影响物种多样性和遗传多样性地理格局形成的因素 —以蛙属、蝾螈科和中国大鲵的系统地理学研究为例

	影响物种多样性和遗传多样性地理格局形成的因素 —以蛙属、蝾螈科和中国大鲵的系统地理学研究为例
其他题名	Geographical patterns on species diversity and genetic diversity of amphibians: cases from Rana, Salamandridae and Andrias davidianus
	袁智勇
学位类型	博士
导师	车静 ; 张亚平
	2015-11
学位授予单位	中国科学院研究生院
学位授予地点	北京
关键词	生物地理跨大陆扩散物种分化人为转移保护
其他摘要	生物多样性格局的形成是生物学研究中的重要科学问题，对物种多样性和遗传多样性地理格局的研究则是其重要组成部分。本文从进化和生物地理学的角度出发，分别以两栖类的三个类群为研究对象，从种上和种下两个方面入手，利用分子遗传学的方法，探讨不同时空尺度下造成物种多样性和遗传多样性地理格局形成的主要影响因素。本文首先以广泛分布于欧、亚和美洲大陆的蛙属物种为研究对象，利用3个线粒体基因片段和6个核基因片段，构建该类群的系统发育关系，并在此基础上重建该类群在不同地区间的生物地理和物种分化历史。研究结果揭示蛙属起源于东亚，先后两次独立的通过白令路桥扩散进入北美，从东亚经中亚一次扩散进入欧洲。随后，对分布于北半球的17个两栖爬行动物类群进行统计比较，发现通过“跨白令路桥”的迁移路线在两栖爬行动物中具有普遍性，这与植物类群的研究结果一致。物种分化分析结果显示新旧大陆不同的地质、气候演化历史对各自地区的物种分化影响不同。祖先物种扩散进入新大陆后，由于存在较多可利用生态资源而经历了典型的适应性辐射，分化速率由高逐渐降低。墨西哥高原及其邻近地区地处温带和热带转型区，加上本身复杂的地质历史，该地区物种分化对美洲地区整体的物种多样性积累贡献最高。旧大陆的类群在起源后分化速率一直较慢，直到29–18 Ma 期间经历了物种生成速率的快速增加，然后逐渐变缓。结合生物地理、物种分化，时间估算和地质历史的研究，揭示了渐新世至中新世东亚地质、气候环境的变化，尤其是东亚岛屿的剧烈构造运动以及气候波动所偶联的海平面变化很大程度上促进该时间段内物种的快速分化。（第二章）接着，以分布于欧亚大陆的蝾螈科物种为研究对象，检测造成欧洲和亚洲的物种多样性差异格局的两个主要假说：“物种生成率差异假说”和“物种灭绝率差异假说”。结合本研究和已发表的线粒体基因数据，重建蝾螈科物种的系统发育关系，并进行时间估算和物种分化分析。结果显示，欧洲蝾螈类与亚洲蝾螈类的物种灭绝率差异不显著，但后者的物种生成率显著高于前者，因而支持“生成率差异假说”，并指出两个地区不同的环境异质性程度可能是造成其物种生成率差异的主要原因。另外，对两次独立扩散进入亚洲的两个支系的物种分化分析结果显示两者具有不同的分化模式。对繁殖生境进行祖先性状重建的结果显示这两个类群各自的祖先支系具有不同的生活习性，可能是造成其后代物种扩散进入亚洲后分化差异的主要原因。（第三章）最后，以中国大鲵为研究对象，探究历史自然因素和近期人为因素如何影响该物种遗传多样性地理格局的形成。通过对中国大鲵野生种群和养殖种群的“非损伤”样品采集，利用2个线粒体基因片段和15个微卫星位点，构建中国大鲵的群体遗传结构，并对其遗传多样性进行评估。线粒体结果显示，中国大鲵呈现明显的地理遗传结构，这与其本地适应和生境间的隔离作用相关。微卫星结果显示，大部分的野生群体和养殖群体遗传结构混杂，这与近期人为对中国大鲵的广泛转移相关，人为的转移作用严重影响了中国大鲵在不同地理空间上的遗传完整性。结合本研究的结果，对该物种的管理以及重点优先保护的种群提供了科学的建议。（第四章）; Understanding how and why biodiversity varies over geographic space and evolutionary time is the fundamental question in biology. Patterning of species diversity and genetic diversity are keys to understanding how ecological and evolutionary processes generate biological diversity. In this study, we build the evolutionary history of three taxa of Amphibians (within family, within genus and within species) and investigate the major factor(s) shaped their patterns of species diversity and genetic diversity through historical biogeography. Firstly, we use a phylogenetic approach to investigate the evolutionary processes responsible for the observed distributional patterns and diversity in the true frogs, genus Rana, across Eurasia and the Americas. A well-resolved, time-calibrated phylogeny is estimated from sequences of six nuclear and three mitochondrial loci sampled from most species of Rana. Analyses involving several biogeographic models consistently support an “Out of Asia” pattern with two independent dispersals of Rana from East Asia to North America via Beringian land bridges. This route is the prevailing transcontinental dispersal route within 17 families of amphibians and reptiles, and is largely consistent with the pattern seen among lineages of Holarctic plants. The more species-rich lineage of New World Rana appears to have experienced a rapid radiation following its colonization into the New World, especially with its expansion into montane and tropical areas of Mexico and Central America. In contrast, Old World Rana exhibit different trajectories of diversification; diversification in the Old World proceeded very slowly at first and later underwent a distinct elevated speciation rate shift at around 29–18 Ma. Environmental changes and especially intensive tectonic movements along the Asian margin from Oligocene to early Miocene are associated with the elevated rate shift of net diversification. Secondly, to understanding how speciation rate and extinction rate directly cause the large-scale patterns of species diversity in Europe and Asia, we investigate the evolutionary history of the newts, Salamandridae, which distribute broadly across these these regions. Based on mitochondrial data, we built a time-calibrated phylogeny of Salamandridae to estimate speciation and extinction rates associated with the European and Asian newts. Overall, both two regions show a similar extinction rates. However, speciation rate is significantly higher in the Asia than in Europe regions, which could be associated with the different environmental heterogeneity of these two areas. In addition, different processes of diversification characterized by the two major lineages of Asian newts, which were independently dispersal from Europe during a similar time. Ancestral state reconstruction show that different ancestral breeding habitats of the two lineages contributed to the patterns. It suggests that including the extrinsic environmental factors, intrinsic lineage-specific traits also influence diversification. Lastly, we use the Chinese giant salamander, Andrias davidianus, to explore how natural factors and anthropogenic activities drive the patterns of genetic diversity and genetic structures. This extremely endangered species is the object of recent and intensive human translocation and urgently needs protection. We evaluate its genetic structure based on mitochondrial and microsatellite DNA data to explore the relative roles played by these drivers on this species. Our analyses show that both natural and anthropogenic factors are responsible for its current genetic differentiation and structure. Localized divergence associated with habitat isolation results in matrilineal geographic structuring. However, human translocations significantly influence its recent evolutionary history by leading to widespread nuclear genetic admixture. Uninformed genetic mixing may negatively impact sustainable future of the salamander by threatening its genetic integrity. Genetic analyses lead to some management recommendations.
语种	中文
文献类型	学位论文
条目标识符	http://ir.kiz.ac.cn/handle/152453/11974
专题	科研部门_分子进化与基因组多样性（张亚平）科研部门_两栖爬行类多样性与进化（车静）
作者单位	中国科学院昆明动物研究所
推荐引用方式 GB/T 7714	袁智勇. 影响物种多样性和遗传多样性地理格局形成的因素 —以蛙属、蝾螈科和中国大鲵的系统地理学研究为例[D]. 北京. 中国科学院研究生院,2015.

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