Mercredi 25
Développements et applications des MPC

› 16:00 - 16:40 (40min)
Ancestral states reconstruction: example of the perianth in Ranunculaceae
Laetitia Carrive  1, *@  
1 : Laboratoire Écologie, Systématique, Évolution
Université Paris Sud - Paris XI
* : Auteur correspondant

Ranunculaceae are a large family of flowering plants comprising ca. 2500 species including common species, for example the buttercups, columbines, monkshoods and hellebores. Their flowers are highly variable in their morphology and the family lacks a constant floral formula or floral synapomorphies. However, it is easily recognizable in the field and it always appears to be a monophyletic group in cladistic analyses, whether morphological or molecular. The analytical study of morphological evolution and the use of comparative methods are thus important to understand the specificities of ranunculacean flowers. In the past recent years, several phylogenies of Ranunculaceae and closely related families have been published. Therefore it is now possible to build a synthetic phylogenetic framework of the Ranunculales using already available sequences. This enables the study of floral traits at the scale of the whole order, hence improving the confidence and uncertainty estimation in ancestral states reconstruction at the level of Ranunculaceae themselves. In this framework, structural characters of the perianth (such as phyllotaxy and differentiation) were reconstructed using Reversible Jump Monte Carlo Markov Chains. This Bayesian method integrates various sources of uncertainty (on the topologies, the parameters, branch lengths etc.). The analyses explore all the model space and thus allow to examine and ponder a variety of different evolutionary scenarios for each character. 


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