Almost all of my work involves analyzing mathematical models to help understand the dynamics of ecological and evolutionary processes. I have worked on a range of problems in population, community, and evolutionary ecology. Over the last two decades, I have primarily worked on optimal foraging behaviour under predation risk, the coevolution of interacting species, the interaction of species in variable environments, the ecological effects of evolutionary change, adaptive movement in patchy environments, and the impacts of harvesting on population size. I began my academic life working on competition for shells between hermit crabs, and have worked on a diverse array of within-species problems ranging from the evolution of anisogamy to the evolution of senescence. My main project since retiring at the end of 2012 has been to develop a critical analysis of the structure and use of theory in ecology and evolution. Part of this involves developing new theory on the population-level consequences of evolutionary and environmental change. I have also been involved in a number of projects related to fisheries.