Phylogenetic relationships and evolutionary traits in Ranunculus s.l. (Ranunculaceae) inferred from ITS sequence analysis Elvira Ho ¨ randl a, * , Ovidiu Paun a , Jan T. Johansson b , Carlos Lehnebach c , Tristan Armstrong d , Lixue Chen e , Peter Lockhart c a Department of Systematic and Evolutionary Botany, Faculty of Life Sciences, University of Vienna, Rennweg 14, A-1030 Vienna, Austria b Botaniska Institutionen, Stockholms Universitet, S-10691 Stockholm, Sweden c Allan Wilson Centre, Institute of Molecular BioSciences, Palmerston North, New Zealand d Landcare Research, Private Bag 92170, Auckland, New Zealand e School of Pharmacy, Yan Tai University, Yan Tai, China Received 31 August 2004; revised 26 January 2005 Available online 21 March 2005 Abstract Ranunculus is a large genus with a worldwide distribution. Phylogenetic analyses of c. 200 species of Ranunculus s.l. based on sequences of the nrITS using maximum parsimony and Bayesian inference yielded high congruence with previous cpDNA restriction site analyses, but strongly contradict previous classifications. A large core clade including Ranunculus subg. Ranunculus, subg. Bat- rachium, subg. Crymodes p.p., Ceratocephala, Myosurus, and Aphanostemma is separated from R. subg. Ficaria, subg. Pallasiantha, subg. Coptidium, subg. Crymodes p.p., Halerpestes, Peltocalathos, Callianthemoides, and Arcteranthis. Within the core clade, 19 clades can be described with morphological and karyological features. Several sections are not monophyletic. Parallel evolution of morphological characters in adaptation to climatic conditions may be a reason for incongruence of molecular data and morphol- ogy-based classifications. In some mountainous regions, groups of closely related species may have originated from adaptive radi- ation and rapid speciation. Split decomposition analysis indicated complex patterns of relationship and suggested hybridization in the apomictic R. auricomus complex, R. subg. Batrachium, and the white-flowering European alpines. The evolutionary success of the genus might be due to a combination of morphological plasticity and adaptations, hybridization and polyploidy as important factors for regional diversification, and a broad range of reproductive strategies. Ó 2005 Elsevier Inc. All rights reserved. Keywords: Evolution; Molecular phylogenetics; Ranunculus; Ranunculaceae; Split decomposition 1. Introduction Ranunculus (buttercups) represents the largest genus within Ranunculaceae, comprising ca. 600 species (Tam- ura, 1995) and distributed on all continents. Most spe- cies are found in temperate to arctic/subantarctic zones; in the tropics they are rare and restricted to high mountain areas. Buttercups are established in various terrestrial or aquatic habitats from lowlands to high alpine zones, and terrestrial species are often specialized in extreme, mainly cold/humid, but sometimes also xeric conditions. Various morphological adaptations and dif- ferent reproductive strategies such as vegetative repro- duction (stolons, bulbils), self-compatibility (e.g., in water-buttercups, Cook, 1966; in high alpine species, Pickering, 1997a,b; Riveros, 1991), and agamospermy (R. auricomus complex; see, e.g., Nogler, 1984; R. par- nassifolius L. and R. kuepferi Greut. et Burdet; Huber, 1988) may be important factors for their ability to colo- nize habitats at higher altitudes and latitudes. Within certain mountain systems, high species diversity is 1055-7903/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.ympev.2005.02.009 * Corresponding author. Fax: +43 1 4277 54099. E-mail address: elvira.hoerandl@univie.ac.at (E. Ho ¨ randl). Molecular Phylogenetics and Evolution 36 (2005) 305–327 MOLECULAR PHYLOGENETICS AND EVOLUTION www.elsevier.com/locate/ympev