Phylogeny, Ecology, and Morphological Evolution in the Atelid Cranium

Abstract

Reconstructing evolutionary relationships of living and extinct primate groups requires reliable phylogenetic inference based on morphology, as DNA is rarely preserved in fossil specimens. Atelids (family Atelidae) are a monophyletic clade and one of the three major adaptive radiations of south and central American primates (platyrrhines), including the genera Alouatta, Ateles, Brachyteles, and Lagothrix, and are diverse in morphology, body and brain size, locomotion, diet, social systems, and behavioral ecology. Molecular phylogenetic relationships of the extant atelid genera are well resolved, yet morphological analyses often support alternative phylogenetic relationships to molecular data. We collected geometric morphometric data from the crania of atelid taxa for phylogenetic analysis of the cranium, cranial base, and face and tested the hypotheses that cranial data maintain a phylogenetic signal, cranial base morphology most closely reflects the atelid molecular phylogeny, and facial and overall cranial morphology are shaped by diet and have experienced greater homoplasy. All analyses supported genus monophyly, and facial morphology maintained a strong phylogenetic signal inferring the atelid molecular phylogeny and a sister relationship between Brachyteles and Lagothrix, whereas results from the cranial base and whole cranium supported Ateles–Lagothrix and/or Alouatta–Brachyteles clades reflecting homoplasy and ecological and dietary similarities. A phylogenetic signal in the atelid face is important for future studies integrating fossil taxa and supports evidence that congruence between molecular and morphological phylogenetics in primates is module and clade specific.