1. School of Biological sciences, University of Bristol, Bristol BS8 1TQ, UK
2. CIRAD, UMR INTERTRYP, F-34398 Montpellier, France
3. INTERTRYP, Univ Montpellier, CIRAD, IRD, 34000 Montpellier, France
4. Centre for Research in Animal Behaviour, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QG, UK
5. Department of Zoology, Mathematical Ecology Research Group, University of Oxford, Oxford OX1 3PS, UK
6. St Peters College, Oxford OX1 2DL, UK