Molecular systematics of cyperaceae tribe cariceae and genus Carex.

摘要

A phylogenetic analysis of Cyperaceae tribe Cariceae was conducted using chloroplast DNA sequences from the gene ndhF and trnL intron, and trnL-trnF intergenic spacer. Molecular data reveal a monophyletic Cariceae with 100% bootstrap support. Within Cariceae the South African genus Schoenoxiphium forms a clade that is sister to the rest of the tribe. Carex is paraphyletic with respect to Kobresia, Cymophyllus and Uncinia. Cymophyllus and Uncinia are nested within an assemblage containing Kobresia, Cymophyllus, and several unispicate Carex species. At the subgeneric level within Carex, only Carex subgenus Vignea appears monophyletic. Some unispicate Carex species appear to be derived from Kobresia-like ancestors and are closely related to Uncinia while others appear related closely with subgenera Carex and Vignea. Neither subgenus Carex or Indocarex was monophyletic, although the two subgenera together form a monophyletic group. Several well supported clades were identified within the Cariceae , including the Schoenoxiphium clade, Uncinia clade, Carex subgenus Indocarex/ Carex clade, and subgenus Vignea clade; however, relationships among some clades are only moderately support.;Within the Carex/Indocarex clade, Carex cruciata and C. perakensis var. borneensis form a clade sister to the rest of the taxa. For the remaining species, the monophyly of sections Fecundae, Montanae, and Polystachyae were supported based on current sampling. Several large sections sampled in this study were found to be polyphyletic; these include sections Atratae, Frigidae, and Hymenochlaenae. Many branches were unresolved in these analyses suggesting the need for additional data. The short branches and low levels of sequence divergence suggest rapid or recent diversification for this large genus.;Based on available fossil and phylogenetic data, a biogeographic reconstruct suggests a northern hemisphere origin of tribe Cariceae during the Tertiary. Long distance dispersals followed by diversification appear to be important factors in the biogeographic history of tribe Cariceae.