Phylogeny and Biogeography of Taxus (Taxaceae) Inferred from Sequences of the Internal Transcribed Spacer Region of Nuclear Ribosomal DNA

摘要: Species of Taxus, particularly Taxus baccata , have long been cultivated as ornamentals in Europe and North America. Ten species are generally recognized, but phylogenetic relationships among these remain unclear. We used sequences the nuclear ribosomal DNA ITS region to infer relationships. Three four New World form a well-supported clade, within which Pacific coastal T. brevifolia is sister clade containing floridana globosa northwestern Florida northern Mexico, respectively. canadensis, more widely distributed eastern America, appears be closely related Old taxa than other species. This relationship, though weakly supported our analysis, consistent with leaf anatomical features. chinensis mairei southeast Asia cuspidata Japan northeastern China, Africa. Our phylogeny implies that intercontinental disjunctions entailed at least two vicariance events: an initial split between T.floridana-T. brevifolia-T. rest, later separating canadensis from