Fitting Classification to Match Evolution: A Case of Molecular Systematics in the Plant Genus Columnea (Gesneriaceae).
Large taxa with many species are difficult to study evolutionarily because sampling all species at one time is infeasible. To study these large genera they can be divided into smaller units. Phylogenetic analysis identifies evolutionary units (monophyletic groups) within larger taxa. Columnea is a large genus with about 300 species, distributed in the Neotropics. Previous subgeneric classifications haven’t been tested using modern phylogenetic methods to verify that the subgeneric units are equivalent to evolutionary units. Molecular phylogenetics was applied to test the previous classifications to see if they reflect evolutionary units. Species were sampled to represent all previous subgeneric classification systems as well as morphological and geographical range of the genus. DNA sequencing of chloroplast and ribosomal RNA genes were utilized as the data for phylogenetic analysis. Maximum parsimony, maximum likelihood, and Bayesian inference were used as the methods to generate phylogenetic hypothesises. No previous subgenera classifications reflected monophyletic groups that were recovered in this analysis. An alternative subgenera classification is proposed based on the results of this phylogenetic analysis.