Phylogeny of cissus (vitaceae) focusing on south american species
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Widespread in the tropics, Cissus includes more than 300 species with great morphological diversity. Of the 78 species found in the New World, 64 grow in South America. This paper investigates phylogenetic relationships within Cissus, focusing on the South American species, insufficiently sampled in previous studies. Both plastid (trnL intron, trnL-F intergenic spacer, rps16) and nuclear ribosomal internal transcribed spacer (ITS) DNA sequences were analyzed with parsimony, likelihood and Bayesian inference. Divergence times were estimated with relaxed-clock Bayesian molecular dating. The evolution of leaf shape was reconstructed using parsimony. South American Cissus is resolved as not monophyletic. It consists of three clades: Cissus striata, Cissus trianae, and core Cissus. A clear separation between the Cissus striata clade and the other Cissus species was observed based on molecular and morphological characters. The relationship between the only species of the Cissus trianae clade and those of core Cissus is not clarified by our data. The geographic disjunction between the New and Old World taxa of core Cissus was estimated to have originated in the Late Eocene, and diversification in the Americas started in the Oligocene. In spite of the plasticity of leaf shape within species or individuals, this character is considered useful for infrageneric classification.