Large‐scale phenotypic and genetic studies of the salmonid genus Thymallus (grayling) in the Palaearctic suggest that most major phylogeographic lineages represent good biological species. Evaluating such a premise in areas involved in palaeo‐hydrological dynamics where multiple species are found in sympatry should serve to assess the level of reproductive isolation, the traditional sine qua non of species recognition. Molecular sequence (mtDNA) and microsatellite (nDNA, seven loci) analysis of grayling in the upper Bureya River watershed support the occurrence of three distinctive species of grayling living in sympatry in this large oligotrophic tributary of the Amur River. One of these lineages is primarily found throughout the Lena River basin and is recognized as Baikal‐Lena grayling Thymallus baicalolenensis; the second, the upper Amur grayling Thymallus grubii is found over large areas of the Amur catchment including the entire headwater region; and the third, the Bureya grayling Thymallus burejensis is endemic to the study area. A limited number of hybrids were identified, primarily between Baikal‐Lena grayling T. baicalolenensis and Bureya grayling T. burejensis with little to no signs of introgression among non‐hybrid individuals. Morphological distinctiveness among populations of these species living in sympatry was greater than between populations living in allopatry, suggesting character displacement. Divergence estimates among taxa range up to 6.2 MY, and allopatric origins for all three species’ is suggested. To our knowledge, this is the first data‐based confirmation of three species of grayling living in sympatry.

中文翻译：

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在阿穆尔河偏远支流的同种异体中发现了多种河鳟（ Thymallus sp.）

对古北界鲑鱼属 Thymallus (grayling) 的大规模表型和遗传研究表明，大多数主要的系统地理学谱系代表了良好的生物物种。在涉及多个物种的古水文动力学领域评估这样的前提应该有助于评估生殖隔离水平，这是物种识别的传统必要条件。对布里亚河上游流域中的鳟鱼的分子序列 (mtDNA) 和微卫星 (nDNA，七个位点) 分析支持在阿穆尔河的这条大型寡营养支流中生活着三种独特的鳟鱼物种。这些谱系之一主要在勒拿河流域发现，被认为是贝加尔湖-勒拿河鱼 Thymallus baicalolenensis；第二，上游阿穆尔河鲈鱼 Thymallus grubii 分布在阿穆尔流域的大片区域，包括整个源头区域；三是研究区特有的Bureya Greyling Thymallus burejensis。确定了数量有限的杂交种，主要是在贝加尔湖-莱纳河豚 T. baicalolenensis 和布列亚河豚 T. burejensis 之间，在非杂交个体中几乎没有渗入迹象。生活在同域中的这些物种的种群之间的形态特征比生活在异域中的种群之间更大，这表明特征发生了位移。分类群之间的差异估计范围高达 6.2 MY，并建议所有三个物种的异域起源。据我们所知，这是对三种生活在同一地区的鳟鱼的首次基于数据的确认。