Lazarus Lizards: Thermoregulation and Water Loss in the Podarcis muralis (Common Wall Lizard)

Student: Ciara Pettit ’23 and Sierra Spears ’22
Research Mentor: Eric Gangloff (OWU Department of Biological Sciences)

Ectotherms, or “cold-blooded” organisms such as the common wall lizard (Podarcis muralis) depend on their environment to regulate their body temperature. This is quickly becoming a problem, as climate change is causing environmental temperatures to rise and precipitation rates to become less predictable. Our study examines how wind can affect the rates of dehydration in P. muralis and patterns of thermoregulatory behavior. This is important to understand so we can quantify the potential effects of the ongoing climate crisis.

Climate change is progressing, subsequently warming the environment and altering precipitation patterns. This can inhibit the ability of wildlife to carry out natural behaviors, and therefore reduce fitness in their natural habitat. Ectotherms are affected by climate change because they rely on the environment to thermoregulate. Wind has a profound impact on the thermoregulation of animals, as it reduces their body temperature by cooling the animal and substrate, and impacts water loss. We can determine the water loss (or dehydration levels) by studying the hematocrit levels (ratio of red blood cells to plasma in blood). New statistical approaches to analyzing animal movement patterns, such as hidden Markov models (HMMs), give us insight into how behavior is affected by dehydration. We studied these phenomena in the Common Wall Lizard (Podarcis muralis), an invasive species brought from Europe to Cincinnati in 1951.

To study the effects of wind on thermoregulation, we conducted thermal preference trials in arenas with a gradient of 20-550. We did two experiments on each lizard, one with wind and the other without. The lizards then underwent a waiting period of 12 days, and then another thermal preference trial was conducted, this time with the opposite wind treatment. During the trial, we used a thermal imaging camera to collect body temperature data, and a digital camera to track the lizards’ movement. We predicted that the P. muralis would prefer the cooler side of the windy gradient to reduce their water loss, as wind is a constraint on their thermoregulation. These results provide insight as to how P. muralis are affected by the oncoming climate crisis.