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 interna...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.展开更多
文摘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.
