Knowledge Resource Center for Ecological Environment in Arid Area
| 田鼠亚科和仓鼠亚科多样性形成及其代表类群的谱系地理学研究 | |
| 其他题名 | Formation of biodiversity of Arvicolinae and Cricetinae and phylogeography of their representative taxa |
| 吕雪 | |
| 出版年 | 2016 |
| 学位类型 | 博士 |
| 导师 | 杨奇森 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 生物多样性的形成和维持过程一直是生物学家探索的焦点，而爆发性辐射分化则是生物多样性形成过程中一个显著的模式。田鼠亚科（Arvicolinae）是北半球温带和寒带地区快速辐射分化的典范，其物种数达到28属151种，分布遍布全北区，占据了多种生态位。与之相反，其姐妹群仓鼠亚科（Cricetinae）却仅有7属18种，且大部分仅局限于欧亚内陆的干旱区。本研究试图分别从亚科水平和种群谱系地理格局的层面探讨：（1）田鼠亚科的适应辐射过程；（2）两亚科物种多样性形成巨大差异的原因以及（3）这两个亚科中不同生态型的代表种（仓鼠亚科的小毛足鼠Phodopus roborovskii和田鼠亚科的黑腹绒鼠Eothenomys melanogaster）对晚上新世以来环境变化的响应。通过对田鼠亚科102个种的气候和生物地理特征进行分析，验证了气候生态位保守性和大陆间迁移所带来的生态机遇效应对田鼠亚科分化的影响。结果表明：田鼠亚科沿降水梯度的定居时间与物种多样性呈现非常显著的正相关关系，说明气候生态位保守性决定了田鼠亚科沿降水梯度分布的物种多样性格局；另一方面，温度特征与分化速率之间呈现出间接相关性，显示出田鼠亚科定居在温暖的古北区所带来的生态机遇效应在其分化过程中的重要性。而对仓鼠亚科气候特征的分析后发现：仓鼠亚科的分布区大多局限于较干旱的区域，且适应的降水生态幅较窄，仓鼠亚科的降水生态位和生态幅之间表现出较田鼠亚科更为强烈的相关性。两亚科各种的气候生态位重叠度基本一致，且重叠性均较高；两者属级降水生态幅与分化速率之间呈现正相关，说明干旱环境对全球旱生物种的多样性形成过程具有强烈的限制作用，从而解释了干旱环境中仓鼠亚科物种多样性较低的原因。此外，干旱环境还进一步对仓鼠亚科起到物种的过滤作用，使其在降水梯度上形成较弱的系统发育关系；而沿温度梯度两亚科的生态位和生态幅并未发生明显的分化，也进一步阐明降水在这一不平衡的物种多样性形成的重要意义。作为仓鼠亚科的分布中心，蒙古高原位于亚洲内陆，拥有典型的大陆性气候，并在第四纪冰期旋回中经历了剧烈的气候变化。为研究气候变化如何影响仓鼠亚科物种的种群遗传结构，以及蒙古高原是否存在沿海洋—大陆梯度的避难所，本研究对小毛足鼠的种群历史动态和谱系地理结构进行了探索。通过重建小毛足鼠的种群历史动态变化趋势、谱系地理扩散途径、重塑其在各历史时期的适生区，研究了其分布范围的变化情况。结果显示：蒙古高原内部小毛足鼠的遗传多样性普遍高于周边地区，而生态位模拟中蒙古高原也始终是小毛足鼠的高度适生区；谱系地理扩散分析也发现，蒙古高原既是小毛足鼠的起源中心，也是它的保留以及扩散中心，蒙古高原高度同质性的生境使得种群之间可以进行广泛的基因交流，从而导致高原内部的种群间没有明显的谱系地理结构。另外，末次间冰期的环境条件更适宜小毛足鼠生存，其种群数量的增加以及适生区范围的扩大皆发生在末次间冰期；同时，末次冰盛期和现代的适生区范围变化反映了沿经度梯度变化的过程，而这两者的适生区范围较末次间冰期均有大幅度的退缩。该结果支持了蒙古高原作为小毛足鼠在第四纪气候变化中的保留和扩散中心的观点。末次间冰期适生区的扩张和适生区沿经度梯度的变化都强调了降水在气候变化过程中对适应干旱、半干旱环境的物种的重要性。而对适应于高山森林环境的黑腹绒鼠来说，其分布的中国南部地区拥有非常独特的地形景观，总体上西高东低的地势以及平原、丘陵山系的间断分布使得黑腹绒鼠呈现断续分布的模式。尽管这种分布模式在分布于这一地区的高山物种中非常多见，但对其成因的系统研究却很少。本研究综合谱系地理和生态因素，通过分析了黑腹绒鼠在各个时期分化的情况，探索了其间断分布的形成过程以及上新世以来的地质气候事件对其种群遗传结构的影响。结果显示：黑腹绒鼠种群已经形成了分化明显的三个支系——西南支系、中部支系和东南支系；对各支系的分化时间和谱系地理分析表明，黑腹绒鼠的间断分布格局很大程度上是因为上新世以来青藏高原隆升以及一系列造山运动及盆地沉降过程，而使得其种群分别以云贵高原、川西北高原和武夷山为中心发展分化而形成。更新世冰期环境变冷也有助于其不同地点以及不同支系之间的基因交流；位于云贵高原的西南支系最大程度上保留了黑腹绒鼠祖先基因型，支系总体的遗传多样性与每个地点的遗传多样性之间的关系，说明对西南支系来说，高山的隔离作用较强而导致核苷酸多样性总体较低但样点内较高的现象，而对位于四川盆地周边山地的中部支系和位于东南沿海以及台湾岛的东南支系来说，低海拔区域的山体对其隔离作用则更加明显。综合以上研究结果，本研究得出了较以往更直观的结论：（1）在密度制约的前提下气候生态位保守性不能完全解释的生物多样性格局，而生态机遇效应则对于大陆间的物种多样性格局，甚至气候梯度上的物种多样性格局都有重要影响作用；（2）干旱环境对物种多样性有限制作用，表现为对物种降水生态幅的限制作用；（3）无论是种上或种下水平，对于干旱环境的物种来说水都是限制因子；（4）对于高山森林环境的物种来说，山系的形成对其遗传和分布格局有着决定性作用，第四纪环境变化也对其遗传格局有重大影响。 |
| 英文摘要 | The formation and maintenance of biodiversity remains the most central topics to biologists. Explosive radiation represents a conspicuous process in the generation of biodiversity. Arvicoline rodents (Arvicolinae, Cricetidae) represent one of the most prominent and intriguing rapid radiations among mammals in temperate and cold environments of the Northern Hemisphere, which comprise 151 species in 28 genera. In contrast, as sister group of arvicoline rodents, cricetid rodents (Cricetinae, Cricetidae) comprise only 18 species in seven genera, and mostly distribute in arid and semi-arid environments of interior Asia. In this study, based on both broad taxonomic scale of these two subfamilies and intraspecific phylogeography, we aim to explore 1) ecological cause of the explosive radiation within arvicoline rodents, 2) reasons of imbalanced diversity between these two sister subfamilies and 3) response to environmental changes since the Late Pliocene in two representative species of different eco-type, Phodopus roborovskii (Cricetinae) and Eothenomys melanogaster (Arvicolinae).We characterized climatic and biogeographic variables for 102 species of arvicoline rodents, testing the effects of climatic niche conservatism and ecological opportunity resulting from transition between biogeographic regions on arvicoline diversification. We found that the amount of time a lineage has occupied a precipitation niche is positively correlated with diversity along a precipitation gradient, suggesting climatic niche conservatism. On the other hand, an indirect relationship exists between temperature and diversification that is associated with ecological opportunity as arvicoline rodents colonized warm Palearctic environments. In contrast, we found that cricetid rodents were restricted to drier environments and had narrower niche breadths than arvicoline rodents. The relationship between precipitation niche positions and niche breadths was much stronger in cricetid rodents than in arvicoline rodents, but niche overlap was similar and extensive in both groups. In addition, the results showed a significant positive relationship between genus-level precipitation niche breadths and net diversification rates, suggest that arid environments have strongly shaped the global speciation pattern of arid-adapted taxa by constraining those with small precipitation niche breadths. This mechanism may explain the prevalence of exclusively arid-adapted taxa and the low species richness of cricetid rodents. Aridity has acted as a filter on cricetid rodents, forming a weak phylogenetic relationship among them along the precipitation gradient. In contrast, the pattern that neither of the groups showed significant differentiation along the temperature gradient emphasizes the importance of precipitation to the imbalanced diversification of arvicoline and cricetid rodents. As a distribution centre of cricetid rodents, the Mongolian Plateau, which is situated in the interior of Asia and possesses a typical continental climate, experienced harsh climatic conditions during the Quaternary glacial fluctuations. Although these events likely had huge impacts on the local animal populations, the current effects have hardly been explored. To understand how climatic changes affect the intraspecific genetic diversity and divergence in representative of the whole group, and to explore whether the Mongolian Plateau supported a refugium along an oceanic-continental gradient, we investigated the demographic and phylogeographic history of an endemic cricetid species Phodopus roborovskii. We reconstructed the demographic variation, the phylogeographic diffusion, and modelled the potential habitat during historical periods. The genetic diversity in the Mongolian Plateau was the highest among all the localities, and the Mongolian Plateau was a suitable habitat throughout the modelled historical periods. A phylogeographic diffusion analysis emphasized the importance of the Mongolian Plateau as the centre of origin, preservation and spread for P. roborovskii. The homogeneous landscape provided the opportunity for a wide gene flow, which resulted in low resolution of the phylogenetic relationships. Moreover, P. roborovskii was favoured by the interglacial condition, with both its demographical and geographical ranges expanded within the interglacial periods. The range variation from the Last Glacial Maximum to the current condition reflects a distinct longitudinal shift, while both ranges largely contracted from that of the Last Interglacial. Our results support that the Mongolian Plateau served as a refugium and spread centre for P. roborovskii during the Quaternary climate fluctuations. The interglacial expansion and the longitudinal shifts highlighted the important effects of precipitations on the distribution range of species adapted to arid and semi-arid during glacial oscillations.For mountain-dwelling arvicoline species Eothenomys melanogaster, its distribution area have particular landscapes. The terrain was high in the west and low in the east and intervened with plains and hilly areas. Therefore, the distribution pattern of E. melanogaster was disjuct because its mediate-high elevation-dwelling habit. Although such pattern was common within montane species of this area, there are few studies focus on the formation of such disjuct distribution and its genetic impact. Integrating geological and ecological factors, we analysed the patterns of genetic divergence and distribution during different historical periods, to explore effects of geological and climatic events since the Pliocene on the formation of disjuct distribution and genetic structure. We found that there are three distinct lineages, the Southwest Lineage, the Central Lineage and the Southeast Lineage. The divergence time and phylogeographical analysis indicate that the disjuct distribution of E. melanogaster likely shaped because of the uplift of Qinghai-Tibetan Plateau and other orogeny since the Pliocene, and the lineages were then developed centred on the Yunnan-Guizhou Plateau (YGP), Northwest of Sichuan and Wuyi Mountain. The cooling periods during the Pleistocene facilitate genetic communication among localities and lineages. The low overall genetic diversity and high diversity within each locality suggest that the mountains acted as barriers in the Southwest Lineage, which situated on the YGP, and this lineage remained the most ancestral polymorphism. Low lands may intercept gene flow more in Central and Southeast Lineages, which situated in the edge of Sichuan Basin and Wuyi Mtn., respectively, and manifest as high overall genetic diversity and low within each sampling locality.In this study, we come to more distinct conclusions: (1) climatic niche conservatism alone did not fully explain diversity patterns under density-dependence, and the effect of ecological opportunity have greatly impact on diversity pattern among biogeographic regions and along climatic gradients, (2) arid environment constrain species richness by constricting species’ precipitation niche breadth, (3) for arid-adapted species, precipitation act as limit factor for both interspecific or intraspecific level, and (4) for mountainous forest-dwelling species, orogeny and tectonic events were crucial in genetic structure and distribution pattern, whereas climatic changes in the Quaternary also have great impact on genetic structure. |
| 中文关键词 | 田鼠亚科 ; 仓鼠亚科 ; 气候因子 ; 祖先性状重建 ; 生态位保守性 ; 生态机遇 ; 分化速率 ; 不平衡的物种多样性 ; 谱系地理。 |
| 英文关键词 | Ancestral reconstruction Arvicolinae Climatic factors Cricetinae Diversification rate Ecological opportunity Imbalanced species richness Niche conservatism Phylogeography. |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 动物学 |
| 来源机构 | 中国科学院动物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287674 |
| 推荐引用方式 GB/T 7714 | 吕雪. 田鼠亚科和仓鼠亚科多样性形成及其代表类群的谱系地理学研究[D]. 中国科学院大学,2016. |
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