1. Department of Zoology, North Carolina State University, Raleigh, NC 27695–7617, USA.
2. Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50010, USA.
3. Department of Biology, Box 351800, University of Washington, Seattle, WA 98195–1800, USA.
4. Department of Zoology, Post Office Box 118525, University of Florida, Gainesville, FL 32611–8525, USA.