大石鸡边缘种群的遗传结构

GENETIC STRUCTURE OF EDGE POPULATION IN PRZEWALSKI'S ROCK PARTRIDGE (ALECTORIS MAGNA)

大石鸡 (Alectorismagna)分布于青海西部、东部 ,甘肃中部和宁夏西部的干旱和半干旱区 ,由于环境变化 ,其种群向甘肃南部森林被砍伐的地区扩散 ,形成边缘种群。本研究采用聚合酶链式反应 (PCR)和直接测序的方法获得了采自甘肃的大石鸡一个边缘种群和两个中心地理种群共 39个个体的线粒体DNA (mtDNA)控制区基因 (D loop) 4 5 6～ 45 7个核苷酸的基因序列 ,16个变异位点 (占整个序列的 3 5 % )有 15个单倍型。边缘扩散种群有 3种单倍型 ,M6与另两个种群共有 ,单倍型频率为 0 10 8,而M4和M5为其特有 ,单倍型频率分别为 0 0 81和 0 0 2 7。边缘种群的单倍型比率和遗传多样性分别为 37 5 %和 0 5 49。中心地理种群 1和种群2各有 7个单倍型 ,除M 6为两个种群共有 ,其余为各自所特有。单倍型比率分别为 46 7%和 5 0 0 % ,遗传多样性分别是 0 72 9和 0 786。边缘种群的单倍型比率和遗传多样性均低于中心地理种群。

Alectoris magna is endemic to China, which distributes in arid region and semi arid zone from western Qinghai, central Gansu to western Ningxia Huizu Autonomous Region. Because of the environmental changes, some populations of A. magna have expanded their range to regions of recent deforestation by humans in southern Gansu, and have colonized to form new edge populations. In this paper the hypervariable domain Ⅰ of the mtDNA control region (D loop) from A. magna populations in edge and central region was studied. In 39 A. magna samples and five A. chukar outgroups, the entire mtDNA D loop was PCR amplified. The 456-457 nucleotides of the DNA D loop domain Ⅰ have been sequenced by dideoxy chain termination method. The 16 variable sites(3 5% of the entire sequence) defined 15 haplotypes. The edge dispersal population has three haplotypes, and shared M6 with other two populations. Its haplotype frequency was 0 108 in the edge dispersal population. M4 and M5 were only found in the edge dispersal population, their frequencies were 0 081 and 0 027 respectively. The population 1 and population 2 of the central population each had 7 haplotypes, sharing M6. The proportion of haplotype and genetic diversity were 37 5% and 0 594 respectively in the edge dispersal population. In the population 1 and population 2 the proportions of haplotype were 46 7% and 50 0% respectively and the genetic diversity separately 0 729 and 0 786 This result suggested that the edge dispersal population had lower proportions of haplotype and genetic diversity than the two central geographical populations (population 1 and 2).