1. U.S. Geological Survey Fort Collins Science Center Fort Collins Colorado USA
2. Nature Serve, Western Regional Office Boulder Colorado USA
3. Instituto de Biología, 3er Circuito de CU s/n, Universidad Nacional Autónoma de México, Copilco Coyoacán Universidad Nacional Autónoma de México Mexico City Mexico
4. Center for Population Biology and Department of Evolution and Ecology University of California Davis California USA