My reseach is focused on the ecology of populations and communities with a focus on invasive weeds and pests. In particular, how do species originating from elsewhere arrive, establish and spread at new locations. The answers to these questions are critical to managing the problems posed by introduced weeds and pests. In addition, species introductions provide unique opportunities to test fundamental questions about the way ecological communities are sturctured. We use a varitey of approaches to answer these questions ranging from glasshouse experiments to large-scale field studies, all underpinned by theory and strong quantitative methods.