紫貂种群进化历史及系统地理格局形成机制的研究

The sable is a circumboreal species affected significantly by the Quaternary ice.The studies on phylogenesis,evolitionary hsitory and population genetic structure of the species has attracted a special attention.In previous studies, being confined to molecular marker and target range, the problem entitled with "evolutionary history and formation mechanism of phylogeographic patterns of the sable" has not well solved. We, therefore, undertook a study on this problem in sable populations from Russian,North-eastern China and Northern Mogolia with serveral markers, including cranial characters, mitogenome and microsatellite. Sable population genetic structure is analyzed to reveal the phylogeny,current distribution traits,and the formation mechanism of phylogeographic patterns. Correlative geological events are also discovered and authenticated based on analysis combining sable population geographical distribution, as well as the evolutionary history of sable populations. Our objectives are: (i) to estimate sable evolutionary units and their divergence time, and to discuss their corresponding the center of species formation and diffusion or glacial refugia, and to estimate the impact of human activities on the species evolution and distribution, and to reveal evolutionary history and formation mechanism of phylogeographic patterns of the sable populations.(ii)to describe variation among sable subspecies and populations,for well subspecies classifying with new evidences;(iii) to illustrate evolutionary significant units and population history relationships of the sable populations in south-eastern area, for supporting sable re-introduction in north-eastern China.

紫貂是受第四纪冰期影响典型的北方物种，其系统发生、种群进化历史和遗传结构的研究吸引了众多学者。先前的研究由于受分子标记和研究区域的局限，使得"紫貂种群进化历史及系统地理格局形成机制"问题没有清晰阐明。为此，本研究拟以俄罗斯、中国东北和蒙古北部的紫貂种群为对象，利用头骨形态学指标、mtDNA基因组和微卫星多种标记，分析紫貂种群遗传结构，揭示系统发育关系以及现有分布特征，探讨其系统地理格局形成机制；结合种群地理分布来发现和验证与其相关的地质事件，揭示种群的进化历史。其目标和意义是：更精确地划分紫貂进化单元和评估其分化时间，探讨每个单元对应的起源-扩散的中心或冰期避难所，评估人类活动对紫貂种群进化和空间分布的影响，揭示研究区域紫貂种群进化历史及系统地理格局形成机制；评估紫貂种群和亚种间的差异，为紫貂亚种分类提供新的证据；明确东南分布区紫貂进化显著单元，为中国紫貂重引入计划提供有力的科学依据。

近20年来，紫貂种群的遗传多样性、系统地理格局以及貂熊亚科内的系统发育关系、亚种分类等科学问题受到国内外很多学者的关注。本研究利用线粒体基因组、微卫星、主要组织相容性复合体（MHC）中的DRB基因、头骨形态学指标分别探究了上述问题。结果表明不同地理种群在线粒体4个蛋白质编码基因区的遗传多样性差异显著，不同种群间遗传分化水平也不尽相同，微卫星分析也得出了类似的结果。在MHC-DRB基因中发现了个体中普遍存在假基因的现象，不同地理种群的核苷酸多态性差异较小。基于线粒体基因组的紫貂种群系统发育关系显示地理分布与系统进化分支间没有明显的关联性，遗传结构模糊。相反，基于微卫星的亚种系统发育关系又显示出较为清晰的遗传结构。基于线粒体基因组和新的化石记录重建了貂熊亚科系统发育关系，得到了各物种更为准确的分化时间。最后，成功建立了基于微卫星的紫貂个体识别技术，部分头骨形态学指标可以用于紫貂亚种分类。本研究说明线粒体基因组可以用于分析貂熊亚科动物、紫貂种群的系统发育关系；不同分子标记分析结果可能存在差异，需要进一步综合分析讨论。本研究的结果可以用于打击紫貂偷猎犯罪，为紫貂种群的保护提供科学的依据。