Temperature Adaptation and Acclimatization

How animals adjust their physiology and biochemistry to cope with the temperature of their environment, over a season, a lifetime, or evolutionary time.

Definition

Temperature adaptation is the evolutionary adjustment of an animal's physiology and biochemistry to its thermal environment, while acclimatisation is the reversible physiological adjustment an individual makes in response to seasonal or experimental changes in temperature, both serving to maintain function across thermal challenges.

Scope

This topic covers the ways animals adjust to temperature: the effect of temperature on biological rates, metabolic compensation that buffers performance across temperatures, biochemical adaptation of enzymes and membranes, and the strategies of cold and heat tolerance including antifreeze and freeze tolerance. It distinguishes reversible acclimatisation within an individual from evolutionary adaptation across populations. Coverage is comparative and mechanistic.

Core questions

• How does temperature affect the rates of biological processes?
• How do animals keep performing across a range of temperatures?
• How are enzymes and membranes adjusted to function at different temperatures?
• How do animals survive freezing or near-freezing conditions?

Key theories

Metabolic temperature compensation

Through acclimatisation and adaptation, animals can blunt the strong dependence of biological rates on temperature, so that an individual's or species' performance at its usual temperature is more uniform than the raw temperature sensitivity of reactions would predict.

Biochemical adaptation of proteins and membranes

Animals adjust enzyme variants, protein concentrations, and membrane lipid composition (homeoviscous adaptation) so that catalytic function and membrane fluidity remain appropriate at the prevailing temperature.

Mechanisms

Because chemical reaction rates rise with temperature, an ectotherm's processes speed up when it warms and slow when it cools, summarised by the temperature coefficient. To offset this, animals adjust over time: acclimatisation alters enzyme amounts and metabolic pathways so that a cold-acclimatised animal performs better in the cold than a warm-acclimatised one at the same temperature. At the molecular level, organisms express enzyme variants suited to their temperature and modify the lipid composition of membranes to keep fluidity constant (homeoviscous adaptation). Cold-adapted animals may accumulate antifreeze proteins or solutes that prevent or control ice formation, and some tolerate freezing of their extracellular fluids. Heat-tolerant animals rely on protective proteins and stable molecular structures. These adjustments span reversible within-life acclimatisation and longer-term evolutionary adaptation.

Clinical relevance

Studies of thermal adaptation clarify how cellular and molecular function is maintained across temperatures and underlie applications such as cold preservation of cells and tissues. This entry is educational reference material and does not provide medical guidance.

History

Hochachka and Somero's work on biochemical adaptation established how enzymes and membranes are tuned to temperature, and DeVries's discovery of antifreeze glycoproteins in polar fish revealed a striking molecular solution to life in freezing seas, framing temperature adaptation as a problem solved at the molecular level.

Key figures

• Peter Hochachka
• George Somero
• Knut Schmidt-Nielsen
• Arthur DeVries

Seminal works

• hill2016
• schmidtnielsen1997
• randall2002

Frequently asked questions

What is the difference between adaptation and acclimatization?

Adaptation refers to inherited adjustments shaped by evolution across generations, whereas acclimatization is a reversible adjustment an individual makes within its own lifetime, such as in response to the change of seasons.

How do some fish avoid freezing in polar seas?

They produce antifreeze proteins that bind to tiny ice crystals and stop them growing, allowing the fish to remain unfrozen in water that is colder than its blood would otherwise freeze.