Yoshihara Tomoko, Kikuchi Misaki, Akiba Yuki, Horiguchi Masaharu, Takasu Masaki, Tozaki Teruaki
Kamiagata Branch, Tsushima City Office, Nagasaki 817-1602, Japan.
Saikai National Park Kujukushima Zoological and Botanical Garden, Nagasaki 857-1231, Japan.
J Equine Sci. 2022 Dec;33(4):63-69. doi: 10.1294/jes.33.63. Epub 2022 Dec 28.
The Taishu horse in Tsushima is one of eight Japanese native breeds. The breed is on the verge of extinction due to a rapid decrease in numbers since the 1960s owing to motorization in Japan. In this study, we aimed to confirm the pedigree information of 52 horses by genotyping 31 microsatellites in order to avoid inbreeding. Parentage verification failed to identify genetic contradictions among trios (sires, dams, and foals) registered with the Japan Equine Affairs Association (JEAA). Pedigree information registered at the JEAA was obtained and adequately understood. Additionally, the genetic diversity of the Taishu horses was evaluated and compared with those of other Japanese native breeds. The average values for the number of alleles, observed heterozygosity, expected heterozygosity, and inbreeding coefficient were 4.7, 0.643, 0.632, and -0.02, respectively. Using the Structure software, the 52 horses were classified into three subgroups based on the individuals with more than 50% of specific genetic components. The phylogenetic trees created based on neighbor-joining classification tended to be consistent among the stallions. The effective population size was 27.5 and lower than that required for maintaining 90% genetic variation in the source population over a period of 100 years (47.5). Compared with the other Japanese breeds, the Taishu horse population included in the current study exhibited moderate genetic diversity. Our study will contribute to reconsideration of the breeding strategy of Taishu horses.
对马岛上的太苏马是日本八个本土马种之一。自20世纪60年代以来，由于日本的机动车化导致数量迅速减少，该马种濒临灭绝。在本研究中，我们旨在通过对31个微卫星进行基因分型来确认52匹马的谱系信息，以避免近亲繁殖。亲子关系验证未能在日本马业协会（JEAA）登记的三重奏（父本、母本和幼驹）中发现基因矛盾。获取并充分理解了JEAA登记的谱系信息。此外，还评估了太苏马的遗传多样性，并与其他日本本土马种进行了比较。等位基因数量、观察杂合度、预期杂合度和近亲繁殖系数的平均值分别为4.7、0.643、0.632和-0.02。使用Structure软件，根据具有超过50%特定遗传成分的个体，将52匹马分为三个亚组。基于邻接法分类创建的系统发育树在种马之间往往是一致的。有效种群大小为27.5，低于在100年期间维持源种群90%遗传变异所需的大小（47.5）。与其他日本马种相比，本研究中纳入的太苏马种群表现出中等程度的遗传多样性。我们的研究将有助于重新考虑太苏马的育种策略。
