Behind the mountains and over the sea: the Changbai Mountain Range provided <i>Rana coreana</i> with a Chinese residence permit all along

The Changbai Mountain Range is generally perceived as a barrier to amphibian distribution, but it might not be playing this role anymore. <i>Rana coreana</i> was first described as a Korean endemic species, split from <i>Rana amurensis</i>, which ranges at more northern latitude. The species was then found on the Shandong peninsula in China, where it was first described as <i>Rana kunyuensis</i>, before being synonymised with <i>R. coreana</i>. So far, the contact zone with <i>R. amurensis</i> was expected to be in the vicinity of Pyongyang in DPR Korea, west of the Baekdu Mountain Range. However, the species is known from a population further north, and during surveys in Dalian in Liaoning Province, China, we found <i>R. coreana</i> on the southern slopes of the Laoling Mountain Range facing the Yellow Sea. Our phylogenetic analyses based on mitochondrial ribosomal markers showed the individual to cluster with <i>R. coreana</i> samples from the Korean Peninsula. In addition, our ecological niche models showed the presence of suitable habitats outside of the known range of the species, deserving further investigation. The habitat of the species at this new locality is similar to the one known in the three range nations, and highlights the need for more surveys in northeast China as the barrier formed by the Changbai Range is more porous than originally expected.长白山山脉通常被视为两栖动物分布的屏障，但它或许已不再扮演这一角色。<i>Rana coreana</i>最初被描述为韩国特有种，由分布于更北纬度的<i>Rana amurensis</i>分化而来。该物种随后在中国山东半岛被发现，最初被描述为<i>Rana kunyuensis</i>，后与<i>R. coreana</i>同义。迄今为止，人们推测<i>R. coreana</i>与<i>R. amurensis</i>的接触带位于朝鲜民主主义人民共和国平壤附近、白头山脉以西。然而，目前已知该物种存在更北的种群；在中国辽宁省大连市的调查中，我们于面向黄海的老岭山脉南坡发现了<i>R. coreana</i>。基于线粒体核糖体标记的系统发育分析（phylogenetic analyses）显示，该个体与来自朝鲜半岛的<i>R. coreana</i>样本聚为一支。此外，我们的生态位模型（ecological niche models）显示，该物种已知分布范围外存在适宜栖息地，值得进一步研究。该物种在这一新分布地的栖息地与已知的三个分布国的栖息地相似，这凸显了在中国东北地区开展更多调查的必要性——长白山形成的屏障比原先预期的更具通透性。