Geographic variation and biogeography of terrestrial vertebrates around the Tokara Strait, northern Ryukyus, Japan

托卡拉海峡，通常被认为是东方和古动物区系的边界，被认为是一直中断分散的陆生动物，因为它最初形成于晚第三纪。然而，几个谱系的陆生动物实际上分布在这个海峡两岸，从历史地理学和种群系统学的角度来看，这是一个有趣的课题。为了阐明分散和隔离的陆地动物在吐噶喇海峡，我们研究了几种脊椎动物的相对程度的分化人群之间在这个海峡。结果表明，在大多数谱系中，如Ateuchosaurus pellopleurus，Gekko hokouensis和Eumeces marginatus，海峡两岸的种群之间的差异很小。这表明在海峡的海外扩散的发生。 ...更多信息 t在这些谱系中出乎意料的高频率。这一结果强烈地表明，在琉球群岛和台湾的其他地区，黑潮似乎是该地区最具影响力的生物扩散媒介，一些在海峡两岸零星分布的分类群被认为是陆桥扩散的残余在托卡拉海峡形成之前。然而，我们的研究表明，在一些这样的分类群中，海峡两岸的代表之间没有姐妹关系（例如，Cistoclemmys，包括化石类群），以及其他（例如，中华盘螺（Pelodiscus sinensis），无疑显示出密切的遗传亲缘关系，已被人工运过海峡。这一结果通过证实托卡拉海峡的悠久历史，间接支持了前三个谱系频繁的海流辅助扩散假说。少

The Tokara Strait, usually regarded as a boundary of the Oriental and Palearetic faunal realms, is considered to have been consistently interrupting dispersals of terrestrial fauna since its initial formation in the late Tertiary. However, several lineages of terrestrial animals are actually distributed on both sides of this strait, making interesting subjects from view points of historical biogeography and population systematics. To elucidate the dispersal and isolation of terrestrial animals across the Tokara Strait, we examined for several vertebrates the relative degrees of differentiations among populations around this strait. Quantitative morphological and allelic data were analyzed for distances among populations.Results have indicated that in most lineages examined, such as Ateuchosaurus pellopleurus, Gekko hokouensis and Eumeces marginatus, populations in both sides of the strait showed very little variation. This indicates the occurrence of oversea dispersals across the strai … More t in an unexpectedly high frequency in these lineages. This results strongly suggest the possible overstimation of the isolation effect of insularization upoiv the terrestrial organisms in other areas of the Ryukyus and Taiwan, where the Kuroshio Current, seemingly the most influensive agent of orga-nismal dispersals in this region, is dominant as in the Tokara Strait.Some taxonomic groups showing more sporadic distributions on both sides of the strait have been considered as remnants of landbridge dispersals prior to the formation of the Tokara Strait. However, our studies have revealed that there are no sister-relationships between representatives of both sides of the strait in some of such taxa (e.g., Cistoclemmys, including the fossil taxa), and that others (e.g., Pelodiscus sinensis), surely showing close genetic affinities, have been transported artificially across the strait. Such a result circumstantially support the frequent seacurrent-aided dispersal hypothesis for the former three lineages by confirming the long history of the Tokara Strait. Less