Amphibian supercooling capacity is not limited to sub-zero thermal environments

Area of Science:

• Herpetology
• Ecology
• Physiology

Background:

• Amphibian freeze tolerance involves controlled freezing and cryoprotectants.
• Freeze avoidance (supercooling) relies on inhibiting ice formation and is mainly observed in Northern Hemisphere species.
• The occurrence, ecological role, and mechanisms of amphibian supercooling are poorly understood.

Purpose of the Study:

• To investigate latent supercooling capacity in amphibians beyond freezing environments.
• To explore the potential role of skin-associated bacteria in freeze avoidance.
• To assess cold and dehydration tolerance in tropical montane amphibians.

Main Methods:

• Metagenomic analysis of skin microbiota.
• Field experiments on syntopic amphibian species from Roraima-tepui, Venezuela.
• Assessment of thermal and dehydration tolerance limits.

Main Results:

• Amphibian supercooling capacity can be latent and not restricted to cold climates.
• Two syntopic tropical montane species exhibited significant differences in thermal and dehydration tolerance.
• Physiological freeze avoidance correlated with low critical thermal minima and high dehydration tolerance.

Conclusions:

• Supercooling in tropical amphibians may be facilitated by cryoprotective dehydration and potentially by antifreeze-producing skin microbiota.
• These traits are crucial for species persistence in thermally variable montane environments under climate change.
• Further research is needed to confirm the role of skin microbiota in amphibian freeze avoidance.