ibclogo XVI International Botanical Congess


Abstract Number: 31
Session = 8.10.2


EVOLUTION OF LIFE-HISTORY TRAITS IN THE GENUS MEDICAGO L. AMBIGUITY OF RECONSTRUCTION AND CONFLICT WITH THEORETICAL PREDICTIONS


Gilles Béna, Jean-Marie Prosperi, Bernard Lejeune and Isabelle Olivieri, Université Montpellier 2, 34095 Montpellier Cedex 05, France


We present a molecular phylogeny including most species of the genus Medicago L. (Fabaceae). Based on the consensus of the 336 most parsimonious trees, life-history and mating system characters are mapped and a putative history of the genus is suggested. The most parsimonious reconstruction suggests an undetermined ancestral state, and recurrent evolution towards perenniality and outcrossing. Based on theoretical predictions, morphological characters and classical hypotheses of the history of the genus, different assumptions about the ancestral state and different weighting schemes of evolution between the character states are made. Assuming an outcrossing perennial ancestral state (partly supported by morphological features) does not fundamentally change the reconstruction. In order to meet theoretical expectations, various weighting schemes favouring evolutions towards annuality and selfing are applied. Influence and validity of such weighting schemes are discussed and the relevance of such phylogenetic approach are discussed.


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