Dr Owen Lewis, Department of Zoology, University of Oxford

Food webs are networks of feeding interactions among species within ecological communities. Focusing on high-diversity tropical forest ecosystems I will describe empirical studies of bipartite food webs (involving plants, insect herbivores and their parasitoids) that are fully quantified in terms of the abundance of interacting species and the frequency of each interaction. I will present evidence that these ‘quantitative food webs' can inform us about (1) the dynamic processes organising biological diversity; (2) the consequences of species extinction or invasion; and (3) the effects of humans on ecosystem organisation, integrity and functioning.