近日,，國際著名雜志PLoS One在線刊登了中科院昆明動物研究所研究人員的最新研究成果“Phylogeographic Study of Apodemus ilex (Rodentia: Muridae) in Southwest China,，”，文章中,，作者在哺乳動物分子系統(tǒng)地理學研究獲得新進展,。
喜馬拉雅-橫斷山地區(qū)是世界性的生物多樣性熱點地區(qū)之一，也是中國西南山地生物多樣性熱點地區(qū)生物多樣性保護優(yōu)先區(qū),。該區(qū)域有著地球上最復雜水系,、山系和復雜的地質歷史，其獨特的自然地理條件使該區(qū)域成為中國乃至世界各種自然資源最富集的地區(qū)之一,，同時又保存著若干本區(qū)特有的生物類群,，使其成為若干生物演化的中心，形成了自身的生物多樣性特色,，構成了一座生物資源豐富的物種基因庫,。青藏高原地形的改變和橫斷山脈的走向被廣泛認為是影響我國西南地區(qū)物種空間分布和遺傳多樣性因素的重要因素。因此,，喜馬拉雅-橫斷山地區(qū)不僅是動物孓遺的重要避難中心,，還是研究生物地理學很好的模式系統(tǒng)。但是,，迄今,，關于該區(qū)域地質歷史事件和氣候變遷如何影響生物遺傳多樣的研究卻少有報道。
昆明動物研究所遺傳資源與進化國家重點實驗室獸類生態(tài)與進化組的劉琦等同學在導師蔣學龍研究員指導下,，以鼠科中最古老的屬之一—姬鼠屬（Apodemus）為研究對象,，在喜馬拉雅-橫斷山地區(qū)廣泛采集姬鼠標本并收集相關采集地和標本生態(tài)信息，在查對姬鼠屬種類的化石標本及其記錄的基礎上,，以喜馬拉雅-橫斷山地區(qū)特有的瀾滄江姬鼠（Apodemus ilex）為生物地理學研究模型,，展開姬鼠屬的起源與演化和生物地理學研究?；谥腥A姬鼠（A. draco）和瀾滄江姬鼠（A. ilex）的分類地位仍然廣存爭議,，研究針對采集自喜馬拉雅-橫斷山地區(qū)51個采集點共計203個中華姬鼠復合種群（A. draco complex）樣品結合姬鼠屬其他11個種進行了分子系統(tǒng)發(fā)育研究、松散分子鐘估算和生物地理分析,。研究結果顯示,，瀾滄江姬鼠（Apodemus ilex）和中華姬鼠（A. draco）是位于姬鼠屬的分支末端的兩個姐妹種；瀾滄江姬鼠（Apodemus ilex）的獨立地位得到驗證,，大約在上新世末期2.25個白萬年前與中華姬鼠（A. draco）獨立分化開,；瀾滄江姬鼠（Apodemus ilex）在更新世中期的玉龍冰期以瀾滄江為界分化為東西兩個大的支系；在更新世中晚期,，瀾滄江以西的種群又在麗江冰期以怒江為界分化為兩個亞支系,，瀾滄江以東的種群也在同期分化為兩個亞支系,；在冰期前后，各種群存在以河谷為阻限的南北多次擴散,。研究結果表明,，喜馬拉雅-橫斷山地區(qū)復雜的地質地貌，尤其是水流湍急地縱谷對種群的隔離是造成這種小型嚙齒類分化的主要原因,，同時,，古氣候的變化是驅動該物種各亞支系的分化和擴散的重要因素；該結果也從分子生物地理學的角度暗示了喜馬拉雅-橫斷山地區(qū)部分水系的形成先后假說以及河流襲奪假說,，提示我們繼續(xù)利用比較生物地理學研究方法探討該復雜區(qū)域的地質歷史,、氣候變遷對生物多樣性的影響。（生物谷Bioon.com）
doi:10.1371/journal.pone.0031453
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Phylogeographic Study of Apodemus ilex (Rodentia: Muridae) in Southwest China
Qi Liu1,2#, Peng Chen1,2#, Kai He1,2#, C. William Kilpatrick3, Shao-Ying Liu4, Fa-Hong Yu5*, Xue-Long Jiang1*
Background The Mountains of southwest China have complex river systems and a profoundly complex topography and are among the most important biodiversity hotspots in the world. However, only a few studies have shed light on how the mountains and river valleys promote genetic diversity. Apodemus ilex is a fine model for investigating this subject. Methodology/Principal Findings To assess the genetic diversity and biogeographic patterns of Apodemus ilex, the complete cytochrome b gene sequences (1,140 bp) were determined from 203 samples of A. draco/ilex that were collected from southwest China. The results obtained suggested that A. ilex and A. draco are sistergroups and diverged from each other approximately 2.25 million years ago. A. ilex could be divided into Eastern and Western phylogroups, each containing two sub-groups and being widespread in different geographical regions of the southern Hengduan Mountains and the western Yunnan - Guizhou Plateau. The population expansions of A. ilex were roughly from 0.089 Mya to 0.023 Mya. Conclusions Our result suggested that A. ilex is a valid species rather than synonym of A. draco. As a middle-high elevation inhabitant, the phylogenetic pattern of A. ilex was strongly related to the complex geographical structures in southwest China, particularly the existence of deep river valley systems, such as the Mekong and Salween rivers. Also, it appears that the evolutionary history of A. ilex, such as lineage divergences and population expansions were strongly affected by climate fluctuation in the Late Pleistocene.
