中国山羊mtDNA D-loop遗传多样性及其起源研究

采用DNA测序技术分析了中国9个山羊品种（板角山羊、成都麻羊、贵州黑山羊、贵州白山羊、黔北麻羊、马头山羊、陕南白山羊、黄淮山羊和雷州山羊）共计128个个体的mtDNA D-loop全序列。结果表明：山羊mtDNA D-loop全序列长度为1212-1213bp，检测到102个变异位点，约占分析位点总数的8．42％，可变位点中转换占99个，颠换2个，1个转换/颠换共存；界定了92种单倍型，有78种为各品种独享单倍型，另外14种为群体内或群体间共享单倍型。9个山羊品种单倍型多样度为0．9333-1．0000，核苷酸多样度为0．7062％-1．8265％，表明中国山羊品种遗传多样性丰富。根据92种mtDNA单倍型构建了中国山羊的NJ分子系统树，聚类表明，中国山羊mtDNA D-loop序列单倍型分为支系A和支系B两大类。支系A包括75种单倍型，代表95个样本，占总数的74．22％；支系B包括17种单倍型，代表33个样本，占总数的25．78％，说明中国山羊存在支系A和支系B两大母系起源。对中国山羊mtDNA D-loop的支系A和支系B进行核苷酸不配对分布曲线分析和Fu的Fs中性检验，分析表明，支系A的分布曲线呈单峰形，Fs值为-24．6491，P值为0．0000，显著偏离中性，表明山羊支系A曾经历群体扩张；支系B呈近似双峰分布，Fs值为-3．3947，P值为0．0980，中性检验差异不显著，表明山羊支系B没有经历群体扩张，群体大小保持相对稳定。山羊支系B可能起源于中国。

The Genetic Diversity of mtDNA D-loop and the Origin of Chinese Goats

The complete sequences of mitochondrial DNA D-loop of 128 individuals in nine Chinese goat (Capra hircu) breeds were analyzed by DNA sequencing technology. The results show that the length of mtDNA D-loop in Chinese goats is 1 212-1 213 bp.There are 102 polymorphic sites, accounting for 8.42% of 1 212 bp sequence. Ninety-two mtDNA haplotypes were determined. The haplotype diversity and nucleotide diversity are 0.9333-1.0000 and 0.7062%-1.8265%, respectively. The results indicate that the genetic diversity of Chinese goats is very abundant. The NJ tree indicates that Chinese goats have two types of maternal origins from lineage A and lineage B. The possibility of lineage B originating from China is also discussed.