褐马鸡圈养种群的mtDNA控制区多态性

D-loop sequence variation of mitochondrial DNA in Captive Brown-eared Pheasant ( Crossoptilon mantchuricum)

褐马鸡(Crossoptilon mantchuricum)是我国特有的濒危鸟类,国家一级保护动物。为了保护褐马鸡的种质资源,从分子水平上评价褐马鸡的遗传多样性,对山西省庞泉沟自然保护区、太原市动物园的褐马鸡种群20个个体,线粒体DNA D-loop区全序列进行了克隆和测定,使用Clustal X、DnaSP4.0、Mega3.1等生物信息学软件,对全部20条序列开展了比对分析,确定了多态位点与单倍型数目,计算了核苷酸多样性和单倍型多样性;比较了两个种群的遗传变异,初步探讨了褐马鸡种群的遗传多样性和遗传结构。结果表明:20条褐马鸡线粒体DNA D-loop区全序列长度在1236 1237bp之间,其中A、T、G和C 4种核苷酸的平均含量分别为31.0%、26.8%、27.5%和14.8%,A+T含量(57.8%)高于G+C含量(42.3%)。排除1处核苷酸的插入或缺失后,共检测出26个突变位点,占分析序列总长度的2.1%,其中包括25处单一多态位点和1处简约信息位点。20个个体检测出13个单倍型,其中11个个体具有独特的单倍型,2个共享单倍型。褐马鸡两个种群的单倍型多样性(h)为0.911 0.933,核苷酸多样性(π)为0.002 0.003,单倍型间的遗传距离为0.003 0.002。根据单倍型构建了褐马鸡两个种群的NJ分子系统树。聚类表明,2个种群的个体并没有按相应的地理位置进行聚类。揭示褐马鸡具有较高的单倍型多样性和较低的核苷酸多样性,种群的遗传变异较低;两个种群单倍型间的遗传距离较近,遗传多样性参数接近,统计分析无显著差异,两个种群尚未表现出明显的遗传分化,且两个种群间有基因流存在。

Brown-eared Pheasant （Corossoptilon mantchuricum） is a critically endangered endemic species, listed in the national first-class protected bird in China. Since its population size is believed to be declining because of ongoing habitat loss, hunting and other human activity disturbance. For geographical barrier （Yellow River） and natural vegetation destruction （Vegetation of Taihang Mountain）, Brown-eared Pheasant has formed three isolating populations in its distribution area including western Shanxi, north-western Hebei, western Beijing and central Shaanxi. Moreover, gene flows through these populations was obstructed. In order to protect the genetic resources of Brown-eared Pheasant and evaluate its genetic diversity at the molecular level, the complete mitochondrial DNA D-loop sequences of 20 Brown-eared Pheasants from Pangquangou Natural Reserve and Taiyuan Zoo were cloned and sequenced, respectively. These sequences were aligned to determine the polymorphic loci and the number of haplotypes by Clustal X, DnaSP4.0 and Mega3.1. In addition, the nucleotide diversity （π） and haplotype diversity （h） were calculated by the softwares above. The genetic variation of Brown-eared Pheasant between Pangquangou Natural Reserve and Taiyuan Zoo in Shanxi was analyzed, and the variations among the sequences, 13 haplotypes were identified with 1 --7 variation loci. 11 of them occurred in a single individual and 2 were shared haplotypes. The haplotype diversity （ h ）, nucleotide diversity （ π ） and genetic distances estimated from mtDNA D-loop region within each population of Brown-eared Pheasant from Taiyuan Zoo and Pangquangou Natural Reserve in Shanxi varied from 0. 911 -- 0. 933, 0. 002 -- 0. 003, and 0. 002 -- 0. 003, respectivly. The Neighbor- Joining molecular phylogenetic tree of mtDNA D-loop in the 2 captive Brown-eared Pheasant groups in Shanxi was constructed according to the 13 haplotypes. The NJ tree showed that the phylogenetic relationship of the Brown-eared Pheasant individuals was not correlative to their geographical locations. The differences between the two populations on the two genetic diversity parameters were not statistically significant, which meaned that there were no significant genetic differences occurred in the two populations, and there were gene flows between the two populations. These results strongly proved that the population of caprive Brown-eared Pheasant is in poor genetic diversity status.