| Phylogenetic relationships of the Ranunculaceae and related taxa are investigated at family, generic and specific levels, using three molecular markers that are known to evolve at different rates. They are chloroplast rbcL, nuclear 26S rDNA, and ITS. DNA sequences were either directly sequenced or obtained from GenBank and publications. They are analyzed using distance and discrete character methods to infer phylogenetic relationships.; At the family level, the phylogenetic position of the Ranunculaceae within the angiosperms is inferred from a total of 54 rbcL sequences. The Ranunculaceae belongs to a lineage including the Ranunculales, Papaverales and eudicots. Within the order Ranunculales (excluding Sargentodoxaceae, Coriariaceae, and Sabiaceae), a sister group relationship between the Ranunculaceae and Berberidaceae is topologically supported. In addition, inclusion of two controversial genera, Glaucidium and Hydrastis, within the Ranunculaceae is clearly supported.; For generic level comparisons within the Ranunculaceae, relationships among 22 genera represented by 35 species are inferred based on the sequences from a 1,066 bp long segment of 26S rDNA. The inferred phylogeny suggests that the T-chromosome group is not monophyletic, but consists of three independent lineages: (1) Hydrastis, (2) Xanthorhiza and Coptis, and (3) Thalictrum, Aquilegia, and Enemion (Aquilegia group). For the R-chromosome group, it also suggests several interesting relationships that have not been recognized by conventional systematics. The molecular phylogeny appears highly congruent with karyological and phytochemical characters, but not with major morphological characters such as fruit types.; Specific to generic relationships within the Aquilegia group of the Ranunculaceae are studied using the ITS region (ca. 610 bp). Thirty-five OTUs representing six genera (Aquilegia, Dichocarpum, Enemion, Leptopyrum, Paraquilegia, and Thalictrum) were included. ITS sequences are easily aligned within the Aquilesia group, but are largely unalignable between ingroup and outgroup taxa due to large sequence divergence. This alignment difficulty alone supports the monophyly of the Aquilegia group, but the root could not be identified. The inferred molecular phylogeny, which included a large number of Aquilegia and Thalictrum species, not only supports the monophyly of each genus but also suggests contrasting patterns of evolutionary history of these two genera. |
