Evolutionary trade-offs between heat and cold tolerance limit responses to fluctuating climates

Area of Science:

• Evolutionary biology
• Climate change adaptation
• Reproductive physiology

Background:

• Predicting species' responses to climate change requires understanding their evolutionary potential to handle temperature fluctuations during reproduction.
• Existing vertebrate research primarily examines reproduction under extreme temperatures in stable, temperate environments.

Purpose of the Study:

• To investigate the genetic basis of reproductive thermal tolerance to temperature fluctuations in ostriches.
• To assess the potential for evolutionary adaptation to changing temperatures in a species from a variable climate.

Main Methods:

• Studied ostriches from variable tropical and subtropical African environments.
• Analyzed genetic factors influencing heat and cold tolerance during reproduction.
• Examined selection and heritability of thermal tolerance traits.

Main Results:

• Both heat and cold tolerance were found to be under selection and heritable in ostriches.
• Evidence suggests a negative genetic correlation between heat and cold tolerance.
• This genetic constraint may limit the species' adaptive potential to fluctuating temperatures.

Conclusions:

• Heritable thermal tolerance in ostriches indicates potential for evolutionary adaptation to mean temperature shifts.
• Genetic constraints between heat and cold tolerance are a critical, overlooked factor in climate change responses.
• Understanding these constraints is vital for predicting species' survival in changing environments.