Fig. 1. Natural and laboratory temperatures experienced by adult Austrofundulus limnaeus. (A) Temperature record for 5 consecutive days in a typical ephemeral pond inhabited by A. limnaeus (Podrabsky et al., 1998). (B) Adult male fish were exposed to four different thermal acclimations. For the cycling temperature (20–37°C) treatment (black line) fish were collected (open circles) every 4 h for the first three daily cycles and then again every 4 h on day 5 and day 14. Control fish (gray line) kept at 26°C were collected (open squares) every 4 h on day 1 and day 14. Fish exposed to constant 20°C (blue line) were collected (open blue diamonds) at 24, 48, 72, 96, 168 and 336 h. Fish exposed to constant 37°C (pink line) were collected (open pink squares) as the 20°C fish, except for the 336 h time point. Time 0 for the temperature cycling is 12:30 h at a temperature of 26°C. Note the broken axis in B. While five temperature cycles were sampled during the 2-week acclimation, the temperature was continually cycling.