Daniel Simberloff is Nancy Gore Hunger Professor of Environmental Studies in the Department of Ecology and Evolutionary Biology at the University of Tennessee, Knoxville. His previous books include "Ecological Communities: Conceptual Issues and the Evidence" and "Strangers in Paradise: Impact and Management of Nonindigenous Species in Florida."Marcel Rejmanek is Professor in the Department of Evolution and Ecology at the University of California, Davis. Among other books and publications he coedited "Plant Invasions: General Aspects and Special Problems "and "Biological Invasions: A Global Per...