Figure 2.

Temperature and metabolic niches. (a) Variation in resting metabolic rate in teleost fish (Clarke & Johnston 1999). Note the wider range of values at higher temperatures. (b) Diagram showing how absolute aerobic scope also increases with temperature. This arises because resting metabolic rate increases positively with temperature and relative aerobic scope (the ratio of active to resting metabolism) is temperature invariant. Although the model was based on data for teleost fish, it also applies to other ectotherms (Clarke 2003). (c) Energetic niches in mammals (black) and birds (grey). Data are for field metabolic rate, and have been corrected for body mass assuming a mass exponent of 0.75 (redrawn from Anderson & Jetz 2005). Note the wider range of values at higher temperatures.