The bitterling Tanakia lanceolata is a primary freshwater fish with wide distribution range in Japan; therefore, analysis of this species will yield much information on the formation of Japanese freshwater fish fauna. However, populations of this species are threatened by several human activities. To reveal the genetic population structure of T. lanceolata and the process of its formation, as well as its genetic status, we conducted phylogenetic analyses and estimated divergence times based on partial sequences of the mitochondrial DNA cytochrome b gene, using specimens collected across the distribution range. The results of the analysis showed that Japanese T. lanceolata is monophyletic and consists of seven local population groups that diverged from the Late Pliocene to the Middle Pleistocene. The population structure in western Japan was similar to that of other freshwater fishes (e.g., separation by the Suzuka Mountains), although there were several differences in population boundaries and the presence/absence of a secondary contact zone. The Central Highlands in central Honshu are the primary, or at least the most effective, geological barrier responsible for population divergence in Japanese freshwater fish species. However, the small genetic differentiation of the T. lanceolata population between the western and eastern sides of the Central Highlands suggested recent dispersal and gene flow across the region after uplift of the highlands. The genetic population structure indicated extensive genetic disturbance in the Kanto Region. Our results provide information on the formation process of the Japanese freshwater fish fauna, which could aid conservation efforts toward T. lanceolata.

中文翻译：

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从线粒体细胞色素 b 基因序列推断日本刺尾鱼 (Teleostei: Cyprinidae) 的系统地理学

刺鲇鱼是日本主要的淡水鱼，分布范围很广；因此，对该物种的分析将产生关于日本淡水鱼群形成的大量信息。然而，该物种的种群受到一些人类活动的威胁。为了揭示 T. lanceolata 的遗传种群结构及其形成过程，以及其遗传状态，我们进行了系统发育分析，并基于线粒体 DNA 细胞色素 b 基因的部分序列，使用在整个分布中收集的标本进行了系统发育分析并估计了分歧时间范围。分析结果表明，日本 T. lanceolata 是单系的，由 7 个从上新世晚期到中更新世分化的当地种群组成。日本西部的种群结构与其他淡水鱼类的种群结构相似（例如，被铃鹿山脉分隔），尽管在种群边界和次要接触区的存在/不存在方面存在一些差异。本州中部的中央高地是造成日本淡水鱼种群分化的主要或至少是最有效的地质屏障。然而，中部高地西部和东部之间 T. lanceolata 种群的小的遗传分化表明，在高地隆起后，该地区最近发生了扩散和基因流动。遗传种群结构表明关东地区存在广泛的遗传干扰。我们的结果提供了有关日本淡水鱼群形成过程的信息，