Phylogenetic Relationships in Anemone (Ranunculaceae) Based on Morphology and Chloroplast DNA

Abstract

-Phylogenetic relationships of 36 species of Anemone (Ranunculaceae) and seven related genera were explored with three independent data sets: chloroplast DNA restriction sites, nuclear ribosomal DNA restriction fragments, and morphological/cytological variation. In the chloroplast DNA work, 245 phylogenetically informative restriction sites were identified using ten restriction enzymes. The phylogeny based on conventional data 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 nuclear ribosomal DNA data. Molecular and morphological characters established Clematis as the most suitable outgroup for the phylogenetic analyses. Many of the terminal groups of the cladograms resulting from the molecular and morphological data sets were similar, but basal branching patterns were substantially different. Because the molecular tree was substantially less homoplastic and had higher bootstrap and decay values than the morphological tree, it was accepted as the more reliable in determining basal relationships. Both morphological and chloroplast DNA phylogenies demonstrate that few of the sections of Anemone as established by previous classifications are 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 Anemone. Independent data sets provide phylogenetic hypotheses useful in interpretations of character evolution. A preliminary, revised classification is proposed. Several hypotheses are offered to explain the unusual geographic distributions found in Anemone. Anemone s. str. consist of 70-90 species of perennial, low-growing herbs (Ulbrich 1905-1906; pers. obs.). The genus is characterized by a rosette of basal leaves, an involucrate peduncle bearing a single flower or compound inflorescence, a perianth of petaloid sepals, and an achene fruit. There is considerable morphological variation within the genus. The perennating structures are upright stems, rhizomes, or tubers. The basal leaves vary from trilobed to several times ternate, rarely pinnate. The involucral leaves are various in number and form, sometimes reduced and bract-like. The achenes are glabrous to tomentose, few to many in number, with various morphologies of the style. Base chromosome numbers are either seven or eight. Species are most numerous in the Northern Hemisphere, but also occur in mountainous and cooler regions of the Southern Hemisphere. They inhabit a wide range of habitats including arctic and alpine tundra, prairie, woodlands, Mediterannean regions, and semidesert. Several previous classifications placed Anemone and Clematis in the same tribe, Anemoneae (Langlet 1932; Tamura 1967). A sister genus to Clematis from Africa, Clematopsis, should also be included in this tribe (Hutchinson 1920). Anemoneae are regarded as most closely related to the tribes Ranunculeae and Adonieae. Cladistic analyses based on morphology of the Ranunculaceae (Hoot 1991) place Anemone in a clade with Clematis, Hepatica, Pulsatilla, and Ranunculus, united by two derived character states, presence of achenes and the chemical compound ranunculin. It is not at all clear which of these genera are most closely related to Anemone. The delimitation of Anemone has been debated for years. Early classifications often included the genera Hepatica, Pulsatilla, Knowltonia, Barneoudia, and Oreithales within Anemone (Jan-