Phylogenetics of Iriarteeae (Arecaceae), cross-Andean disjunctions and convergence of clustered infructescence morphology in Wettinia

Abstract

The Neotropical palm tribe Iriarteeae is ubiquitous in several lowland and montane biomes across northern South America, but the phylogenetic relationships among genera and species remain unresolved. A well resolved phylogenetic tree is key to exploring morphological evolution in the tribe, including striking features such as the complex and unique inflorescence structures in Wettinia. We generated data from five plastid (ndhA, petD-rpoA, psbK-trnS and trnG) and six nuclear (AG1, CISPs 4 and 5, PRK, RPB2 and WRKY21) molecular loci to infer the phylogeny. We explored the evolutionary patterns of trait evolution using the D statistic and stochastic character mapping. All genera were inferred as monophyletic and their relationships were recovered with strong to moderate support. Based on these results we synonymize the two species of Iriartella under I. setigera and resurrect Socratea montana from S. rostrata. Interspecific relationships were mostly consistent with current morphological classification. One exception concerns trait evolution in Wettinia, in which the clustered infructescence was found to have evolved at least four times. Phylogenetic signal for this trait was weak and randomly distributed across the tree, probably representing convergence. Our results provide a robust phylogenetic framework for Iriarteeae, largely corroborating current morphological classification and laying the groundwork for macroevolutionary studies in the tribe.