title: Geographical isolation caused the diversification of the Mediterranean thorny cushion-like Astragalus L. sect. Tragacantha DC. (Fabaceae).
abstract: Understanding the origin and evolution of Mediterranean vascular flora within the long-term context of climate change requires a continuous study of historical biogeography supported by molecular phylogenetic approaches. Here we provide new insights into the fascinating but often overlooked diversification of Mediterranean xerophytic plants. Growing in some of the most stressing Mediterranean environments, i.e. coastal and mountainous opened habitats, the circum-Mediterranean Astragalus L. sect. Tragacantha DC. (Fabaceae) gathers several thorny cushion-like taxa. These have been the subjects of recent taxonomical studies, but they have not yet been investigated within a comprehensive molecular framework. Bayesian phylogenetics applied to rDNA ITS sequences reveal that the diversification of A. sect. Tragacantha has roots dating back to the Pliocene, and the same data also indicate an eastern-western split giving rise to the five main lineages that exist today. In addition, AFLP fingerprinting supports an old east-west pattern of vicariance that completely rules out the possibility of a recent eastern origin for western taxa. The observed network of genetic relationships implies that contrary to what is widely claimed in the taxonomic literature, it is range fragmentation, as opposed to a coastal-to-mountain ecological shift, that is likely the main driver of diversification.
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale (IMBE), Aix Marseille Université, CNRS, IRD, Avignon Université, Marseille, France; Laboratoire Image Ville Environnement (LIVE), Université de Strasbourg, CNRS, Strasbourg, France. Electronic address: hardion@unistra.fr.
authors.forename: Laurent
authors.initials: L
authors.lastname: Hardion
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale (IMBE), Aix Marseille Université, CNRS, IRD, Avignon Université, Marseille, France.
authors.forename: Pierre-Jean
authors.initials: PJ
authors.lastname: Dumas
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale (IMBE), Aix Marseille Université, CNRS, IRD, Avignon Université, Marseille, France; Laboratoire Caractérisation Génomique des Plantes, Faculté des Sciences, Université Saint-Joseph, Mar Roukoz, Mkalles, Lebanon.
authors.forename: Farah
authors.initials: F
authors.lastname: Abdel-Samad
authors.affiliation: Laboratoire Caractérisation Génomique des Plantes, Faculté des Sciences, Université Saint-Joseph, Mar Roukoz, Mkalles, Lebanon.
authors.forename: Magda
authors.initials: M
authors.lastname: Bou Dagher Kharrat
authors.affiliation: Natural History Museum Rijeka, Lorenzov prolaz 1, 51000 Rijeka, Croatia; University of Primorska, Faculty of Mathematics, Natural Sciences and Information Technologies, Glagoljaška 8, SI-6000 Koper, Slovenia.
authors.forename: Bostjan
authors.initials: B
authors.lastname: Surina
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale (IMBE), Aix Marseille Université, CNRS, IRD, Avignon Université, Marseille, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Affre
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale (IMBE), Aix Marseille Université, CNRS, IRD, Avignon Université, Marseille, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Médail
authors.affiliation: Centro Conservazione Biodiversità, Dipartimento di Scienze della Vita e dell'Ambiente, Università degli Studi di Cagliari, Cagliari, Italy.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Bacchetta
authors.affiliation: Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale (IMBE), Aix Marseille Université, CNRS, IRD, Avignon Université, Marseille, France.
authors.forename: Alex
authors.initials: A
authors.lastname: Baumel
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D001499:Bayes Theorem; D057231:Climate Change; D004275:DNA, Ribosomal / Q000235:genetics; D017753:Ecosystem; D019143:Evolution, Molecular; D007887:Fabaceae / Q000145:classification* / Q000235:genetics*; D019083:Mediterranean Region; D010802:Phylogeny; D058974:Phylogeography
chemical_list: D004275:DNA, Ribosomal
keywords: Biodiversity; Biogeography; Phylogeography; Plant; Speciation; Vicariance