title: The abrupt climate change at the Eocene-Oligocene boundary and the emergence of South-East Asia triggered the spread of sapindaceous lineages.
abstract: OBJECTIVE
  Paleoclimatic data indicate that an abrupt climate change occurred at the Eocene-Oligocene (E-O) boundary affecting the distribution of tropical forests on Earth. The same period has seen the emergence of South-East (SE) Asia, caused by the collision of the Eurasian and Australian plates. How the combination of these climatic and geomorphological factors affected the spatio-temporal history of angiosperms is little known. This topic is investigated by using the worldwide sapindaceous clade as a case study.
  
  
  METHODS
  Analyses of divergence time inference, diversification and biogeography (constrained by paleogeography) are applied to a combined plastid and nuclear DNA sequence data set. Biogeographical and diversification analyses are performed over a set of trees to take phylogenetic and dating uncertainty into account. Results are analysed in the context of past climatic fluctuations.
  
  
  RESULTS
  An increase in the number of dispersal events at the E-O boundary is recorded, which intensified during the Miocene. This pattern is associated with a higher rate in the emergence of new genera. These results are discussed in light of the geomorphological importance of SE Asia, which acted as a tropical bridge allowing multiple contacts between areas and additional speciation across landmasses derived from Laurasia and Gondwana.
  
  
  CONCLUSIONS
  This study demonstrates the importance of the combined effect of geomorphological (the emergence of most islands in SE Asia approx. 30 million years ago) and climatic (the dramatic E-O climate change that shifted the tropical belt and reduced sea levels) factors in shaping species distribution within the sapindaceous clade.
authors.affiliation: Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK. s.buerki@kew.org
authors.forename: Sven
authors.initials: S
authors.lastname: Buerki
authors.forename: Félix
authors.initials: F
authors.lastname: Forest
authors.forename: Tanja
authors.initials: T
authors.lastname: Stadler
authors.forename: Nadir
authors.initials: N
authors.lastname: Alvarez
mesh_terms: D001210:Asia, Southeastern; D005075:Biological Evolution; D057231:Climate Change; D014644:Genetic Variation; D010163:Paleontology; D010802:Phylogeny; D018087:Plastids / Q000235:genetics; D029631:Sapindaceae / Q000235:genetics / Q000502:physiology*
keywords: Biogeography; Eocene–Oligocene boundary; Sapindaceae; South-East Asia; climate change; diversification