Phylogeny and evolution of morphological characters in tribe Chamaedoreeae (Arecaceae)
Within the palm family, molecular analyses have resulted in a need to re-evaluate characters previously considered useful to establish hypotheses of relationships among groups. Recent phylogenetic analyses of tribe Chamaedoreeae have shown that characters traditionally used as strong indicators of relationship, such as presence of solitary flowers and dioecy, are homoplasious within this tribe. In the largest genus, Chamaedorea, published molecular analyses recover well-supported groups not previously proposed based on morphological characters and at the same time resolve some of the current subgenera as polyphyletic. In this study we further explore the phylogenetic relationships in Chamaedoreeae and search for morphological synapomorphies for the monophyletic groups recovered. Phylogenetic analyses of morphological, nuclear (PRK, RPB2), and plastid (matK, ndhF, trnD-trnT, rps16 intron, trnL-trnF) data are performed and morphological characters are subsequently optimized on the resulting topologies. Although most of the morphological characters included are highly homoplasious, the inclusion of morphological characters in the phylogenetic analyses improves the resolution within Chamaedoreeae, particularly among species of Chamaedorea. With the exception of Synechanthus and Wendlandiella, all the genera and subgenera in Chamaedoreeae are defined by a combination of homoplasious characters, none of which is unique within the tribe. Two of the seven subgenera of Chamaedorea included in our analyses, C. subg. Eleutheropetalum and subg. Stephanostachys, are supported as monophyletic with a number of morphological synapomorphies also used in the original descriptions of these subgenera. Some morphological characters not used in the traditional subgeneric classification of Chamaedorea, such as leaf sheath structure and pistillode, gynoecium and filament connation, though homoplasious, are resolved as synapomorphies and, therefore, potentially useful when defining subgenera within this genus.
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