It has long been recognized that plants and animals profoundly affect one another's characteristics during the course of evolution. However, the importance of coevolution as a dynamic process involving such diverse factors as chemical communication, population structure and dynamics, energetics, and the evolution, structure, and functioning of ecosystems has been widely recognized for a comparatively short time. Coevolution represents a point of view about the structure of nature that only began to be fully explored in the late twentieth century. The papers presented here herald its...