SICB 2017: It’s Getting Hot in Here: How Brown Anoles Respond to Extreme Heat in Greenhouses

This post was written by Brittney Ivanov, research technician in Michele Johnson’s lab at Trinity University.

Austin Hulbert, an undergraduate in Dan Warner’s lab at Auburn University, presented a poster on the behavior of brown anoles (Anolis sagrei) in a novel environment: a few very hot greenhouses in Auburn, Alabama. Brown anoles are an invasive species, most notably in Florida, but some populations have been found farther north in states including Louisiana, Alabama, Mississippi, and Georgia. As ectotherms migrate to higher latitudes, they often have to deal with different thermal environments and must alter their behaviors accordingly. Austin was interested in determining the activity patterns of a population of brown anoles inhabiting a group of greenhouses in Alabama.

During the summer he found that temperatures inside the greenhouses were consistently higher than those outside. Temperatures drastically increased each morning, up to peak temperatures between 11am and 3pm (on average, 45°C inside the greenhouse and 37°C outside). In the evenings, the temperatures again cooled. Austin surveyed the greenhouses and the surrounding areas for anoles during the morning, peak, and evening hours and determined the type of substrate each individual was using (i.e. brick or concrete, ground, metal, or wood). On average, brown anoles were more abundant inside the greenhouses than outside during the morning and peak times. He also found that more of the brown anoles perched on wooden substrate in the morning and evening. During peak hours more lizards perched on the ground. Because temperatures are often cooler closer to the ground, the lizards may be altering their behavior to deal with the extreme heat in the greenhouses during the hottest part of the day. While the visual survey focused on lizards perched in the open areas visible to the surveyor, there may have been individuals hiding under undisturbed objects as a means to keep cool during peak hours. In the future, Austin would like to compare the thermal tolerance of this group of brown anoles to those of populations in Florida to determine if inhabiting these greenhouses has resulted in adaptions to tolerate their more extreme temperatures.