The Lizard Gut Microbiome Changes with Temperature and Is Associated with Heat Tolerance

Area of Science:

• Microbiology
• Ecology
• Physiology
• Climate Change Biology

Background:

• The gut microbiota plays a crucial role in vertebrate host functions.
• Environmental temperature shifts can alter gut microbiota composition and host physiology in lab settings.
• Limited data exists on temperature effects on wild vertebrate gut microbiota, especially in ectotherms vulnerable to climate change.

Purpose of the Study:

• To investigate the impact of temperature increases on the gut microbiota of wild-caught western fence lizards (Sceloporus occidentalis).
• To determine if changes in gut microbiota composition are associated with host thermal tolerance in lizards.
• To understand the implications of warming temperatures for ectotherm physiology and fitness in natural populations.

Main Methods:

• Wild-caught western fence lizards (Sceloporus occidentalis) were experimentally exposed to a cool-to-warm temperature transition.
• Gut microbiota composition was monitored throughout the temperature exposure.
• Host thermal tolerance was measured at the experiment's conclusion.

Main Results:

• Elevated temperatures altered and destabilized the gut microbiota composition in Sceloporus occidentalis.
• Warming led to a decrease in specific Firmicutes bacteria and an increase in pathogenic bacterial clades.
• Increased gut microbiota compositional turnover was observed in lizards exposed to warmer temperatures.
• Gut microbiota composition was significantly associated with lizard thermal tolerance.

Conclusions:

• Environmental warming can significantly alter the gut microbiota of wild ectotherms like the western fence lizard.
• Changes in gut microbiota composition are linked to host thermal tolerance, with potential consequences for physiological performance.
• These findings highlight the interconnectedness of climate, gut microbiome, and host fitness in natural populations.