Thermoregulation in endotherms: physiological principles and ecological consequences

Area of Science:

• Physiological Ecology
• Thermoregulation Biology
• Climate Change Ecology

Background:

• Newton's law of cooling has long described metabolic rate (MR) variation with ambient temperature (T a) in endotherms.
• Existing models often use a U-shaped curve, primarily for resting metabolic rates.

Purpose of the Study:

• To explore theoretical consequences of Newton's law of cooling for thermoregulation.
• To introduce the thermoregulatory polygon as a framework for endotherm responses.
• To expand the understanding of thermoregulation beyond resting states.

Main Methods:

• Theoretical exploration of Newton's law of cooling.
• Development of the thermoregulatory polygon concept.
• Application of the framework to ecological and evolutionary questions.

Main Results:

• The thermoregulatory polygon defines the equilibrium between heat production and dissipation, indicating thermoregulatory possibility.
• This polygon integrates activity, behavior, and environmental factors impacting energy balance.
• The framework aids in studying limits to thermoregulation, allometry, and thermal insulation.

Conclusions:

• Thermoregulatory polygons offer a powerful, predictive tool for understanding ecological impacts of thermoregulation.
• This approach can elucidate constraints on fitness traits (survival, reproduction) and species responses to climate change.
• Formal mechanistic models are crucial for advancing physiological ecology and predicting climate change effects.