title: Radiation and repeated transoceanic dispersal of Schoeneae (Cyperaceae) through the southern hemisphere.
abstract: OBJECTIVE
  The broad austral distribution of Schoeneae is almost certainly a product of long-distance dispersal. Owing to the inadequacies of existing phylogenetic data and a lack of rigorous biogeographic analysis, relationships within the tribe remain poorly resolved and its pattern of radiation and dispersal uncertain. We employed an expanded sampling of taxa and markers and a rigorous analytic approach to address these limitations. We evaluated the roles of geography and ecology in stimulating the initial radiation of the group and its subsequent dispersal across the southern hemisphere.
  
  
  METHODS
  A dated tree was reconstructed using reversible-jump Markov chain Monte Carlo (MCMC) with a polytomy prior and molecular dating, applied to data from two nuclear and three cpDNA regions. Ancestral areas and habitats were inferred using dispersal-extinction-cladogenesis models.
  
  
  RESULTS
  Schoeneae originated in Australia in the Paleocene. The existence of a "hard" polytomy at the base of the clade reflects the rapid divergence of six principal lineages ca. 50 Ma, within Australia. From this ancestral area, Schoeneae have traversed the austral oceans with remarkable frequency, a total of 29 distinct dispersal events being reported here. Dispersal rates between landmasses are not explicable in terms of the geographical distances separating them. Transoceanic dispersal generally involved habitat stasis.
  
  
  CONCLUSIONS
  Although the role of dispersal in explaining global distribution patterns is now widely accepted, the apparent ease with which such dispersal may occur has perhaps been under-appreciated. In Schoeneae, transoceanic dispersal has been remarkably frequent, with ecological opportunity, rather than geography, being most important in dictating dispersal patterns.
authors.affiliation: Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
authors.forename: Jan-Adriaan
authors.initials: JA
authors.lastname: Viljoen
authors.forename: A Muthama
authors.initials: AM
authors.lastname: Muasya
authors.forename: Russell L
authors.initials: RL
authors.lastname: Barrett
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Bruhl
authors.forename: Adele K
authors.initials: AK
authors.lastname: Gibbs
authors.forename: Jasper A
authors.initials: JA
authors.lastname: Slingsby
authors.forename: Karen L
authors.initials: KL
authors.lastname: Wilson
authors.forename: G Anthony
authors.initials: GA
authors.lastname: Verboom
mesh_terms: D001315:Australia; D029785:Cyperaceae / Q000235:genetics*; D018744:DNA, Plant; D017753:Ecosystem; D019143:Evolution, Molecular; D049810:Genetic Speciation; D005843:Geography; D008957:Models, Genetic; D009792:Oceans and Seas; D010802:Phylogeny; D063148:Plant Dispersal
chemical_list: D018744:DNA, Plant
keywords: Cyperaceae; Schoeneae; biogeography; dispersal–extinction–cladogenesis; habitat shift; niche conservatism; polytomy prior; transoceanic dispersal