Introduction to the symposium: environment, energetics, and fitness: a symposium honoring Donald W. Thomas.

*Department of Animal Physiology, Institute of General and Molecular Biology, Nicolaus Copernicus University, ul. Gagarina 9, PL 87-100 Toruń, Poland; Department of Natural Resource Sciences, McGill University, Macdonald Campus, Ste-Anne-de-Bellevue, Qc, H9X 3V9, Canada; Department of Biology, University of California, Riverside, CA 92521, USA; and Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, 84990 Midreshet Ben-Gurion, Israel