Knowledge Resource Center for Ecological Environment in Arid Area
| 黄耆属三个近缘物种的分子系统学和谱系地理学研究 | |
| 其他题名 | The molecular phylogenetic and phylogeographic study of three related species in Astragalus L. |
| 张杰 | |
| 出版年 | 2016 |
| 学位类型 | 硕士 |
| 导师 | 张明理 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 乌拉特黄耆、边陲黄耆和A.coluteocarpus Bioss.是黄耆属中的三个形态上十分相似的近缘物种。为了明确它们之间的分子亲缘关系以及探讨分子证据能否支持边陲黄耆为一个独立的物种，我们从分子水平上对它们进行了分析。此外，为了研究古地质事件及气候变迁对西北干旱区山地植物空间遗传分布格局的影响，我们选取这三个近缘物种作为研究对象来进行了谱系地理研究。 \n\n我们测定了这三个近缘物种共33个样本的ITS和trnL-F序列。基于ITS+trnL-F联合序列，运用Mega6.06软件计算了种内和种间的遗传距离，并利用Mega6.06和Mrbayes3.2软件分别构建了ML树和BI树。结果显示：乌拉特黄耆、边陲黄耆和A.coluteocarpus Bioss.的种内平均遗传距离分别为0.000、0.001和0.003；乌拉特黄耆和边陲黄耆之间平均遗传距离为0.010，而这两个物种与A.coluteocarpus Bioss.之间的平均遗传距离分别为0.015和0.016；乌拉特黄耆和边陲黄耆种间的平均遗传距离远大于它们物种内的遗传距离；ML树和BI树具有相似的拓扑结构，均分为了三个分支，其中每个物种的所有个体都聚集在一个单独的分支上且不存在种间交叉现象。因此，本研究揭示了这三个近缘物种的分子亲缘关系，分子证据说明边陲黄耆应该是一个独立的种。\n\n我们共收集三个物种的23个居群共计169个样本，其中包括乌拉特黄耆7个居群共计69个样本，边陲黄耆12个居群共计85个样本和Astragalus coluteocarpus Bioss. 4个居群共计15个样本。根据筛选出的三个（accD-psaI、trnC-rpoB和trnV）叶绿体DNA序列的变异位点得到15个单倍型，每个物种各5个单倍型，物种之间不存在共享的单倍型。单倍型的系统发育树及网络图显示每个物种基本都属于一个单独的分支。分子方差分析显示物种间有很高的遗传变异。中性检验和错配分析显示三个物种近期均没有经历居群的扩张过程。根据被子植物叶绿体DNA平均突变率得到种间分化时间在5.40 Mya (Million years ago)到3.75 Mya 之间，种内的分化时间主要发生在2.34Mya-0.21Mya之间。结果表明物种种子有限的扩散能力等可能导致了种间限制性基因流。种间的分化与第三纪青藏高原及其周边山系的隆升和持续增强的干旱化过程有关；而种内的遗传多样性与第四纪更新世冰期-间冰期循环有关。 |
| 英文摘要 | Astragalus hoantchy Franch., A.dshimensis Gontsh. and A.coluteocarpus Bioss. are three related species morphologically. To explore their genetic relationship and A.dshimensis Gontsh.whether as a separate species or not, we conduct a molecular level study on these species. In addition, the three sister species of Astragalus L.were chose as model species to investigate the impacts of ancient geological and climatic events in northwest of China on the spatial genetic structure of mountains plants. \n\nWe sequenced the ITS and trnL-F sequences of 33 individuals of the three species in this study. The intraspecific and interspecific genetic distances were calculated by Mega 6.06, the phylogenetic trees of Maximum Likelihood (ML) method and Bayes Inference (BI) were respectively reconstructed by Mega 6.06 and Mrbayes3.2. The results shown that the intraspecific genetic distances of A.hoantchy Franch., A.dshimensis Gontsh. and A.coluteocarpus Bioss. were 0.000, 0.001 and 0.003 respectively, the average interspecific genetic distances between A.hoantchy Franch. and A.dshimensis Gontsh.was 0.010, that of both with A.coluteocarpus Bioss. were 0.015 and 0.016 respectively. Additionally, the average interspecific genetic distance between A.hoantchy Franch. and A.dshimensis Gontsh. was indicated to be larger than their intraspecific genetic distance. The phylogenetic trees used ML and BI method have a similar topological structure in which three distinct clades were comprised of individuals of three studied species respectively. This study not only revealed the genetic relationship of the three related species but also provided the molecular evidences that support A.dshimensis Gontsh.as a separate species.\n\nWe collected 169 individuals belonging to 23 populations of the three sisiter species, including 7 populations and 69 individuals of A.hoantchy Franch., 12 populations and 85 individuals of A.dshimensis Gontsh. and 4 populations and 15 individuals of Astragalus coluteocarpus Bioss.. According to screened three chloroplast regions accd-psaI, trnC-rpoB and trnV there were identifed 15 haplotypes, including 5 haplotypes (H1, H2, H3, H4 H5) in A. coluteocarpus Bioss., 5 (H6, H7, H8, H9,H10) in A.dshimensis Gontsh. and 5(H11, H12, H13, H14, H15) in A.hoantchy Franch.. No haplotypes have been shared between species. Haplotypes network and phylogenetic tree suggested that they clustered into three divergent lineages which mostly correspond to the three species. AMOVA (Analysis of Molecular Variance) showed the high levels of genetic differentiation occured at interspecific. Neutral tests and mismatch distribution analysis support no species had experienced demographic expansions recently. Based on the average substitution rate of cpDNA in Angiosperms, the genetic divergence time of interspecific were calculated at 5.4 Mya (Million years ago)-3.75 Mya, while the intraspecific divergence mainly happened at 2.34 Mya-0.21Mya.Our results demonstrated that the high restrict gene flow at interspecific were because of the limit dispersal ability of seeds. The species-level divergence was most likely triggered by rapid uplift of Tibet Plateau and its adjacent mountains and the continuously enhanced aridification in Central Asia, while development of genetic variation at the intraspecific level might be attributed to climatic cycles in the Quaternary. |
| 中文关键词 | 黄耆 ; 分子系统学 ; 谱系地理学 ; 间断分布 ; 近缘种 |
| 英文关键词 | Astragalus Molecular phylogenetics Phylogeography Related species Disjunct distribution |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生物工程 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287804 |
| 推荐引用方式 GB/T 7714 | 张杰. 黄耆属三个近缘物种的分子系统学和谱系地理学研究[D]. 中国科学院大学,2016. |
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