Molecular phylogeny of the Aquilegia group (Ranunculaceae) based on internal transcribed spacers and 5.8S nuclear ribosomal DNA
1997
Ro, K.E. | McPheron, B.A.
Specific to generic relationships within the Aquilegia group of the Ranunculaceae (taxa with Thalictrum-chromosome type and base number of x = 7 or 6) were studied using internal transcribed spacer 1 (ITS 1), 5.8S rDNA and ITS 2 sequences (c. 610 bp). Thirty-five OTUs representing 32 species and six genera (Aguilegia, Dichocarpum, Enemion, Leptopyrum, Paraquilegia, and Thalictrum) were either directly sequenced or obtained from previous publications. ITS sequences were easily aligned within the Aquilegia group, but were largely unalignable between ingroup and outgroup taxa due to extensive sequence divergence. This alignment difficulty alone supports the monophyly of the Aquilegia group, but the most ancient branch (root) could not be identified based on an outgroup analysis. Data were analyzed using distance and discrete character methods to infer phylogenetic relationships among the included taxa. The inferred molecular phylogeny, which included a large number of Aquilegia and Thalictrum species, not only supports the monophyly of each of those genera, but also suggests the following: (1) Aquilegia ecalcarata, which was sometimes placed in Semiaquilegia, should be retained within Aquilegia; (2) North American Aquilegia species are likely to form a monophyletic group; (3) except for distribution data, other important taxonomic characters of Aquilegia, such as pollinator, flower color or habitat, are subject to frequent homoplasies; (4) Thalictrum thalictroides, which was often treated as the monotypic genus, Anemonella, should be retained within Thalictrum; (5) the current sub-generic classification of Thalictrum should be revised; and (6) the pattern of chromosome polyploidy is consistent with the inferred Thalictrum phylogeny.
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