Phylogenomic relationships and historical biogeography in the South American vegetable ivory palms (Phytelepheae)

The palm tribe Phytelepheae form a clade of three genera and eight species whose phylogenetic relationships and historical biogeography are not fully understood. Based on morphological similarities and phylogenetic relatedness, it has been suggested that Phytelephas seemannii and Phytelephas schottii are synonyms of Phytelephas macrocarpa, implying the existence of only six species within the Phytelepheae. In addition, uncertainty in their phylogenetic relationships in turn results in blurred biogeographic history. We inferred the phylogenomic relationships in the Phytelepheae by target-capturing 176 nuclear genes and estimated divergence times by using four fossils for time calibration. We lastly explored the biogeographic history of the tribe by inferring its ancestral range evolution. Our phylogenomic trees showed that P. seemannii and P. schottii are not closely related with P. macrocarpa, and therefore, support the existence of eight species in the Phytelepheae. The ancestor of the tribe was widely-distributed in the Chocó, Magdalena, and Amazonia during the Miocene at 19.25 Ma. Early diversification in Phytelephas at 5.27 Ma could have occurred by trans-Andean vicariance after the western Andes uplifted rapidly at ∼ 10 Ma. Our results show the utility of phylogenomic approaches to shed light on species relationships and their biogeographic history.