 AFLP primer combinations, of which 94 (75.20%) were polymorphic, The Polymorphic percentage varies from 32.8%(xs) to 55. 2%(ga) according to different populations and has a mean value of 42.0%; Unbiased expected heterozygosity varies from He=0. 1237 (yx) to He=0. 1847(ga) and has an value of 0.2150 over all loci; Effective number of alleles(Ne) from 1.1854(xs) to 1.2979(ga). Compared to other species among Quercus, Q. senescens show lower genetic variation level, It may be because of the complicated terrain and fragmented habitat of Q. senescens. It was indicated that genetic variation level of different population was negatively correlated with elevation, which matched up to Li jin' s results of study on Quercus aquifoliodes Rehd. et Wils of Quercus sect. Heterobalanus (Oerst .) Menits. But as for the relationship mentioned above between genetic variation level and elevation, there exists the possibility of coincidence due to limited cover range at vertical direction, different distribution and fragmented habitats. 2. Genetic structure Analysis of molecular variance (AMOVA) revealed 30.41% genetic variation among populations and 69. 09% genetic variation within population. It is higher than the upper limit of genetic (Gst from 0.01 to 0. 17) based on 33 species of genus Quercus. It was comparable with the AMOVA results of 4 species of red oaks by Richard and Nassertal, but anyway which show significant differentiation among Q. senecens populations. The main factor responsible for this high level of differentiation among populations is probably the historical geographical and low level gene flow among populations of genetic isolation in a harsh mountainous environment. At the same time it is considered here that the low level of genetic variation of Q. senescens as a result of small population size leads to genetic drift and inbreeding, which will cause in turn the further decrease of fitness and level of genetic variation, ultimately cause the significant genetic differentiation. And adaptive variation can also cause intensely the same result. 3. Biogeography The cause of geographical distribution pattern was discussed based on AFLP results together with fossil information and geological development in this paper. It was indicated that Q. senescens seems originated in Himalayas and Hengduan Mountains areas with the rise of Himalayas at early Miocene. Influenced by small-scale glacial at early Quaternary, Q. senescens withdrew from Xixiabangma and converged on the Hengduan Mountains areas. During the warm interglacial period of mid-Pleitocene, part of Q. senescens dispersed to central of Yunnan along the Hengduan Mountains chains and another part dispersed northward to higher latitude areas, thereout constructed the present-day distribution pattern of Q. senescens. The ancestral distribution area of Q. senescens was mapped on the dendrograms from AFLP markers too, which result is match up to the presented above on the whole.
页数75
语种中文
文献类型学位论文
条目标识符http://ir.kib.ac.cn/handle/151853/724
专题昆明植物所硕博研究生毕业学位论文
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王淑霞. 灰背栎遗传多样性、遗传结构及生物地理学研究所[D]. 中国科学院昆明植物研究所. 中国科学院昆明植物研究所,2004.
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