Validating the timing of New World monkey dispersal routes by lineage dispersal modeling and description of the Amazonian eastward route

New World monkeys (NWM) comprise a group of extant and extinct taxa exclusive to the Neotropics. Lineage dispersal modeling was employed to test the validity of previously reported biogeographic patterns in NWM. Specifically, this research sought to confirm whether the dispersal timings of these patterns were supported by the modeling results. Species geographic distributions of extant platyrrhines were used to obtain a bioregionalization scheme. A lineage dispersal model was constructed based on multiple-area range, likelihood inference of rate, and stochastic mapping under likelihood. Based on published phylogenies, ten trees were randomly sampled and, for each tree, ten stochastic mappings were simulated. Results were presented as event counts and averages across the 100 stochastic mappings, and the timings of the inferred dispersal routes were compared to the timings of 12 biogeographic pattern hypotheses gathered from the literature. The modeling analysis provided directional and temporal support for eleven of the twelve patterns. Lineages most frequently dispersed from Western Amazonia towards other bioregions. For four dispersal routes, events initiated earlier than previously reported. The Western Amazonia bioregion served as both the ancestral area and primary source of platyrrhine lineages. Analyses revealed a novel biogeographic pattern, namely the “Amazonian eastward” dispersal route, which started in the Miocene epoch, during the establishment of the transcontinental Amazon River system, and lasted until recently in an increasing trend of dispersal rate. This route showed the greatest number of dispersal events during the macroevolution of NWM.