Temperature has species-specific effects on corticosterone in alligator lizards

Area of Science:

• Physiological Ecology
• Endocrinology
• Herpetology

Background:

• Vertebrates release glucocorticoids, like corticosterone (CORT), during stress to initiate a survival response.
• Extreme temperatures threaten ectotherm survival, making CORT a potential key stress response component.

Purpose of the Study:

• To investigate how body temperature influences CORT levels in northern and southern alligator lizards.
• To determine if CORT responses to temperature are species-specific and adapted to thermal environments.

Main Methods:

• Experimentally exposed two lizard species (Elgaria coerulea, E. multicarinata) to four temperatures (10, 20, 28, 35°C) for 5 hours.
• Measured plasma CORT levels before and after adrenocorticotrophic hormone (ACTH) challenge.
• Compared laboratory CORT levels to those of field-active lizards.

Main Results:

• CORT elevated at high temperatures (28, 35°C) in both species.
• Low temperatures (10°C) elevated CORT only in southern alligator lizards.
• ACTH challenge significantly increased CORT in both species across all temperatures.
• Laboratory CORT levels mirrored field measurements in southern alligator lizards.

Conclusions:

• Body temperature directly impacts CORT levels in alligator lizards.
• Species-specific CORT responses to temperature suggest adaptation to distinct thermal niches.
• These findings have implications for understanding ectotherm biogeography and climate change impacts.