Fig. 6. Diagram showing how the time-lagged logistic growth curve can be analogous to the temporal course of _O2max during acclimation in a negative feedback control system (in this hypothetical case, the animal went from a warm to a cold temperature, as in the present study; see Fig. 1). N_t, population size at time t; r, maximum rate of growth and/or of acclimation; , length of the delay between stimulus and response. _O2max `warm' and <sub>O2max</sub> `cold' (dotted lines) represent the values of _O2max at `equilibrium' - i.e. when the animal is actually acclimated to warm and cold conditions. These values are analogous to the initial population size at t=0 (N₀) and the carrying capacity of the habitat (K), respectively.