Phylogeny and of €upatorium (Eupatorieae, Asteraceae): Insights from Sequence Data of the nrDNA ITS Regions and cpDNA RFLP

• Main Authors: Motomi Ito, Kuniaki Watanabe, Yoko Kita, Takayuki Kawahara, D. J. Crawford, Tetsukazu Yahara
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: European disjunction- phytogeography; Bering Land Bridge
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.492.3134; http://seibutsu.biology.kyushu-u.ac.jp/~yahara/publication/Ito%26al2000Eupatorium.pdf

The relationships of eastern North American-eastern Asian-European disjuncts in the genus Eupatorium were examined by sequencing the internal transcribed spacers (ITS) of nuclear ribosomal DNA and restriction site analysis of chloroplast DNA. Molecular data provided strong evi-dence that (1) this genus originated in North America, (2) the genus diverged into three morphological species groups, €utm&ium, T-aganthes and Uncasia in North America, and (3) one of the North American Uncasia lineages migrated into temperate Europe and eastern Asia over the Bering land bridge. The estimated divergence times support a late Miocene to early Pliocene migration from North America to Eurasia via the Bering land bridge. A European species was sister to all of the eastern Asian species examined. The disjunct distribution pattern of the genus Eupatorium is incongruent with the classical Arcto-Tertiary geoflora con-cept.