Evidence for evolutionary determinism in the signal design of lizards?

Photographs of a subset of lacertid lizard species used in this study. From the left top to the right bottom: Acanthodactylus beershebensis, Lacerta bilineata, Dalmatolacerta oxycephala, Podarcis melisellensis, Tropidosaura gularis, Podarcis siculus, Heliobolus lugubris, Algyroides nigropunctatus, Lacerta media.

Photographs of a subset of lacertid lizard species used in this study. From the left top to the right bottom: Acanthodactylus beershebensis, Lacerta bilineata, Dalmatolacerta oxycephala, Podarcis melisellensis, Tropidosaura gularis, Podarcis siculus, Heliobolus lugubris, Algyroides nigropunctatus, Lacerta media.

The vast array of signals used in animal communication is a continuous source of awe and a hot topic in evolutionary and behavioral research. One important factor contributing to the signal diversity we witness today is ‘signal efficacy’: the ability of a signal to travel efficiently through the environment and attract the receiver’s attention. With this in mind, natural selection is expected to mold signal design for maximum efficacy of information transmission and detectability, leading to signal variation among populations/species living in different environments. To illustrate, a recent study by Tess Driessens and colleagues assessed the degree of variation in the dewlap design of Anolis sagrei by comparing 17 populations distributed across the Caribbean (Fig. 1).

Phylogenetic relationships among seventeen Anolis sagrei populations. Pie charts illustrate dewlap pattern proportions for each population per sex (black = solid; light grey = marginal; dark grey = spotted). Photographs represent male and female dewlaps of typical individuals from every population.

Fig. 1 — Phylogenetic relationships among 17 Anolis sagrei populations. Pie charts illustrate dewlap pattern proportions for each population per sex (black = solid; light grey = marginal; dark grey = spotted). Photographs represent male and female dewlaps of typical individuals from every population.

Their findings showed large interpopulational variation in dewlap size, pattern, and color, and more interesting, they established a link between the dewlap design of brown anoles and the environment they live in. Lizards occurring in more ‘xeric’ environments had a higher proportion of solid dewlaps with a higher UV reflectance; lizards inhabiting ‘mesic’ environments had predominantly marginal dewlaps showing high reflectance in red. This was true for both males and females. Like Ng et al. (2011) and their observations on dewlap variation in A. distichus across an environmental gradient, Driessens et al. (2017) interpret their findings as evidence for adaptive divergence of a signaling apparatus.

Surprisingly though, while there are numerous great examples of comparative studies finding support for convergent evolution in visual and acoustic signaling systems, (e.g. Endler 1992; Fleishman 1992; Nicholls & Goldizen 2006, to say a few), similar (comparative) studies, but then, on the phenotype of chemical signals are almost entirely lacking. This is probably due to the combination of only very recent developments in chemical analytical and statistical comparative tools, the time researchers need to assemble a large-scale multi-species chemical dataset, and perhaps due to our own predisposition to visual and auditory signals. Currently, the proper analytical tools for studying natural products chemistry are available and affordable, permitting comprehensive taxon-wide research on the evolution of chemical signal diversity and design. Ultimately, there has never been a better time as now to be a comparative chemical ecologist.

Photograph of the cloacal region of a male lacertid lizard (Lacerta agilis), showing his numerous femoral pores with protruding glandular secretion.

Photograph of the cloacal region of a male lacertid lizard (Lacerta agilis), showing his numerous femoral pores with protruding glandular secretion.

Finally, three Belgians, two Spaniards and one Greek (sounds like the start of a joke with ample potential) took up the challenge to examine variation in the chemical signal design of lizards. Although underrepresented in studies on chemical signal diversity, lizards are an excellent group for investigating chemical signal evolution, as many of them they bear numerous glands on their thighs that secrete waxy substances, which they deposit while moving through their habitat. These secretions are often considered the leading source of chemical signals involved in lizard communication.

The study started with a quest. A quest to collect gland secretions of as many species as possible (within a PhD timeframe). Luckily, we were fortunate enough to be able to count on the help of many collaborators (Shai Meiri, Chris Broeckhoven, …). We focussed on lacertid lizards, as they are a species-rich family distributed over a wide geographical area, and known to rely strongly on chemical communication in several contexts.

In total, we sampled secretions from 64 species throughout, Europe, Africa, and Asia, covering a wide array of habitats and climate regions: from the Mediterranean maquis over the alpine meadows in the Pyrenees Mountains, to the sandy Israeli dunes and the Kalahari Desert of South Africa (Fig. 2). Back in the lab, we determined the chemical composition and chemical ‘richness’ (number of different chemical compounds) of the secretions using GC-MS, and obtained climate data for all catch-localities from online databases.

Map showing the sample localities of the 64 lizard species under study.

Fig. 2 — Map showing the sample localities of the 64 lizard species under study.

Our gathered data showed considerable variation in the chemical richness and composition of lacertid secretion. Shared-ancestry failed to explain among-species patterns of variation, hinting that chemical signals may change relative rapidly. Most interestingly, our findings revealed a strong relationship between the environmental conditions species live in and the chemical composition of their glandular secretions. On the one hand, lizards living in ‘xeric’ environments, characterized by high temperatures and arid conditions, contained higher proportions of stable and heavy-weight compounds in their secretions. Hot and dry conditions increase the evaporation rate of chemicals, and so, decreasing the longevity of a signal. Stable and heavy-weight compounds most likely reduce evaporation rate and counteract the rapid signal fade-out through evaporation, generating a highly persistent scent-mark. On the other hand, species inhabiting wet, humid conditions produced highly aromatic and low-weight secretions containing numerous different compounds. This chemical mix probably creates a volatile-rich signal that can be used for long-distance airborne communication.

While we cannot deny that these findings of convergent evolution in the design of chemicals signals are fascinating, some would say this outcome is not unexpected.

“[…] a cadre of scientists has taken the […] view, that convergence is the expectation, that it is pervasive, and that we should not be surprised to discover that multiple species […] have evolved the same features to adapt to similar environmental circumstances. From this perceived ubiquity, the scientists draw a broader conclusion: evolution is deterministic, driven by natural selection to repeatedly evolve the same adaptive solutions to problems posed buy the environment. — J. Losos (Improbable Destinies, p. 33)

Nonetheless, I am confident to state that using by far the largest comparative dataset amassed to-date to examine patterns of chemical signal divergence, we have provided strong evidence for a significant relationship between chemical signal design and prevailing environmental conditions, which may results from differential selection on signaling efficacy (Baeckens et al. 2017).

T-shirt Contest for Anolis Symposium VII Now Open!

T-shirt from the 1999 Anolis symposium at Penn State

T-shirt from the 1999 Anolis symposium at Penn State

As you may have heard in the announcement of the 7th Anolis symposium, we are searching for the official t-shirt design! You’re all surely aware of how talented our community is, as exemplified by past photo and poetry competitions, so we are asking you all to submit your best designs! A panel of discerning anolologists will choose the winning design, and the winner will receive glory, bragging rights, and pride in knowing that their artwork will be memorialized in t-shirt form for all to admire (the winner will also receive a free shirt).

Designs must meet the following criteria:
Style: line drawings are preferred
Size: Must fit neatly into a 8” x 8” square
Number of colors: 2
File type: high-quality .jpg, .png files or illustrator files.

Also, lease be aware that we may have to make minor alterations to the winning design in order for it to fit onto a t-shirt.

Front of the shirt from the 2009 symposium

Front of the shirt from the 2009 symposium

Please send all submissions to anolis2018@gmail.com with the subject line “anole t-shirt contest” by October 20, 2017!

Stay tuned for the winning design, and may the odds be in your favor! We look forward to seeing all of your submissions. For more information on the symposium, be sure to check out the official page!

p.s. Who still has a t-shirt from the 1989 meeting? Photo?

Back of the t-shirt from the 2009 symposium at Harvard

Back of the t-shirt from the 2009 symposium at Harvard

Request for Anolis aquaticus Photos and Sightings

Photo by Anolis aquaticus from wildherps.com.

Hello anole enthusiasts!

A quick note and a request from your Anolis aquaticus correspondent. Our new paper on stress-related body color brightening in Anolis aquaticus was recently selected as Editor’s Choice in the Canadian Journal of Zoology. In it, we document a genus-atypical direction of color change following exposure to a stressor, possibly related to optimizing camouflage in the water anole’s unusual habitat. Enjoy!

We are embarking on a new research direction with these wonderful watery critters. In our early stages of surveying, I’d like to ask for your help.

We are exploring morphological and behavioral variation across the water anole’s range to explore several hypotheses related to coloration, habitat lighting, temperature, and stress.
For example, dewlap coloration seems to be fairly variable: water anole dewlaps from our sites at Las Cruces Biological Station are red-orange (left), but at Osa the dewlaps are much yellower (e.g., screen shot taken from Brave Wilderness’s video* on the water anole, right).

In addition, we’re also interested in knowing a little more about water anoles in the riparian zones that are found in otherwise deforested tropical pasture lands. We’ve put together a map of all known collection sites of museum specimens and published studies (sites shown without exact coordinates in the interest of species’ protection; grey sites are approximate).

Anolis aquaticus collection and sightings

You can help by sharing with us your photographs of water anoles (dewlaps are of special interest, but any photographs would be appreciated) and/or locality data** of Anolis aquaticus sightings or collection. Locations of sightings in pasture/agricultural areas are especially needed!

Lindseyns @ gmail.com
Lindsey.swierk @ yale.edu

Thank you for your help!

*A very enthusiastic group called Brave Wilderness posted a video about their search for the “mysterious” water anole. I have mixed feelings about it and its less-than-perfectly-accurate information, but it certainly captures kids’ imaginations!

**To keep this charismatic species safe and help prevent poaching, please send any GPS coordinates to me directly rather than posting them publicly.

Anolis garmani in South Florida; 11 June 2016

Anolis garmani, the Jamaican giant anole; Miami-Dade county, Florida (11 June 2016, Nikon D7100).

Anolis garmani, the Jamaican giant anole; Miami-Dade county, Florida (11 June 2016, Nikon D7100).

Every year, I try to get down to south Florida at least a couple of times to stomp around for non-native anoles and other lizards. To date, I’ve only managed to find and photograph three Jamaican giant anoles, Anolis garmani, in south Florida — three individuals over two specific visits to the Miami-Dade area. The first two were in June of 2016, and the third (and largest) was in August 2017. The garmani featured here was the second wee giant from that first visit.

I’d been anxious to photograph garmani for quite some time, and we (James Stroud, Eric-Alain Parker, and myself) were more than a little jazzed to get our hands on both of those garmanis.  A. garmani was quite high on my holy-grail list for south Florida non-natives, and, whereas this garmani may have been lacking in the “giant” aspect, it certainly didn’t lack in its color play. The lead image above through the following three profile shots were all taken within the span of two minutes (1:26pm through 1:28pm):

Anolis garmani [B], 11 June 2016 (1)

Anolis garmani [B], 11 June 2016 (2)

Anolis garmani [B], 11 June 2016 (3)

When we first spotted this particular wee giant biding its time in the plenty of existence, it was sporting the familiar bright emerald green:

Anolis garmani [B], 11 June 2016 (5)

Minutes later, in hand and not too thrilled about its potential lifespan outlook, the colors shifted quite dark…

Anolis garmani [B], 11 June 2016 (4)

…and then, more comfortably, back to a more-emerald green base:

Anolis garmani [B], 11 June 2016 (6)

Looking down from above, it had a fairly typical anole head from a central Floridian’s perspective…

Anolis garmani [B], 11 June 2016 (8)

But looking up from below? An extremely awesome speckled circus of contrast and patterning:

Anolis garmani [B], 11 June 2016 (7)

Yeah, this was one hell of a lizard to get to work with. Actually, all three of them were. I’ll save the bulk of photographs for the other two individuals for a future time, but for quick reference, here’s a single shot of each:

This is the first individual we found on June 2016:

Anolis garmani [A], 11 June 2016

And here’s the much-larger male Eric and I tracked down (and almost caught) in August 2017:

Anolis garmani, 06 August 2017

~ janson

Are Brown Anoles in Florida Really Driving Green Anoles to Extinction III: A Post-Irma Update

Almost anyone who cares about anoles in the US  is aware of the hypothesis that the arrival of brown anoles (Anolis sagrei) into Florida has driven declines in the abundance of native green anoles  (A. carolinensis). Though there is certainly evidence that this hypothesis may be valid to some extent, we’ve previously wondered if the decline is as severe as folks seem to think it is. Have green anoles instead simply shifted to higher perches where we don’t see them as often? An informal mark-recapture effort conducted in Gainesville FL suggests that green anoles may in fact be quite abundant, and  based on the evolutionary history of green and brown anoles across their ranges, we do in fact expect green anoles to shift upwards where they co-occur with brown anoles.

Green anoles, increasingly elusive in Florida

Green anoles, increasingly elusive in Florida

We now have yet another piece of evidence that green anoles may be thriving at the tops of trees , just out of sight. Because of Hurricane Irma, which wreaked havoc across Florida last week, many of those tree canopies have fallen to the ground. And Miami herpetologist Steven Whitfield  reported yesterday seeing “more green anoles in the past two days than I have in the two months before that.” This observation was confirmed by other local biologists as well, in comments on Whitfield’s initial Facebook post that said “Green anoles are all over the place. Seems they were around up in the canopy, but now the canopy is on the ground so they’re easy to see.”


Help Train iNaturalist’s Artificial Intelligence to Identify Anole Species from Photographs!

iNaturalist has built an artificial intelligence that can identify species from photographs. You can read more about this work here. It’s a powerful tool to help connect people to the natural world and help grassroots conservation efforts overcome species identification issues.

This artificial intelligence now works on about 20,000 species globally for which we have sufficient data to on which to train the model. We need your help to make it work better on the genus Anolis!
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There are 416 known species of anole, but only 197 species have been observed on iNaturalist. And only about 25 species have enough observations (~20) to include in the artificial intelligence.

We need your help to:

  1. Upload your photos of anoles, particularly those which are data deficient in iNaturalist
  2. identify photos of anoles posted by others so that they can be used to train the artificial intelligence

To get started, navigate to the genus Anolis page on iNaturalist by clicking on ‘Species’ in the menu and searching for the genus Anolis.
Asset 9@3xOnce you’re on the genus Anolis page, 1. you can see the current count of how many Anole species of the total have been observed. Click ‘View all’ to see the full histogram. 2. Clicking on the Trends tab will list some of the ‘Wanted’ species that haven’t yet been observed as well as recent additions to the tally. As more Anole observations are uploaded and identified, the stats on this page will update.
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Upload your photos of anoles
First Log In or Sign Up to iNaturalist.
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Then Click ‘Add’ from the dropdown in the main menu to launch the upload tool.
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Drag your anole photos into the upload tool. Each card represents a single observation, you can drag them to combine them. Make sure you add 1. identifications, 2. dates, and 3. locations to each card. Then, 4. submit your observations.
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Identify photos of anoles posted by others
Assuming you’re logged in to your account, Click ‘Identify’ under ‘Observations’ in the main menu to launch the identify tool.
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From the identify tool, 1. Enter ‘Anoles’ in the ‘Species’ field and 2. optionally add a country or other location into the ‘Place’ field to filter observations of Anoles that need identifications. 3. Click on an observation to view it in more detail. If you can identify it, 4. click ‘Add ID’, choose a species, and 5. Save your identification.
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Genomic Signatures of Climate Adaptation in Anolis cybotes

Anolis cybotes, female from Barahona, Dominican Republic

Anolis cybotes, female from Barahona, Dominican Republic

Katharina Wollenberg Valero & Ariel Rodríguez

Thermal adaptation is the evolution of the ability to persist in novel thermal environments. Phenotypic characters that allow such adaptation, as well as the resulting shifts in the geographic distributions of species, are an emerging field of study in the midst of a changing global climate. Yet, the genomic basis of such phenotypic adaptation is less well understood, so recent efforts of evolutionary biologists are now aiming at one emerging question: Which genes determine thermal adaptation, and are these the same across different populations and species? Luckily, Anolis is yet again at the forefront of novel discoveries being made in this field (see Campbell-Staton et al., 2017).

Many studies have independently identified genes that are responding to changes in the thermal environment, be it through change of expression under an acute stress, or through changes in the DNA sequence as evolutionary response. In 2014, we gathered information on such thermal adaptation candidate genes from Drosophila to Homo sapiens from the literature.

From the published evidence, we extracted a set of gene functions that potentially underlie climatic adaptation. We were able to match these with functions that are known from phenotypic thermal adaptation (Wollenberg Valero et al., 2014). Interestingly, the products of these genes (Proteins, RNAs) were found to be functionally related with each other thus forming gene networks within the cellular environment.

The Caribbean Anolis cybotes is widely distributed across Hispaniola, and thrives in hot, xeric environments just as well as in cooler and more humid montane environments. The rift valley of Lago Enriquillo heats up to 40.5 °C (104.9 °F), and a few instances of frost were reported at the highest peak (Pico Duarte at 3,098m elevation) – so population survival across these climatic extremes does not seem to be a trivial endeavor.

Populations of this species show pronounced differences between montane and lowland forms in morphology, physiology, behavior, and perch use (Wollenberg et al., 2013Muñoz et al., 2014), which led us to expect that at least some of this variation should have a genetic basis. Thus, we set up to test whether Anolis cybotes displays any signatures of genomic adaptation to the diverse kinds of environments it inhabits, and whether any genes showing evidence for selection can also be subsumed under the candidate functions we defined previously.

We sampled tissue of these lizards from several high and low elevations (the specimens being the same as in Wollenberg et al., 2013), and looked for variation according to climatic differences via RAD sequencing and subsequent analysis with LFMM. RAD sequencing generates a reduced representation of the target genome, producing thousands of short sequences representing the distribution of the restriction enzyme’s cutting sites throughout the genome. Owing to this property, it cannot be expected that this type of data will necessarily contain “the total set of adaptation genes”; to this effect, detailed genome sequencing is required and such studies have been done in some model organisms (stickleback fish, beech mice, Drosophila, etc.). Continue reading Genomic Signatures of Climate Adaptation in Anolis cybotes

Dying Anoles with Eye Problems in Louisiana


AA reader Jonathan McFarland sent in these disturbing photos with the following remarks:

“I hope you can shed some light on what’s happening to the wild anoles in my Louisiana suburban yard. This week I have found two adolescents with both eyes bleeding or infected. The attached pictures show only one side of the specimens but in each case both eyes appeared as shown. Any info you could provide would be much appreciated.”

Thoughts, anyone?


Anolis Symposium VII to be Held March 17-18, 2018 at Fairchild Botanical Gardens in Miami

IMG_7932 Jamaican giant anole (Anolis garmani) – one of the many non-native anoles you may see in Miami, FL.

In 2018 it will be nearly ten years since the last Anolis symposium was held at the Museum of Comparative Zoology at Harvard University. Given the rapid advances and exciting new discoveries in Anolis biology, it’s time to organize the 7th Anolis symposium! So, with this official announcement, please mark the weekend of March 17-18th 2018 in your calendars to come and visit the wonderfully tropical lizard-world of Miami, FL!

The aim of the symposium is to bring together Anolis biologists from diverse backgrounds to share their excitement and discoveries for these marvelous lizards. In this symposium, we hope to foster cross-disciplinary collaborations of people working with anoles and to broaden our general understanding of their biology and natural history. Miami was chosen not only for its spectacular anole diversity, but because of its ready access to anolologists living outside of mainland United States.

Miami, FL, is an ideal place in the USA to host this meeting! Over the past 100 years, eight species of Caribbean anoles have joined one native species in becoming established in south Florida. This meeting will be held on the weekend of March 17-18th 2018, which broadly overlaps with at least one weekend of the Spring Break holiday for most US schools, and does not conflict with other major meetings as far as we’re aware. We hope that this will facilitate good attendance! The symposium will be held at the Fairchild Tropical Botanic Gardens, which is home to a diverse community of exotic lizards, including six (!) species of anoles (read more about them here and on Anole Annals here!).

This post serves as a ‘save the date‘ – stay tuned the Symposium page for more information on conference registration, abstract submission for oral and poster presentations, and article submission for the Anolis Newsletter VII.

12671732_10154152036842074_4486533256117940736_o (2) Puerto Rican crested anoles (A. cristatellus) in Fairchild Tropical Botanic Gardens

Updates on the Development of Anolis as a “Model Clade” of Integrative Analyses of Anatomical Evolution

Staging series page 1

The first plate from the Sanger et al. (2008) Anolis staging series.

Long time readers of this blog will likely remember the many posts I’ve made trumpeting the utility of anoles for integrative analysis of anatomical diversity, studies that gain perspective from disparate biological fields. The community has come a long way since we published the first staging series of anole embryology only nine years ago. To some this may be old news, but I still find this pace exciting and personally motivating. Decades of ecological and evolutionary studies have created a strong foundation upon which to build new insights about the molecular and developmental underpinnings of anatomical diversity. My lab’s questions boil down to trying to shed light on the developmental origins of adaptive anatomical variation. Otherwise stated, where did the requisite phenotypic variation arise from during the adaptive radiation of anoles. The inherently comparative nature of these studies led me to use anoles as a “model clade,” a group of species that provides the capacity to obtain evolutionary insights the way that “model species” have provided pure developmental biologists and geneticists the power to deduce insights in their areas.

One of the highest hurdles to the progression of Anolis as a model system has been long-term access to living embryos. Although comparative biology is a powerful approach for evolutionary studies, one of the hallmark lessons of modern Evo-devo is the need to experimentally validate the candidate molecular changes associated with anatomical evolution. If I hypothesize that Gene X underlies some phenotypic difference between two species, I must 1) show that it is expressed at the time when the difference arises and 2) somehow tweak the expression of Gene X at that time and in that tissue to show that the changes parallel those observed in nature. To do this you must have access to an embryo in culture, unencumbered from its opaque shell.

Over the past several years several people have been working on ways to gain access to lizard embryos. The first report of a culturing method was by Tschopp et al., who used lentivirus to trace cell migration into the genitalia and limbs. I have not personally been able to consistently replicate those conditions, especially for later embryos. Bonnie Kircher and I, however, recently published two relatively “simple” culturing protocols as part of a new book, Avian and Reptilian Developmental Biology. One of the challenges of earlier culturing attempts was bacterial and fungal growth. As a first step to combatting these invaders, we developed a protocol to sterilize the eggs, soaking the eggs in a weak bleach solution (yes, a literal bleach solution). From there we were off and running.

The first method we describe, following from advice from Raul Diaz, has worked on eggs a few days old to those that are nearly half way through their incubation period. Using a fine pair of scissors, we separate the outer opaque lays of the shell from the inner membranes that surround the embryo and yolk. This bag-of-embryo is then transferred to a small culture dish with a nutrient rich media and drugs to further combat bacterial and fungal contamination. This culturing system has worked well for up to ten days, roughly from the time the limbs are developing digits to the time that the limbs have visible scales on them. (Check out the video!) In principle, this method will allow better access to the embryo for viral injection or the application of small molecule inhibitors that disrupt particular signaling pathways.

Be warned, the second method is a little more Frankensteinian. Because the membranes cover the embryo, visualizing development remains difficult. To circumvent this problem, we developed a protocol where we explant a piece of anole tissue, such as the developing

A developing A. sagrei foot explanting onto a chicken embryo

A developing A. sagrei foot explanting onto a chicken embryo

limb, to a chicken embryo. Both anole and chicken seem to fare well at 33 degrees Celsius, below the standard incubation conditions of the chicken and above that of our anoles. Development appears to proceed normally in the explanted tissue, just as it does would in an embryo within its own shell. These experiments still have a relatively low success rate, but when the explant takes, it works well. To better visualize the tissue for imaging we also stained the tissue with a vital fluorescent dye before the transfer, giving the tissue a wonderful Halloween feel.

The work is far from over. These culturing protocols are just the first step and will not work for all applications. More technically challenging steps especially await those that want to manipulate the anole genome or target distinct patterns of gene expression. This is only the start of what’s to come. For more details about these protocols you can download the chapter here.

Knight Anoles Introduced to Another Island: Abaco, Bahamas

Photo by Joel Sartore

The knight anole is really getting around these days: Turks & Caicos, Grand Bahama, Grand Cayman and many other islands. Now they’ve  made it to Abaco, Bahamas, where one individual was captured and possibly two others seen (see article in IRCF Reptiles and Amphibians)Abaco Scientist has an insightful discussion of introduced reptiles and amphibians on Abaco.

Female Green Anole with Sand on Her Head–Been Egg-Laying?

Photo-chronicler of Floridian natural history Karen Cusick has done it again. We’ve been captivated by her backyard photos before, but here’s photo of a female green anole with sand on its snout. Been digging holes to bury her eggs, maybe? And while Karen observed the little lady lizard, it suddenly darted into the bushed and emerged with a meal!


Anolis Lizards Have Their Own Homing Device

Carolina Anole

Lizards are active creatures, often running around in new territories to explore and find food. Sometimes they encounter challenges that keep them from running too far. When they wander away from home, how do they get back? It’s a question that’s led researchers to study this topic.

After watching the daily routines of Anolis lizards by using tracking devices placed on their backs, researcher Manuel Leal learned that they return to the same home again and again. This established the next question which was to find out how the lizards knew how to get back. Birds have a similar ability to find their way home. Although the exact method has not been discovered, it’s possible that lizards have similar abilities and functioning as birds in finding their own again.

They Claim Their Homes

Anolis lizards, especially males, claim trees as home territories, fighting to keep any newcomers off their bit of land. They’ve proven that they remember exactly where they stake out their claim, and like all animals, they like structure in their environment, including the location of where they spend their days and nights. Some studies prove that after disorienting the lizards and placing them a far distance from their home, they can still find their way back within 24 hours.

Then They Listen

U.S.  Geological Society geologist John Hagstrum proposed that in order to get back home, pigeons use sounds wave; extensive studies on pigeons show that they use low-frequency sound waves to create an acoustic map of where they are. This way, they can identify predators and safe spaces to land. Some have wondered whether  Anolis lizards might have similar capabilities that are advantageous for homing.

It’s hard to argue that lizards use any other method to get where they came from. Tests have proven shown results that indicate that lizards don’t have the ability to use any magnetic senses or distinguish polarizing light. Still, they manage to baffle scientists who wonder at their complex societies and developed capabilities.

If you want to learn a little more on the topic of how Anolis lizards find their way home, you can see a short film done by Days Edge Productions that follows Leal as he conducts his study.

An Update on Taking Toepad Pictures


I’ve taken more than four hundred toepad pictures using the new macro photography technique I introduced  in an earlier post and I’ve learned a few tricks that I want to share in this update.

First and foremost, I highly recommend this approach. For those of you looking to capture a lot of toepad data, particularly in the field, this kit is way faster and more portable than using a flatbed scanner and the images I’m getting are at least as sharp.


A few tips:

  • Petri dishes work great as a clear platform to place the lizard feet on. I found that the 60 mm diameter dishes were much easier to balance atop the lens (~40 mm in diameter) than the larger dishes I’d originally shown.
  • I cut and taped a scale bar to one edge of the petri dish so I wouldn’t have to worry about juggling a lizard and a tape measure.
  • Make sure you have several petri dishes – they scratch fast – and keep some ethanol and a kimwipe close at hand.


  • The app that lets you remotely trigger your iPhone is absolutely maddening. Do not download it. I’m not even going to relink the name. Instead, I suggest a much more stable alternative: connect your phone to your computer with the USB cable, open QuickTime Player, select File > New Movie Recording and click the down arrow next to the record button. This will give you the option to select your attached iPhone as a recording device. This live-view is far more stable and less frustrating. *Windows and android users I’m afraid I haven’t had an opportunity to sort out a solution for those platforms. If you know of something that works, please include in the comments!

Screen Shot 2017-08-21 at 3.47.58 PM

Unfortunately, through the live view all you can see is whether the lizard is in position. You cannot remotely trigger the shutter this way. That means you’ll need a second pair of hands to help. I found it worked best when my partner was in charge of putting the ID tag in the frame after I’d placed the lizard foot and then pushing the volume button on the side of the phone to trigger the camera shutter.

  • Lighting is really important. I suggested a headlamp in the previous post providing an oblique light source through the diffuser around the lens. I tried using a microscope fiber optic light source but I was really unhappy with the “warmth” of the light. I found that the white-LEDs in my headlamp produced a much more realistic looking image (see above). Also, make sure you don’t have any light sources above/behind the subject. Backlighting confuses the camera’s auto-contrasting and results in dark and sometimes unfocused images.

red dewlap

Florida Greens and the Suprascapular Spot

Miami-Dade county, Florida; 18 March 2017

Miami-Dade county, Florida; 18 March 2017

After scampering about much of North America the past few decades, I once again live  in my hometown of Ormond Beach, Florida — on the northern edge of Volusia county. When I was a kid, back in the late 70s and early 80s, I spent much of my time tangling with and studying our local anoles. The Carolina greens (A. carolinensis) were dominant back then, covering our walls, windows, trees, and (sometimes by forced measure) our ear lobes. Every now and then I’d find a Cuban brown (A. sagrei) — usually around the shopping centers and strip malls. Nowadays, of course, that coin has flipped. The Carolina greens have moved back up into the higher foliage and the Cuban browns dominate our shrubs, walls, and windows.

I remember actually finding a Cuban brown anole on our property in 1984 or so. I was in 4th grade, drunk on Star Wars and lizards. I managed to catch the little non-native lizard and put it in my anole terrarium (a homemade wood-and-open-screen enclosure my dad and I built). I was in the habit of catching anoles (and the occasional snake), keeping and watching them for a day or two, and then releasing them back into the yard. Needless to say, the Carolina green already in the enclosure wasn’t too thrilled with his new roommate. Though guilt eventually kicked in the following day, I admit I was somewhat delighted by the defensive/discomfort color play of that poor Carolina green. Usually, they’d be cool, smooth emerald green with very little patterning… but distressed or riled up Carolina greens certainly know how to put on a good color and pattern show.

Soon enough, I released the Carolina green back into the yard and kept the Cuban brown for another day or two. This little moment of tension, however, leads me to the point of this post: the distress patterns of our local Carolina green anoles. More specifically, I’m interested in the presence of a supraspacular dark spot that shows up with some individuals. It’s a dark spot with light trim that sometimes appears just above and behind the front shoulder line — as seen in this particularly ornate individual photographed in Miami-Dade county on 18 March 2017:

This Miami-Dade individual really stuck out to me. It’s patterning was distinct. It was quite large. It had that supraspacular spot. Most notably, it was still wielding quite a bit of green. Could this be A. porcatus? Like many naturalist-lizard enthusiasts, I tend to catch myself up in the eternal cycle of porcatus-or-not? when I’m in south Florida. Heh. Nowadays,  my assumptions generally fall on the side of A. carolinensis unless I’m with somebody more in-the-know who can tell me differently with confidence; this hasn’t happened yet. Honestly, I have a hard time seeing a clear difference between the two. I’m glad I’m not alone.

Though distinct, this fabulously mottled Green wasn’t the only Green I’ve photographed with that supraspacular spot. Here’s an impressive male tangling with a Cuban brown anole in the Lower Keys of Monroe county, Florida, on 08 June 2007:

Further north, in my home territory, I’ve only noticed and photographed two individuals with that spot, albeit with less figure-ground contrast between the spot and the trim.

Orange county, Florida (05 September 2011):

Anolis carolinensis, 05 September 2011

Alachua county, Florida (05 December 2011):

Anolis carolinensis, 05 December 2011

Both were in WTF-dark-mode (as I call it).

Of note, I spent a few years in Valdosta, Georgia, intensely watching anoles. Continue reading Florida Greens and the Suprascapular Spot

Condition Dependence of Shared Traits Differs between Sympatric Anolis Lizards

A male slender anole (Anolis limifrons)

A male slender anole (Anolis limifrons)

A walk through a tropical rainforest can reveal astonishing forms and colors of organisms – from vibrant poison frogs and coral snakes to the vegetative camouflage of stick insects and other cryptic creatures. Perhaps some of the most dramatic displays of variation can occur between the sexes, where males and females can differ so greatly in appearance that they resemble different species. Research in many systems has demonstrated that much of this variation is driven by sexual selection, the force responsible for the evolution of traits that are important for acquiring mates. Individuals may invest as much energy as possible into such sexually selected traits because doing so will give them a competitive advantage for mate acquisition. These traits are therefore considered condition dependent, as their expression is dependent upon the energetic condition of the individual that possesses them. While condition dependence has been the subject of many studies, it is not well known how it may vary between closely related species that share the same traits. If closely related species vary in condition dependence of their shared traits, then this implies that condition dependence could be important for the evolutionary diversity of sexually selected traits.

The rainforest at the La Selva Biological Station in Costa Rica

The lowland rainforest at the La Selva Biological Station in Costa Rica

Together with students from Grinnell College and Reed College, and as part of an OTS (Organization for Tropical Studies) course that I took as an undergraduate at the University of Virginia, we took to the lowland jungles of Costa Rica to answer this question. We studied two anole species from Costa Rica, the slender anole (Anolis limifrons) and the ground anole (Anolis humilis). Specifically, we tested whether several traits that they had in common exhibited condition dependence, including dewlap size, aspects of jaw morphology, and sprinting speed. To test for condition dependence, we first calculated two conventional indices of body condition, the residual index and the scaled mass index, which both take into account an organism’s mass, given its length. We then obtained residuals from the relationship between our variables of interest (dewlap size, jaw width, jaw length, and sprint speed) and snout-vent length (a measure of body length), which allowed us to control for the fact that trait sizes often scale with the overall size of an animal. Finally, we used bivariate linear regressions to test the effect of our indices of body condition on our residual traits of interest, with a significant positive relationship suggesting condition dependence. We found that dewlap size (a trait important for sexual signaling) and jaw width (a trait important for bite force and male combat) exhibited condition dependence in ground anoles, but not in slender anoles. In contrast, neither sprint speed nor jaw length were condition-dependent in either species. Importantly, the presence of condition dependence in one species, but not the other, implies that the condition dependence of shared traits is evolutionarily labile. Additionally, by detecting condition dependence in the dewlap of ground anoles, which have a larger dewlap given their body length when compared to slender anoles, our findings may indicate that the strength of sexual selection differs between these two species. Lastly, our research suggests that variation in condition dependence of the dewlap among species could contribute to the extraordinary diversity of dewlaps in the Anolis genus.

If you would like to read the full paper, published in the Journal of Experimental Zoology Part A, go to:http://onlinelibrary.wiley.com/doi/10.1002/jez.2076/epdf

Signals and Speciation: Do Dewlap Color Differences Predict Genetic Differences?

Dewlap and genetic differences between co-occurring Anolis distichus and A. brevirostris

Dewlap and genetic differences between Anolis distichus and A. brevirostris at sites where they co-occur on Hispaniola.

Here at Anole Annals, we’re all familiar with the replicated evolution of different anole ecomorph types in the Greater Antilles. However, divergence into these different ecomorph classes is not enough to explain how the group became so speciose on these islands. Additional factors must therefore have promoted speciation throughout the history of the group.

One potential factor is the flashy anole dewlap. Dewlap diversification across anoles has led to the remarkable array of dewlap color, pattern and size we see today. If dewlap differences did indeed drive speciation in anoles, or are involved with the maintenance of species boundaries, we might expect that as differences in dewlap color and pattern increases between species, genetic differentiation will also increase through fewer hybridization events.

In our study that just came out in the Journal of Herpetology, Rich Glor, Anthony Geneva, Sabina Noll and I set out to test this using two widespread species from the Anolis distichus species complex, A. distichus and A. brevirostris. These two species co-occur in many locations on Hispaniola and, while they often differ in dewlap color where they do co-occur (yellow with an orange patch vs. all pale yellow), in other areas, they co-occur with similarly pale dewlaps. Using mitochondrial DNA, microsatellite and AFLP data, we investigated patterns of genetic differentiation at four sites: two where the species differ in dewlap color, one where the species share the same dewlap color, and another where pale dewlapped A. brevirostris co-occurs with two A. distichus subspecies (one with a similarly pale dewlap and the other with an orange dewlap).

In general, we found that A. distichus and A. brevirostris looked like “good species,” with strong genetic differentiation and little evidence of hybridization, even at a site where they share the same dewlap color. This suggests that dewlap color differences are not associated with genetic differentiation in a manner one might expect if dewlaps were involved in the speciation process or in maintaining species boundaries. However, at the site where A. brevirostris co-occurs with two A. distichus subspecies with both similar and dissimilar dewlap colors, we found some evidence of hybridization and the species were not as highly genetically differentiated. This discrepancy suggests that site-specific factors could be influencing the dewlap’s role in speciation or maintaining species boundaries. For example, as Leo Fleishman’s and Manuel Leal’s work has shown (e.g. 1, 23), the dewlap’s effectiveness as a signal is dependent on the light environment. Further understanding about the environmental differences among our study sites, how species utilize the available light microhabitats within each site, and how the dewlap looks to anoles at each site could provide more insight into our findings.

On the other hand, perhaps we need to be looking beyond the dewlap and focusing instead on whole signaling displays. Anole behavioral displays can also be strikingly different among species (e.g. 1) and may instead be the key to understanding species diversification in Greater Antillean anoles.

Arthropod Predators of Anoles

Orange-legged wandering spider (Cupiennius coccineus) consuming house gecko (Hemidactylus frenatus) at Sirena Biological Station, Corcovado, Costa Rica

Red-legged wandering spider (Cupiennius coccineus) consuming a house gecko (Hemidactylus frenatus) at Sirena Biological Station, Corcovado, Costa Rica

When someone first asked me about the major predators of anoles, my first thought was to talk about curly-tailed lizards (Leiocephalus carinatus) in the Caribbean, vine snakes (Oxybelis spp.) in the neotropics [see my previous post on anole predation by O. aeneus at La Selva], and birds. I think that as herpetologists, we tend to fall into the trap of thinking of invertebrates as “lesser” taxa to be preyed upon by small vertebrates like lizards, and in turn for small vertebrates to be eaten by larger vertebrates.

I, too, when thinking about how selective pressures shape morphological variation in mainland and island habitats turned to fellow herps and birds as the primary predation pressure for mainland anoles. However, it wasn’t until I arrived in Costa Rica that I discovered the high prevalence of voracious arthropods, and I realized that our beloved lizards had much more to fear!

Orange wandering spider (Cupiennius getazi) with egg sac at La Selva Biological Station, Costa Rica

Orange wandering spider (Cupiennius getazi) with egg sac at La Selva Biological Station, Costa Rica

Red-legged wandering spider (Cupiennius coccineus) eating a pink katydid (Tettigoniidae: Phaneropterinae) at La Selva Biological Station, Costa Rica

Red-legged wandering spider (Cupiennius coccineus) eating a pink katydid (Tettigoniidae: Phaneropterinae) at La Selva Biological Station, Costa Rica

A large adult female mantis (Phasmomantis championi) at La Selva Biological Station, Costa Rica

A large adult female mantis (Phasmomantis championi) at La Selva Biological Station, Costa Rica

Conehead katydid (Tettigoniidae: Conocephalinae: Vestria sp.) at La Tarde, Osa Peninsula, Costa Rica

Conehead katydid (Tettigoniidae: Conocephalinae: Vestria sp.) at La Tarde, Osa Peninsula, Costa Rica

In a single night at La Selva, I could easily find dozens of large wandering spiders (Ctenidae), and if I pointed my headlamp higher in the trees I could see eyeshine from hundreds of spiders. Given the high density of large ctenids at La Selva, it is not unlikely that anoles and small tree frogs constitute a major portion of their diet. In fact, I wouldn’t be surprised if large arthropods are one of the most common predators of mainland anoles in some regions.

The same might be the case for giant mantids of the genera Macromantis and Phasmomantis, and conocephaline katydids sporting fearsome mandibles (e.g. Copiphora spp.). Since the invasive Chinese mantids (Tenodera sinensis) in North America are well documented to prey on hummingbirds almost equal in size to the mantids [see Nyffeler et al. 2017], surely larger and bulkier species in the neotropics can take lizards much smaller than themselves. Even though wandering spiders and conehead katydids are primarily nocturnal hunters, I have heard many stories of these arthropods being implicated in anole and tree frog predation. Research looking into how ctenids and nocturnal katydids forage would help determine if they can actually detect sleeping anoles or if predation events occur from the arthropods simply running in to the anoles while on the move.

If anyone here on Anole Annals has any anecdotal or photographic records, please comment below.

To throw a twist on this discussion, is it possible for a spider to prey on a lizard two and a half times its size? A new paper about a vertebrate-eating jumping spider (Salticidae) describes just that! Considering arthropods as possible major players in anole predation could shed light on behavioral and ecological studies of mainland anoles.

Figure 1 from Nyfeller et al. 2017, showing female jumping spiders (Phidippus regius) consuming Carolina anoles (Anolis carolinensis) and Cuban tree frogs (Osteopilus septentrionalis)

Figure 1 from Nyfeller et al. 2017, showing female jumping spiders (Phidippus regius) consuming Carolina anoles (Anolis carolinensis) and Cuban tree frogs (Osteopilus septentrionalis)

Here are a few more spider photos to wrap up this blog post.

Jumping spider (Salticidae: Phiale cf. guttata) eating an assassin bug (Reduviidae)

Jumping spider (Salticidae: Phiale cf. guttata) eating an assassin bug (Reduviidae)

Red-legged wandering spider (Cupiennius coccineus) consuming house gecko (Hemidactylus frenatus) at Sirena Biological Station, Corcovado, Costa Rica

Another angle of a red-legged wandering spider (Cupiennius coccineus) consuming a house gecko (Hemidactylus frenatus) at Sirena Biological Station, Corcovado, Costa Rica

Threat display of a Brazilian wandering spider (Phoneutria boliviensis) from Tárcoles, Costa Rica. A ctenid with medically significant venom.

Threat display of a Brazilian wandering spider (Phoneutria boliviensis) from Tárcoles, Costa Rica. A ctenid with medically significant venom.