About This Project

Green anoles (Anolis carolinensis) morphs from green to brown, and it is not known why. In this experiment, the effect of stress levels and the correlation of light levels and temperature on the frequency and duration of color change in A. carolinensis will be tested. I hypothesize that stress levels in addition to environmental conditions such as light and temperature affect color change in A. carolinensis. This research will provide insight into an unusual behavior of a common lizard.

Ask the Scientists

What is the context of this research?

The green anole (Anolis carolinensis) has the ability to change color from bright green to dark brown. While scientists know how this color change occurs, it is not yet know why. There have been multiple hypotheses about the color change before, including for advertisement and social signaling, thermoregulation, and as a result of stress. None of these hypotheses have been consistently supported with field studies, therefore a controlled environment is more likely to produce consistent data that will either support or deny the hypotheses.

What is the significance of this project?

Green anoles are common in the wild and in the pet trade. Despite this, a controlled experiment trying to discover the reason for the color change has never been conducted. If it is found that green anoles turn brown as a result of stress, that would mean the color change of green anoles is indicative of their brain function and ‘emotions’. This means that they are able to wear their ‘emotions’ on the outside, so understanding the effects of stress on them is easily observable and non-invasive. In addition, due to their easy care requirements, and the simplicity of replicating its natural environment, green anoles are perfect for experimental work, making them a perfect model organism for the genus Anolis. This could open a window into the effects of environmental stressors on anoles.

What are the goals of the project?

To determine the cause of the color change in green anoles, I will be creating a basic model of the anoles natural habitat to test and house them in. Anoles will be tested separately to ensure that conditions in terrariums are kept constant. To test stress, a disk will be pushed from one side of the terrarium to the other multiple times. There are 3 scenarios to test the correlation between light levels and temperature on color change: lights on, heat off; lights on, heat on; and light off, heat off. This will determine if anoles change color for thermoregulation. Color will be scored as a ratio of green to brown intensities, where a larger score indicates a greener color. It is likely that anoles change color as a result of stress, and not for thermoregulation purposes.