Effect of lack of continental ice sheet on speciation in Palaearctic birds.

与北欧和北美北部的大部分地区不同，东部古北区被认为在第四纪冰期几乎没有冰川。在这样的地质历史条件下，它是如何影响古鸟类的物种形成和遗传特征的？为了评估这一点，我研究了欧亚大陆东部各种繁殖的雀形目鸟类的系统地理。结果，我发现了几个物种在日本和/或周边地区的物种之间存在着很大的DNA差异。这些物种包括北极林莺、东方绿翅雀、淡腿叶莺、伊吉玛叶莺、黑面斑雀、云雀、水仙苍蝇和黑天堂苍蝇。这些结果表明，在几次连续的冰期中，谱系保持了它们的完整性。没有冰盖的隔离机制造成的剩余谱系可能解释了物种形成的新方式。

Unlike northern Europe and most of northern North America, the Eastern Palearctic is believed to have been almost unglaciated during the Quarternary glacial periods. Under such geological history condition, how it affects speciation and genetic characteristic of Palaearcitc birds? To evaluate this, I studied the phylogeography in east Eurasia of various breeding passerine birds. As a result, I found several species that have deep DNA divergence within species in Japan and/or surrounding area. Such species are Arctic Warbler, Oriental Greenfinch, Pale-legged Leaf Warbler, Ijima's Leaf Warbler, Black-faced Bunting, Skylark, Narcissus Flycatcher and Black Paradise Flycatcher. These results indicate that lineages have maintained their integrity through several successive glaciations. Remaining lineages caused by the isolation mechanism without the ice sheet may explain the new way of speciation.