Kakoi Hironaga, Tozaki Teruaki, Gawahara Hitoshi
Laboratory of Racing Chemistry, 1731-2 Tsuruta-machi, Utsunomiya, Tochigi 320-0851, Japan.
Biochem Genet. 2007 Apr;45(3-4):375-95. doi: 10.1007/s10528-007-9083-0.
To assess the genetic diversity of Japanese native horse populations, we examined seven such populations using mitochondrial DNA (mtDNA) and microsatellite analyses. Four reference populations of Mongolian horses and European breeds were employed as other equids. In the mtDNA analysis, the control region (D-loop) of 411 bp was sequenced, and 12 haplotypes with 33 variable sites were identified in the Japanese native horses. The phylogenetic tree constructed by haplogrouping and using worldwide geographic references indicated that the haplotypes of the Japanese native horses were derived from six equid clusters. Compared with the foreign populations, the Japanese native populations showed lower within-population diversity and higher between-population differentiation. Microsatellite analysis, using 27 markers, found an average number of alleles per locus of 9.6 in 318 native and foreign horses. In most native populations, the within-population diversity was lower than that observed in foreign populations. The genetic distance matrix based on allelic frequency indicated that several native populations had notably high between-population differentiation. The molecular co-ancestry-based genetic distance matrix revealed that the European populations were differentiated from the Japanese and Mongolian populations, and no clear groups could be identified among the Japanese native horse populations. The genetic distance matrices had few correlations with the geographic distribution of the Japanese native populations. Based on the results of both mtDNA and microsatellite analyses, it could be speculated that each native population was formed by the founder populations derived from Mongolian horses. The genetic construction of each population appears to have been derived from independent breeding in each local area since the time of population fission, and this was accompanied by drastic genetic drift in recent times. This information will help to elucidate the ancestry of Japanese native horses.
为评估日本本土马种群的遗传多样性，我们使用线粒体DNA（mtDNA）和微卫星分析对7个这样的种群进行了检测。另外选用了4个蒙古马参考种群和欧洲品种作为其他马类。在mtDNA分析中，对411 bp的控制区（D环）进行了测序，在日本本土马中鉴定出12种单倍型，共33个可变位点。通过单倍型分组并使用全球地理参考构建的系统发育树表明，日本本土马的单倍型源自6个马类集群。与外来种群相比，日本本土种群的种群内多样性较低，种群间分化较高。使用27个标记的微卫星分析发现，在318匹本土和外来马中，每个位点的平均等位基因数为9.6。在大多数本土种群中，种群内多样性低于外来种群。基于等位基因频率的遗传距离矩阵表明，几个本土种群的种群间分化显著较高。基于分子共祖的遗传距离矩阵显示，欧洲种群与日本和蒙古种群存在分化，在日本本土马种群中无法明确划分出明显的群体。遗传距离矩阵与日本本土种群的地理分布几乎没有相关性。基于mtDNA和微卫星分析的结果，可以推测每个本土种群是由源自蒙古马的奠基种群形成的。自种群分裂以来，每个种群的遗传结构似乎都源自每个当地的独立繁育，并且在近代伴随着剧烈的遗传漂变。这些信息将有助于阐明日本本土马的血统。
