Community Ecology 

Natural communities provide essential services for human well-being, for example soil formation, food provisioning, climate regulation, or recreational grounds. How these communities are organized and how they function are the leading questions of our research. Natural communities are composed of a myriad of species interacting in many different ways. The way they are organized can be visualized as networks where nodes are species and links are interactions. We studied mostly trophic interactions (who eats whom), whose networks (food webs) represent the roadmaps of energy flows in ecological systems. We analyzed the architectures of these networks and built models to understand and predict their structure. More recently, we moved to the functioning of ecological systems, which requires following the dynamics of the species in communities. This is a difficult question and we chose simple microcosms to tackle this problem. We work with natural microbial systems inhabiting the rainwater-filled leaves of the carnivorous plant Sarracenia purpurea. They are composed mostly of bacteria decomposing the insects attracted by the plant, and of protozoans consuming these bacteria. These communities are sampled in the field and studied in the lab where they are maintained in incubators. We manipulate the composition of these communities to study basic questions about their dynamics, for example the effect of competition between protozoans on the coexistence of species in the communities, or the effect of different temperature regimes on total biomass productivity. This research is grounded in theoretical models that are developed in our group, in collaboration with Dr. Rudolf Rohr. Apart from this line of research, we also work in the field on applied and conservation questions, for example the effect of beaver dams on aquatic communities, or, in collaboration with Dr. Gwenaël Jacob, on the genetic population structure of the endangered Capercaillie.