Temporal variation in thermal plasticity in a free-ranging subalpine lizard

Area of Science:

• Ecology
• Physiology
• Herpetology

Background:

• Ectotherms rely on external sources for thermoregulation, making them vulnerable to environmental temperature fluctuations.
• Seasonal environments pose challenges for ectotherms, necessitating thermal plasticity for survival and function.
• Most research on thermal plasticity is lab-based, with limited data from free-ranging animals in natural settings.

Purpose of the Study:

• To investigate temporal thermal plasticity in adult male White's skinks (Liopholis whitii) during their activity season in a natural, high-elevation environment.
• To assess how thermal tolerances and performance change across a single activity season in a wild population.
• To compare field-based findings with existing laboratory-derived knowledge on ectotherm thermal plasticity.

Main Methods:

• Monitoring of ambient thermal variation across the study site and throughout the activity season.
• Repeated capture and physiological testing of marked individuals (White's skinks) at three intervals during the season.
• Measurement of critical thermal minimum, critical thermal maximum, thermal tolerance breadth, and thermal performance.

Main Results:

• Evidence of temporal plasticity was found in the critical thermal minimum and thermal tolerance breadth.
• No significant temporal changes were observed in the critical thermal maximum.
• Thermal performance was also plastic, though no specific temporal trends were identified.

Conclusions:

• White's skinks exhibit temporal thermal plasticity in their natural habitat, particularly in their critical thermal minimum and tolerance breadth.
• This study provides rare, field-based evidence of seasonal thermal adaptation in a free-ranging ectotherm population.
• Findings underscore the necessity of integrating field research with laboratory experiments to fully comprehend ectotherm thermal plasticity in ecologically relevant contexts.