Adaptations and maladaptations due to evolution at constant, but not at fluctuating temperatures

Area of Science:

• Evolutionary biology
• Environmental adaptation
• Yeast genetics

Background:

• Climate change causes more frequent extreme temperatures and faster fluctuations.
• Theoretical models predict different adaptations in constant vs. fluctuating environments.
• Population size may influence fitness trade-offs in fluctuating environments.

Purpose of the Study:

• Evaluate adaptation to fluctuating temperatures.
• Investigate the effect of population size on adaptation and trade-offs.
• Determine if temperature fluctuations or constant extremes pose stronger selective pressures.

Main Methods:

• Evolution experiment using fission yeast (Schizosaccharomyces pombe).
• Evolved small and large populations for 500 generations under constant and fluctuating temperatures.
• Competed evolved strains against ancestral strains in various environments to assess adaptation and trade-offs.

Main Results:

• Significant adaptation and maladaptation observed only under constant heat, not fluctuating temperatures.
• Population size did not significantly impact adaptation capacity or trade-offs.
• Fitness trade-offs did not constrain adaptation to fluctuating temperatures.

Conclusions:

• Constant extreme temperatures are stronger selective pressures than temperature variations.
• Adaptation to fluctuating temperatures may require longer evolutionary timescales.
• Fitness trade-offs are unlikely to limit adaptation in fluctuating thermal environments.