Le vendredi 12 septembre 2014 à 13h00, en salle de conférences de l'OSUR, campus de Beaulieu, bât.
Le vendredi 12 septembre 2014 à 13h00
, en salle de conférences de l'OSUR, campus de Beaulieu, bât. 14b, UR1Phylogenetic affinities and dispersal of Southern Hemisphere buttercups (Ranunculus); the French-Kiwi connectionRésumé :Ranunculus
(buttercups) is a cosmopolitan plant genus that comprises c. 600 species. The highest number of species is found in temperate lowland and alpine regions of the world. Ranunculus have also reached remote places such as New Zealand (NZ) and several sub-Antarctic islands where lineages have diversified and endemic species have evolved. Uncovering the phylogenetic affinities of these island lineages can provide valuable information to understand dispersal and diversification of plants in the Southern Hemisphere (SH). Phylogenetic analysis of nuclear and chloroplast markers of SH buttercups have revealed that diversification and colonisation of different ecological niches have occurred after long distance dispersal events both in NZ and South America. For NZ, in particular, phylogenetic results indicate that NZ Ranunculus are not a monophyletic group and that their closest affinities are to species from other land masses such as Australia, the Northern Hemisphere, southern South America and islands in the Southern Oceans (Kerguelen Islands). Findings suggest that colonisation of Ranunculus
into the SH has been a dynamic process with several long distance dispersal events and colonisation via different routes. Bird transportation and oceanic currents are the most likely vectors for long dispersal for this group.Contact : Carlos LEHNEBACK