Cercis (L.) (Leguminosae) consists of approximately 8 species, disjunctly distributed in eastern and western Asia, southern Europe, and North America. Phylogenetic analysis was performed using sequences of the internal transcribed spacer (ITS) of the nuclear ribosomal DNA. The two North American and one Southern European and Western Asian species consistently form a clade, nesting within the eastern Asian species, suggesting a slightly closer relationship between the North American and Southern Europe-Western Asian species than each with the Eastern Asian species of Cercis . A close relationship between the eastern and western North American species is furthermore demonstrated, although with weaker support. The possibilities of migration via either the Bering land bridges or the North Atlantic land bridges could not be precluded; it suggests that the biogeographic patterns in the Northern Hemisphere are complex.
紫荆属的系统发育和生物地理学研究
郝刚 张奠湘* 郭丽秀 张明永 邓云飞 文香英
（中国科学院华南植物研究所，广州51065）
摘要：紫荆属 (CercisL .)约含 8种 ,间断分布于亚洲东、西部 ,欧洲南部和北美。应用核糖体DNA的ITS基因序列研究紫荆属的系统发育关系。在最简约性分析中 ,北美的两个种和南欧、西亚的一个种构成一单系群而隐藏于东亚的种类中。这表明紫荆属北美的种类和南欧、西亚的种类之间的关系比它们各自与东亚的种类的关系要密切。研究还发现北美洲东、西部的种类可能具较近亲缘。紫荆属以白令陆桥或北大西洋陆桥为迁移途径的可能性似乎都不能排除 ;北半球的生物地理分布式样可能具有复杂的起源
关键词： 紫荆属；豆科；系统发育；ITS；生物地理；亚洲；北美洲；间断分布
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