Complex biogeographic patterns in Androsace (Primulaceae) and related genera: evidence from phylogenetic analyses of nuclear internal transcribed spacer and plastid trnL-F sequences.

We conducted phylogenetic analyses of Androsace and the closely related genera Douglasia, Pomatosace, and Vitaliana using DNA sequences of the nuclear internal transcribed spacer (ITS) and the plastid trnL-F region. Analyses using maximum parsimony and Bayesian inference yield congruent relationships among several major lineages found. These lineages largely disagree with previously recognized taxonomic groups. Most notably, (1) Androsace sect. Andraspis, comprising the short-lived taxa, is highly polyphyletic; (2) Pomatosace constitutes a separate phylogenetic lineage within Androsace; and (3) Douglasia and Vitaliana nest within Androsace sect. Aretia. Our results suggest multiple origins of the short-lived lifeform and a possible reversal from annual or biennial to perennial habit at the base of a group that now contains mostly perennial high mountain or arctic taxa. The group containing Androsace sect. Aretia, Douglasia, and Vitaliana includes predominantly high alpine and arctic taxa with an arctic-alpine distribution, but is not found in the European and northeastern American Arctic or in Central and East Asia. This group probably originated in Europe in the Pliocene, from where it reached the amphi-Beringian region in the Pleistocene or late Pliocene.