Mean (± SE) routine metabolic rate (RMR) at three acclimation temperatures in four groups of killifish.

Each group comprised a species pair from either low altitude (A. splendopleure and A. ahli) or from high altitude (A. cameronense and A. exiguum), with two generations per species, an F0 generation captured in the wild and an F1 generation bred in captivity. Metabolic rate is expressed as rates of oxygen uptake (µg h−1), corrected to a body mass of 350 mg, n = between 11 and 13. A 2-way ANOVA on log-10 transformed values found an effect of group (df = 3, F = 3.512, P = 0.017), temperature (df = 2, F = 37.637, P†, significantly different from 25°C; §, significantly different from 28°C, PText S7 for details).