title: Back to Gondwanaland: can ancient vicariance explain (some) Indian Ocean disjunct plant distributions?
abstract: Oceans, or other wide expanses of inhospitable environment, interrupt present day distributions of many plant groups. Using molecular dating techniques, generally incorporating fossil evidence, we can estimate when such distributions originated. Numerous dating analyses have recently precipitated a paradigm shift in the general explanations for the phenomenon, away from older geological causes, such as continental drift, in favour of more recent, long-distance dispersal (LDD). For example, the 'Gondwanan vicariance' scenario has been dismissed in various studies of Indian Ocean disjunct distributions. We used the gentian tribe Exaceae to reassess this scenario using molecular dating with minimum (fossil), maximum (geological), secondary (from wider analyses) and hypothesis-driven age constraints. Our results indicate that ancient vicariance cannot be ruled out as an explanation for the early origins of Exaceae across Africa, Madagascar and the Indian subcontinent unless a strong assumption is made about the maximum age of Gentianales. However, both the Gondwanan scenario and the available evidence suggest that there were also several, more recent, intercontinental dispersals during the diversification of the group.
authors.affiliation: Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa Institut für Spezielle Botanik und Botanischer Garten, Johannes Gutenberg-Universität, Anselm-Franz-von-Bentzelweg 9a, 55099 Mainz, Germany.
authors.forename: Michael D
authors.identifier: http://orcid.org/0000-0003-0403-4470
authors.initials: MD
authors.lastname: Pirie
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland Swiss Institute of Bioinformatics, Quartier Sorge, 1015, Lausanne, Switzerland.
authors.forename: Glenn
authors.initials: G
authors.lastname: Litsios
authors.affiliation: Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
authors.forename: Dirk U
authors.initials: DU
authors.lastname: Bellstedt
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland Swiss Institute of Bioinformatics, Quartier Sorge, 1015, Lausanne, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Salamin
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland jonathan.kissling@unine.ch.
authors.forename: Jonathan
authors.identifier: http://orcid.org/0000-0002-1078-4000
authors.initials: J
authors.lastname: Kissling
mesh_terms: D019143:Evolution, Molecular; D019419:Evolution, Planetary; D029965:Gentianaceae / Q000145:classification* / Q000235:genetics / Q000502:physiology*; D019156:Indian Ocean; D008969:Molecular Sequence Data; D010802:Phylogeny; D063148:Plant Dispersal; D010940:Plant Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D010940:Plant Proteins
keywords: Exaceae; calibration; dating; long-distance dispersal; vicariance