Phylogenetic relationships in Anemone based on morphology and chloroplast DNA variation.

Abstract

Phylogenetic relationships of 46 species of Anemone (Ranunculaceae) and 6 related genera were explored with two independent data sets: chloroplast DNA restriction site mutations and morphological variation. In the chloroplast DNA work, restriction sites from ten enzymes were mapped 419 sites (including autapomorpies) were scored for the phylogenetic analysis. The phylogeny based on morphology was derived from 27 characters for the same taxa used in the molecular work. A subset of species complexes was examined with additional chloroplast and ribosomal DNA data. The use of several independent data sets provided phylogenetic hypotheses that could be compared and used in interpretations of character evolution. A cladogram resulting from a combination of all data sets provided a robust phylogeny useful in classification. Molecular and morphological characters establish Clematis as the most suitable outgroup for the phylogenetic analyses. Morphological and cpDNA phylogenies demonstrate that few of the sections of Anemone as established by previous classifications were monophyletic. The phylogenies based on chloroplast DNA restriction sites and the combined data sets indicate that Pulsatilla, Hepatica, and Knowltonia should be subsumed within Anemone. Various morphological characters indicate that Barneoudia and Oreithales should also be included within the genus. A preliminary, revised classification of Anemone is proposed. Several hypotheses are offered to explain the unusual geographic distributions found in Anemone, including the puzzling Asian and austral connection found in the basal clades of the chloroplast DNA tree. Two types of rearrangements were found in the chloroplast genome: an extension of the inverted repeat and seven inversions within the large single copy region. Two of the inversions appear to be homoplastic, appearing in separate clades in the chloroplast DNA restriction site analysis. The possible causal mechanisms for the large number of inversions are discussed.