SICB 2018: Role of Testosterone in Mediating Female Aggression in Anolis Lizards

An example of an aggressive display by a lizard. Photo Credits: Neil Losin Photography

Testosterone has long been though to influence male aggression behaviors. But can this same hormone influence aggressive behaviors in females too? Ellee Cook addressed this question in her talk titled “Investigating the potential for testosterone to mediate territorial aggression in female Anolis lizards.”

Ellee focused on studying a population of Anolis gundlachi in the forests of Puerto Rico. Ellee studied the response of focal females to a staged territorial intrusion by another female who was placed on a cage lid, and compared it to a scenario where she directly approached the lizard. She captured the focal females after twenty minutes of the trial and measured their size and took a blood sample to estimate the circulating levels of testosterone. Her prediction was that higher levels of aggression would be correlated with higher levels of testosterone.

Her data showed that females were indeed aggressive towards intruding females and had much higher displays of aggression in comparison to when they were presented only a lid or were directly approached. Surprisingly (or not so surprisingly), testosterone was not a significant predictor of female aggression. In fact, none of the hormonal measures corresponded to female aggression. This finding could have resulted for several reasons: A) the amount of testosterone detected in females was much lower than that found in males, making variation in testosterone almost impossible to detect; B) High aggression may be caused by spontaneous spikes in testosterone that may be hard to detect; C) Female aggression may be governed by a completely different mechanism.

This study raises an important question about the relevance and drawbacks of existing paradigms which are male-centric and thus cloud our understanding when it comes to female behaviors. Cheers to more feminist paradigms in biology!