Article Review: Liklihood of Anolis sagrei to attack in response to territorial intrusions (males vs females)

This article was written by Aaron M. Reedy, Brandon D. Pope, Nicholas M. Kiriazis, Cara L. Giordano, Cheyenne L. Sams, Daniel A. Warner, and Robert M. Coxa. It was published in 2017 in the journal: Behavioral Ecology. The URL for this article is: https://academic.oup.com/beheco/article/28/5/1323/4080394

“Female anoles display less but attack more quickly than males in response to territorial intrusions”

This article discussed the liklihood of attack in regards to territorial intrusion in Anolis sagrei in both males and females. Anolis sagrei is more commonly referred to as the Brown Anole. These lizards are often involved in social interactions, however they typically are found in densities of 1 lizard per square meter. Males are typically two to three times larger than females and are known to have a bite that is 400% more powerful than females. It is a common observation that males tend to be more aggressive than females, but often times, little studies are actually performed on the comparison of male to female territorial attacks and the liklihood of each to attack. This article wanted to perform an experiment to determine more accurately which sex, male or female, are likely to react more aggressively to intruders. 

They performed this study using two islands in the Guana Tolomoto Matanzas Estuarine Research Reserve. The observations for this study took place during the brown anole’s reproductive season. 85 territorial intrusions were simiulated during this experiment. The experiment was carried out by having a focal lizard within its territory (one of the two islands) and introducing a tethered (attached to a fishing pole and fishing line) stimulus lizard (from the other island ensuring the two lizards had never encountered) into the focal lizard’s territory. The experiments were performed with male vs male and female vs female. The trials lasted 15 minutes or until the focal lizard either attacked or fled and each lizard was subjected to 3 trials (all with different stimulus lizards). It was observed and recorded whether or not the trial ended in an attack, a flee, or if nothing happened after 15 minutes. Additionally, movements towards or away from the stimulus lizard, dewlap extensions, and head bobs/push ups were also recorded (all of which are potentially aggressive or warning displays). It is important to note that when the stimilus lizard was introduced, it was placed at or below the perch height of the focal lizard (never above). Additionally, the side of introduction was switched during the trials (left side and right side) because lizards lack a corpus callosum (which integrates the right and left hemispheres of the brain) and can show more of a propensity to attack towards certain sides. 

The total results were as such: as 66 of 85 lizards (77.6%) attacked, 10 of 85 (11.8%) fled, and 9 of 85 (10.6%) did nothing. Upon further scrutiny of the results, they showed that males were more likely to attack the stimulus lizard than females (37 of 43 males vs 29 of 42 females). However, this result was marginally non significant. The latency of attack was where the results became interesting. In regards to latency, females had a highly significant difference in comparison to males in quickness of their attack. This means that females were way more likely to attack more quickly than males. Females also had fewer displays prior to their attack. The results showed that 97% of focal females attacked the stimulus female within five minutes. Only 68% of males attacked within five minutes. 

This These results help us to understand more completely the behaviors of the brown anole specificalldddy, but may also help us to infer there territorial strategies of other species as well. This study has shown us that, based on the females quick willingness to attack, that their risk for combat may be significantly less than their male counterparts. It is often seen in many species that males have some form of sexual dimorphism that can often help them to protect their territories or their “own” may that be horns or size. In these brown anoles, males are substantially larger and have a much more aggressive bite force than that of females. For this reason, it seems in their favor to display more and wait longer to attack their territory because getting involved in combat may bet costly for both lizards. I find this article incredibly interesting in that it allows us to have a larger understanding in the way these lizards (and potentially other species) live and survive.  These individuals may have a thought process that we as humans have no idea about and by continuing research in aspects such as this may be able to inform us more as to what they are capable of.