It is suggested that dispersal and vicariance led to speciation in Mesoamerican taxa during the Pleistocene, as a consequence of climatic fluctuations and resulting range disjunctions, but few biogeographic studies have been developed to assess their relative roles. Based on a mitochondrial DNA dataset, we analyzed the evolutionary history of Turdus assimilis, a species distributed in Mesoamerica and northwestern South America. Phylogenetic patterns, divergence times, and biogeographic analyses suggest a South American ancestor for T. assimilis, which split from T. albicollis between 1.4 and 3.0 Ma ago. The analysis suggests the colonization of Mesoamerica and the Chocó region by small numbers of founder individuals. Furthermore, genetic divergence, reciprocal monophyly, an ancient disjunction, and clear phenotypic differences suggest that the population from the Chocó region, T. a. daguae, represents a separate species from T. assimilis.