在距今约2万年前的末次盛冰期（the Last Glacial Maximum，LGM），伴随冰盖体积的增长，海平面下降。这种情况在LGM结束后的气候转暖中发生逆转，即冰盖消融，海平面上升。在大陆沿海以及海岛地区，海平面的升降造成了海陆变迁，这一过程很可能对这些地区内史前人类的迁徙活动产生重要的影响。在东亚地区，海南岛与大陆的连接与分离就是LGM以来的海陆变迁过程的例证之一。
为了探讨这次事件是否在当今海南岛人群的遗传结构中留有相关印记，张亚平院士指导下的研究生彭旻晟，贺军栋和刘海昕对来自3个群体的共计285份黎族样本的线粒体DNA（mtDNA）遗传多样性进行了分析。结合之前发表的数据，结果显示海南岛人群与广西人群的遗传关系较为密切；来自大陆的近期移民对海南岛人群有着较大贡献。更为细致的研究发现，mtDNA单倍型类群M12，M7e和M7c1*是揭示人类早期移居海南岛的候选标记；而基于mtDNA全序列测定的系统地理学分析表明早期移民发生在大约距今7千至2万7千年前。这个时间范围内，海南岛与大陆处于连接状态，因此提供了人类移居海南岛的有利条件。同时，近期在海南岛的考古学工作中发现的一些旧石器遗迹，时间推测在晚更新世，也对该研究结果提供了支持。
该工作于2月15日发表于国际开源刊物《生物医学中心--—进化生物学》（BMC Evolutionary Biology）。（生物谷Bioon.com）
生物谷推荐原文出处：
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.
