基于线粒体DNA的中国亚洲象种群遗传多样性及种群遗传结构

Population genetic structure and population genetic diversity analysis based on mitochondrial DNA of Asian elephant(Elephas maximus) in China

亚洲象是我国国家一级保护动物。本文利用非损伤性取样法,以亚洲象粪便中脱落的肠道上皮细胞为DNA来源,选用线粒体DNA作为分子标记,对分布于我国境内的亚洲象种群的遗传结构和种群遗传多样性进行研究。本研究得到mtDNA序列片段长度为556bp,经对178个个体进行扩增结果分析,共得到24个单倍型。在5个地理种群中,除南滚河种群外,其他4个种群中的114个个体共享同一单倍型,南滚河种群与其他种群间未观察到共享单倍型。系统发生分析,观察到中国境内现有亚洲象种群在进化上分为两大分支,α和β。其中分支α中包含除南滚河种群外的4个地理种群,分支β仅含有南滚河种群,表明南滚河种群与其他4个地理种群间存在明显分化。遗传多样性分析结果表明,中国境内的亚洲象种群的遗传多样性水平较低,分析原因认为是栖息地破碎化阻断了种群间有效的基因交流。

The Asian elephant（Elephas maximus） is the most endangered probiscidean,and occurs in China only in Yunnan Province.With non-invasive sampling using elephant dung as a DNA source,the population genetic structure and diversity is explored using mitochrondrial DNA.A 556 bp fragment of mitochondrial DNA was obtained and 24 unique haplotypes were observed from PCR analysis of 178 individuals.One haplotype（MLSYSMMY1） is shared among 4 conservation areas Mengla（ML）,Shangyong（SY）,Simao（SM） and Mengyang（MY）,including 114 of 178 individuals,which differs from that found in the Nangunhe（NGH） area.Two highly divergent clades,α and β,of Asian elephants in China are observed using phylogenetic analyses and are verified by neighbour-joining（NJ）,maximum parsimony（MP） and maximum likelihood（ML） approaches.The result showed that the α clade includes 4 popolations（ML,SY,SM and MY） and the β clade only includes the Nangunhe population.This also shows that there is high genetic divergence between the Nangunhe population and the other 4 populations.Mitochondrial DNA data analysis showed that genetic diversities in all of the 5 Asian elephant populations are very low,and resulted from habitat fragmentation which separated the effective genetic flow among the 5 populations.