【作者】 肖力宏；

【导师】 宝音陶格涛； 王印政；

【作者基本信息】 内蒙古大学 ， 生态学， 2005， 硕士

【摘要】 本研究在对分布于中国东南苦苣苔Conandron ramondioides(苦苣苔科)的11个种群的生态环境进行野外调查基础上,以花发育基因Gcycl的单核苷酸多态性(SNPs)为分子标记,研究苦苣苔的Gcycl基因在种群水平的变异及种群的遗传多样性和遗传结构及其进化机制,进而推断种群进化的历史,并讨论SNPs分子标记在研究非模式植物种群史中的应用潜力。主要结论如下: 1.苦苣苔种群分布于阴坡山谷中,通常出现在溪流源头的常绿阔叶杂木林下的花岗岩石壁上。调查的种群全部位于相似的原生生境,种群较小并呈片断化分布。种群内个体集群分布,个体数量与生境的湿润程度具有相关性。种子主要随水流传播,也可借助于蒴果开裂的力量传播。对苦苣苔各种群的观察显示,除将乐种群(JL04)和潜山种群(QSh21)外,其他种群的叶脉、叶柄、花序亭、苞片和萼片均光滑无毛。我们认为在中国东南的苦苣苔种群中存在两种生态型。 2.苦苣苔Gcycl基因774个分析的碱基中共检测到18个SNPs位点,其中11个是非同义替代。形态观察发现花的对称性并没有发生改变,说明这些非同义替代不影响所编码蛋白质的功能,因此,可以认为Gcycl基因在种群水平上的进化符合“中性理论”。 3.苦苣苔的遗传多样性水平较低(H=0.041(±0.0318),He=0.0952(±0.1300),Ho=0.0089(±0.0118))。大部分的遗传变异存在于种群间(Gst=0.564),种群内更多还原

【Abstract】 Based on materials of 11 populations of Conandron ramondioides collected from SE China, we have carried out a study on the genetic variation of populations in C. ramondioides by analyzing on single nucleotide polymorphisms of the floral developmental gene Gcycl controlling the floral symmetry. This study aims to explore the molecular evolution of Gcycl gene and formation of the genetic diversity and structure of populations within C. ramondioides. And we have also discussed the potential implication of SNP marker in non-model organisms.The main conclusions are as follow:1. The populations of C. ramondioides are distributed in valley of mountain shady slope, and they are usually found on granite rock at the headstream under evergreen broadleaf forest. The investigated populations all lie in the similar native habitat, and the populations are small and fragmented. Individuals in populations are clumped and the number of individuals is correlative with the moisture degree. Seeds are dispersalmainly by water, and the force of the dehiscencing capsular fruit. Morphological observation shows that there are many unicellular glandular hairs on the petiole and leaf vena, and dense multi-cellular epidermal hairs on the sepal, bract and peduncle in some individuals of the QSh21 and JL04 populations. In other populations, the petiole, leaf vena, sepal, bract and peduncle are smooth. Therefore, we suggest that the populations of C. ramondioides from SE China belong to two ecotypes.2. 18 SNPs are detected within the analyzed 774bp of Gcycl gene of C. ramondioides, in which 11 SNPs are non-synonymous. Morphogenetic observation has shown that there is no obvious variation in the floral symmetry. This result suggests that these non-synonymous substitutions do not the secondary structure of coded protein. Therefore, we can conclude that the evolution of Gcycl gene at population level is in accord with the Neutral Theory.3. C. ramondioides processes a lower genetic diversity. Average heterozygosity, expected heterozygosity and observed heterozygosity are 0.041(±0.0318), 0.0952 (±0.1300), 0.0089(±0.0118), respectively. The most genetic diversity is due to variation between populations (Gst=0.546), and the genetic variation within population is small (Ht=0.097, Hs=0.042). The lower level genetic diversity within each population and higher genetic differentiation between populations were owing to the fragmented and isolated populations which frequent inbreeding and limited gene flow.4. The pair of genetic distance UPGMA cluster analysis between populations shows that the genetic distance among populations is not fully correlated with thegeographic distribution of the 11 populations in SE China. According to the ecology environment, reproductive pattern and paleogeography of C. ramondioides, we suggest that this species might be existed in present area during pre-glacial even in Tertiary before the separation of Taiwan, Ryukyu, Japan archipelago from Eurasia. Continuous distribution area might be fragmented into isolated populations both due to the climate change during ice age and human activity. The results of the pair of genetic distance UPGMA cluster analysis between populations support the conclusion that the populations of C. ramondioides from SE China belong to two ecotypes.5. Our results have shown that SNP is a useful molecular marker for the study on the population history in non-model organisms.更多还原