I’m a professor of biology at Washington University in Saint Louis. I teach courses on evolution and biodiversity, and I am in charge of a new biodiversity center that is a collaboration between Wash. U., the Saint Louis Zoo, and the Missouri Botanical Garden.
What aspects of anole biology do you study, and what have you learned?
I’ve studied anoles for 32 years. In that time, I’ve studied their habitat use, biomechanics, behavior, evolutionary relationships, and many other aspects of their biological diversity. Probably the two key findings from my work—done in collaboration with many students, postdoctoral fellows and colleagues—are that the same set of habitat specialists (a.k.a., “ecomorphs”) have evolved independently on the four islands of the Caribbean in the Greater Antilleans (confirming ideas first put forward by Ernest Williams and Stan Rand) and that anoles adapt rapidly enough that evolution experiments can be conducted in nature, and evolutionary change observed over a small number of years.
How and why did you start studying anoles?
I did science projects on anoles in 8th and 12th grades, but it wasn’t until college, when I had the privilege of working with Ernest Williams and Greg Mayer at Harvard, that I learned about them in a serious way. Then, in graduate school, I went through many failed projects before re-discovering anoles on a summer field course offered by the Organization of Tropical Studies in Costa Rica. I’ve worked on anoles ever since.
What do you love most about studying anoles?
Not only are they fascinating creatures, but they can be studied in many different ways, allowing a wide variety of approaches to be taken to understand how they live their lives and how they’ve evolved.
What is your favorite anole species?
How can I pick just one? Species-for-species, the Jamaican radiation of anoles is the most fabulous, but there are many fabulous species: Anolis vermiculatus comes to mind, the Chamaeleolis clade. There are too many excellent anoles to choose just one…or 10!
Where can people learn more about you and follow you online?
I’m a professor in the Department of Biological Sciences at the University of Rhode Island. I teach classes in ecology, evolution and global change biology and conduct research on anoles with my students and postdocs. We study the evolutionary ecology of invasive species and urbanization, primarily in Miami, and the eco-evolutionary dynamics of anoles on small islands in the Bahamas. We combine lab and field work to answer questions about how anoles respond to the rapid environmental change caused by humans.
What aspects of anole biology do you study, and what have you learned?
I’m an evolutionary ecologist, which means my research spans a wide range of topics including behavior, ecology, evolution, genetics, morphology, and physiology. I’m fundamentally interested in how organisms respond to rapid changes in their environments and humans are often the cause of rapid environmental change, such as climate change, species invasions, and urbanization. Over twenty species of anoles have been introduced to places outside of their native ranges and a common theme for these invasions is that they originate from multiple locations in the native ranges of each species. Once introduced to a new area, anoles from different places in their native range interbreed to produce highly variable populations in non-native areas. Anoles readily evolve during these invasions, producing morphologies and physiological tolerances that differ from native-range populations. Another dimension of global change is urbanization and anoles respond in a variety of ways to city life. We have found that anoles living in cities change how they escape from predators, how they forage, where they perch and how they thermoregulate because of the urban heat island effect.
How and why did you start studying anoles?
I started working on anoles during my Ph.D. when I joined Jonathan Losos’ lab at Washington University in St. Louis in 2000 and I met an energetic and vibrant group of people passionate about ecology, evolution and anoles! I was dead-set on studying the quantitative genetics of anoles; I wanted to study the genetic basis of morphological traits and how natural selection works to shape the morphological variation we see in anoles. Like most fledgling dissertation plans…my plan changed after a few years. In my case, it was because of an exciting opportunity to visit Cuba and sample brown anole populations throughout the island. I then learned that this same species was introduced to Florida, Hawaii, Grand Cayman and many other places and I was hooked on figuring out the history of the invasion where did introduced population come from in the native range and how many times have they been introduced? I sequenced lots of DNA to use as markers of the geographic sources in the native range and I applied these same techniques to several other species of anoles introduced to Florida from the islands of the Greater Antilles – Hispaniola, Jamaica and Puerto Rico. The DNA sequences worked like an identification card to reveal the native-range origin of lizards sampled in introduced populations.
What do you love most about studying anoles?
I like working with great colleagues and students on challenging research questions, traveling to interesting locations in the Caribbean and south Florida, feeling like I can answer any question in ecology and evolution with anoles, and last but not least, I love catching lizards!
What is your favorite anole species?
I’m not sure I could pick just one. I love Anolis allisoni with its beautiful purple, blue and green coloration, but Anolis equestris, a crown giant, is so impressive with its large size and powerful jaws. I will always remember witnessing this species come out of nowhere running down a large trunk to chomp a poor little unsuspecting brown anole for lunch. But I have the most respect for the brown anole, Anolis sagrei, this species can live almost anywhere from tiny little islands in the Bahamas to the urban core of Miami. That’s one tough lizard!
Where can people learn more about you and follow you online?
The best place to learn more about my research is at our lab website – Kolbe Lab. We regularly update the lab news, personnel profiles and the scientific publications page.
I am an Assistant Professor in Biology at Rutgers University—Camden studying the evolutionary genomics of anoles. Before that I was a Postdoctoral Fellow at Harvard University in the laboratory of Jonathan Losos. I started working on anoles during my PhD in Ecology and Evolutionary Biology at the University of Rochester. My research combines a variety of evolutionary disciplines including population genomics, phylogenetics, and experimental animal crosses to ask questions about how new species arise.
What aspects of anole biology do you study, and what have you learned?
I study speciation, which is the process that leads one species to become two or more distinct species. I am interested in what evolutionary forces drive this process. One thing we have learned about speciation in anoles is that populations that are very similar by most measures can still show signs of speciation in progress.
How and why did you start studying anoles?
I have studied a lot of different organisms in my career – including fruit flies, fish, and freshwater mussels. I have even contributed to a paper on naked mole rats! While these studies have been great fun to work on, I have always loved lizards. My very first research project involved documenting the reptiles in a newly formed Florida State Park. Since then, lizards have always been a consistent theme in my work, even as I have branched out into other groups. As I became interested in studying the process of speciation, anoles seemed like an obvious choice. There are over 400 species of anoles, so they are clearly very good at speciation!
What do you love most about studying anoles?
Anoles are unique in that they straddle the divide between model and non-model organisms. Many of the most important discoveries made in evolutionary genetics have come from so-called model organisms like fruit flies, mice, and yeast. While we have made great strides in understanding the genetics and genomics of these species, our knowledge of their biology in nature is relatively limited. In contrast, decades of research on anoles, performed by countless scientists, has generated a tremendous amount of knowledge concerning the ecology and natural history of these lizards. In the last 15 years, we have added genomics to our anole research toolkit to the point where anoles are just a few steps behind model organisms in terms of the genetic tools available. I believe working on anoles now is as exciting as it has ever been as we now have the ability to combine these two bodies of knowledge to better understand how new species of anole arise.
What is your favorite anole species?
That’s a really difficult question. I’ve dedicated many years to studying Anolis distichus and Anolis sagrei and both are fascinating, charismatic species. Rather than pick between the two species I am closest to, I am going to stray outside of the species I have studied and say my favorite is Anolis conspersus. This species is hands down the prettiest lizard I have ever seen in person. In 2016, I had the opportunity to see the species up close in the only place it occurs naturally, the Caribbean island of Grand Cayman. I spent hours watching and photographing them and every time I thought I had seen the most striking body and dewlap coloration, the next would blow me away. While I haven’t had the occasion to do any research on Anolis conspersus, I hope to study them someday and pay these stunning lizards another visit.
Where can people learn more about you and follow you online?
Anoles are well known for the sharp differences in dewlap colour and size between females and males. However, this is not true for all the species of the genus. Anolis heterodermus is a large arboreal lizard that inhabits shrubs and small trees in the cloudy Andean forests in Colombia and northern Ecuador. Although males are slightly bigger than females, this species has no apparent sexual dimorphism in dewlap size or colouration. Anolis heterodermus is a slow-moving lizard that relies mainly on its body colour pattern to camouflage from predators, thus its common name Andean “chameleon.” Moreover, these lizards have a long prehensile tail which is very useful when moving through thin branches. Interestingly, males curl and swing their tail to their opponents during aggressive encounters.
The body colour pattern is incredibly variable in this species, but all animals have a small patch of bluish scales in the base of the tail. After keeping some of these lizards in captivity, I noticed that the colouration and size of this patch changed dramatically between animals, and even within the same animal over the course of the day. Every time I arrived at the lab in the morning, the patch was small and reddish (Fig. 1A) but after midday, it seemed bigger and with an intense blue colouration (Fig. 1B).
Figure 1: Colour and size variation in the tail patch of Anolis heterodermus. The same male has A) a reddish patch at 06:40 h and B) a bluish patch at 14:47 h.
I thought that the colour and/or size of this tail patch were somehow related to a male’s quality and that could be the reason why males display their tail in the combats. If my hypothesis was correct, males (but not females) would have a larger variation in patch colour and size that is dependant on the time of the day. With the help of some colleagues, I collected males and females of A. heterodermus across the Eastern Cordillera of Colombia. I housed the lizards separately and took photographs (Fig. 1) from each animal every hour between 6:30 to 18:00 h. On each photo, I measured the colour and size of the tail patch. Colour was scored as the ratio of blue vs. red intensities (Blue:Red score), where a larger score indicates bluer scales.
I found that the tail patch of Anolis heterodermus changed from red to blue throughout the day and was generally bluer in males. However, contrary to my hypothesis, the colour change was similar between females and males (Fig. 2). In addition, the coloured patch remained the same size throughout the day in both males and females but was bigger in males.
Figure 2. Diurnal colour change in the tail patch of males and females of Anolis heterodermus. Larger values of the Blue:Red score indicate bluer scales.
Active colour change in lizards often occurs in the context of intraspecific communication (e.g. territorial and courtship behaviour). However, my animals were kept isolated from each other; thus is unlikely that the change in colouration per se is conveying social information. Intriguingly, the highest values of blue colouration for both males and females were reached around midday, which corresponds to the natural peak of activity of the species and possibly to higher body temperatures. In this case, the colour change might be an indicator of animal activity or arousal. This could also explain why the blue colouration disappears at night (personal observation).
Finally, the fact that the patch was significantly bigger and bluer in males compared to females supports the hypothesis that the patch can be relevant in male interactions. It would be interesting to test if the colouration and size of the patch are related to male performance or overall quality.
These are just some of the many questions that still need to be answered about the colour change in the Andean “chameleon,” and this study highlights the importance of observations in the laboratory to identify traits that might be important but difficult to observe in nature.
Original article: Iván Beltrán(2019)Diurnal colour change in a sexually dimorphic trait in the Andean lizard Anolis heterodermus (Squamata: Dactyloidae),Journal of Natural History,53:1-2,45-55.DOI: 10.1080/00222933.2019.1572245
As we all know, anoles are super diverse, but how diverse exactly? I often read that there are ~400 species of anoles, but how many precisely? And what about subspecies? And who described them?
Other AA authors (e.g. Greg Mayer, Rich Glor) have written about these questions in the past, but I’d like to add to this thread of anole history by using a great new resource – Peter Uetz’s reptile database. If you’ve ever googled any reptile species, you’ve probably found yourself on the Reptile Database website at some point, which has great info on species taxonomy, distribution, and often natural history. But recently, the database itself was published in Zootaxa with some interesting stats and plots of reptile species descriptions over time. The database is nuts – it contains information on the taxonomy of literally every reptile species! It’s a really incredible resource. And since it’s got every reptile, it has every anole! So I decided to explore the Anolis section of this database.
First, a couple details – the main data contained in the database is the species taxonomy, species description date, and author(s) of the description. For the main summaries here, I treat every author of a species description as “describer” whether they are the lead author or not, so if someone is a lead author on one description, but a coauthor on nine others, they will be summarized as describing 10 species. However, the info on number of coauthors per description and author order is retained. Also important to note that the database only contains current taxonomy; species or subspecies that have been sunk/synonymized/etc. won’t appear.
So let’s jump in! According to the Reptile Database at the time of publication (Jan 2018), there are 427 species of anoles. The number of new species descriptions peaked in the 1860’s, again in the 1930’s, and again in recent years. A number of you reading this are no doubt represented on this plot!
In total, Anolis species have been described by 171 different researchers. 21% of these species descriptions were done by just three people: E. D. Cope, Ernest Williams, and Gunther Koehler (currently active). Wow! Many of the remaining authors (47%) only described one species. The rest fall somewhere in the middle. After the three mentioned above, the researchers who have described the most species are Garrido (26), Boulenger (22), Barbour (18), Schwartz (18), Dumeril (15), Hedges (15), Poe (15), and Smith (15).
We’ve looked at how species have been described by different researchers, but I was curious to know how collaborative this process has been – how many authors normally contribute to a given species description? Well, 274 species descriptions were written by one author, 92 by two authors, and 61 by three or more authors. So most anole species were described by one or two authors.
As one might expect, as science as a whole has become more collaborative, the number of coauthors for species descriptions has increased over time. Almost all descriptions up to the early 1900’s were done by one author, while in the 2000’s that’s almost never been the case.
Now what about subspecies? According to the Reptile Database, there are currently 144 described subspecies from 36 different species. Most of those species have just a few subspecies, but a few of them have higher numbers, with a maximum of 11 in A. distichus and A. equestris. In the case of subspecies, 52% were described by just three people! Albert Schwartz, Orlando Garrido, and Skip Lazell (hi Skip!). Subspecies descriptions really hit a peak in the 1970s.
Most of the species that are split into subspecies are distributed in the Caribbean islands (33 of the total 36). Is this just because more phylogeography and taxonomy work has been done on the islands? Or is this another example of how patterns of diversification are different between mainland and island environments? I think probably the first.
Lastly, what was the first anole described? I thought it was A. carolinensis, but was surprised to learn that it was actually A. bimaculatus! Although that species was originally described as Lacerta bimaculata, later reassigned to Anolis. The first species actually described as Anolis was still not A. carolinensis though – it was A. auratus! Described by F. M. Daudin in 1802. So why is A. carolinensis the type specimen for the genus? Well, in 1963, Hobart Smith, Ernst Williams, and Skip Lazell petitioned* to change the type species to A. carolinensis due to a dubious prior designation of the genus type. The ICZN voted to approve their proposal, and granted the change in 1986**. For those interested in a deep dive, take a look at the 1986 decision**, which describes the back-and-forth between the the original proposers, the nay voters (Dupuis and Holthuis), a yay voter (Thompson), Jay Savage, and A. F. Stimson in the Bulletin of Zoological Nomenclature.
I hope you’ve enjoyed this brief history of Anolis by the numbers. Stay tuned for Part II: a look at the history of the Anolis collection at the Museum of Comparative Zoology!
An orange Anolis sagrei used in the study. Image by Beth Reinke.
Readers of Anole Annals know that Florida populations of Anolis sagrei now include red-orange individuals [1, 2, 3]. I learned more about this new color by conducting the first scientific study on orange skin coloration in Anolis sagrei.
Before I go any further, I owe a thank you to those who documented their orange A. sagrei findings on Anole Annals. Previous posts confirmed that what I was seeing in the lab wasn’t an anomaly. As I learned more about the sightings of these orange anoles, it became apparent that the orange phenotype was rather common. The posts also helped me understand when this odd coloration was first noticed (only in the last decade!). I was even able to meet with one contributor in person.
The first thing I noticed was that there is quite a bit of diversity in the distribution of orange coloration on the bodies of the lizards themselves. Most of the posts on Anole Annals showcase full-bodied orange lizards [1, 2, 3]. I found that partial orange coloration was just as common. Take, for example, this male whose orange coloration was limited to his tail and hind legs.
A biologist’s first intuition is to wonder how differences in coloration might influence survival. Most of my research project was focused on identifying fitness differences between brown and orange lizards. I was working under the impression that orange skin suddenly appeared in the population and became common very quickly. I knew that there are cases when new phenotypes become common for no reason (genetic drift). Nonetheless, we don’t normally expect to see a new phenotype become common in a short amount of time. I suspected that orange lizards had an easier time surviving or breeding than the brown ones. But I was surprised that a color as conspicuous as orange could be so successful. I reasoned that it couldn’t have helped them camouflage, so why are orange lizards surviving and reproducing?
Maybe it had something to do with mate choice. Since males use their orange dewlaps to attract females, it might be that a completely orange male would look particularly stunning to a female. Even though orange might have made the males an easier target for predators, the effect on reproductive success may have outweighed the risk of predation. This is the hypothesis that I had in mind for most of the project and the one that made the most sense to me. It’s fitting, then, that when I ran a behavioral experiment in the lab, the females didn’t care at all about color! They were much more interested in males that performed a lot of pushups and head bobs (behaviors that many species of lizards use to communicate). These pushups and head bobs demonstrate a male’s physical fitness to a female.
Maybe orange reflected something in their physiology, then? I ran two different experiments to test endurance and sprint speed. The tests of endurance and sprint speed in particular took up most of the time of the project; it turns out live animals don’t usually do what you need them to do. Despite their penchant for sprinting out of sight in the wild, getting lizards to run in the lab was more difficult than you might guess. The endurance tests involved a custom-built lizard-sized treadmill. More often than not, the lizards would treat it like a moving sidewalk you’d find at the airport. Other times they’d wriggle into the machine itself (at no risk to them) and I’d have to take apart the treadmill, one screw at a time, to fish them out. No images of that, sadly.
To measure sprint speed, I needed the lizards to run up a wooden pole. Here’s a video of me trying to convince lizards to run up that pole.
I became more interested in paleontology after this project. Dead animals behave more predictably.
After all that, the data didn’t point to any difference in orange and brown lizards’ endurance or sprinting ability. I took a step back to get to the bottom of something I knew I could answer. I wanted to identify the pigments that they were using to color their skin. Having read about what gives Anolis sagrei dewlaps their red and orange color, I was expecting to see two classes of pigments in orange lizard skin: carotenoids and pterins. No one had extracted pigments from even brown A. sagrei skin before, but I wasn’t expecting to see much in non-orange skin.
I boiled lizard skin in all sorts of carcinogenic solutions to extract the pigments. Then I separated the two types of pigments in test tubes – carotenoids at the top and pterins at the bottom.
As expected, the dewlaps had both types of pigments. Unexpectedly, brown lizard skin contained pterins. I thought this was a little odd since we don’t see red or orange on brown lizards. But, no one had done this before, so I didn’t quite know what to expect. Like brown lizard skin, orange lizard skin had pterins, but not carotenoids. This surprised me because it suggested that the orange color in orange lizards might not be due to the addition of a pigment so much as the absence of one. Melanin (another class of pigment that produces brown and black colors) typically masks the effects of other pigments that may be present. So, although I was unable to test this myself, I now suspect that the orange color is caused by a lack of melanin.
It was time to revisit that camouflage idea. I had taken for granted that orange was too conspicuous to conceal a lizard, but I needed the data to back up my claim. I collected quantitative data on brown and orange lizards’ skin color by using a spectrophotometer, which records color as the wavelengths of light reflected off a surface. The result is something that looks like this:
What A. sagrei dewlaps look like to a spectrophotometer.
One of my collaborators, Dr. Beth Reinke, applied these data to a visual model to predict how A. sagrei’s bird predators would see the new color. She identified that orange anoles are less conspicuous to bird predators. Now the strongest lead is what I had ruled out when I first began the project: camouflage!
So what’s up with orange A. sagrei? The color doesn’t make them more attractive to mates nor does it correlate to increased physical fitness. Because orange and brown skin contain the same kind of orange-producing pigment, my best guess for the mechanism is a lack of melanin in the areas that appear orange. And, although the new color looks conspicuous to humans, it may help orange individuals hide from bird predators. The benefits of orange as camouflage may explain why the new color persists in south-Floridian populations of A. sagrei.
There’s a lot left to know about orange anoles. A good next step would be to test the “orange as camouflage” result in the field. Additionally, research into the genetic basis of this phenotype may identify how it arose and the mechanism behind it. Some breeders have suggested that orange coloration is genetically dominant over brown coloration. This is something I wanted to identify in breeding experiments, but time ran out before I graduated from college.
Orange A. sagrei remain enigmatic. I hope to hear more about orange anoles from enthusiasts in the lab and the field!
Paper: Erritouni YR, Reinke BA, Calsbeek R (2018) A novel body coloration phenotype in Anolis sagrei: Implications for physiology, fitness, and predation. PLoS ONE 13(12): e0209261. https://doi.org/10.1371/journal.pone.0209261
Brown anoles (A. sagrei) thrive in urban environments.
More and more research is highlighting how living in cities impacts the organisms that exploit urban habitats. Some research in anoles even highlights how organism may be adapting via evolution to these novel urban habitats!
We found that for all groups of anoles studied (male and female brown anoles, and male crested anoles), lizards living in the urbanized habitats were larger (see figure below), but showed no differences in body condition, or how much body mass they had per unit length. Larger body size can be associated with increased fitness in anoles, so the larger size of urban lizards could represent an advantage for anoles living in cities.
Lizards from urban (blue) habitats were larger than those from natural (green) habitats.
Despite cities being known to have higher temperatures (the urban heat island effect), including at our study sites, we found no differences in the temperatures that lizards from urban and natural sites preferred. Our preferred temp values were in line with those found for native range populations of these species, which suggests that we are not seeing adaptation of preferred body temperature to the warmer conditions in very urban parts of Miami. This means that lizards living in cities could end up having higher body temperatures than they would prefer, a potential cost to using urban environments, though see Andrew Battles’ recent paper for a more detailed look at this issue!
Lastly, we examined the presence of parasites in the body cavities of these lizards. Most of the parasites that we found were nematodes in the digestive tract, though we also found some pentastomids, crazy crustacean parasites, in the lungs of crested anoles! We found no difference in the presence of parasites in lizards from urban or natural sites, although brown anoles did consistently have parasites more often than crested anoles. When we looked at parasite infection intensity, or the number of parasites in lizards that had them, we did see that brown anoles in urban habitats had significantly higher parasite loads than those in natural habitats. This result indicates that increased parasitism could be a cost of living in cities for anoles, though it may vary from species to species.
Crested anoles from both urban (blue) and natural (green) habitats have similar levels of infection intensity (number of parasites) to brown anoles in natural habitats, but brown anoles in urban habitats show significantly higher levels of infection intensity.
Overall, our work suggests that there may be advantages (larger body size) and costs (non-optimal body temperatures, higher parasite loads) for anoles living in cities, and that these may vary even between species that are quite similar ecologically. Anoles are an emerging study system in urban ecology, so stay tuned for what should be a fascinating variety of papers on city-loving anoles in the near future!
Christopher J Thawley, Haley A Moniz, Amanda J Merritt, Andrew C Battles, Sozos N Michaelides, Jason J Kolbe; Urbanization affects body size and parasitism but not thermal preferences in Anolis lizards, Journal of Urban Ecology, Volume 5, Issue 1, 1 January 2019, juy031, https://doi.org/10.1093/jue/juy031
Recently, the guys over at SquaMates Podcast — a podcast about all things herpetological — asked if I would be interested in joining them for a special episode on anoles to discuss the recent Anolis Newsletter VII. The podcast is hosted by Mark D. Sherz, Ethan Kocak, and Gabriel Ugueto, who was responsible for the wonderful drawing which graced the cover of ANVII.
The Anole Special, “Episode 8: The Last Anole”, has just gone live and you can listen to it at the link below. Here’s hoping the title isn’t true and there are many more anole episodes to come in the future!
In a somewhat autobiographical romp through the history of species delimitation, David Hillis, in a recently published article in the Journal of Herpetology, details the state-of-the-field in terms of phylogenetic and species delimitation, detailing both the many advances that have been made over the last few decades, but also pointing out where things are out of whack and need some recalibration. There’s much more to the article than the figure above, but that’s a good place to start!
UCLA professor Shane Campbell-Staton was recently interviewed on the science podcast Ologies, hosted by Alie Ward. Shane is a thermophysiologist and anolologist (you may remember the stories about A. carolinensis and the polar vortex on AA a couple of years ago (here, here, and here). That’s not all Shane has going on though; his lab is branching out in lots of different directions (listen to learn about some cool/hot new projects) and he’s also hosting The Biology of Superheroes Podcast. As per usual, Shane’s interview is filled with jaw-dropping factoids (bees that cook their wasp predators), words of wisdom (write tomorrow’s to-do list every night before bed), lots of lizards, and many an endearing anecdote (though we never did find out who wins Superman vs. Ali).
You can listen to the full interview here, or on iTunes, Spotify, or wherever you get your podcasts.
