【作者】 张传军；

【导师】 肖娅萍；

【作者基本信息】 陕西师范大学 ， 植物学， 2007， 硕士

【摘要】 太白红杉(Larix chinesis Beissn.)为松科(Pinaceae)落叶松属(Larix)植物，是我国的特有种，仅分布于陕西省境内秦岭山地高海拔地段，分布区极其有限，已被列为国家二级保护植物。太白红杉是秦岭山区分布最高的乔木树种，多以纯林群落分布于高海拔地段，是很重要的水源涵养林，同时在高山地区的水土保持，稳固山石，生态环境的改善都有重要的意义。所以，在自然物种的保存、特有居群的保护、科学研究、生态效益和经济效益等方面，都具有被保护和研究的价值。尽管已对太白红杉的遗传多样性进行了一些的研究，但是还存在一些问题：①由于研究手段的局限性，其结果不一致，如多态位点的比率、基因流、聚类结果等相差较大；②对作为太白红杉主要分布地的太白山居群研究还不深入；③太白红杉随海拔的升高在形态学上发生了显著的变化，是否其遗传多样性也发生了变化。这些问题都有待进一步的解决。本论文主要针对以上存在的3个问题，运用FISH-AFLP技术对光头山、牛背梁和太白山3个居群的太白红杉进行了生物多样性的分析。因为太白山居群面积最大并且生长状况最好，因此进行了重点的研究。通过对太白山、牛背梁、光头山3个居群，58份试验材料，8对引物的AFLP分析，得到如下结果：(1) 58个供试个体、8对引物所得到的总条带数总共为26509条；平均每个个体为457条；平均每对引物扩增条带为3314条；扩增带随着分子量的递增，数目显著减少。条带多集中于分子量70-300bp之间，分子量越小，材料扩增的条带越多。研究显示，不同的计数起点和终点的选择，对最终结果影响很大。(2) RAPD、SSR、ALLOZYME和AFLP四种方法比较显示，所测位点容量、多位点的比率、Shannon基因多样性指数、Nei的遗传距离进行的UPGMA聚类分析等方面差异较大，但总体所反映的太白红杉居群的遗传多样性水平和遗传结构是一致的，即太白红杉的遗传多样性水平较高，且主要分布在居群内部，居群之间的变异较小。(3)太白红杉自然居群遗传多样性和遗传结构：8对AFLP引物共检测了1728个位点，其中1123个位点具有多态性。光头山、牛背梁和太白山3个居群的多态带数(nιp)分别为688、615和1035。种水平多态位点百分率(P)达64.99％，作为地方种，太白红杉具有良好的遗传基础。太白红杉种水平等位基因数(A)为1.9878；种水平有效等位基因数(Ae)为1.2553。太白红杉种水平Shannon信息多样性指数(I)为0.2448；居群内遗传多样性(Hpop)为0.2012，居群内遗传多样性所占比率(％)(Hpop/Hsp)为0.8219。太白红杉种水平Nei遗传多样性指数(Ht)为0.1498，各居群的变化与Shannon信息多样性指数(I)的变化规律一致。居群内遗传多样性(Hs)为0.1310，基因分化系数(Gst)0.1236，即居群间的遗传多样性占12.36％。基因流(Nm)为3.7572＞1，理论上，基因流可以抵制居群内遗传漂变的作用，防止居群之间的遗传分化的发生。太白红杉居群间的遗传一致度(I)较高，平均为0.9737；遗传距离(D)较小，平均为0.02677。结合居群间遗传多样性所占比率(％)((Hsp-Hpop)/Hsp)和基因分化系数(Gst)，说明太白红杉居群间尽管存在一定的分化，但比较小。通过遗传距离的UPGMA聚类分析，牛背梁和光头山首先归并在一起，其次才与太白山聚类在一起。这与三者的地理位置是相吻合的。(4)对太白山居群不同海拔(＜3200m，3200m-3300m，3300m-3400m和＞3400m)个体的分析表明，尽管各个海拔段的植株的遗传多样性有一定的差距，但差距不大。综上所述，太白红杉显示了较高水平的遗传多样性，应该不是因为遗传多样性低而导致濒危；遗传结构分析显示，尽管各居群间有一定的变异，但变异较小，绝大部分的多样性集中于居群内部；太白山作为太白红杉生长分布的集中地区，该地区的居群最大，且具有最高的遗传多样性，应该重点保护。更多还原

【Abstract】 Larix chinensis Beissn., an endemic species to China, belongs to the genus Larix Milland only distributes on several peaks of Qinling Mountains in Shaanxi Province. It hadbeen listed as second grade plant species of state in need of conservation.L. chinensis is very important water-nurturing forest located in the top of the forest inMt. Qingling. And it also has the significant significance for the conservation of waterand soil, the stable stone, the ecological environment improvement. So it has theconservative and research value on the respect species conservation scientific research,ecology and economy.Though there have been some studies of the genetic diversity of L. chinensis, thereare also some questions need to study. Such as, the percentages of polymorphism, thenumber of migrants per generation and the results of UPGMA dendrogram are verydifferent in the former studies. As the largest and the best growing population of L.chinensis, Taibaishan population needs more thorough research. The L. chinensis hashad the remarkable change along with elevation elevating in the morphology, its geneticdiversity also has had whether the change. These questions all wait for the further study.This paper, using AFLP as the molecular maker technique, mainly deals with geneticstructure and genetic diversity in the three populations of Guangtoushan, Niubeiliangand Taibaishan, especially the study of the Taibaishan population.(1)Using eight pairs primer combinations, 58 individuals from three populations wereanalyzed with AFLP. The results indicate that the whole number of bands is 26509; theaverage number of each individual is 457; the average number of each primercombination is 3314. The bands mainly distributed among 70-300bp and the smaller ofbands, the larger of the number of the bands.The study shows that the results is very different if the different selection of length ofbands.(2)The results of the different methods of RAPD, SSR, ALLOZYME and AFLPindicate the sites of the number of polymorphic bands, the percentage of polymorphism,Shannon diversity index, UPGMA dendrogram based on Nei’s (1978) genetic distanceare very different. But the whole genetic diversity and genetic structure are identical. The genetic diversity is high and the most genetic diversity is within population.(3)Using eitht pairs primer combinations, 58 individuals from three populations wereanalyzed with AFLP. 1728 bands were detected, and there were 1123 polymorphicbands among them. The numbers of polymorphic bands are respectively 688, 615, 1035in the Guangtoushan, Niubeiliang and Taibaishan population. The percentages ofpolymorphism are 64.99% at species level. As a local species, L. chinensis has a highergenetic diversity.Observed number of alleles and effective number of alleles are respectively 1.9878and 1.2553 at species level. Shannon diversity index is 0.2448 at species level. Thepartitioning of the diversity (Shannon’s index) within and between populations of L.chinensis for eight primer combinations are respectively 0.2012 and 0.8219.Nei’s indexis 0.1498 at species level of L. chinensis and within populations of Nei’s index is 0.1310.The coefficient of gene differentiation is 0.1236. It shows that the most diversity arewithin populations.The number of migrants per generation is 3.7572. Theoretically, Nm is enough toresist the effect of genetic drift and prevent population from subdivision.The Nei (1978) genetic identity and genetic distance show that genetic identityamong population of L. Chinesis is very high with a mean of 0.9737, and the mean ofgenetic distance is 0.02677. They show that high genetic similarity was found amongpopulation of L. Chinesis. Dendrogram resulting from UPGMA method clusteringbased on Nei (1978) genetic distance shows that the Guangtoushan and Niubeiliangpopulation has higher similarity. This is identical with the geography distance of thepopulations.(4)Analysis of the different altitude (＜3200m, 3200m-3300m, 3300m-3400m and＞3400m) of L. Chinesis in the Taibaishan population shows that this species changedlittle with the change of the altitude.In short, the result of this study shows that Larix chinesis Beissn. has a higher geneticdiversity, and it is most within populations. The population of Taibaishan has the highestdiversity and requires that priority is protected.更多还原