Effect of dewlap size on combat trial performance in Anolis sagrei

Abstract

Anolis sagrei, or brown anoles, often display their dewlaps during combat with other males. These dewlaps are brightly-colored tissue under their chin that can be expanded by the anole. We sought out to see if the size of these dewlaps was associated with the anole’s aggression or dominance during combat. We also wondered if the size of an anole’s dewlap could point toward other factors such as their bite force or chance of winning a fight. We tested these ideas by performing a series of tests. We measured bite force on a force transducer, and we determined the area of the anoles’ dewlaps by outlining them in an image processing software. We then examined combat trials between similarly-sized sexually mature male brown anoles. Our results showed that dewlap size was positively correlated with both maximum bite force and body length. However, dewlap size was not correlated with the anole’s chance of winning or their levels of aggression.