1. Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996, USA.
2. IUCN Invasive Species Specialist Group, and Italian National Institute for Environmental Protection and Research, Rome, Italy.
3. Institute of Botany, Academy of Sciences of the Czech Republic, Průhonice, and Department of Ecology, Charles University, Prague, Czech Republic.
4. Island Conservation, 100 Shaffer Road, Santa Cruz, CA 95060, USA.