Acclimation to constant and variable temperatures in plethodontid salamanders—I. Rates of oxygen consumption

1. 1. In preliminary experiments, salamanders of three species ( Desmognathus ochrophaeus, Plethodon cinereus and Plethodon jordani ) required 5–11 days to complete metabolic acclimation to a constant warm temperature; the rate of oxygen consumption ( V O 2 ) decreased 16–28% during acclimation. 2. 2. Unfed animals of each species underwent cyclic exposure to 5 and 21°C at three different cycle periods (12 hr, 4–5 days, 51 days), or constant exposure to 14°C for 102 days. 3. 3. The experimental treatments significantly affected the ( V O 2 ) measured at 5, 14, 17.5 and 21°C. 4. 4. The direction and magnitude of the acclimatory effects upon ( V O 2 ) were inconsistent among species and among experimental temperatures, and resulted in little energy saving. 5. 5. The ( V O 2 ) during exposure to cyclic temperatures averaged only 83% of that during preliminary experiments, perhaps as a response to starvation.