1. School of Computer Science and Mathematics, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK
2. Department of Biosciences, Durham University, Durham DH1 3LE, UK
3. School of Mathematics and Statistics, University of St Andrews, St Andrews KY16 9SS, UK
4. Conservation and Research, Chester Zoo, Cheshire CH2 1LH, UK
5. Department of Biology, Faculty of Science, Utrecht University, 3584 Utrecht, The Netherlands