Recently, anthropogenic alterations have had severe and negative impacts on the terrestrial and aquatic species and environments. To conserve species that have a small and limited habitat, it is necessary to focus on fine-scale population structure and its effects on persistence. The deepbodied bitterling Acheilognathus longipinnis is an endangered freshwater fish that occupies ponds scattered in lateral bars in the Kiso River. In this study, we conducted multi-locus microsatellite DNA analysis to evaluate both fine-scale population structure and genetic diversity, in order to conserve A. longipinnis. The smaller number of loci deviating from the Hardy–Weinberg equilibrium in ponds scattered in individual lateral bars compared to the whole river system suggests that A. longipinnis forms a local breeding population in units of ponds. The population was roughly split between the river banks and the local population located in ponds in the mid-channel bar showed intermediate relationships with the river bank populations. Gene flow between local populations was not always homogeneous and was not influenced by geographical distances between local populations or the direction of river flow. The dispersal of A. longipinnis across both river bank sides may be constrained and is probably affected by the ecological characteristics of A. longipinnis and the hydrological regimes. Consequently, A. longipinnis in the Kiso River is maintained as a complex of multiple local populations with appropriate gene flow among them. To conserve A. longipinnis, both the persistence of the unstable ponds and moderate genetic exchanges by individual migration are required.

最近，人为改变对陆地和水生物种和环境产生了严重的负面影响。为了保护栖息地小而有限的物种，有必要关注精细的种群结构及其对持久性的影响。深体苦鱼Acheilognathus longipinnis是一种濒临灭绝的淡水鱼，栖息在木曾河中散布在侧栏的池塘中。在这项研究中，我们进行了多位点微卫星 DNA 分析，以评估精细规模的种群结构和遗传多样性，以保护A. longipinnis。与整个河流系统相比，散布在单个侧向坝中的池塘中偏离哈代-温伯格平衡的位点数量较少，这表明A. longipinnis以池塘为单位形成当地繁殖种群。人口大致分布在河岸之间，位于中河坝池塘的当地人口与河岸人口呈中间关系。当地种群之间的基因流动并不总是同质的，并且不受当地种群之间地理距离或河流流动方向的影响。A. longipinnis在河岸两侧的扩散可能受到限制，并且可能受到A. longipinnis生态特征和水文状况的影响。因此，A. longipinnis木曾河中保持着多个本地种群的复合体，它们之间有适当的基因流动。为了保护A. longipinnis，不稳定池塘的持久性和个体迁移的适度遗传交换都是必需的。