Doctoral Dissertation Improvement: Response of the Gastrointestinal Bacterial Community to a Seasonally Changing Diet in Two Wild Sympatric Primate Species

University Of Southern California, Los Angeles CA

Investigators

Abstract

Gastrointestinal bacteria play a pivotal role during digestion. Without these bacteria, an animal is unable to extract sufficient nutrients from its food. In highly variable environments, it is crucial that the gut bacteria responsible for breaking down food can react to rapidly changing diets and maintain their digestive role. The PIs in this project first examine these bacteria in a wild population of primates in Madagascar to understand their composition across seasonal environments. These results will be compared with those from captive primates to first, illuminate the impact a captive diet has on gastrointestinal bacteria, and second, aid in the creation of a more appropriate diet for captive animals, based on the metabolic capabilities of their gastrointestinal bacteria. Results can also translate to executable conservation action by informing the identification of suitable habitat reserves, based on the digestibility of the plants within, considering endangered animals and shrinking forests. Expanding lemur reserves to contain plants with a compatible chemical profile to these animals' bacterial capabilities will aid the survival and success of these flagship species. The effect of variable diets on gut bacteria has only begun to be measured, and real-world studies on wild populations are lacking. This research focuses on wild sympatric populations of a generalist herbivore, the ring-tailed lemur (Lemur catta), and a specialist herbivore, Verreaux's sifaka (Propithecus verreauxi), in the seasonal forest of Beza Mahafaly Special Reserve, Madagascar. The composition of the diet of these lemurs is measured in conjunction with behavioral observations of feeding and chemical analysis for cellulose and phenolic content of the foods consumed. Gut bacteria in freshly collected lemur feces are measured using fluorescent in situ hybridization (FISH). All measurements occur across both the wet and dry seasons to track the changes in gut bacteria and ingested cellulose and phenolics as the foods available in the forest change seasonally. Results from the wild lemurs will be compared with those from captive lemurs.