Knowledge Resource Center for Ecological Environment in Arid Area
| 温带荒漠建群灌木红砂的进化历史研究 | |
| 其他题名 | The evolution history of Reaumuria soongarica, a dominant shrub in temperate deserts |
| 石勇 | |
| 出版年 | 2016 |
| 学位类型 | 博士 |
| 导师 | 马小飞 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 第四纪气候震荡和地质变迁严重影响着亚洲内陆的干旱化进程，同时对温带荒漠生态系统和生物多样性的形成产生重大影响。为了理解荒漠建群植物的物种形成过程，我们以广布于温带荒漠的建群灌木红砂(Reaumuria soongarica)为代表，基于双亲遗传的核基因序列变异，利用隔离迁移模型、ABC(Approximate Bayesian Computation)模拟和生态位模拟，探讨了物种形成早期阶段的生态维持机制。因为缺乏参考基因组序列，我们首先调查了红砂的转录组，并获得了77647条Unigene序列，其中有一半(43054条)得到了注释。在此基础上，我们筛选出了9个低拷贝的中性基因，并调查其在41个红砂群体(325个个体)上的遗传变异。这些红砂群体的样本覆盖了塔克拉玛干沙漠、古尔班通古特沙漠、柴达木盆地、库姆塔格沙漠、巴丹吉林沙漠、腾格里沙漠以及蒙古戈壁沙漠等温带荒漠大部分区域。基于多位点核基因的遗传多态性，结合共祖模拟和生态位模型，我们分析了红砂的种内分化和杂交历史、群体动态、基因流和生态分化等情况。结果表明，红砂的进化过程主要分为三个阶段：第一阶段，受昆仑-黄河运动的影响，红砂约于0.714 Ma在东西方向上发生了明显的遗传分化；第二阶段，东部支系和西部支系分别于0.543 Ma和0.287 Ma发生至少两次杂交，促进了古尔班通古特沙漠的红砂北部支系的起源；第三阶段，北部支系和其他支系出现了明显的生态位分化，且正处于面对大量基因流的生态物种形成阶段。我们的数据表明，荒漠植物的物种形成过程伴随着其生境干旱化的过程，且严重受到第四纪地质变迁和气候震荡的影响。相比于其他植物，荒漠植物的物种形成过程更为复杂，尤其在物种形成的早期阶段，涉及到诸如遗传分化、多次杂交、基因流伴随和生态位建立等过程。我们的结果有力地支持荒漠植物的物种形成是一个在时间和空间上不断变化的过程，为深刻理解物种形成机制提供了新的证据和模型，同时，为进一步利用基因组手段深入探讨荒漠植物的适应性进化机理打下了坚实的基础。 |
| 英文摘要 | The climatic oscillations and geographic events during the Quaternary period seriously changed the desertification of the Asian Central Arid, as well as the establishment of ecosystem and biodiversity in temperate deserts. To understand the early stage speciation process of desert plant species, we investigated the evolutionary history and ecological mechanism of Reaumuria soongarica, which is a typical desert shrub species widely distributed in temperate deserts, based on the polymorphism of biparental inherited nuclear genes and simulation modeling such as Isolation with Migration (IM), Approximate Bayesian computation (ABC) and Ecological niche modeling (ENM). Due to paucity of genome references, we investigated the transcriptome of R. soongarica for the first time, and obtained 77,647 unigenes, half of which were annotated (43,054 unigenes). Based on these reference sequences, we screened nine single-copy nuclear genes which are not derived from neutral, and investigate their genetic variation in 41 R. soongorica populations (325 individuals). These samples covered most areas of temperate deserts, including the Taklimakan Desert, Gurbantünggüt Desert, the Qaidam Basin, Kumtag Desert, the Badain Jaran Desert, the Tengger Desert and Mongolia's Gobi Desert. Based on multi-locus genetic polymorphism of nuclear genes, combining coalescent simulation and ENM, we explored the intraspecific differentiation and hybridization, population dynamics, gene flow patterns and ecological differentiation between different populations. The results showed that the evolutionary history of R. soongarica is divided into three stages: firstly, due to the Kunlun-Yellow River tectonic movement, R. soongarica was significant differentiated in genetic at about 0.714 Ma between the eastern lineage and western lineage; secondly, the eastern lineage and western lineage were hybrid at least twice at about 0.543 Ma and 0.287 Ma, respectively, which facilitated the origination of the northern lineage endemic in Gurbantünggüt desert; thirdly, significant niche differentiations were detected among eastern lineage, western lineage and northern lineage, and the northern lineage is on the stage of ecological speciation in the face of gene flow. Our data suggest that the evolution of desert plant species are associated with their habitats desertfication, and severely affected by the climate oscillation and geologic events in the Quaternary period. Compared to other plant species, the speciation of desert plant species is more complicated, especially when the spcies is on the early stages of speciation, which would be involved in a variety of evolutionary events, such as genetic differentiation, multiple hybridizations, speciation with gene flow and the colonization of new niches. Our results provided compelling evidence that speciation is a multi-level process unfolding through time and space, and developed a deep understanding of speciation by a new non-model plant. Moreover, our work established a solid foundation for investigating the adaptive evolutionary mechanisms of desert plants through deep genome sequencing. |
| 中文关键词 | 亚洲内陆干旱区 ; 分化 ; 杂 交 ; 基因流 ; 生态物种形成 |
| 英文关键词 | Arid Central Asian Divergence Hybridization Gene Flow Ecological Speciation |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287694 |
| 推荐引用方式 GB/T 7714 | 石勇. 温带荒漠建群灌木红砂的进化历史研究[D]. 中国科学院大学,2016. |
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