Author: Winter Beckles

Graduate student in the Uy lab at the University of Miami. Using introduced species of Anolis lizards to study the influence of anthropogenic factors on signal divergence and speciation.

Claire Dufour, Postdoctoral Fellow at Harvard University, presents her research at the 2018 Joint Congress on Evolutionary Biology in Montpellier, France.

In another excellent study exploring the effects of anthropogenic activity on evolution in anoles, Postdoctoral Fellow Claire Dufour is investigating how the recent introduction of Anolis cristatellus from Puerto Rico to the island of Dominica may be driving changes in the display behavior of Anolis oculatus, a Dominica native. Specifically, Dufour is asking whether interactions between the A. cristatellus and A. oculatus are consistent with patterns of Agonistic Character Displacement, in which interference competition between the newly sympatric species results in shifts in traits affecting the rate, intensity, and outcome of interspecific aggression.

To begin, Dufour and colleagues constructed a pair of robots that mimicked the typical look and display behavior of a male A. oculatus and A. cristatellus. She then traveled across Dominica and presented over 130 wild male A. oculatus with one of the two robots, and recorded the display behavior exhibited in response. Beyond measuring the duration of the response display, Dufour also tracked the proportion of time spent by the A. oculatus engaging in any of nine specific display behaviors, such as dewlap extensions, push ups, nuchal crest presentations, and others. By repeating this experiment among populations of A. oculatus existing sympatrically with A. cristatellus, as well as populations not yet invaded by A. cristatellus, Dufour was then able to ask whether variation in display time or composition among the native anoles could be attributed to the presence of A. cristatellus. Indeed, this turned out to be the case.

Anolis oculatus living in allopatry from the introduced A. cristatellus were found to engage in longer display bouts when presented with the conspecific robot, and shorter display bouts when presented with the unfamiliar A. cristatellus robot. Alternatively, A. oculatus occupying habitats already intruded by the A. cristatellus increased the duration of time spent displaying, regardless of which robot was presented. In addition, A. oculatus were also found to alter the behavioral composition of their displays when occupying habitats shared by the introduced A. cristatellus.

Dufour and colleagues capitalized on a rare opportunity to document the very early stages of a species invasion, and in turn improve our understanding of how human-mediated species introductions can promote evolutionary change. As changes in behavior are often the first response to novel competition, these results are consistent with the criteria of Agonistic Character Displacement, and support the claim that the introduction of crested anoles in Dominica has indeed driven a shift in the behavior of native anole communities. While the consequences of these shifts on the outcome of interspecific competition are still unclear, it will be interesting to see how differences in display behavior develop over time, and further, whether these initial changes in display behavior could lead to additional shifts in behavior or morphology among these newly interacting species.

Evolution 2018: Speed Is Key for Anoles in the City

By Winter Beckles

On August 25, 2018

In Education and Anoles, New Research, Research Methods

Dr. Kristin Winchell at the 2018 Joint Congress on Evolutionary Biology

Human activity is well recognized as having evolutionary consequences, and studies on the prolific Anolis genus continue to show us just how adaptable these lizards can be. Dr. Kristin Winchell, a Postdoctoral Research Associate at Washington University in St. Louis, MO, is investigating the relationship between human activity and evolution in Puerto Rican crested anoles, with a current focus on how selection across urban habitats might be driving changes in morphology and behavior among the lizards.

In an elegantly designed study, Winchell and colleagues collected over 120 male crested anoles (Anolis cristatellus) from forests and urban areas across the island. The team then assessed the ability of these anoles to perform a series of tasks representing normal daily activities, such as sprinting and clinging. By comparing anole performance on natural substrates like wood to their performance on more urban substrates such as concrete and metal, the team determined that the lizards consistently performed better on natural substrates, yet decreased their velocity when perches were inclined. Specifically, the crested anoles sprinted at less then half of their maximum speed on painted concrete, up to 32% slower on metal compared to wood bark tracks, and as much as 34% slower when surfaces were steeply inclined.

Winchell and colleagues measured differences in limb length and toe pad morphology among urban-caught and forest-caught anoles.

In addition to performance assessments, detailed scans of toe pad and skeletal morphology were collected and analyzed, allowing Winchell to identify differences in morphological traits underlying any variation in performance. Upon comparison, the pattern was clear: lizards living in cities had significantly longer limbs, more lamellae on their front toe pads, and larger overall rear toe pads. Longer hindlimbs in particular were found to positively influence velocity across substrate types, surely a selective advantage for anoles tasked with sprinting between the amply spaced urban perches. However, the urban phenotype is not without cost, as longer forelimbs were found to negatively influence velocity on more steeply inclined surfaces, as well as increasing the lizard’s likelihood of slipping. As all urban populations measured shared these phenotypic traits, however, the advantage of increased speed seems to be worth the costs.

As rates of urbanization continue to increase, further studies examining the response of taxa adapting to urban environments will be imperative. With Winchell’s plan to explore performance and morphological differences in other anole species living across the urban-forest continuum, it will be exciting to learn how these traits are affected within species originating from other territorial and arboreal microhabitats.

Anolis equestris: Miami’s Favorite Cannibal

By Winter Beckles

On April 9, 2015

In Anole Photographs

Anolis equestris with a smaller Anolis equestris in its jaws.

An Anolis equestris captures a smaller A. equestris in South Miami.

Cannibalism in Anolis equestris is nothing new, but that doesn’t make it any less surprising to witness! On a morning stroll in South Miami this past weekend, I noticed a flash of green movement on a tree. Upon closer inspection I realized there was a medium-large A. equestris with a smaller A. equestris wedged between its jaws. I hurried to snap a few photos with my wife’s phone, and while they aren’t Neal Losin-caliber (ha ha), I still wanted to share them with my favorite anole community!

Once I got too close, the A. equestris decided it was time to take its meal higher up the tree. An unsuspecting A. distichus saw the approaching A. equestris and began to dewlap enthusiastically. You can see the A. distichus near the top of the last photo. Enjoy!

Bark Anoles Strutting Their Stuff in Miami

By Winter Beckles

On February 12, 2014

In Anole Videos, Introduced Anoles, Natural History Observations

In August of last year, my wife and I made the move from Maryland to Florida so that I could begin my graduate work on signal evolution at the University of Miami. All of my research experience to that point had been centered on avian communication, but it wasn’t long after moving to Miami that my attention was drawn to the massive number of anoles displaying throughout my community. I’ll admit, one year ago my interest in anoles did not go beyond thinking that they were just another cool group of reptiles. However, in the six short months since moving to the area, it will come as no surprise to the Anole Annals community that I am hooked on these fascinating lizards.

This post serves as a friendly hello to everyone here at AA, as well as a quick note of gratitude to all who contribute to making this site such a fun and informative place for all things anole. On that note, I thought it was time I share something myself, and so I’ve included a video I recently recorded of two male bark anoles sizing each other up on a tree near my home. Of course, the video clarity seemed much nicer on my phone, but nonetheless, I hope you all enjoy!

httpv://youtu.be/R-1RlH38DCw