1. The Holden Arboretum Kirtland Ohio 44094 USA
2. Department of Plant Sciences University of California Davis California 95616 USA
3. Department of Ecology and Evolution University of California Santa Cruz California 95064 USA
4. Biological Science Department Clemson University Clemson South Carolina 29634 USA
5. Boyd Deep Canyon Desert Research Center Indian Wells California 92210 USA
6. Department of Biology University of Nevada Reno Nevada 89557 USA
7. Department of Environmental Science and Policy University of California Davis California 95616 USA
8. Department of Evolution and Ecology University of California Davis California 95616 USA