The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)


Mechanical properties of Pentaclethera macrophylla seed pods and ingestive strategies of the western pied colobus monkey (Colobus polykomos)

DAVID J. DAEGLING1, WILLIAM S. MCGRAW2, BRITTANY R. BURROWS1, JAMES D. PAMPUSH1, DIÃACRO G. BERTIN3 and FERDINAND OURO3.

1Anthropology, University of Florida, 2Anthropology, The Ohio State University, 3Tai Monkey Project, Cote d'Ivoire

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Colobus polykomos from Taï Forest, Cȏte d’Ivoire seasonally specializes on Pentaclethera seeds, the access to which requires substantial ingestive effort to broach the surrounding woody pod. Pentaclethera pods are large, stiff (up to 700 MPa, comparable to pine woods), and moderately tough by primate food standards (~800 J/m2). The pods are highly anisotropic in stiffness but essentially isotropic in toughness.

Colobus polykomos is sympatric with the Upper Guinea red colobus (Procolobus badius), an eclectic frugivore-folivore, and the sooty mangabey (Cercocebus atys), a dedicated hard-object feeder. Data on food-specific ingestive behaviors were collected for all three taxa to determine how feeding strategies are influenced by the size, shape and mechanical properties of selected foods. We tested a prediction that both Cercocebus atys and Colobus polykomos would engage in greater incisal and masticatory work than P. badius by virtue of the former’s reliance on large, stress-limited foods.

Masticatory cycles per ingestive event are generally higher in the colobines than in Cercocebus, which is potentially explicable by both the use of cheek pouches in mangabeys and the more displacement-limited diet of the colobines. Incision frequency per ingestive event is similar overall across taxa, although relative to averages for other foods this frequency increases over ten-fold when Colobus processes Pentaclethera. Both feeding and morphological data suggest that Colobus has compromised masticatory efficiency for maintenance of sufficient gape, resulting in a gnathodental complex characterized by low canine dimorphism (i.e., females possess large canines), and which facilitates exploitation of large, tough foods such as Pentaclethera.

Supported by NSF BCS-0922429 and 0921770

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