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

Digestive Strategies: Scaling of Feeding Time and Gut Retention


1Committee on Evolutionary Biology, University of Chicago, 2Department of Anthropology, Field Museum of Natural History, 3Anthropological Institute and Museum, University of Zurich

Friday 1:30-1:45, Ballroom C Add to calendar

Feeding mechanisms and behaviors must evolve in consort with digestive physiology for efficient energy harvesting. A dichotomy in digestive strategies has been suggested: the “efficiency” strategy characterized by low relative dry matter intake (rDMI) with long mean retention time (MRT) and the “high intake” strategy of high rDMI with short MRT. Here, we evaluated this model by analyzing relationships among feeding time, body mass and mean retention time in primates. Values for feeding time, MRT and body mass for 20 primate species were taken from the literature. We ran comparative analyses using both raw data and phylogenetic generalized least squares (PGLS). Using PGLS, feeding time is significantly correlated with body mass, but MRT is not. There is a statistically significant negative relationship between feeding time and MRT when body mass is controlled for (p=0.049). When the relationships between feeding time and both MRT and body mass are examined, including an interaction between MRT and body mass, the overall model is significant (p=0.032). This interaction effect indicates that the relationship between feeding time and MRT is negative in small-bodied primates but positive in large-bodied primates. At a body mass of ca. 2.6 kg., there is no change in feeding time with MRT. These results suggest that the efficiency strategy works well for primates of small body mass, but primates with large body masses must change their digestive strategy to one characterized by long feeding times and long MRTs.

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