1. Department of Biological Sciences California State University at Los Angeles Los Angeles CA90032 USA
2. Control and Dynamical Systems California Institute of Technology Pasadena CA91125 USA
3. Department of Ecology and Evolutionary Biology University of Kansas Lawrence KS66045 USA
4. Kansas Biological Survey University of Kansas Lawrence KS66047 USA
5. Department of Ecology and Evolutionary Biology University of Arizona Tucson AZ85721 USA
6. Laboratory of Populations Rockefeller University New York NY10065 USA
7. Earth Institute and Department of Statistics Columbia University New York NY10027 USA
8. Department of Statistics University of Chicago Chicago IL60637 USA