Rapid diversification rates in Amazonian Chrysobalanaceae inferred from plastid genome phylogenetics

Abstract We studied the evolutionary history of Chrysobalanaceae with phylogenetic analyses of complete plastid genomes from 156 species to assess the tempo of diversification in the Neotropics and help to unravel the causes of Amazonian plant diversification. These plastid genomes had a mean length of 162 204 base pairs, and the nearly complete DNA sequence matrix, with reliable fossils, was used to estimate a phylogenetic tree. Chrysobalanaceae diversified from 38.9 Mya (95% highest posterior density, 95% HPD: 34.2–43.9 Mya). A single clade containing almost all Neotropical species arose after a single dispersal event from the Palaeotropics into the Amazonian biome c. 29.1 Mya (95% HPD: 25.5–32.6 Mya), with subsequent dispersals into other Neotropical biomes. All Neotropical genera diversified from 10 to 14 Mya, lending clear support to the role of Andean orogeny as a major cause of diversification in Chrysobalanaceae. In particular, the understory genus Hirtella diversified extremely rapidly, producing > 100 species in the last 6 Myr (95% HPD: 4.9–7.4 Myr). Our study suggests that a large fraction of the Amazonian tree flora has been assembled in situ in the last 15 Myr.