The Rand Flora describes the disjunct phytogeographical pattern of a wide range of taxa distributed at the periphery of Africa and adjacent islands, as well as the Arabian Peninsula. We focused on Volutaria (Compositae: Cardueae: Centaurineae), a genus of ca. 18 species that
conforms to the Rand Flora pattern; yet its phylogeny, interspecific relationships, and biogeographical history remain poorly known. We aim to construct a robust phylogeny that will allow us to interpret the biogeography and the diversification of this genus, together with its present distribution
pattern, and to ascertain whether the latter arose by single or multiple gradual expansion processes, vicariance, or long-distance dispersal events. We sampled all extant Volutaria species, covering its entire geographical range, and generated sequences of nuclear-ribosomal DNA and
three plastid regions, which were analyzed by Bayesian inference and maximum parsimony. Samples yielding more than one sequence in direct sequencing were cloned. Historical biogeographical analysis was performed using BioGeoBEARS based on a phylogeny dated using a relaxed molecular clock calibrated
with a previous dating undertaken for the tribe Cardueae. Volutaria is a monophyletic taxon, having an Asian ancestor, and its present diversity is represented by four main clades that emerged in the Miocene. The earliest taxa of Volutaria to diverge are preserved in North Africa,
whereas clades that diverged more recently have done so on both sides of the Sahara. This process involved both ancient and recent interspecific introgression and hybridization events, as indicated by incongruities between plastid and nuclear results, and by cloning of the ITS region. The
distribution of Volutaria around two diversity poles conforms to the Rand Flora pattern, but this did not arise by a single event or process. Instead, the historical biogeography of Volutaria involves at least one migration wave from east to west, followed by the extinction of
ancestral taxa and subsequent expansion and retraction events, together with speciation processes on both sides of the Sahara. The intense tectonic and climatic changes that occurred in North Africa and western Asia throughout the Neogene and Pleistocene periods might explain the present diversity
and distribution pattern of the genus.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Article Media
Document Type: Research Article
Botánica (Dpto. Biología Animal, Vegetal y Ecología), Universidad Autónoma de Barcelona, 08193 Bellaterra, Spain, CREAF, Universidad Autónoma de Barcelona, 08193, Bellaterra, Spain;, Email: [email protected]
Institut Botànic de Barcelona (IBB – CSIC – ICUB), Pg. del Migdia s. n., 08038 Barcelona, Spain
Laboratoire d'Ecologie Alpine, CNRS UMR 5553, Université Grenoble Alpes, 2233 Rue de la Piscine, 38041 Grenoble Cedex 9, France
Publication date: 03 May 2016
More about this publication?