1. School of Resource Management, Burnley Campus, The University of Melbourne, 500 Yarra Boulevard, Richmond, VIC 3121, Australia
2. Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada;
3. Australian Centre for Precision Agriculture, McMillan Building A05, The University of Sydney, NSW 2006, Australia;
4. Biology Department, University of York, P.O. Box 373, York YO10 5YW, UK;
5. Department of Primary Industries, Victorian Institute of Dryland Agriculture, P.O. Box 260, VIC 3401, Australia;