Graduate School of Fisheries and Environmental Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan.
Faculty of Fisheries, Kagoshima University, 4-50-20 Shimoarata, Kagoshima, 890-0056, Japan.
Genetica. 2021 Apr;149(2):117-128. doi: 10.1007/s10709-021-00117-7. Epub 2021 Apr 9.
The Ayu (Plecoglossus altivelis altivelis) population on Yaku-shima Island, Kagoshima Prefecture, Japan represents the southernmost population of the subspecies and is considered to be facing extinction. We investigated the genetic characteristics of Ayu in the Miyanoura River (MYU) in the northeast of the island and the Kurio River (KRO) in the southwest of the island, using partial sequences of mitochondrial (mt) control region and polymorphic microsatellite (simple sequence repeat: SSR) loci. The mtDNA analysis revealed that the Yaku-shima Island population was significantly differentiated from other Ayu populations; additionally, the MYU and KRO populations were significantly different from each other in terms of mtDNA (pairwise Φ = 0.5826, P < 0.01) and SSR (pairwise Φ = 0.1598, P < 0.01) analyses, indicating very little or no gene flow between them. The mtDNA haplotype diversity values were minimal for KRO and somewhat lower for MYU (h = 0.8176) than for each population from the mainland of Japan (Honshu-Kyushu) and the Korean Peninsula (h = 0.9905-1.0000). The mean values of expected heterozygosity (He) of SSRs were also lower in KRO (mean He = 0.555) than in MYU (mean He = 0.649). A considerably small effective population size (N = 100.1 for MYU, 151.2 for KRO) and a bottleneck effect for Yaku-shima Island population were suggested by SSR analysis. These findings underscore the importance of monitoring the genetic diversity of Ayu on Yaku-shima Island and the necessity of designing conservation policies for each river's population.
日本鹿儿岛县屋久岛的牙鲆（Plecoglossus altivelis altivelis）种群是该亚种最南端的种群，被认为面临灭绝的威胁。我们通过线粒体（mt）控制区和多态性微卫星（简单重复序列：SSR）位点的部分序列，对岛屿东北部的宫浦川（MYU）和西南部的九留米川（KRO）的牙鲆遗传特征进行了调查。mtDNA 分析表明，屋久岛种群与其他牙鲆种群存在显著分化；此外，MYU 和 KRO 种群在 mtDNA（成对 Φ=0.5826，P<0.01）和 SSR（成对 Φ=0.1598，P<0.01）分析方面存在显著差异，表明它们之间几乎没有或没有基因流。KRO 的 mtDNA 单倍型多样性值最低，而 MYU 的 mtDNA 单倍型多样性值（h=0.8176）略低于日本本州-九州（Honshu-Kyushu）和朝鲜半岛（h=0.9905-1.0000）的每个种群。KRO 的 SSR 预期杂合度（He）均值也较低（KRO 的平均 He=0.555），而 MYU 的 SSR 预期杂合度均值（MYU 的平均 He=0.649）较高。SSR 分析表明，MYU 的有效种群大小（N=100.1）和 KRO 的有效种群大小（N=151.2）都相当小，并且屋久岛种群存在瓶颈效应。这些发现强调了监测屋久岛牙鲆遗传多样性的重要性，以及为每条河流的种群设计保护政策的必要性。
