The metabolic theory of ecology (MTE) is an intriguing but controversial theory that attempts to explain ecological patterns at all scales on the basis of biochemical principles. The MTE considers the basal metabolic rate of organisms to be determined by biomass and temperature. The considered universal temperature dependence (UTD) of the basal metabolic rate for organisms is given by an Arrhenius-type relation.

Those assumptions imply that the Arrhenius relation can be scaled up from single enzyme reaction to whole metabolic network reactions, excluding that evolving in different temperatures might cause changes in the enzymatic reactions involved in the basal metabolic rate of organisms. Variations in the metabolic enzymes across organisms as well as within acclimation and adaptation can result in differences in the slope and intercept of the respiratory temperature response given by the Arrhenius relation.

The differences in the respiratory temperature response within acclimation and adaptation are shown by a metadata analysis and own data including several ectotherm organisms.

Results/Conclusions  

The results show that the MTE focuses on immediate temperature effects mediated by biochemical reactions. This immediate response to temperature is explained by the Arrhenius relation with respect to differences in the temperature dependencies of various biochemical reactions. Acclimation and adaptation of organisms take place at a longer timescale. Changes in the metabolic reactions within acclimation and adaptation result in a basal metabolic rate, which is relatively independent of the prevailing temperature.

Within acclimation and adaptation changes in the metabolic reaction occur. Therefore the thermodynamic principles of enzymes given by the Arrhenius relation do not hold within acclimation and adaptation. The relative temperature independence of the metabolic rate within acclimation and adaptation results from changes in the intercept of the respiratory temperature dependences caused by changes in the metabolic reactions.