1. Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa.
2. U.S. Geological Survey, Fort Collins Science Center, Fort Collins, CO 80526, USA.
3. Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996, USA.
4. Center for Ecology and Conservation Biology, Department of Biology, Boston University, Boston, MA 02215, USA.