Race Track for Lizards

We often think of lizards being powered by the sun. It is true that they do not regulate their body temperature internally. They need to spend time both in the sun and the shade to properly thermoregulate.

This means too much sun can be a negative thing. McMillan et al 2011 were interested in if western fence lizards, Sceloporus occidentalis, sprinting speed would be impacted by heat exposure.

They collected 13-15 lizards from 4 sites that include both northern and southern California at various elevations. It is important to note that higher elevations tend to be cooler than lower elevations.

The authors built a custom race track for the lizards. They measured the lizard’s sprint speed at 71°F (22°C) then the lizards were split into two groups. One was in the heat treatment and ran after being exposed to temperatures of a 104°F (40°C) which the lizards can experience in the wild.

The second group was in the control so there second race was at the original 71°F (22°C). It’s important for studies to have control treatments so that scientists can make sure the variable they’re testing is what’s causing any effect they may be seeing. You only change one variable at a time but the control remains constant throughout the entire experiment.

They found that lizards at higher elevations or from the cooler northern California had reduced sprint speeds after being exposed to heat. Which makes sense. Most people who are used to cooler temperatures would have a hard time operating in hotter than normal temperatures.

Why is this research important if the answers seem so simple? Well we need the data to support policy change around climate change from the local to state to federal to international level.

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