Intraspecific support for the climate variability hypothesis: oxidative damage in lizards after acute temperature...

Area of Science:

• Ecology
• Physiology
• Climate Change Biology

Background:

• Climate variability poses challenges for ectotherms, influencing their physiological resilience.
• The climate variability hypothesis suggests species from variable environments are more resilient, but intraspecific testing is limited.
• Mitochondrial function and reactive oxygen species are implicated in thermal resilience due to temperature-dependent metabolic rates.

Purpose of the Study:

• To investigate intraspecific variation in oxidative damage in prairie lizards (Sceloporus consobrinus) along a latitudinal gradient.
• To test the climate variability hypothesis within a single species by examining responses to thermal challenges.
• To determine the role of cold exposure and rewarming in triggering oxidative damage and its reversibility.

Main Methods:

• Prairie lizards from northern, central, and southern populations were subjected to controlled thermal exposures (18°C and 37°C).
• Oxidative damage was quantified by measuring 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels.
• Two experiments assessed damage after cold exposure and subsequent rewarming rates.

Main Results:

• Oxidative damage (8-OHdG) increased in central and southern populations after cold exposure, but not in the northern population.
• Northern lizards exhibited no increase in oxidative damage, supporting the climate variability hypothesis.
• Southern lizards showed increased damage with faster rewarming rates, while damage was reversible 24 hours post-exposure.

Conclusions:

• Provides the first intraspecific evidence for the climate variability hypothesis in a vertebrate ectotherm.
• Northern lizards possess mechanisms to mitigate cold-induced oxidative damage, indicating adaptation to variable climates.
• Mitochondrial function and oxidative resilience are crucial for thermal tolerance in ectotherms facing climate change.