Elevational variation in body-temperature response to immune challenge in a lizard

Area of Science:

• Ecology
• Animal Behavior
• Immunology

Background:

• Immunocompetence, crucial for combating pathogens, incurs costs like increased energy expenditure and predation risk, especially during fever in ectotherms.
• The balance between fever's costs and benefits is influenced by environmental thermal quality, leading to varied thermoregulatory strategies across different habitats.

Purpose of the Study:

• To investigate how environmental thermal quality affects the thermoregulatory responses of ectotherms to immune challenges.
• To test the hypothesis that alpine ectotherms, facing high thermoregulation costs, would not exhibit fever, unlike their temperate counterparts.

Main Methods:

• Studied Psammodromus algirus lizards from alpine and non-alpine habitats in Sierra Nevada, Spain.
• Measured preferred body temperature before and after immune system activation using a pyrogen.

Main Results:

• Non-alpine lizards surprisingly decreased their preferred body temperature post-immune challenge, likely to conserve energy and reduce predation risk.
• Alpine lizards, as predicted, maintained their preferred body temperature, aligning with the hypothesis of prohibitive fever costs in high-altitude environments.

Conclusions:

• The study suggests that high-altitude ectotherms may forgo fever due to the extreme costs associated with thermoregulation and limited reproductive windows.
• Environmental conditions significantly shape immune-related thermoregulatory behaviors, with alpine lizards prioritizing energy conservation over fever.