近日，國(guó)際著名雜志PLoS One在線刊登了中科院昆明動(dòng)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(dòng)物分子系統(tǒng)地理學(xué)研究獲得新進(jìn)展,。
喜馬拉雅-橫斷山地區(qū)是世界性的生物多樣性熱點(diǎn)地區(qū)之一,，也是中國(guó)西南山地生物多樣性熱點(diǎn)地區(qū)生物多樣性保護(hù)優(yōu)先區(qū)。該區(qū)域有著地球上最復(fù)雜水系,、山系和復(fù)雜的地質(zhì)歷史,，其獨(dú)特的自然地理?xiàng)l件使該區(qū)域成為中國(guó)乃至世界各種自然資源最富集的地區(qū)之一，同時(shí)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(gòu)成了一座生物資源豐富的物種基因庫(kù),。青藏高原地形的改變和橫斷山脈的走向被廣泛認(rèn)為是影響我國(guó)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(dòng)物孓遺的重要避難中心,，還是研究生物地理學(xué)很好的模式系統(tǒng),。但是，迄今,，關(guān)于該區(qū)域地質(zhì)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(bào)道,。
昆明動(dòng)物研究所遺傳資源與進(jìn)化國(guó)家重點(diǎn)實(shí)驗(yàn)室獸類生態(tài)與進(jìn)化組的劉琦等同學(xué)在導(dǎo)師蔣學(xué)龍研究員指導(dǎo)下，以鼠科中最古老的屬之一—姬鼠屬（Apodemus）為研究對(duì)象,，在喜馬拉雅-橫斷山地區(qū)廣泛采集姬鼠標(biāo)本并收集相關(guān)采集地和標(biāo)本生態(tài)信息,，在查對(duì)姬鼠屬種類的化石標(biāo)本及其記錄的基礎(chǔ)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(xué)研究模型,，展開(kāi)姬鼠屬的起源與演化和生物地理學(xué)研究,。基于中華姬鼠（A. draco）和瀾滄江姬鼠（A. ilex）的分類地位仍然廣存爭(zhēng)議,，研究針對(duì)采集自喜馬拉雅-橫斷山地區(qū)51個(gè)采集點(diǎn)共計(jì)203個(gè)中華姬鼠復(fù)合種群（A. draco complex）樣品結(jié)合姬鼠屬其他11個(gè)種進(jìn)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(jié)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(gè)姐妹種,；瀾滄江姬鼠（Apodemus ilex）的獨(dú)立地位得到驗(yàn)證,，大約在上新世末期2.25個(gè)白萬(wàn)年前與中華姬鼠（A. draco）獨(dú)立分化開(kāi)；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(gè)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(gè)亞支系，瀾滄江以東的種群也在同期分化為兩個(gè)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(kuò)散。研究結(jié)果表明,，喜馬拉雅-橫斷山地區(qū)復(fù)雜的地質(zhì)地貌,，尤其是水流湍急地縱谷對(duì)種群的隔離是造成這種小型嚙齒類分化的主要原因，同時(shí),，古氣候的變化是驅(qū)動(dòng)該物種各亞支系的分化和擴(kuò)散的重要因素,；該結(jié)果也從分子生物地理學(xué)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(shuō)以及河流襲奪假說(shuō)，提示我們繼續(xù)利用比較生物地理學(xué)研究方法探討該復(fù)雜區(qū)域的地質(zhì)歷史,、氣候變遷對(duì)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.
