1Anthropology, Northern Illinois University, 2Anthropobiology and Sustainable Development, University of Antananarivo, 3Research, ONG Sadabe, 4Anthropology, Hunter College, 5Graduate Center, CUNY
April 18, 2020 3:15PM, Diamond 3
Primates are traditionally categorized into broad dietary guilds (frugivores, folivores, insectivores) but these are “fuzzy” boxes and primatologists have rarely explored actual nutritional divergence among species, which nutrients drive foraging choices, and how this varies across guilds and clades.
We analyzed food chemistry for folivorous sifakas (Propithecus diadema, n=61 foods) and frugivorous brown lemurs (Eulemur fulvus, 69 foods) at Tsinjoarivo, Madagascar (overlapping home ranges). Considering fruit (81% of brown lemur diet, 37% for sifakas), the two lemurs rarely ate the same foods, yet there was no evidence of nutritional divergence (no significant differences in available protein, fiber, sugar, or nonstructural carbohydrates). For leaves (14% of brown lemur diet, 54% for sifakas), dietary overlap was again minimal. Brown lemur leaves were higher in available protein and sifaka leaves were higher in nonstructural carbohydrates; brown lemur leaves were also higher in simple sugars than leaves selected by neither species. Brown lemurs thus appear to select leaves for protein (their leaves average 10.0% vs just 3.9% in their fruits) and simple sugars (well-suited to fast gut passage and cathemerality), while sifakas select for nonstructural carbohydrates (an energy source well-suited to slow gut passage) but not protein (leaves average 7.1%, similar to non-selected leaves).
Further research is necessary to examine how selection rules vary seasonally, the interaction between nutrient absorption and gut retention times, and the effects of PSMs. These advances will elucidate the physiological constraints that cause divergence in food selection, which will aid in better understanding feeding competition and guiding conservation efforts.
Funded by National Geographic Society, Eppley Foundation for Research, and Northern Illinois University.