Vicariance or long-distance dispersal: Historical biogeography of the pantropical subfamily Chrysophylloideae (Sapotaceae)

Aim- Continental disjunctions in pantropical taxa have been explained by vicariance or long-distance dispersal. The relative importance of these explanations in shaping current distributions may vary, depending on historical backgrounds or biological characteristics of particular taxa. We aimed to determine the geographical origin of the pantropical subfamily Chrysophylloideae (Sapotaceae) and the roles vicariance and dispersal have played in shaping its modern distribution.Location- Tropical areas of Africa, Australasia and South America.Methods- We utilized a recently published, comprehensive data set including 66 species and nine molecular markers. Bayesian phylogenetic trees were generated and dated using five fossils and the penalized likelihood approach. Distributional ranges of nodes were estimated using maximum likelihood and parsimony analyses. In both biogeographical and molecular dating analyses, phylogenetic and branch length uncertainty was taken into account by averaging the results over 2000 trees extracted from the Bayesian stationary sample.Results- Our results indicate that the earliest diversification of Chrysophylloideae was in the Campanian of Africa c.-73-83-Ma. A narrow time interval for colonization from Africa to the Neotropics (one to three dispersals) and Australasia (a single migration) indicates a relatively rapid radiation of this subfamily in the latest Cretaceous to the earliest Palaeocene (c.-62-72-Ma). A single dispersal event from the Neotropics back to Africa during the Neogene was inferred. Long-distance dispersal between Australia and New Caledonia occurred at least four times, and between Africa and Madagascar on multiple occasions.Main conclusions- Long-distance dispersal has been the dominant mechanism for range expansion in the subfamily Chrysophylloideae. Vicariance could explain South American-Australian disjunction via Antarctica, but not the exchanges between Africa and South America and between New Caledonia and Australia, or the presence of the subfamily in Madagascar. We find low support for the hypothesis that the North Atlantic land bridge facilitated range expansions at the Palaeocene/Eocene boundary.