1. Endocrine Research Laboratory Department of Anatomy and Physiology University of Pretoria Onderstepoort South Africa
2. Department of Zoology and Entomology University of Pretoria Pretoria South Africa
3. National Zoological Gardens of South Africa Pretoria South Africa
4. Department of Animal Ecology and Conservation Biocentre Grindel University of Hamburg Hamburg Germany
5. Department of Integrative Biology and Evolution University of Veterinary Medicine Vienna Austria