1 3 The effects of ecology and evolutionary history on robust capuchin 4 morphological diversity 5 6 7 Kristin A. Wright a,⇑ Q1 , Barth W. Wright a , Susan M. Ford b , Dorothy Fragaszy c , Patricia Izar d , 8 Marilyn Norconk e , Thomas Masterson f , David G. Hobbs g , Michael E. Alfaro h , Jessica W. Lynch Alfaro i,j 9 a Department of Anatomy, Kansas City University of Medicine and Biosciences, Kansas City, MO, USA 10 b Department of Anthropology and Graduate School, Southern Illinois University, Carbondale, IL, USA 11 c Department of Psychology, University of Georgia, Athens, GA, USA 12 d Department of Experimental Psychology, Institute of Psychology, University of São Paulo, Brazil 13 e Department of Anthropology, Kent State University, Kent, OH, USA 14 f Department of Health Sciences, Central Michigan University, Mount Pleasant, MI, USA 15 g Seminole State College, Sanford, FL, USA 16 h Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, USA 17 i Institute for Society and Genetics, University of California, Los Angeles, Los Angeles, CA, USA 18 j Department of Anthropology, University of California, Los Angeles, Los Angeles, CA, USA 19 20 21 23 article info 24 Article history: 25 Received 26 March 2013 26 Revised 25 June 2014 27 Accepted 8 August 2014 28 Available online xxxx 29 Keywords: 30 Sapajus 31 Robust capuchin monkeys 32 Morphological variation 33 Evolution 34 Cebidae 35 Platyrrhini 36 37 abstract 38 Recent molecular work has confirmed the long-standing morphological hypothesis that capuchins are 39 comprised of two distinct clades, the gracile (untufted) capuchins (genus Cebus, Erxleben, 1777) and Q2 40 the robust (tufted) capuchins (genus Sapajus Kerr, 1792). In the past, the robust group was treated as a 41 single, undifferentiated and cosmopolitan species, with data from all populations lumped together in 42 morphological and ecological studies, obscuring morphological differences that might exist across this 43 radiation. Genetic evidence suggests that the modern radiation of robust capuchins began diversifying 44 2.5 Ma, with significant subsequent geographic expansion into new habitat types. In this study we 45 use a morphological sample of gracile and robust capuchin craniofacial and postcranial characters to 46 examine how ecology and evolutionary history have contributed to morphological diversity within the 47 robust capuchins. We predicted that if ecology is driving robust capuchin variation, three distinct robust 48 morphotypes would be identified: (1) the Atlantic Forest species (Sapajus xanthosternos, S. robustus, and S. 49 nigritus), (2) the Amazonian rainforest species (S. apella, S. cay and S. macrocephalus), and (3) the Cerrado– 50 Caatinga species (S. libidinosus). Alternatively, if diversification time between species pairs predicts 51 degree of morphological difference, we predicted that the recently diverged S. apella, S. macrocephalus, 52 S. libidinosus, and S. cay would be morphologically comparable, with greater variation among the more 53 ancient lineages of S. nigritus, S. xanthosternos, and S. robustus. Our analyses suggest that S. libidinosus 54 has the most derived craniofacial and postcranial features, indicative of inhabiting a more terrestrial 55 niche that includes a dependence on tool use for the extraction of imbedded foods. We also suggest that 56 the cranial robusticity of S. macrocephalus and S. apella are indicative of recent competition with sympat- 57 ric gracile capuchin species, resulting in character displacement. 58 Ó 2014 Elsevier Inc. All rights reserved. 59 60 61 62 1. Introduction 63 Morphological evidence has long supported the division of capu- 64 chin monkeys into two types: the gracile or untufted capuchins 65 (here and throughout referred to as genus Cebus, Erxleben, 1777), 66 and the robust or tufted capuchins (referred to throughout as genus 67 Sapajus, Kerr, 1792). While species diversity has always been recog- 68 nized in the gracile capuchins, until recently the widespread robust 69 capuchins were treated as a single species. The lumping of all robust 70 capuchins into one species for data analyses has obscured any pat- 71 terns of geographical or phylogenetic variation in this group (Lynch 72 Alfaro et al., 2014). Here we review the history of morphological 73 studies of the robust capuchins, as well as recent molecular and bio- 74 geographic evidence for the evolutionary history of this clade. Then 75 we provide hypotheses about expected trends in morphological 76 variation within robust capuchins on the basis of ecology and http://dx.doi.org/10.1016/j.ympev.2014.08.009 1055-7903/Ó 2014 Elsevier Inc. All rights reserved. ⇑ Corresponding author. Address: Department of Anatomy, Kansas City Univer- sity of Medicine and Biosciences, 1750 Independence Avenue, Kansas City, MO 64106-1453, USA. Fax: +1 816 654 7531. E-mail address: kwright@kcumb.edu (K.A. Wright). Molecular Phylogenetics and Evolution xxx (2014) xxx–xxx Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev YMPEV 4993 No. of Pages 12, Model 5G 5 September 2014 Please cite this article in press as: Wright, K.A., et al. The effects of ecology and evolutionary history on robust capuchin morphological diversity. Mol. Phy- logenet. Evol. (2014), http://dx.doi.org/10.1016/j.ympev.2014.08.009