Anole Annals

The brown or festive anole, Anolis sagrei, is an invasive species in several countries in the Americas and Asia. This species is native to Cuba, the Bahamas, and the Cayman islands. Following introductions, A. sagrei can reach high population densities and undergo rapid range expansion. In a recently published contribution, we provide the first record of this aggressive invasive lizard in Brazil.

In 2017, we recorded specimens of A. sagrei within the limits of an International Airport in the metropolitan area of the city of Rio de Janeiro, southeastern Brazil. The observation of juveniles and mating couples suggests that the species is established locally.

The origin, geographic extent, and potential for spread of A. sagrei in Rio de Janeiro and Brazil are currently unclear. It is also unclear whether this species will be able to colonize natural habitats, such as the surrounding Atlantic Rainforest.

The establishment of brown anole populations elsewhere has led to shifts in substrate use by native anoles and promoted major shifts in the structure of local insect assemblages. As such, this species has the potential of affecting local ecological communities in Brazil. However, the effects of A. sagrei on the local fauna – including native lizards that we sampled in the area – are difficult to predict.

This is the second case of an established exotic anole species in Brazil. Populations of the Cuban green anole, Anolis porcatus, were recently detected in several sites in the Baixada Santista coastal region, state of São Paulo.

To know more:

Oliveira J.C.F., Castro T.M., Drago M.C., Vrcibradic D., Prates I. (2018). A second Caribbean anole lizard species introduced to Brazil. Herpetology Notes, 11: 761-764.

PDF available here (at the bottom of the webpage).

Evolution 2018: Sex Chromosome Evolution

By Kristin Winchell

On September 4, 2018

In New Research

“Squamates Playing Poker” – a clever depiction of sex chromosome evolution (image by Anna Minkina shared with permission from Tony Gamble; read more about the image on the Gamble lab website)

Anole Annals contributor Yann Bourgeois reports on the talk by Tony Gamble on sex chromosome evolution. While this talk wasn’t specifically about anoles, our favorite lizards are no stranger to this topic, as discussed previously here on Anole Annals. Gamble builds on his previous work in an impressive analysis of sex chromosome evolution across squamates and snakes. We can look past the anoles taking the back-seat on this one because the talk was fascinating and sure to be of interest to readers here. Yann Bourgeois reports:

How sex chromosomes originate is one of the most intriguing questions of evolutionary biology. It is also a complex one, as the mechanisms that lead to their formation are not clearly understood and our knowledge is mostly based on model species that are not necessarily representative (most of them have strongly heteromorphic sex chromosomes). It is generally thought that sex chromosomes emerge as new alleles at a sex-determining gene stop recombining with each other. Since sex-ratio has to reach an equilibrium, balancing selection maintains the two alleles at high frequencies, and strong linkage locks together loci involved in reproductive isolation and mating. As the two non-recombining blocks diverge they accumulate mutations that can be used to discriminate them using molecular tools. In the most extreme case, one of the two chromosomes degenerates, such as the Y chromosome in humans.

Most sex-determining systems fall into two categories: ZW systems where the male is homozygous ZZ and females are heterozygous, and the classical XY system with XY males and XX females. We know from previous research that anoles fall into the XX/XY category (although some species are XXXX/XXY). However, in general in squamates and snakes in particular, the evolution of sex-chromosomes is poorly known. Early studies mostly focused on heteromorphic chromosomes, which are so divergent that they can easily be identified through cytogenetics. But heteromorphic sex chromosomes like those in anoles and other squamates are not necessarily visible, and other tools are needed to identify which system occurs in a given species.

In his talk, Gamble showed how to use RAD-seq or RNA-seq to identify loci associated with sex, and to discriminate between XY and ZW systems (for more information on this approach, check out his 2015 paper in Molecular Biology and Evolution). For example, in an XX system, all males will be heterozygous at sex-linked loci while all females will be homozygous at the same sites. Depth of coverage will also be twice as low at X-linked loci for males than for females as they harbor a single X chromosome. Using this set of molecular methods, Tony demonstrates that there is a high turn-over of sex-determining systems in squamates and snakes, with more than 40 transitions between ZW and XY, half of those transitions being found in geckos.

It is also possible to map those sex-associated loci to reference genomes to identify syntenic blocks that may be repeatedly recruited during sex-chromosome evolution. For example, in the crested gecko (Correlophus ciliatus), most sex-associated loci map on chicken’s chromosome 10. Some genes may have a higher likelihood to be recruited when a new sex chromosome appears, but whether this can be extended to specific syntenic blocks remains an open question. This is made even more difficult by the fact that sex-determining genes in squamates are not yet known with certainty. This ongoing work on macro-evolutionary dynamics of sex chromosomes will provide interesting findings that may be linked to the evolution of mating strategies and speciation in anoles.

Lizard Eats Frog!

By Jonathan Losos

On September 4, 2018

In All Posts

Greg Pauly, the world’s authority on the anoles of California [1,2], kindly passed this information along to AA:

While doing some background research on Coquis, I came across this observation of an anole attempting to eat a Coqui. It appears the Coqui survived but it also has significant damage to one leg. I saw your 2015 blog on this topic, so clearly we know anoles eat the occasional frog, but maybe this iNat photo series is still of interest.

Evolution 2018: Whole Genome Sequencing Sheds Light on Genetic Diversity of Green Anole

By Kristin Winchell

On September 3, 2018

In New Research

Anolis carolinensis (photo by Cowenby, Wikipedia)

Whole genome sequencing approaches are rapidly becoming more accessible and gaining popularity. The development of powerful analytical tools for these data has enabled novel approaches to answering outstanding evolutionary questions. Yann Bourgeois, a post-doc at NYU- Abu Dhabi, is the first to take a whole genome approach to understand the population genomics of Anolis carolinensis in the southeastern United States. Yann presented his work in a poster at Evolution 2018 in Montpellier.

Yann sequenced 27 individuals from across the native range representing the five unique genetic clusters (Gulf Atlantic, Carolinas, North Eastern Florida, North Western Florida, South Florida). He found that the Gulf Atlantic and Carolina populations were nested within the Florida populations, supporting the hypothesis of a northward expansion from southern Florida. He was able to estimate that this colonization of regions north of Florida likely occurred in the past 100,000 years. Interestingly, he also found that this dispersal event was associated with a reduction in X chromosome diversity, suggesting that dispersal was either male biased or that there has been positive selection on the X chromosome.

Whole genome sequencing of 27 individuals from across the native range reveals population genetic structure

Taking this one step further, Yann then investigated patterns of recombination via secondary contact among the genetic clusters. Yann and his colleagues found that there has been gene flow between clusters over periods of secondary contact with interspersed periods of isolation. Limited introgression between Florida and the northern populations suggests local adaptation in the northern populations.

Yann and his colleagues have provided an interesting first look at the evolutionary history of Anolis carolinensis from a genomic perspective. The revealed patterns of expansion, reduced diversity, isolation, and secondary contact raise interesting questions about the origin of new genetic clusters (and perhaps species) and their maintenance with ongoing or periodic gene flow.

For more information on this exciting research, check out the pre-print of the manuscript.

Evolution 2018: Variation in Anole Epigenome Correlates with Climate

By Kristin Winchell

On September 3, 2018

In All Posts

Anolis cristatellus (photo by K. Winchell)

Evolution 2018 may have been a week and a half ago, but the fun doesn’t have to stop just yet. Shane Campbell-Staton reports on the talk by Guin Wogan:

As we all know by now, contemporary climate change is expected to cause problems for species across the globe. Understanding the mechanisms that will allow species to cope with these changes, through acclimation and/or adaptation, is one of the most pressing issues of contemporary biology. Reptiles, and lizards in particular, have been a model for studying the effects of climate on extinction, gene flow, performance, and adaptation. Yet, only recently have we really begun to understand the genetic mechanisms associated with survival and persistence in the face of changing environments. In this year’s Epigenetics and Adaptation session of the Evolution Meeting, Guinevere Wogan – a postdoctoral researcher in Ian Wang’s Lab at UC Berkeley – presented a first look at how variation in the epigenome correlates with climate variation with and between anole species.

Wogan et al. used reduced representation bisulphite sequencing to search for epigenomic associations with environment in two wide ranging species – Anolis cristatellus on Puerto Rico and Anolis cybotes on Hispaniola – both species that occur in a wide variety of habitats from cool, wet forests to dry, arid scrubland. They found some indication of convergent methylation profiles under similar climates within species, suggesting epigenetic signals may be important for acclimation and/or adaptation to local climate. However, this association was not perfect potentially due to habitat use differences between populations. Additionally, they found that variation in climate between populations explains a large degree of variation in methylation profiles between popualtions within each species (75.6% in A. cristatellus and 39.1% in A. cybotes), again suggesting an important role of epigenetic modification in contributing to survival in local environments. However, local climate isn’t the only factor effecting variation in epigenetic modification; they also found strong species level differences in methylation, even when populations occurred in similar environments.

As they continue to work on this study, it will be very exciting to see what further patterns emerge. As we collectively seek to better understand the mechanisms involved in environmental adaptation and acclimation, Wogan et al. are exploring an extremely understudied aspect of Anolis biology that is bound to shed valuable light on the subject. I’ll certainly be on the lookout for this manuscript in the near future.

Observations on Anolis onca in Colombia

By Nathan Manwaring

On September 2, 2018

In All Posts

Typical Habitat of Anolis onca, close to the ocean.

Anolis onca

I kept Anolis onca, as a hobbyist, in the late 90s; they were available via European breeders who had obtained them on Isla Margarita, Venezuela. I had some breeding success with them at that time, and have always found them fascinating. I assumed their range was specific to Margarita Island, but only later via Anole Annals saw a photo from Manaure and realized that they were also found in Colombia. I travel frequently to Colombia and know that area of the northeast where the photos were taken, so when I was in the area, I would look for them.

Typical Habitat with Milkweed

I first saw them about 4 years ago, during a day trip near Rioacha, the Departmental Capital of La Guajira. The first ones I saw were very small juveniles which were sunning themselves in very thick piles of discarded branches, and so were difficult to catch, handle and photograph. In a subsequent trip in 2017, I enlisted the help of some of the local Wayuu (the indigenous group that is predominant in that area of the country). They called them the “lizard that doesn’t move,” which is a very apt description of their habits.
The habitat in the region is characterized as being dry Chaparral (though with very few trees), and is very windy. While looking for Anolis onca, we would find nests of the local dove species, which choose to nest on the ground versus in the low lying trees probably due to the wind. The main shrub is a species of Milkweed, and animals were found within yards of the Ocean.

I am no newbie to looking for Anolis, but A. onca really is very different in its behavior compared to many of the anoles I had previously observed in the wild. While you often find them on the ground in the midst of thickets of vegetation on the beach, they are very slow and deliberate in their movements and as you approach them. They only seldom move when approached, even when you are very close to them. They are almost twig anole-like in their behavior and obviously rely on camouflage as their first line of defense.

Despite the sparse nature of vegetation in their habitat, ground dwelling habitats and relatively large size for an anole (about 4-5 inches SVL and 6-7 inches in TL), they are a challenge to find. I would estimate that we saw only one animal every 1.5 hours of searching (there were three of us actively looking). We probably saw nine over about 12 hours of searching.

I would be very curious to hear from others who have observed them in the wild, and if Anolis annectens, which is closely related, is similar in its habits.

A. onca male flaring Dewlap on Capture

What Colombian Anole Species Could These Two Be?

By Javier Cortes Suarez

On August 30, 2018

In Anole Photographs, Ask the Experts, Natural History Observations, Notes from the Field

I found these two specimens in my farm located in the municipality of Santa Sofia, department of Boyacá, Colombia. The living specimen was found near a stream in a wet area, while the dead specimen was found in the house of the farm. The farm is located in an Andean forest at about 2300 meters above sea level where plants such as oaks and eucalyptus trees predominate, among others.

Out of Puerto Rico?: A Puerto Rican Anole Hatchling in Need of an ID

By Chris Thawley

On August 27, 2018

In Introduced Anoles, Natural History Observations

The nursery trade is a known vector for many invasive species including anoles. Anoles have quite the affinity for laying eggs in the moist soil of potted plants, which may then be transported to various locations. Indeed, the nursery trade is the suspected vector for introductions to Hawaii and California of A. carolinensis and A. sagrei and likely accelerated their spread within those states. In fact, citizen scientists on iNaturalist document a reasonable number of brown anoles well outside their normal range. These observations have a distribution that suspiciously coincides with locations of Home Depots and Lowes. However, while the nursery trade is a suspected vector for other species of anoles, verified instances of long-distance transport via the trade are fewer and farther between.

An (as yet) unidentified anole hatchling transported from Puerto Rico to Virginia. From user kimjy3 on iNaturalist.org

One recent observation on iNaturalist documented a hatchling anole that popped out of a potted plant shipped from Puerto Rico as the user unwrapped it…in Alexandria, Virginia. Can anyone on Anole Annals having experience with Puerto Rican anoles and their hatchlings help ID this little one? The user reports that the anole does not have blue eyes; instead they are brown or black.

Feel free to add IDs/comments on the iNaturalist observation as well!

Evolution 2018: Dominica Anoles Change Up Their Displays when Faced with New Competition

By Winter Beckles

On August 25, 2018

In Education and Anoles, Introduced Anoles, New Research, Research Methods

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.