The gut microbiome of the western lowland gorilla (Gorilla gorilla gorilla): implications for overall ecology

Our closest evolutionary relatives, non-human primates, display a breadth of behavioral, anatomical and physiological adaptations, which allow them to exploit a myriad of habitats. Detailed representation of these adaptive tools has constituted the basis of our knowledge of primate ecology and evolution. Nonetheless, gut bacteria, which play central roles in the physiological adaptability of mammals, have been usually overlooked in primate studies. Here, I use a combination of high throughput molecular approaches to study the compositional and functional landscape of gut bacterial communities in western lowland gorillas (Gorilla gorilla gorilla). This primate species exhibits a set of unique ecological features that make it ideal to test hypotheses of how primates respond to change and the extent to which gut bacteria have impacted primate fitness, ecological plasticity, and evolution. In chapter 1, I review the main dynamics that define the ecological organization of western lowland gorillas, with an emphasis on diet as a major driver behind these factors. Conversely, I highlight why the characterization of gut microbial communities is key to further expand our current knowledge of gorilla ecology. In chapter 2, I present a view on how gut bacterial community composition in lowland gorillas can be understood through their macro-ecological interactions; including their relationships with humans. I further highlight the role of diet on governing gorilla ecology and gut bacterial communities by showing that gut metabolomic profiles mirror foraging behaviors. Chapter 3 follows a longitudinal approach to show that gut bacteria composition and function shift as gorillas face foraging challenges associated to energy harvest across seasons. As such, I propose that, along with behavioral and physiological adaptations, gut bacteria contribute significantly to gorilla foraging plasticity. In chapter 4, a compositional and functional comparison with gut bacterial communities in mountain gorillas (Gorilla beringei beringei) is used as model to reconcile the evolutionary aspects of primate diversity and cosmopolitanism, through the contributions of gut bacterial communities. As such, we argue that species-specific microbiome arrangements largely reflect dietary signals and particular niche adaptations in the course of primate evolution Finally, chapter 5 summarizes the main bullet points that highlight the importance of gut bacteria in gorilla ecology. It provides prospectus of relevant primate ecology issues that can be addressed through the molecular characterization gut bacterial communities as far as nutritional ecology, physiological status and intra and interspecific interactions