My name is Roy Ang, and I am currently a Genetics PhD student in the Fraser lab at Stanford University. I am interested in studying the cis-regulatory adaptations that lead to morphological changes and the evolution of different ecomorphs. I do so by studying available genetic data on different anole species and identifying correlations with morphological variation in limb length or lamellae count.
Most of my work now is based on morphological data from Mahler et al. (2010), but I am curious to know if anyone here is collecting similar data on Lesser Antillean anoles, such as A. wattsi or A. leachii? If you happen to be working in this area, I would love to get in touch with you! Please contact me at email@example.com.
Anolis desechensis is a variant of A. cristatellus found on the Puerto Rican island of Desecheo. The island has a diversity of other species, many of them of conservation value, but it has been devastated by introduced species. The good news: concerted actions have removed most of the invaders, and the island is recovering! Read all about it in the post below, which appeared on Cool Green Science.
Recovery: The Salvation of Desecheo National Wildlife Refuge
Good news is scarce in Puerto Rico these days. But if you look 13 miles to the west, on a 358-acre island called Desecheo, you’ll find a mother lode.
Desecheo, once the Caribbean’s most important brown booby breeding habitat, was made a national wildlife refuge in 1976. This was something of a futile gesture because invasive aliens — black rats, feral goats and macaque monkeys — had extirpated the brown boobies (which once numbered around 10,000) along with the seven other nesting sea-bird species. The invasive species also blighted forests and the federally threatened Higo Chumbo cactus, and reduced native land birds, reptiles and invertebrates to a shadow of their former abundance.
Desecheo was an ecological wasteland.
In 1976 there was virtually nothing the U.S. Fish and Wildlife Service could do about that. But in 1994 it acquired a powerful ally with the founding of Island Conservation (IC), a nonprofit team of biologists dedicated to preventing extinctions around the globe. There was and is no shortage of work. Although islands comprise a miniscule fraction of Earth’s landmass they harbor about half of all endangered species. At least 80 percent of the 245 recorded animal extinctions since 1500 have occurred on islands.
IC and multiple partners (frequently The Nature Conservancy) have thus far removed invasive mammals from 59 islands thereby benefitting 1,090 populations of 402 native species and subspecies. Research just released by IC, Birdlife International, the International Union for Conservation of Nature, and the University of California at Santa Cruz demonstrates that 41 percent of the planet’s vertebrates threatened with extinction can be saved by ridding certain islands of invasive mammals.
Last July, after an exhausting, expensive ten-year battle, IC and its partners certified that Desecheo National Wildlife Refuge was free of macaques (if you don’t count a single, aging female) and rats. The last feral goat was removed in 2009.
Such successes were impossible before the advent of recent technology including: the anticoagulant rodenticide brodifacoum, sufficiently fast acting to kill rats before they learn to avoid it; thermal imaging which allows partners to detect alien mammals at night and in forest canopies; GIS (Geographic Information System) for recording precise positions on Earth’s surface so that rodenticide-laced bait can be applied to every part of an island; and satellite imaging to determine when islands lose greenery so eradications can happen when less food is available to aliens.
Even with goats (introduced in 1788) and rats (introduced circa 1900) a few sea birds hung on. What finally did them in were the macaques, unleashed in 1966 for medical research by the then clueless National Institutes of Health.
Ecological Illiteracy Leads to Ecological Wastelands
The most formidable obstacle confronting IC and partners is ecological illiteracy. They get savaged by chemophobes who fear and loathe all poisons in all situations and by animal-rights types who defend alien wildlife, rats included, and decry the often unavoidable, increasingly minor and always inconsequential bykill of non-target wildlife.
The Desecheo project, however, proceeded unopposed. It wasn’t as if Puerto Ricans are more enlightened than other Americans. It’s just that they live in an alien-infested hell of macaques that tear up their gardens and bite them, exposing them to the herpes B virus (relatively harmless to macaques but usually fatal to humans), feral hogs and feral goats which also tear up their gardens, feral cats which infect them and wildlife with toxoplasmosis, and a biblical plague of rats and house mice.
Public reaction was different at Channel Islands National Park off southern California. When IC and partners set about saving and restoring a host of native species including the endangered ashy storm-petrel, imperiled Scripps’s murrelet, Cassin’s Auklet and Anacapa deer mouse by eradicating black rats, they were delayed by litigation. Typical commentary in the local press included: “Species go extinct all the time” and “Who are humans to call other species invasive?” Park rangers were obliged to wear bulletproof vests; and shortly before the first bait application, two men landed on Anacapa Island in an inflatable boat and started flinging pellets of vitamin K — brodifacoum’s antidote.
Had Anacapa been infested with macaques, recovery would have been a political impossibility.
Prudently, IC doesn’t talk it up about how it, the USDA’s Wildlife Services and a nonprofit group called White Buffalo removed macaques from Desecheo. But it’s important for the public to understand just how difficult and heroic was this effort, a first in island recovery. Learning as they worked, the partners first tried baiting and trapping. It failed. They had better results with rifles but had to bring in thermal-imaging equipment when the macaques retreated to the forest canopy.
“It was a hell hole,” recalls White Buffalo’s president, Dr. Anthony DeNicola. “Ninety or 100 degrees with no place to get out of the sun.”
IC and White Buffalo staffers would sit for 14 hours a day, scanning trees and terrain with binoculars. Toward the end it would take them a month to take out one or two monkeys. Finally they had to bring in tagged, sterilized “Judas animals” from Puerto Rico to socialize with the few remaining wild ones and reveal their presence. It took five years to finish the job.
Safe for Birds Again
The reluctance of IC to offer such details in its press releases and interviews doesn’t mean it tries to fly under the radar. “That would be inconsistent with our values,” remarks Heath Packard, IC’s director of government and public relations. It would also be illegal under the National Environmental Policy Act, which requires IC and its federal partners to engage with the public, disclosing alternatives and their various consequences.
“The outreach is always the same,” says IC’s global affairs director, Gregg Howald. “It’s just that results of that outreach vary widely from location to location.”
Citing the Polynesian rat eradication on Lehua Island off Hawaii, completed September 13, Howald offers this: “For years we’d been reaching out to the community with blog postings, talking with people and holding public meetings. It wasn’t until late July that a few vocal individuals realized this was really going to happen and started trying to stop it, making lots of noise and drawing media attention. It was just off the rails. We had a public meeting in which people yelled at us for over two hours. It was horrible. Despite all our outreach, we wound up with a confrontation that started a cascade of anti-project misinformation.”
For example, the Huffington Post ran an op-ed by one Maggie Sergio (whom it identified as a “writer, conservationist and concerned citizen of the planet”) suggesting that five pilot whales, which later beached themselves on Kauai and died (as they commonly do everywhere they exist) were victims of diphacinone — an impossibility. Sergio also claimed that “three aerial poison drops, totaling 11.5 tons of diphacinone” were delivered by helicopter. There isn’t enough diphacinone in the world to drop 11.5 tons. What was dropped was 8.5 tons of bait of which .005 percent was diphacinone. This and other misinformation was recycled by local media.
It was exactly this sort of fear mongering that motivated the partners to use diphacinone, less toxic and therefore less effective than brodifacoum. But apparently it worked. “So far so good,” says Howald. All the rats we collared and monitored died. It will take time to tell for sure [if the project succeeded]. We did state in our environmental assessment that if diphacinone failed, we could come back in with brodifacoum.”
Either way Lehua Island will again be safe for federally threatened Newell’s shearwaters, band-rumped storm-petrels now a candidate for Endangered Species Act protection, wedge-tailed shearwaters, brown boobies, red-footed boobies, Laysan albatrosses, black-footed albatrosses, Christmas shearwaters, Bulwer’s petrels, red-tailed tropicbirds and black noddies.
Recovery of Desecheo’s native ecosystem is just beginning, but already results are spectacular. Despite insect surveys beginning in 1914 dingy purplewing butterflies had never been observed on the island. In April their caterpillars were so abundant they defoliated Almacigo trees. (Leaves quickly regenerated.)
Endemic reptiles are doing much better, particularly Desecheo anoles, Desecheo ameivas and Puerto Rican racer snakes. A Puerto Rican skink, a species rarely observed in the past, has been sighted. Invertebrate density has increased. Native fruit trees and flowers are suddenly flourishing. New leaves, preferred by goats, rats and macaques, are more abundant than in anyone’s memory. Higo Chumbo cacti are rapidly recovering; and forests, particularly understories, appear to be growing faster.
At this writing no one has visited the island since the hurricanes, but there are no refuge buildings on Desecheo; and in the tropics vegetation bounces back quickly. As of mid-October there were new leaves and blooms on Puerto Rico.
In its island-hoping war against introduced aliens IC builds on each victory. “One thing I’ve learned is that you can get so focused on individual projects you start to lose sight of the forest for the trees,” remarks Howald. “Now that we’ve had this success what does it mean? What’s the potential of Desecheo; what’s the leverage?”
The potential and leverage, he explains, is demonstration to regulatory agencies, the funding community and, especially, the public: that the choice is salvation of nearly half the world’s endangered species or the continued presence of alien invasives; that we can’t have both; that if we want the former, we have to take out the latter; and that we can do that without risk to humans or native wildlife populations.
The Florida green anole, Anolis carolinensis, is a trunk-crown anole, usually seen on trees, often high up. So, what’s it doing on grasses low down? Alberto Estrada, an expert on Cuban lizards, reports the following:
It caught my attention to observe several specimens of A. carolinensis (smaller than the one in the photo above) posted on the spikes of the tall grass spikes on the lake shore at Miramar Pineland Park near Pembroke Pines, Broward, FL (25.97 ° N, -80.25W °). In my experience in Cuba with his close relatives A. porcatus and A. allisoni, I do not remember having seen them in such situations. They reminded me of the typical grass anoles such as A. pulchellus from Puerto Rico. As much as I searched, I did not find adults. In Tree Tops Park (26.07ºN, -80.28°W), if I have seen adults on the planks of the platform in the swamp and I have seen juveniles or subadults like the one the photo below in the reeds and on grasses that stand out from the water. I lived and worked for many years in the Ciénaga de Zapata, I had many experiences in marshy environments in the keys that surround Cuba, and I do not remember a single case of seeing the green anoles of Cuba in the same situation. Interesting experience!
In turn, this reminds me of observations I made of Anolis allisoni on Roatan, as evident in the photo below:
Caption from original post: You thought I was kidding about the Roatan allisoni doing their best grass anole imitation? See how many you find in this photo. There are at least five, but maybe I missed some.
Thanks to all who submitted photos for the Anole Annals 2017 calendar contest–we received lots of great submissions! We’ve narrowed it down to the top 24, and now it’s time for you to vote! Choose your 5 favorites in the poll below. You can click on the thumbnail to view full-size images. You have 10 days to vote – poll closes next Friday at midnight (11/17). Spread the word!
It’s been too long since we’ve discussed that pointy-snouted marvel, the Little Cayman anole. Fortunately, Flicker, the bimonthly magazine of the Terrestrial Resources Unit of the Department of the Environment of the Cayman Islands, has ended the drought, featuring a new research project on one of our favorite species in its most recent issue.
For those of you who can’t get enough of Anolis maynardi, check out some previous AA posts [1, 2, 3]. For more, just type “maynardi” into the search bar to the right.
Grand prize winner for the 2016 contest – Anolis equestris potior by Jesus Reina Carvajal
Thanks to all of you that have sent in photos for our calendar contest! For those who haven’t sent anything yet, now’s your chance – there is ONE WEEK left before the deadline (next Monday, November 6) so if you plan to submit, be sure to do so soon!
To remind you, the rules are here:
Submit your photos (as many as you’d like) as email attachments to firstname.lastname@example.org. To make sure that your submissions arrive, please send an accompanying email without any attachments to confirm that we’ve received them. Photos must be at least 150 dpi and print to a size of 11 x 17 inches. If you are unsure how to resize your images, the simplest thing to do is to submit the raw image files produced by your digital camera (or if you must, a high quality scan of a printed image). If you elect to alter your own images, don’t forget that it’s always better to resize than to resample. Images with watermarks or other digital alterations that extend beyond color correction, sharpening and other basic editing will not be accepted. We are not going to deal with formal copyright law and ask only your permission to use your image for the calendar and related content on Anole Annals (more specifically, by submitting your photos, you are agreeing to allow us to use them in the calendar). We, in turn, agree that your images will never be used without attribution and that we will not profit financially from their use (the small amount of royalties we receive are used to purchase calendars for the winners). Please only submit photos you’ve taken yourself, not from other photographers–by submitting photos, you are declaring that you are the photographer and have the authority to allow the photograph to be used in the calendar if it is chosen.
Please provide a short description of the photo that includes: (1) the species name, (2) the location where the photo was taken, and (3) any other relevant information. Be sure to include your full name in your email as well.
A friend of mine sent me the above for identification.
“Anole” I quickly responded, then followed up with, “where are you?” I was shocked by the answer – in New York City! Turns out this little lizard most likely hatched out of a plant purchased about a month ago and quickly made itself at home the New York City apartment of a Fordham graduate student. Look’s like our good friend Anolis sagrei to me, but figured I’d put it to the Anole Annals readers to verify.
Figure 1. Anolis gundlachi, Orocovis, Puerto Rico.
The agroecosystems that produce the life-sustaining stimulant we know as “coffee” have long been used as model systems to study complex ecological interactions and ecosystem services, with numerous studies revealing trophic interactions among coffee plants, pests, and pest-predators. Despite the high abundance and overlapping distribution of Anolis lizards, relatively few studies have addressed their functional role in agriculture. In our recent study titled, “Anolis Lizards as Biocontrol Agents in Mainland and Island Agroecosystems,” my colleagues and I explore the biocontrol potential of anoles against the world’s most devastating coffee pest, the coffee berry borer (Coleoptera: Hypothenemus hampei) in mainland and island settings.
My vision of agricultural landscapes as post-apocalyptic biodiversity deserts was trumped the minute I stepped foot onto a shade coffee farm in Orocovis, Puerto Rico. Far from the dystopian nightmare that I had envisioned, this diversified shade coffee farm bustled with the herpetological glory and natural complexity of a native forest (Fig. 1). Furthermore – and perhaps most importantly – the farmer complained not of issues with crop yield, pests, and disease.
As a plant, coffee occurs naturally in the forest understory and is cultivated traditionally among native shade trees as an understory crop. While pressures to increase production have led many farmers to transition to more intensive practices (i.e., the reduction of shade cover and application of agrochemicals to manage crop pests), these methods are becoming increasingly unsustainable and insufficient in light of emerging biological threats. In addition to climate change and the emerging coffee rust disease, the coffee berry borer poses a unique threat for dozens of coffee growing nations and nearly 20 million small-scale farmers who depend on coffee production as a primary commodity and means of subsistence. While the coffee berry borer (CBB) is capable of inducing 60-90% reductions in yields and persists unaffected by topical pesticides, our understanding of the predator-prey interactions that drive its top-down control and how these factors vary across management regimes and eco-geographic space has profound socio-economic and environmental implications for biological control.
Figure 2. Representative photographs of diversified shade coffee in Mexico (a), diversified shade coffee in Puerto Rico (b), intensive sun coffee in Mexico (c), and intensive sun coffee in Puerto Rico (d).
To assess the biocontrol capacity of anoles, we conducted experimental and field-based tests of how CBB populations respond to anole predation across mainland (Mexico) and island (Puerto Rico) coffee farms with parallel forms of land-use intensity. Anole functional response and infestation reduction potential were assessed by simulating pest outbreaks in the lab, while coffee farms were surveyed along complementary gradients of intensification. Organic, diversified shade coffee farms were representative of low-intensity production, and sun coffee monocultures that included the application of agrochemicals were representative of high intensification (Fig. 2).Continue reading The Not-So-Bitter Future of Coffee: Anolis Lizards as Biocontrol Agents in Mainland and Island Agroecosystems→
Take a look at this picture uploaded to iNaturalist by user braddockbiotech, a Middle School student from Miami-Dade County who is recording observations of non-native anoles in Florida as part of our LizardsOnTheLoose project (in association with the Fairchild Challenge, you can read more about this project on Anole Annals here and here).
The picture shows an adult male Puerto Rican crested anole (Anolis cristatellus) chomping down on a younger juvenile, which is frantically displaying back at it. Why is the smaller anole displaying? An innate anti-predatory response? Or perhaps a targeted response at the male to highlight they are conspecifics?
This year we are incorporating iNaturalist into our #LizardsOnTheLoose project, which aims to record the distributions and habitat use of non-native anoles throughout South Florida. We hope to get more fascinating natural history insights like this as the submissions roll in! If you’re interested in learning more about our #LizardsOnTheLoose anole project, please take a look at this video:
Anolis vermiculatus, by Raimundo López-Silvero Martínez
Another year, another field season (or seasons) come and gone, and now it’s time to share the great anoles we’ve seen! Get ready for the Anole Annals Photo Contest: 2017 Edition.
As in previous years, the Anole Annals team wants to see your best anole photographs for our 2018 calendar.
Here’s how it works: anyone who wants to participate will submit their favorite photos. The editors of Anole Annals will choose a set of 30-40 finalists from that initial pool. We’ll then put those photos up for a vote on this here blog, and the 12 winning photos will be chose by readers of Anole Annals, as well as a panel of anole photography experts. The grand prize winner and runner-up will have his/her photo featured on the front cover of the 2017 Anole Annals calendar, second place winner will have his/her photo featured on the back cover, and they’ll both win a free calendar!
Before we move on, I’d like to issue a correction from last year’s calendar – due to an unfortunate email miscommunication, we accidentally attributed several photos to the wrong photographer. By the time we realized our mistake, the calendar was already in print. We would like to sincerely apologize to Raimundo López-Silvero Martínez and Rosario Basail, whose photos, Anolis vermiculatus (September) and Anolis garridoi (April) respectively, we mis-credited. But please, take a look and appreciate them here! We will be sure to be more careful this year.
Anolis garridoi, by Rosario Basail
Back to business. The rules: submit your photos (as many as you’d like) as email attachments to email@example.com. To make sure that your submissions arrive, please send an accompanying email without any attachments to confirm that we’ve received them. Photos must be at least 150 dpi and print to a size of 11 x 17 inches. If you are unsure how to resize your images, the simplest thing to do is to submit the raw image files produced by your digital camera (or if you must, a high quality scan of a printed image). If you elect to alter your own images, don’t forget that it’s always better to resize than to resample. Images with watermarks or other digital alterations that extend beyond color correction, sharpening and other basic editing will not be accepted. We are not going to deal with formal copyright law and ask only your permission to use your image for the calendar and related content on Anole Annals (more specifically, by submitting your photos, you are agreeing to allow us to use them in the calendar). We, in turn, agree that your images will never be used without attribution and that we will not profit financially from their use (the small amount of royalties we receive are used to purchase calendars for the winners). Please only submit photos you’ve taken yourself, not from other photographers–by submitting photos, you are declaring that you are the photographer and have the authority to allow the photograph to be used in the calendar if it is chosen.
Please provide a short description of the photo that includes: (1) the species name, (2) the location where the photo was taken, and (3) any other relevant information. Be sure to include your full name in your email as well. Deadline for submission is November 6, 2017.
Good luck, and we look forward to seeing your photos!
We’ve seen this before. Anoles are, alas, no match for these large and wily marauders. John Karges provides the story: “The egret was flying down the riparian woodland corridor over a side channel, and abruptly landed in the mid-story thicket overhanging the stream and immediately began a stalk. It lunge-grabbed the anole, and very quickly devoured the adult anole in a matter of seconds.”
And here’s where it went down: 2 Oct 2016 San Antonio Mission NHP, San Antonio, Bexar County, Texas.
The head of the Green Anole is circled in white. The tolerance of the Cornsnake was perhaps aided by what appeared to be full belly.
Snakes love anoles, though their affection is seldom reciprocated. Unsurprising. But, it seems a snake/anole relationship which leaves the anole happy and undigested is not beyond the realm of possibility. In a recent natural history note, published in Herpetological Review, James Stroud and I describe an unlikely friendship I happened upon while working as a field technician in Miami FL. While collecting samples and doing routine maintenance on an automatic water sampler in Everglades National Park, I found a Green Anole (Anolis carolinensis) nestled within the coils of a large Cornsnake (Pantherophis guttatus) inside the external battery housing of the sampling unit. At first, my delight was focused on the snake (such encounters were a big perk of the job), but then I noticed a slender head regarding me cautiously from the safety of the coils. After a moment, the lizard slowly pulled its head fully underneath its protector, and I closed the lid on the snake/lizard duo, content the battery was in working condition. It was a cool day, and I was happy that I did not need to disturb the animals.
Given the tendency of snakes to make meals out of anoles, this encounter struck me as odd. After casually mentioning it to James Stroud, he immediately suggested this as a possible incident of kleptothermy, which describes a thermoregulatory process by which an organism regulates its body temperature by stealing the warmth of other organisms. The snake was certainly much larger, and so even though it was a fellow ectotherm, snuggling up to it would have likely provided some increase in thermal inertia. Thermal benefits aside, did the oblivious(?) guardian also provide protection against smaller Cornsnakes, perhaps more used to preying on anoles of that size? Did the lizard even realize what it had decided to make its bed upon when it crawled into the dark confines of the battery housing? We may never know.
Bermuda’s latest lizard arrival, the brown anole, appears to be thriving but is prompting concern over the island’s endangered natives.
The lizards, first seen in 2014 and recently spotted on the grounds of Aberfeldy Nursery in Paget, are suspected to have arrived from Florida.
One of that state’s most abundant lizards, the anole arrived there from the Caribbean, where it is native to the Bahamas and Cuba.
Popular as pets but aggressive breeders in the wild, the lizard, distinguished by ridges on its back, has proliferated in the southern United States.
According to the Department of Environment and Natural Resources, Bermuda has two distinct populations of brown anoles.
Genetic analysis shows that the two groups came from “separate founding events”, meaning the second did not arise from the first.
Noting the lizard’s capacity to spread rapidly, Jonathan Starling, executive director of the environmental group Greenrock, voiced concern that the anole would ultimately crowd out Bermuda’s imperilled skinks.
“Unlike the three other Anolis species known to be in Bermuda, the common blue Jamaican, the Warwick or Antiguan and the Barbados, this one is primarily a terrestrial species, the rest being arboreal or tree dwelling,” Mr Starling said.
“The endemic Bermuda skink, already at critically low populations, is also a primarily terrestrial species, so this new lizard poses a much bigger threat to it than the others did.
“I am not aware of the current range of this new lizard but I believe it is still confined within Pembroke and Paget parishes, so at the moment it is not coming into conflict with the remaining known skink populations. However it is likely their range will expand and come into contact with known skink populations within a decade, if not sooner.”
The unwelcome development is the latest of many threats to the endemic skink, which are easily trapped and killed by discarded bottles and cans.
Skinks are also at jeopardy from storms, as well as predation from other invasive species such as cats and rats.
“We’d hope that new initiatives, such as mandatory recycling or a bottle bill, would at least reduce that particular threat to skinks, which would likely benefit them in handling the novel threat posed by this invasive lizard,” Mr Starling said.
For anole biologists and enthusiasts, there are several ways to keep up with the latest and greatest anole research. These include RSS feeds, social media outlets such as Twitter, and email alerts from websites like Google Scholar (or from Anole Annals! – see the box on the right-hand side of this page). Nonetheless, the amount of literature that already exists on our beloved anoles can sometimes seem overwhelming. Modern search engines have made identifying this work easier than ever before, and we believe that continuing to promote the visibility and accessibility of anole literature will only strengthen our research community. With that in mind, we have created a resource that we hope will be helpful to those of us who spend our time steeped in anole literature.
The resource is a bibliography of Anolis literature, through the end of 2016, which we have compiled via searches of manuscript databases and manual curation. Here are some things you should know:
We intend to update the bibliography at the end of each calendar year. Thus papers published in 2017 will appear early in 2018.
The bibliography certainly contains errors and omissions. You can help us improve it! The file used to generate the collection can be downloaded, edited, or updated on GitHub. Any suggested edits will be sent to us for approval, and we’re excited for those start coming in.
The bibliography is a BibTeX file, a format used by the Latex markup language. Free software like Bibdesk, JabRef, and BibTool can be used to open BibTex files directly.
Lastly, and most importantly:
Most major citation software packages (e.g. Endnote, Papers, Mendeley, Zotero) can import BibTeX files. By importing the BibTeX filed used to generate this bibliography into your own citation manager, you can have the full value of this collection at your fingertips. Major benefits of doing so include the ability to easily search and filter within the bibliography, and of course, to instantaneously generate a list of citations from any subset of the full list.
We hope that AA readers will find this resource useful. We also look forward to hearing your suggestions for its improvement! Lastly, we’d like to thank members of the Losos Lab for assisting with the construction and curation of the collection.
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).
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.
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.
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 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
Please send all submissions to firstname.lastname@example.org 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
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).
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!