第四紀更新世的冰川運動及氣候變化對中國鳥類物種演化和分布產生了重大影響。近日，中科院動物研究所研究員雷富民帶領「鳥類學研究組」，通過對青藏高原兩種特有類群白腰雪雀和地山雀的比較研究發現：兩個物種都經歷了更新世冰期的瓶頸效應和冰後的種群快速擴張，且擴張時間（0.05-0.16 Ma）和最後一次最大冰期撤退的時間基本一致（0.5-0.175 Ma）。但是，兩個物種具有不同的譜系地理分布格局：白腰雪雀種群擴張自青藏高原東部邊緣的避難地；而地山雀擴張自青藏高原東北及東南邊緣兩個獨立的避難地。這兩種不同的避難地模式，兩個物種不同的擴散能力，及其不同的空間分布特徵是造成這兩種不同譜系格局形成的主要原因。該研究結果發表於Molecular Phylogenetics Evolution上。
而對華南分布及東南亞特有物種灰眶雀鶥線粒體Cytb和COI基因片段的種群遺傳結構和歷史動態研究，卻發現了不同譜系格局和形成機制。灰眶雀鶥種群出現了多個明顯的種群遺傳結構深度分歧，其分歧模式和不同動物地理亞區基本一致。該物種進化歷史非常久遠，推測最近祖先可能存在於晚中新世的中國南方地區。在其漫長的進化過程中，青藏高原隆升所導致的周邊區域環境植被變化、全球範圍內的植被演替以及第四紀冰期迴旋等一系列地質歷史事件和生態環境演變可能是導致灰眶雀鶥種群分化的主要原因。中國南方的複雜地形可能為灰眶雀鶥提供了不同的冰期避難地，而在冰期後這些避難地又阻礙了種群的擴散，從而造成了地理種群之間深度的遺傳分歧和基因流中斷。灰眶雀鶥的東部地理組群中存在明顯的晚更新世種群擴張，反映了晚更新世冰期的氣候變化對中國南方東部的環境影響十分顯著。擴張時間應在晚更新世早期的最大冰盛期，而非末次冰盛期。該研究結果發表於《BMC進化生物學》（BMC Evolutionary Biology）。
這些研究工作得到了國家自然基金與科學院創新項目的支持。（生物谷Bioon.com）
生物谷推薦原始出處：
BMC Evolutionary Biology 2009, 9:143doi:10.1186/1471-2148-9-143
Phylogeography of the Alcippe morrisonia (Aves: Timaliidae): long population history beyond late Pleistocene glaciations
Gang Song1,2 , Yanhua Qu1 , Zuohua Yin1 , Shouhsien Li3 , Naifa Liu4 and Fumin Lei1
1Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101 PR China
2Graduate School of the Chinese Academy of Sciences, Beijing, 100039 PR China
3Department of Life Science, National Taiwan Normal University, Taibei, Taiwan, 116 ROC
4School of Life Science, Lanzhou University, Lanzhou, 730000 PR China
Background
The role of Pleistocene glacial oscillations in current biodiversity and distribution patterns varies with latitude, physical topology and population life history and has long been a topic of discussion. However, there had been little phylogeographical research in south China, where the geophysical complexity is associated with great biodiversity. A bird endemic in Southeast Asia, the Grey-cheeked Fulvetta, Alcippe morrisonia, has been reported to show deep genetic divergences among its seven subspecies. In the present study, we investigated the phylogeography of A. morrisonia to explore its population structure and evolutionary history, in order to gain insight into the effect of geological events on the speciation and diversity of birds endemic in south China.
Results
Mitochondrial genes cytochrome b (Cytb) and cytochrome c oxidase I (COI) were represented by 1236 nucleotide sites from 151 individuals from 29 localities. Phylogenetic analysis showed seven monophyletic clades congruent with the geographically separated groups, which were identified as major sources of molecular variance (90.92%) by AMOVA. TCS analysis revealed four disconnected networks, and that no haplotype was shared among the geographical groups. The common ancestor of these populations was dated to 11.6 Mya and several divergence events were estimated along the population evolutionary history. Isolation by distance was inferred by NCPA to be responsible for the current intra-population genetic pattern and gene flow among geographical groups was interrupted. A late Pleistocene demographic expansion was detected in the eastern geographical groups, while the expansion time (0.2–0.4 Mya) was earlier than the Last Glacial Maximum.
Conclusion
It is proposed that the complicated topology preserves high genetic diversity and ancient lineages for geographical groups of A. morrisonia in China mainland and its two major islands, and restricts gene exchange during climate oscillations. Isolation by distance seems to be an important factor of genetic structure formation within geographical populations. Although glacial influence to population fluctuation was observed in late Pleistocene, it seems that populations in eastern China were more susceptible to climate change, and all geographical groups were growing stably through the Last Glacial Maximum. Coalescence analysis suggested that the ancestor of A. morrisonia might be traced back to the late Miocene, and the current phylogeographical structure of A. morrisonia is more likely to be attributable to a series geological events than to Pleistocene glacial cycles.