Thermoregulation in Vertebrates: Acclimation, Acclimatization and Adaptation


Environments vary enormously in the thermal challenge they impose on the organisms that live in them. Some of these changes occur over very small temporal and spatial scales, and animals respond to these changes by acute modulations of their behaviour and physiology. More chronic changes in thermal environments, such as seasonal changes and latitudinal changes across the globe, require different responses. Three types of response have been recognized in both exothermic and endothermic vertebrates. These are termed acclimation, acclimatization and adaptive responses.

Keywords: body temperature; endothermy; exothermy; acclimation; acclimatization; adaptation

Figure 1.

Schematic diagrams illustrating (a) the lack of a compensatory response to thermal acclimation in an exothermic animal, (b) a translational compensation and (c) a rotational compensation.

Figure 2.

Actual examples of (a) a translational response to thermal acclimation in an exotherm (short‐circuit current across frog epithelium) and (b) a rotational change (oxygen consumption rates of liver slices from striped bass acclimated to cold and warm temperatures). Redrawn from Stone BB and Siddell BD (1981) Journal of Experimental Zoology218: 371–379.

Figure 3.

Activity as a function of temperature of two isozymes of acetylcholinesterase from trout brains. The two forms of the enzyme have different sensitivities to temperature (minima in the Michaelis constant Km), with one form showing peak activity at 20°C and the other peak activity at 2°C. When fish were acclimated at high temperature they produced only the isoform active at high temperature; when acclimated at low temperature they produced only the isoform active at low temperature. At intermediate temperatures they produced a mix of both forms, allowing them to overcome the disruptive effects of temperature on substrate binding. Redrawn from original study by Baldwin J and Hochachka PW (1970) Journal of Biochemistry116: 883–887.

Figure 4.

Insulative value of the fur as a function of fur thickness for four species of arctic mammals in both summer and winter. Summer values are shaded in lilac and winter values are shaded in pink. In all cases there was an increase in fur thickness between summer and winter, but the smaller animals had thinner coats and the extent of increase between summer and winter was also lower in the smaller species. Redrawn from original study by Hart JS (1956) Canadian Journal of Zoology34: 53–57.

Figure 5.

Metabolic rates (oxygen consumption) of natracine snakes from the United Kingdom (45°N) and Spain (30°N), raised in a common environment, as a function of ambient temperature. Redrawn from original study by Davies PMC and Bennett EL (1981) Journal of Comparative Physiology142: 489–494.


Further Reading

Cossins A and Bowler K (1980) Temperature and Life. London: Chapman and Hall.

Davenport C (1996) Low Temperature Adaptations of Animals. Cambridge, UK: Cambridge University Press.

Schmidt Nielsen K (1998) Environmental Physiology of Animals: Adaptation and Environment. Cambridge, UK: Cambridge University Press.

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Speakman, John R(Apr 2001) Thermoregulation in Vertebrates: Acclimation, Acclimatization and Adaptation. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0001825]