For lizards, responding to climate change isn’t just about temperature. It’s also about what happens to their food source.
A warmer, drier climate could mean less food, and thus less energy, less activity, and less ability to adapt, say Ohio University researchers in their study of tree lizards.
Graduate student Anthony Gilbert and Dr. Donald Miles, Professor of Biological Sciences, published “Food, temperature and endurance: effects of food deprivation on the thermal sensitivity of physiological performance” in Functional Ecology, the journal of the British Ecological Society.
Lizards are a group of terrestrial vertebrates at great risk to changes in global climate because their physiological traits are dependent on environmental temperature. The focus of research estimating lizard responses to climate change traditionally relies only on changes in temperature while neglecting other simultaneous changes to the environment.
In arid desert ecosystems, say the researchers, warmer temperatures will alter precipitation patterns, further reducing the scant rainfall these areas already receive. As a result, seasonal prey abundance due to reduced primary productivity is expected to limit food availability for a multitude of predators.
Physiological traits, while dependent on temperature, also can be influenced by energetic state, and this is a relationship that has not received much attention, especially in lizards and with respect to rapidly changing climates.
“We examined whether the relationship between physiology and temperature for the tree lizard (Urosaurus ornatus) is affected by food availability,” Miles says. “We estimated locomotor performance (endurance capacity), thermal preference, and the thermal sensitivity of locomotor performance for fasted and fed groups of U. ornatus to evaluate the effect of food deprivation on thermal physiology.
“We found that food-deprived lizards exhibited reduced endurance running capacity, lowered preferred body temperatures, and a thermal sensitivity of performance favorable for cooler temperatures compared to fed lizards. This indicates that lizards that are unable to forage effectively will restrict themselves to cooler regions of their habitat and be at a physiological disadvantage for being active at warmer periods of the day. This will further restrict foraging opportunities and intensify energetic imbalance”
“Our work demonstrates an energetic mechanism by which changes in climate could lead to shifts in lizard activity and ultimately demographic instability and extinction,” Gilbert adds.
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