@ARTICLE{TreeBASE2Ref18699, author = {Susana Magall?n}, title = {From fossils to molecules: phylogeny and the core eudicot floral groundplan in Hamamelidoideae (Hamamelidaceae, Saxifragales)}, year = {2007}, keywords = {}, doi = {10.1600/036364407781179617}, url = {}, pmid = {}, journal = {Systematic Botany}, volume = {32}, number = {2}, pages = {317--347}, abstract = {Most floral diversity in the core eudicots is based on a structural plan that includes among its most distinctive elements a bipartite perianth and pentamerous merosity combined with a bicarpellate gynoecium. To obtain insights about the origin of this groundplan, the evoultion of its structural components in Hamamelidoideae (Hamamelidaceae, Saxifragales, core eudicots) is explored. Phylogenetic hypotheses were obtained from independent analyses of morphological and molecular data, and from two alternative approaches to integrating morphological and molecular data from living and fossil taxa. In spite of being largely incomplete, fossils were unambiguously placed within particular clades in the well resolved trees obtained from morphological data. Phylogenetic analyses of individual and combined molecular data sets using different optimization criteria resulted in congruent trees that share most of their strongly supported nodes. Although morphological and molecular trees depict different relationships, no supported incongruence exists. A total evidence analysis including only complete taxa was congruent with molecular trees but resolution decreased substantially as incomplete taxa and incomplete characters were included. A parsimony analysis of morphological data constrained with the strongly supported nodes from the total evidence tree resulted in the same backbone relationships as the molecular trees and in the unambiguous placement of incomplete taxa, however, relationships within some clades were unique. The floral characters of ancient fossils and their nested placement in the phylogeny indicate morphological stasis since the origin of major lineages of Hamamelidoideae. Individual floral structural elements display independent evolutionary histories, suggesting that the core eudicot floral groundplan evolved through the accretion of structural components which originated at different points during angiosperm history, some outside eudicots, and others, namely the bipartite perianth and the pentamerous merosity, most likely within core eudicots.} }

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