Jessica Lynch Alfaro: UCLA Center for Society and Genetics

Despite growing interest in capuchin monkeys as model organisms for social learning and cultural evolution, comparative evolutionary study of Cebus behavioral traits across field sites and species have been impeded by the lack of a robust phylogenetic hypothesis for the group. Here I present the first molecular phylogeny of Cebus and use it as a framework to study the evolution of social and foraging traditions, including anointing behaviors and tool use. Using tissue collected from museum specimens of wild-caught capuchins of known provenance across Latin America, I sequenced portions of three mtDNA genes (12s, 800 bp; cytB, 307 bp; d-loop, 435 bp) and reconstructed phylogenetic relationships using likelihood and Bayesian methods. My data revealed Cebus as a monophyletic genus composed of distinct tufted and non-tufted clades. In contrast to morphological studies, the data revealed that C. albifrons and C. libidinosis are each paraphyletic. Genetic diversity in the tufted capuchin clade was concentrated in the Atlantic forest, and the Amazonian tufted capuchins were nested as a subclade within Atlantic forest capuchins. I estimated divergence times within Cebus using external fossil calibrations under the assumption of a relaxed molecular clock and used this timetree to test whether social and foraging traditions have evolved more quickly in tufted versus non-tufted clades. This study provides both the first detailed molecular phylogeny for Cebus and new approaches to examining rates of behavioral evolution for different traits across capuchin populations. Conclusions from this study have implications for the prioritization of conservation funding and data collection.