It is now clear that most animals carry a dense and diverse community of symbiotic microbes – their microbiome - which appear to critically affect many aspects of host biology, from nutrition, through immunology, to behaviour. Work in the Knowles lab seeks to understand the ecological and evolutionary significance of these symbiotic communities, using wild animal model systems. We ask how the microbiome is formed, what drives community dynamics, and how these within-host communities affect host physiology, fitness and adaptation. The details of a DPhil project would be decided in discussion with the student, but would be likely to include a component of fieldwork to collect microbiome samples from a wild animal system, and laboratory work/bioinformatics to analyse them with respect to the research questions at hand. Potential field systems include our current long-term studies of wild mice in Wytham Woods and the island of Skokholm in Wales, or other vertebrate systems depending on the research project.