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Session Schedule & Abstracts

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Thursday 30th June, 2016

Symposium: Determinants of the mammalian feeding system design 4

Room: Salon B   4:30 pm–5:30 pm

Moderator(s): O. Panagiotopoulou & J. Iriarte-Diaz
MFS4-1  4:30 pm  Modulation of feeding energetic costs in primates: the impact of morphology and behavior across body size. Wall CE*, Department of Evolutionary Anthropology, Duke University; Hanna J, Department of Biomedical Sciences, West Virginia School of Osteopathic Medicine; O'Neill MC, Department of Basic Medical Sciences, University of Arizona College of Medicine; Toler M, Center for Functional Anatomy and Evolution, Johns Hopkins University
Abstract: Our work to measure the energetic costs of feeding in primates seeks to evaluate the impact of morphology and behavior on feeding costs. Metabolic rate during feeding and chewing was measured by indirect calorimetry in 12 nonhuman primate species (70g–4.5kg) and humans (55–100kg) eating a variety of raw foods varying in size, toughness, stiffness, and energy content. Resting and postprandial metabolic rates were also measured. Food items requiring large amounts of pre-chewing processing (e.g., Hapalemur feeding on whole bamboo and Daubentonia gnawing wood) incur the largest feeding costs, and these are possibly due to the recruitment of trunk and limb muscles. Analysis of pre-cut pieces of food shows that, within species, net feeding costs per unit of food mass (W/g) are positively correlated with food size, toughness, and stiffness as predicted since jaw-adductors increase recruitment during large, tough, and stiff food chew cycles. A slope of 1.0 is expected if net feeding energetic costs (W) scale in proportion to jaw-adductor muscle mass across species, as predicted when recruitment is a major source of cost during chewing. However, we observe negative scaling of W relative to both body mass (slope=0.65, CI=0.05) and jaw-adductor mass (CIs of estimated slopes between 0.60 and 0.80). This negative relationship may be explained by aspects of morphology and behavior. For example, we find a strong association between high molar shear and low W during insect-feeding demonstrating empirically that tooth design increases the efficiency of food breakdown. Overall, the data provide evidence of significant correlations between energetic costs and food properties, tooth design, and behavior. We suggest that structural (e.g., muscle architecture and occlusal morphology), kinematic (e.g., chewing rate), and behavioral (e.g., food preparation) traits interact to modulate feeding costs. Supported by NSF BCS-1062239.

MFS4-2  5:00 pm  Symposium discussion. Ross CF*, University of Chicago

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