Unraveling the biogeographical history of Chrysobalanceae from plastid genomes

PREMISE OF THE STUDY: The complex geological and climatic history of the Neotropics has had major implications on the diversifi cation of plant lineages. Chrysobalanaceae is a pantropical family of trees and shrubs with 75% of its 531 species found in the Neotropics, and a time-calibrated phylogeny of this family should shed light on the tempo of diversifi cation in the Neotropical fl ora. Previously published phylogenetic hypotheses of this family were poorly supported, and its biogeography remains unclear. METHODS: We assembled the complete plastid genome of 51 Chrysobalanaceae species, and increased taxon sampling by Sanger-sequencing of fi ve plastid regions for an additional 88 species. We generated a time-calibrated tree including all 139 Chrsyobalanaceae species and 23 outgroups. We then conducted an ancestral area reconstruction analysis and estimated diversifi cation rates in the family. KEY RESULTS: The tree generated with the plastid genome alignment was almost fully resolved. It supports the polyphyly of Licania and Hirtella . The family has diversifi ed starting around the Eocene-Oligocene transition. An ancestral area reconstruction confi rms a Paleotropical origin for Chrysobalanaceae with several transoceanic dispersal events. The main Neotropical clade likely resulted from a single migration event from Africa around 28 mya ago, which subsequently underwent rapid diversifi cation. CONCLUSIONS: Given the diverse ecologies exhibited by extant species, we hypothesize that the rapid diversifi cation of Chrysobalanaceae following the colonization of the Neotropics was triggered by habitat specialization during the complex geological and paleoclimatic history of the Neotropics.