在距今約2萬年前的末次盛冰期（the Last Glacial Maximum,，LGM）,，伴隨冰蓋體積的增長,，海平面下降,。這種情況在LGM結束后的氣候轉(zhuǎn)暖中發(fā)生逆轉(zhuǎn),，即冰蓋消融,，海平面上升,。在大陸沿海以及海島地區(qū)，海平面的升降造成了海陸變遷,，這一過程很可能對這些地區(qū)內(nèi)史前人類的遷徙活動產(chǎn)生重要的影響,。在東亞地區(qū)，海南島與大陸的連接與分離就是LGM以來的海陸變遷過程的例證之一,。
為了探討這次事件是否在當今海南島人群的遺傳結構中留有相關印記,，張亞平院士指導下的研究生彭旻晟，賀軍棟和劉海昕對來自3個群體的共計285份黎族樣本的線粒體DNA（mtDNA）遺傳多樣性進行了分析,。結合之前發(fā)表的數(shù)據(jù),，結果顯示海南島人群與廣西人群的遺傳關系較為密切；來自大陸的近期移民對海南島人群有著較大貢獻,。更為細致的研究發(fā)現(xiàn),，mtDNA單倍型類群M12，M7e和M7c1*是揭示人類早期移居海南島的候選標記,；而基于mtDNA全序列測定的系統(tǒng)地理學分析表明早期移民發(fā)生在大約距今7千至2萬7千年前,。這個時間范圍內(nèi)，海南島與大陸處于連接狀態(tài),，因此提供了人類移居海南島的有利條件,。同時，近期在海南島的考古學工作中發(fā)現(xiàn)的一些舊石器遺跡,，時間推測在晚更新世,，也對該研究結果提供了支持。
該工作于2月15日發(fā)表于國際開源刊物《生物醫(yī)學中心--—進化生物學》（BMC Evolutionary Biology）,。（生物谷Bioon.com）
生物谷推薦原文出處：
BMC Evolutionary Biology 2011, doi:10.1186/1471-2148-11-46
Tracing the legacy of the early Hainan Islanders - a perspective from mitochondrial DNA
Min-Sheng Peng , Jun-Dong He , Hai-Xin Liu and Ya-Ping Zhang
Background
Hainan Island is located around the conjunction of East Asia and Southeast Asia, and during the Last Glacial Maximum (LGM) was connected with the mainland. This provided an opportunity for the colonization of Hainan Island by modern human in the Upper Pleistocene. Whether the ancient dispersal left any footprints in the contemporary gene pool of Hainan islanders is in a hot debate.
Results
We collected samples from 285 Li individuals and analyzed mitochondrial DNA (mtDNA) variations of hypervariable sequence I and II (HVS-I and II), as well as partial coding regions. By incorporating previously reported data, the phylogeny of Hainan islanders was reconstructed. We found that Hainan islanders showed close relationship with the populations in mainland southern China, especially from Guangxi. Haplotype sharing analyses suggested that the recent gene flow from the mainland might play important roles in shaping the maternal pool of Hainan islanders. More importantly, haplogroups M12, M7e, and M7c1* might represent the genetic relics of the ancient population that populated this region; and 14 representative complete mtDNA genomes were further sequenced.
Conclusions
The detailed phylogeographic analyses of haplogroups M12, M7e, and M7c1* indicated that the early peopling of Hainan Island by modern human could be traced back to the early Holocene and/or even the late Upper Pleistocene, around 7 - 27 kya. These results correspond to both Y-chromosome and archaeological studies.
