Stenothermy

Stenothermy refers to the physiological condition of organisms that tolerate only a narrow range of ambient or body temperatures. The term is often contrasted with eurythermy, which describes a broad thermal tolerance. Stenotherms tend to have a restricted thermal niche and are frequently adapted to stable microclimates or environments with limited temperature variation.

The basis of stenothermy lies in physiological and biochemical constraints, including enzyme kinetics, membrane fluidity, and metabolic rate, which can limit performance across temperatures. Some stenotherms show limited plasticity in response to temperature changes, meaning they cannot readily acclimate to new temperature regimes. Evolutionary adaptations can narrow the thermal window that supports growth, reproduction, and survival.

Ecologically, stenothermy influences species distributions, community structure, and vulnerability to climate change. Species with narrow thermal tolerances may be highly sensitive to warming or cooling and often depend on stable habitats or microhabitats that buffer temperatures. Changes in mean temperature or temperature variability can shift their ranges or disrupt life-history events such as development and reproduction.

Measurement of stenothermy typically involves determining the limits of thermal tolerance, such as critical thermal minimum and maximum (CTmin and CTmax), or constructing thermal performance curves that map performance across temperatures (e.g., growth or fertility as a function of temperature).

Examples cited in the literature include certain polar and alpine taxa, and other organisms that persist in narrowly defined thermal environments. Stenothermy remains a key concept in physiology and ecology for understanding how temperature shapes life histories and responses to environmental change.