1. School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford OX3 OBP, UK
2. Department of Biology, Eton College, Windsor, Berkshire SL4 6EW, UK
3. Department of Zoology, University of Nairobi, P. O. 30197, Nairobi, Kenya
4. Department of Zoology, Makerere University, P. O. Box 7062, Kampala, Uganda