1. Centre of Excellence for Biosecurity Risk Analysis School of Botany University of Melbourne Parkville 3010 Australia
2. Biology Department University of California Riverside CA 92521 U.S.A.
3. Nicholas School of the Environment Duke University Durham NC 27708‐0328 U.S.A.
4. Department of Philosophy Sydney Centre for the Foundations of Science A14 Main Quadrangle University of Sydney Sydney NSW 2006 Australia
5. Department of Philosophy 151 Dodd Hall, Florida State University Tallahassee FL 32306‐1500 U.S.A.
6. CSIRO Ecosystem Sciences 41 Boggo Road, Dutton Park QLD 4102 Australia
7. Simon Fraser University School of Resource and Environmental Management 8888 University Drive Burnaby B.C. V5A 1S6 Canada