title: The Nutritional Geometry of Resource Scarcity: Effects of Lean Seasons and Habitat Disturbance on Nutrient Intakes and Balancing in Wild Sifakas.
abstract: Animals experience spatial and temporal variation in food and nutrient supply, which may cause deviations from optimal nutrient intakes in both absolute amounts (meeting nutrient requirements) and proportions (nutrient balancing). Recent research has used the geometric framework for nutrition to obtain an improved understanding of how animals respond to these nutritional constraints, among them free-ranging primates including spider monkeys and gorillas. We used this framework to examine macronutrient intakes and nutrient balancing in sifakas (Propithecus diadema) at Tsinjoarivo, Madagascar, in order to quantify how these vary across seasons and across habitats with varying degrees of anthropogenic disturbance. Groups in intact habitat experience lean season decreases in frugivory, amounts of food ingested, and nutrient intakes, yet preserve remarkably constant proportions of dietary macronutrients, with the proportional contribution of protein to the diet being highly consistent. Sifakas in disturbed habitat resemble intact forest groups in the relative contribution of dietary macronutrients, but experience less seasonality: all groups' diets converge in the lean season, but disturbed forest groups largely fail to experience abundant season improvements in food intake or nutritional outcomes. These results suggest that: (1) lemurs experience seasonality by maintaining nutrient balance at the expense of calories ingested, which contrasts with earlier studies of spider monkeys and gorillas, (2) abundant season foods should be the target of habitat management, even though mortality might be concentrated in the lean season, and (3) primates' within-group competitive landscapes, which contribute to variation in social organization, may vary in complex ways across habitats and seasons.
authors.affiliation: Department of Anthropology, Northern Illinois University, DeKalb, Illinois, United States of America; SADABE Madagascar, Antananarivo, Madagascar.
authors.forename: Mitchell T
authors.initials: MT
authors.lastname: Irwin
authors.affiliation: SADABE Madagascar, Antananarivo, Madagascar; Department of Animal Biology, University of Antananarivo, Antananarivo, Madagascar.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Raharison
authors.affiliation: Charles Perkins Centre, Faculty of Veterinary Science, The University of Sydney, Sydney, New South Wales, Australia; School of Biological Sciences, The University of Sydney, Sydney, New South Wales, Australia.
authors.forename: David R
authors.initials: DR
authors.lastname: Raubenheimer
authors.affiliation: Department of Anthropology, McGill University, Montreal, Quebec, Canada; McGill School of Environment, McGill University, Montreal, Quebec, Canada; Wildlife Conservation Society, Bronx, New York, United States of America.
authors.forename: Colin A
authors.initials: CA
authors.lastname: Chapman
authors.affiliation: Department of Anthropology, Hunter College, City University of New York, New York, New York, United States of America; New York Consortium in Evolutionary Primatology (NYCEP), New York, New York, United States of America.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Rothman
mesh_terms: D000818:Animals; D017753:Ecosystem; D002149:Energy Intake; D005260:Female; D005523:Food Supply; D006295:Health Resources / Q000600:supply & distribution*; D007900:Lemur / Q000254:growth & development / Q000378:metabolism*; D008270:Madagascar; D008297:Male; D008954:Models, Biological; D009753:Nutritive Value; D012621:Seasons; D011443:Strepsirhini / Q000254:growth & development / Q000378:metabolism*