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Ellee Cook receives grant to study aggression in female lizards

April 21, 2017

Female Anolis gundlachi perched on a tree

Does testosterone fuel this female Anolis gundlachi‘s display of aggression?

Ellee Cook, a fourth-year graduate student in the Division of Biological Sciences, recently received a research grant from the Animal Behavior Society to study the hormonal basis of aggression in female Anolis lizards.

Male anoles use aggressive display behaviors (think shouting matches on a playground) to establish dominance and defend their territories. Cook has found that, when it comes to protecting their own, some female anoles can be just as feisty and mean as their male counterparts. In males, territorial aggression has been linked to the hormone testosterone – basically, the more testosterone, the bigger the bully. Can this so-called “male” hormone also be fueling differences in female displays of aggression as well? That is the question Cook hopes to answer in this new study.

She will use the grant to stage “shouting matches” (i.e., territorial interactions) among free-living Anolis gundlachi females living in the Luquillo Experimental Forest in Rio Grande, Puerto Rico. She will observe these interactions to determine who is the louder shouter and evaluate if the intensity of shouting is predicted by the concentration of testosterone in the females following the interactions. She hypothesizes that the feistier females will have higher levels of testosterone in their systems.

Elle Cook

Ellee Cook

Cook says the research will clarify whether males and females share a mechanism that drives individual differences in aggressive behavior or if a novel mechanism is at work in females. It also will add to a growing body of literature on female-female competition in animals.

Cook carries out her research in the lab of Dr. Manuel Leal.

Related research strengths:
Behavior, Ecology
Related categories:
Graduate Studies