Thermodynamic effects on the evolution of performance curves

Area of Science:

• Physiological and ecological science
• Evolutionary biology
• Thermodynamics in biology

Background:

• Traditional models of thermal adaptation posit equal fitness for warm- and cold-adapted organisms.
• Recent studies indicate warm-adapted organisms may outperform cold-adapted ones, challenging existing models.
• This performance disparity suggests a thermodynamic effect influencing selective pressures.

Purpose of the Study:

• To investigate how the thermodynamic effect on organismal performance impacts selective pressures on thermal physiology.
• To determine how natural selection shapes thermal optima in response to differing organismal performance.
• To explore the relationship between temperature variation and the optimal thermal mismatch.

Main Methods:

• Theoretical modeling of thermal adaptation and natural selection.
• Analysis of how performance differences between warm- and cold-adapted organisms influence fitness.
• Examination of the role of temperature variation on selective pressures.

Main Results:

• In the absence of a thermodynamic effect, selection favors a thermal optimum matching mean body temperature.
• When warm-adapted organisms outperform cold-adapted ones, selection can favor a thermal optimum exceeding mean body temperature.
• The optimal mismatch between thermal optimum and mean temperature increases with greater within-generation body temperature variation.

Conclusions:

• Thermodynamic effects on performance can shift selective pressures, favoring thermal optima that exceed ambient temperatures.
• The degree of mismatch is influenced by the variation in body temperature within generations.
• These findings may explain observed discrepancies between thermoregulatory behavior and thermal physiology in some species.