#DidYouAnole? – Anolis carolinensis

Anolis carolinensis, 18 March 2017 – floridensis

Photo by Janson Jones

Hey there!

Welcome to #DidYouAnole on Anole Annals for the first time!
I talk about a new anole every week on Twitter (with really good GIFs) and now here too!

This week’s #DidYouAnole is in collaboration with #GuessThatSkull, so if you want a 3D look at an A. carolinensis skull, check it out!

Last week I talked about Anolis porcatus and that A. carolinensis wasn’t a distinct species, but that’s not its fault and it’s still worthwhile to talk about. Since A. carolinensis was described first, that would mean A. porcatus should become carolinensis. So they’re all A. carolinensis!

The American Green Anole or simply, the Green Anole, gets its name from its colour. As most of us know it’s usually green, but it can change to brown, olive shades, grey and can even be blue!

What drives the color change in green anoles? | Experiment

Green anoles display sexual dimorphism, which is when animals have different features based on their sex. Like peacocks and peahens! Females tend to be smaller and have more proportional heads, have a white stripe down their backs and may have a dewlap that is much smaller than a male’s.
(Juvenile males may also have this dorsal stripe though!)

Wildlife - Green Anole Lizard (Anolis carolinensis) - GeorgiaInfo

Photo by Vicki DeLoach

A lot of people have remarked that their native populations of the Green anole have been disappearing due to the introduction of the Brown anole. While it is entirely possible that its population can be affected by A.sagrei, it’s also very likely that these anoles are just partitioning by habitat. That means that Green anoles (trunk-crown ecomorphs) used to roam freely, but now with another anole around, they’ve moved and further adapted to the trees and the Brown anoles (trunk-ground) stayed on the ground where they prefer and are very visible.

Brown anoles are totally jerks though.

Green anoles have a range of dewlap colours. Most commonly bright red to pink, but some populations in southwestern FL have grey dewlaps and are a subspecies, A. c. seminolus, and some in HI have lilac dewlaps. This has been noted a few times by observers and authors on Anole Annals.
Speaking of which, I’m super excited/scared to bring this to you here on Anole Annals. I love this website. I’ve been in articles on here before and now I get to share my anole fan-girling on here myself!

And speaking of the dewlap colours! I draw anole stickers and my carolinensis sticker is now available in grey, and lilac. And there’s a new anole friend waiting there for you too!

Thanks for reading!!

Anoles Who eat Psittacine (Macaws, Parrots, Parakeets) Leftovers!

Bananaquit feeding from a cactus fruit opened by a brown-throated parakeet on the island of Bonaire in the Netherlands Antilles.

Call for contributors to a Caribbean-wide investigation of psittacine-vertebrate commensal relationships!

We are seeking ecologists who have observed vertebrates (here Anoles) feeding on items (fruits, cacti and other stem-sap, or flowers) that some wild native Caribbean psittacine (Macaw, Parrot, or Parakeet) has opened and/or discarded. By opening and/or discarding food items, some psittacines may routinely provide access to resources that might otherwise be out of reach or at least more costly to acquire.

Bananaquit feeding from a parrot-opened orange on the island of Dominica, eastern Caribbean.

We anticipate that the majority of our contributions will be anecdotal and opportunistic field observations. Our deadline to collect all submitted observations is December 1, 2020. All contributors in this project will be listed as co-authors on a manuscript tentatively titled: Caribbean psittacines as indirect controllers of ecosystem dynamics through commensal feeding associations. Here is a template that outlines the types of information that we are hoping to receive from contributors.

Above and to the left are two photos, as examples, of how psittacines provide opportunities for birds to find food (sugary juice, pulp, and even insects) by opening fruit in both an agro-ecosystem and a natural dry forest system.

Please contact Leo Douglas at lrd2107@columbia.edu or leo.douglas@nyu.edu with any questions or for further information. Looking forward to hearing from you!

Anole Genomes Webinar

Tomorrow (30 June 2020) I will be presenting a webinar on our ongoing work assembling Anolis genomes. The webinar is hosted by Dovetail Genomics who provided the core technology we used to generate high quality genome sequences. The talk is at 11AM EST. If you want to watch live and have the chance to ask questions, you can register here. If you can’t make it but still want to hear what we are up to, Dovetail will post the video on their website alongside other speakers in the series.

Sign Up for Bahamas Reptiles Webinar

Here’s the registration page.

Exploring Brown Anole Cognition in the Bahamas

A recent study published in the journal Behavioral Ecology and Sociobiology conducted by Levi Storks and Manuel Leal (University of Missouri) investigates problem-solving abilities in the Anolis sagrei of Great Abaco. 

Abstract: 

Despite evidence that organisms are more likely to exhibit their full range of cognitive abilities under conditions found in nature, studies evaluating cognition under such conditions remain rare, particularly in vertebrate species. Here, we conducted an experiment to evaluate problem-solving and motor self-regulation in free-living arboreal lizards, Anolis sagrei, under natural conditions. We presented lizards with a novel detour problem which challenged individuals to circumvent a transparent barrier in order to obtain a food reward. Individuals varied in their ability to solve the detour problem. Furthermore, those that solved the problem were able to improve their performance across trials by modifying the natural response of attempting to strike the reward through the transparent barrier, providing evidence of motor self-regulation. Solving the problem required individuals to modify their typical foraging behavior, as approaching the prey in a single burst of movement that culminated with an attack was an unsuccessful strategy. Contrary to expectations, our findings provide evidence of motor self-regulation in a visually oriented, sit-and-wait predator under natural conditions, suggesting motor self-regulation is not limited by foraging strategy. Our results also underscore the need to evaluate the cognitive abilities of free-living organisms in the wild, particularly for taxa that perform poorly under laboratory conditions.

You can read the full paper here: Storks, L., and Leal, M. 2020. Thinking outside the box: problem-solving in free-living lizards. Behavioral Ecology and Sociobiology, 74, 75.

Brown Anole Stands up to a Dog

Nancy Greig, Director of the Cockrell Butterfly Center at the Houston Museum of Natural Science, tells the story:

Freddie is my dog, a 27 lb mixed breed, and this photo was taken in my back yard. Freddie’s quite the little hunter – fascinated by cockroaches at night and Anolis sagrei by day. The latter have become extremely abundant here in Houston in the last decade or so, out-competing/displacing the native green anole. There are dozens (hundreds?) in my yard. They tend to stay on or near the ground, unlike the green anole, which seems to prefer (especially now) to be higher up in the vegetation (so not of interest to Freddie, fortunately). Male A. sagrei can get quite large and as you can see here, pretty feisty! The standoff lasted several minutes, and was repeated several times. But I’m afraid Freddie got the better of the plucky fellow in the end.

Meet the Lizard Biologists behind Black Birders Week!

Right now, the United States is wrestling with systemic racism at many levels in our society. And while one may wish to think nature and science stand outside of this issue, this is not the case. Nature-related jobs and hobbies, which many of us AA readers enjoy, are often not safe spaces for Black people for many reasonswe saw a very striking example of this a few weeks ago in Central Park in New York City. So last week, largely in response to that event, a team of Black scientists presented the world with Black Birders Week, a week of social media and online events to showcase the Black naturalist community and share their experiences with Black and non-Black nature lovers alike. And while the event was focused on birding, two of the organizers behind this event are lizard biologists: Chelsea Connor and Earyn McGee! I’d like to highlight these two awesome herpetologists and their efforts in such a great week of outreach and community-building.

Anole biologist Chelsea Connor (Photo courtesy of Chelsea Connor)

Chelsea Connor, one of the co-founders of Black Birders Week, is currently a student at Midwestern State University. She studies the interactions between two anoles in her home country of Dominica, the endemic A. oculatus and the invasive A. cristatellus (some of her research was recently covered on AA). She’s active on Twitter, where she posts fun facts about her study animals and shares her experience as a Black woman in herpetology – follow her at @chelseaherps. She also makes wonderful anole-themed art–check it out and buy stickers here

Earyn McGee is a PhD candidate at the University of Arizona, where she studies the effects of stream drying on lizard communities. She is also a science communicator, educating the public about lizards and showing that Black women belong in wildlife science. She has run a weekly social media #FindThatLizard challenge for several years, introducing the fun of herpetology to many new fans (you can follow her on Twitter @Afro_Herper to play, and support this effort on her Patreon). She also has a new YouTube channel!

Lizard biologist Earyn McGee (Photo courtesy of Earyn McGee)

If you missed the #BlackBirdersWeek event, I encourage you to look it up on social media and online – it’s received lots of press coverage! To get you started, I’m pasting a few articles highlighting Earyn’s and Chelsea’s involvement in Black Birders Week below. And I encourage us all to use this moment to reflect on how we can make our nature-loving communities more welcoming and safe for our fellow naturalists.

 

 

 

Melissa Kemp on Caribbean Paleontology, Ancient Species Introductions and Being #BlackInNature

Melissa Kemp with a Puerto Rican crown-giant anole (Anolis cuvieri). Photo by Melissa Kemp

From the pages of Nova:

BY ALISSA GREENBERG NOVA NEXT

Paleobiologist Melissa Kemp spends a lot of time overturning assumptions. Her excavations don’t involve digging bleached bones out of windswept deserts, but looking for partially preserved lizard fossils in dark, dank jungle caves. Last month, she published a study tracking human-driven species introduction in the Caribbean through the region’s 7,000 years of human habitation—challenging the idea that “restoring” Caribbean biodiversity means taking it back to where it was before Christopher Columbus arrived in the so-called New World around 530 years ago.

Kemp, who runs a lab and teaches integrative biology at the University of Texas at Austin, opened up on Twitter last week about her experience as a Black scientist and outdoorswoman, under the hashtag #BlackInNature—as part of continuing conversations about race in America following the killings of Ahmaud Arbery, Breonna Taylor, and George Floyd, and the harassment of Black birder Christian Cooper. She spoke with NOVA about decolonizing environmental restoration, tropical fossil quirks, and the joys of time outside.

Alissa Greenberg: Let’s start with the hashtag #BlackInNature, which you’ve used in tweeting about your love of spending time outside. What’s important about that time in nature for you? What do you feel like it does for you physically and emotionally?

Melissa Kemp: I love spending time in nature. I live in Austin now, in a much more urban environment than I was raised in. But it’s still very rejuvenating just to go outside and look at the sky, look at the plants, find animals on the property and just see that there’s life there. Even when I’m doing my field research, there’s bursts of active work where we’re hiking through the rainforest trying to get to our site. But then when we get there, it can be very slow. The work that we’re doing is very meditative. So nature is very therapeutic for me. It’s played a very important role for me personally and professionally.

Particularly thinking about the COVID crisis, so many people are trying to find solace in nature during this time. And I think, now more than ever, it really needs to be accessible to everyone, with everything that’s going on—not only to make discoveries in and learn about, but just to enjoy and to feel comfortable enjoying it.

Melissa Kemp tweet #BlackInNature
The hashtag #BlackInNature was used to celebrate Black nature enthusiasts on May 31, the first day of #BlackBirdersWeek.

AG: You mentioned in a tweet that you grew up exploring outside on land your great-great-great-grandfather bought after emancipation. So your family has been there ever since?

MK: Yes. I grew up in Maryland, outside of Baltimore. Not really that far from any city, but very, very rural and situated near a state park. And because of that, I had a lot of nature at my disposal. I grew up listening to stories. My mom and my aunts and uncles would tell stories about how they would go out in the woods and explore. So I always had a connection to nature. I never questioned that connection because I felt like I lived in it—even just knowing that my family had been there for so long. The church cemetery was across the road, so I could go in the woods and see the graves of my ancestors.

AG: You also mentioned in that same tweet that your grandmother taught you to mark recapture, the biology technique to help estimate animal populations.

MK: Especially during the summers when my cousins would be there, and my grandmother had all these kids to deal with, we would go around looking for animals. We always found turtles, eastern box turtles. We would write our initials on them in nail polish, which we really probably shouldn’t have been doing, and take care of them for a night, then release them. She would always tell us, “Look for your turtles,” and we would find them again. Sometimes years later, we would find a turtle and be like, “Wait, that’s MK, that’s my turtle!” She really encouraged us to just go out there and explore. I think it really rubbed off on me.

Winter landscape painting.
A painting by Melissa Kemp of part of her family’s property. Image courtesy of Melissa Kemp

AG: How did you end up working in integrative biology? And why did you choose to focus on islands?

MK: I didn’t come into science in the most traditional way. When I was growing up, I always thought I was going to be an artist. I went to art magnet schools as a kid and trained at a really high level, mostly painting and drawing. I still approach science in a way that is similar to how I approach art. This diligence of working on something for a very long time and also being open to feedback from others to make the work better. Art is a very iterative process. It can take years before a piece is done, and it’s not a sprint, it’s a marathon. I think a lot of the same concepts apply to science as well. And my eye for detail maybe helps me find nuances in materials I look at. When I’m working with fossils I’m constantly looking at different shapes and looking for differences in structures of the different fossils I’m handling.

I study how biodiversity in tropical regions originates both through processes of extinction and diversification, as well as colonization. Particularly, I’m interested in how changes in the environment then impact the different communities of organisms that we have. I’m interested in these past instances of change that we can see through the fossil record, because it’s the key to really understanding the biodiversity that we have today, but also helps us understand how biodiversity might change in the future.

Islands in particular are really interesting biologically, and there’s been a wealth of study of diverse life-forms of islands, particularly lizards. But we don’t really have as much literature on fossil occurrences of lizards. That’s why I started focusing on islands, because we really don’t have a thorough understanding of how we got to present day biodiversity.

Human-driven biodiversity change in the Caribbean did not start in 1492. There is a 7,000-year legacy of change.

AG: You recently published a paper that delves pretty deeply into that topic. Can you summarize what you were looking for and what you found?

MK: We were really interested in investigating how humans have modified the biota of the Caribbean, particularly through which species they’ve introduced. This paper is really thinking about what we are adding to the islands—and what are the impacts of what we’re adding? How do those introductions scale across time? We developed a database of species introductions by going through the archaeological literature, as well as the paleontological literature, to get a sense of what we know about species introductions, and then also what we don’t know.

I think one of the biggest takeaways is the fact that humans have been engineering the landscape for millennia, particularly these places that we think of as recently perturbed. Human-driven biodiversity change in the Caribbean did not start in 1492. There is a 7,000-year legacy of change. We have these terms that I don’t think are representative of the biodiversity of the Caribbean, like “New World.” They’re really terms steeped in European colonization, referring back to the Caribbean as something being “new” to Europeans, when people had been living there for a very, very long time.

When we think about what the Caribbean used to look like, if you ask somebody on the street that question, they’re probably going to think about before Columbus and Europeans came. And we are definitely interested in that period, very much so. But we’re also interested in what it looked like before any humans arrived. And we really want to acknowledge how Indigenous groups in the Caribbean moved around, what species they were bringing, how they were using species, and how their manipulation of the landscape changed biodiversity in the Caribbean.

AG: Why is it important to ask those questions? Not just culturally but also scientifically?

MK: We have to be realistic about what’s actually feasible. The ideal restoration target probably in the head of a lot of people in the public would be what the environment was like before we came and messed it all up. But it’s not a realistic target, in part because we’ve lost so many species that were in the landscape before humans arrived.

What we see in a lot of systems after an extinction of one animal is that you have an extinction cascade where other things go extinct because organisms are interconnected with one another. They don’t exist in silos in the landscape. So, if we remove a pollinator, the plants that were pollinated by it might also undergo decline. They might also go extinct. And that might affect soil erosion, for example. Maybe their roots provided important structure for soil. And if you’re eroding soil, maybe you’re interrupting something else’s habitat. So we would want to restore this system so that that plant is there, and so that that plant is pollinated by an organism in the system—but it might not be possible to do all of those things. So, we have to think about, what is it that we are hoping to accomplish through restoration?

Paleobiologist in cave with headlamp.
Melissa Kemp excavating a cave site on the island of Marie-Galante, Guadeloupe. Image courtesty of Melissa Kemp

Maybe another takeaway from our research would be thinking about introductions of species and what they mean biologically. There’s a lot of different terminologies that we use for introduced species—I think one of the most common one is “invasive,” because we often think about the negative impacts of species introductions. Certainly there were instances where species had very, very negative impacts, but then there are also instances where species don’t seem to be having a negative impact on the environment and maybe are actually doing good things for those ecosystems.

The Caribbean had a lot of endemic mammals prior to human colonization. There were monkeys and a lot of really unique mammals—like these animals called Nesophontes, which are these shrewlike insectivores that are no longer there. We think that a lot of them were really important pollinators in the ecosystem that were then lost. But with the introduction of new birds to the Caribbean, for example, it’s possible that some of that loss of pollinators, that ecological service, may have been restored.

AG: I’ve read that paleontology in the tropics is particularly difficult. What makes it so hard?

MK: The environment of the tropics is not really conducive to fossilization processes. You need stable temperatures, ideally, cold temperatures and dry weather, to get good fossilization—and things covered up really quickly. The tropics are very hot and very humid. It’s just so hot, it’s so wet, that it’s going to erode away very quickly compared to something that’s in the Arctic, for example. There’s much more rapid disintegration when it’s hot and humid. Microbes breaking things down is certainly part of it. Also exposure to UV light—there’s physical damage being done to the material as well as biological damage.

So we don’t have a lot of fossilization in the tropics, but we do have some, particularly in environments where the material is somewhat shielded. Almost all of the work that I conduct is done in caves. We’re going through often heavily forested areas, in limestone landscapes where the humidity and precipitation cuts through the limestone and creates cavities. Usually materials get in there through water flow—when, let’s say, there’s a hurricane.

A lot of it is very fragmented bones. We’re not getting a full lizard, with the skin removed and the bones in perfect position. Some of them have features that are identifiable, some of them do not. I think that’s one of the reasons people have been turned off studying them in the past. A lot you can look at with the naked eye and figure out what part of the skeleton it is, but some of them you need to look at under a microscope.

A tiny lizard jaw fossil in a person's hand.
A fossilized piece of the upper jaw of a lizard, retrieved from cave sediments on the island of Marie-Galante, Guadeloupe. Image courtesy of Melissa Kemp

AG: So what techniques have you used to sort of get around those challenges?

MK: The biggest thing is just not to disregard the data that do exist and brush it aside. If you want to get material from the tropics, it’s not necessarily going to be very, very flashy in the same way that maybe a T. rex skull would be, but there are valuable data out there. Another thing that we do to get around some of the challenges is we just keep on looking. It requires us to interface with people in that area, talking to people about where caves are, if they’ve ever seen fossils.

So it’s very much a community effort, in terms of the work that we do. Finding sites with the help of local people. So local people who are out there exploring the caves for fun often have been a real godsend for us, very helpful in orienting us on the land. They’re almost always happy to show us and then interact with us when we tell them more about what we’re doing. And that’s always really fun.

I think it’s a function of where I do fieldwork that I have always felt safe in the field. I work in spaces where there are very diverse cultures that are not my own, often cultures where Black people are dominant or brown people are dominant. When I worked in Guadeloupe, for example—a French-speaking island in the Lesser Antilles where the majority of people are Black and Creole—if I kept my mouth shut, people just assumed I was from Guadeloupe. Being an outsider hasn’t been a source of fear in those landscapes.

Just seeing my grandmother as a Black property owner in a small town where there were not many other Black property owners was very inspiring. I don’t know if it’s the right word for it, but I felt that the outdoors belonged to me and that it was my right to be there.

AG: To that end, what’s important about the conversations we’re having now, around the incident with Christian Cooper and the #BlackInNature and #BlackBirdersWeek hashtags? What would you hope might come out of them?

MK: It’s important because it reinforces, particularly for us as Black people, that we belong here, that this country is ours. We had a very, very instrumental part in creating what we have today in this country, even as we continue to be oppressed. I think it’s also important for non-Black people to hear that as well, that they recognize those contributions. I feel very privileged to have had a very positive association with the outdoors all my life. Just seeing my grandmother as a Black property owner in a small town where there were not many other Black property owners was very inspiring. I don’t know if it’s the right word for it, but I felt that the outdoors belonged to me and that it was my right to be there.

I heard messages going through school from other people like, “Oh, nature is more of a white space.” But I really rejected those messages because I had this pride in my family history, and my connection to the land, and my family’s connection to the land. I just felt like everyone else had it all wrong, that they just didn’t know the history of this country well enough—how tied, for better or for worse, African Americans are to the land. It’s a very painful history, sometimes, to think about how many Black Americans got to this country, why we were brought to this country in the first place, to work the land that white people didn’t want to work.

For me, at least, learning that history has really made me feel more grounded in the space that I occupy. I’ve always felt grounded because of my very strong family history. But I know a lot of Black Americans don’t have that. Talking to distant cousins that I share lineage with further back, helping them learn about the history of enslavement of our family, has really helped ground them as well.

Whenever people may have made snide comments—“I’m afraid of the woods,” or, “The woods is a white space”—I’m very comfortable with my story and being like, “Well, I’m here. My family’s here. They’ve been on this land for six generations. You can’t tell me it doesn’t belong to me.”

Male Anolis carolinensis Faces Off with Anolis sagrei

 

Introduced brown anoles were washed in with Hurricane Harvey nearly three years ago to my yard near downtown Houston. The yard had established green anoles. Now I see the two species interacting. Here’s an example of two males interacting on my azalea bush in the front yard.

Vasotocin and Chemical Communication in Anolis carolinensis

 

A male green anole basking on my porch in Atlanta, Georgia. (Photo source S. M. Campos)

Growing up in Texas, I often found Anolis carolinensis green anoles (my first love) basking on my front porch and developed an early obsession with studying their natural behavior. Green anoles are the only anole endemic to North America (but see Wegener et al. (2019) suggesting the Cuban green anole, Anolis porcatus, is the same species). Anolis carolinensis are often referred to as American Chameleons due to their ability to switch between green and brown skin colors, despite being a completely different family than true chameleons. In graduate school, I worked with a different lizard genus, Sceloporus (from Greek “skelos” meaning leg, “poros” meaning hole), named for the scent producing glands on their inner thighs called femoral glands. The realization that some lizards modulate their social behavior based on chemical information that is deposited by other lizards was pivotal in my research career. Here, I’ll discuss chemical communication in A. carolinensis and the serendipitous discovery that the neuropeptide arginine vasotocin (AVT) plays some role in stimulating this chemical communication.

Anolis is an important animal model for studying the neuroendocrine control of visual communication due to their hormonal modulation of  vibrant color displays and conspicuous push up displays. Large eyes and brain areas dedicated to processing visual information suggest that detecting and responding to the visual environment is very important to anole survival and fitness. In contrast, anoles do not have the femoral or precloacal glands described in other lizards, which are used to deposit scent marks. Their olfactory bulbs (the portion of their brains that responds to volatile and non-volatile chemical signals) are tiny structures that are nestled in front of their eyes and behind their nares, attached to the rest of the brain by a long narrow nerve tract. Therefore, it is not all that surprising that anoles have long been considered microsmatic, relying very little on their sense of smell.

A CT scan of Anolis sagrei showing the main and accessory olfactory bulbs (yellow and blue arrows, respectively). The main olfactory bulb responds to volatile chemicals detected by the olfactory epithelium in the nose (such as odors in the air) and the accessory olfactory bulb responds to non-volatile chemicals detected by the vomeronasal organ. (Source Photo by Ed Stanley, arrows added by S. M. Campos)

So what is the deal with this peptide hormone, AVT? AVT and its mammalian homologue vasopressin (AVP) regulate social behavior in animals and decades of research has shown that AVT works within the visual sensory system of green anoles to modulate competitive and reproductive interactions. In non-reptilian animals like fish and mammals, AVT/AVP plays a similar role in modulating social interactions through the chemosensory system. Whether AVT influences chemosensory behavior in reptiles is unknown, representing an important gap in our understanding of the evolution of social behavior.

Now, the serendipitous part of the story. My postdoc advisor, Walter Wilczynski, built his career studying how AVT impacts visual communication in social interactions of frogs and green anoles. Previous work showed that green anoles can differentiate between AVT-treated and saline-treated males during live social interactions, but found no obvious differences in visual display rates between AVT-treated and saline-treated males, suggesting differences in behavior may be due to available chemical information. In the present study, we asked  whether an untreated lizard responds to a live AVT-treated male by altering its rate of chemosensory behavior, which we would expect if AVT-males and saline-males emit different chemical signals.

From left to right: Study authors Stephanie M. Campos, Walter Wilczynski, and Valentina Rojas. (Photo source S. M. Campos)

While lizards breathe in odors in a manner similar to humans (olfaction), they also have a secondary sense of “smell” called vomerolfaction. The latter involves using their tongues to bring chemicals from the outside environment into their mouths and deliver those chemicals to the vomerolfactory organ (often referred to as Jacobson’s organ in snakes) located in the roof of their mouths. We can easily quantify chemosensory behavior involving the tongue by counting the number of licks (tongue touches to a substrate, such as a rock), tongue flicks (tongue extrusions into the air), and lip smacks (draws odors into the mouth) a lizard performs. Use of these behaviors give us an estimate of a lizard’s level of interest in the chemical information available in their immediate environment. Chin wiping, or jaw rubbing, is another chemosensory behavior that may either deposit chemical signals or help to detect chemical signals already on a substrate. We provide short video clips in the online version of our article to show each of these behaviors.

In our experiment, we gave adult male green anoles an intraperitoneal injection of either an AVT or saline (control) solution, then introduced an untreated lizard (male or female) into the home tank of the treated lizard for a filmed 30-minute interaction. We measured rates of chemosensory behavior and the latency to perform these different behaviors. Since lizards tend to use higher rates of tongue flick behavior for exploratory purposes as they move around their environments (Cooper et al. 1994; Mason 1992), we also counted short bouts of locomotion.

Untreated males that interacted with AVT-males performed more tongue flicks and lip smacks compared to males that interacted with saline-males. Interestingly, lizards that interacted with AVT-males tended to move around less compared to lizards that interacted with saline-males. This suggests that the higher rates of chemosensory behavior by untreated males that interacted with AVT-males was not simply due to an increase in locomotion. We also found that untreated males moved around more than untreated females, regardless of treatment, demonstrating a general sex difference in locomotion among green anoles. We found no significant differences between treatments in chemosensory behavior performed by untreated females.

Lizards in their home tanks. (Photo source S. M. Campos)

When we examined the behavior of treatment males (which received injections), we found that AVT-males were faster than saline-males to perform a chemical display and, more specifically, a tongue flick toward untreated males. This suggests that AVT increases the level of initial interest in chemical information that is available during asocial encounters.

What about visual displays? We found no significant differences in visual display rates of untreated lizards, but did find that as treatment males performed more visual displays, untreated lizards moved around more (Supplementary Materials).

These results collectively suggest that AVT impacts chemosensory behavior during social interactions in green anoles, even in untreated social partners. More broadly, the mechanisms used by AVT to impact chemosensory behavior may be evolutionarily conserved. Our results are consistent with previous work linking AVP in mammals and AVT in fish to chemosensory-mediated interactions, such that AVT in reptiles deserves more research attention in the future. Furthermore, even in microsmatic lizards like Anolis, the impact of chemical communication on social dynamics should not be ignored. This study examined social dynamics between two live lizards and did not isolate the chemical signal. Thus, further work is necessary to determine whether similar changes in chemosensory displays occur when isolated chemical stimuli are presented to untreated lizards.

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