Author: Jonathan Losos Page 12 of 130

Professor of Biology and Director of the Living Earth Collaborative at Washington University in Saint Louis. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.

Brown Anoles in Spain?

Image result for anolis sagrei spain

Photo by Peter May (https://media.eurekalert.org/multimedia_prod/pub/web/191913_web.jpg?w=650)

A year ago, we mentioned reports of brown anoles (A. sagrei) in Germany, green anoles (A. carolinensis) in southern Spain and the Canary Islands (reviewed here), as well as a report of Cuban knight anoles (A. equestris) also on the Canary Islands, and asked if there were other sightings. Now we have one!

Reader Rick Wallach writes in:

I just returned to Miami from a week in Alcala de Henares near Madrid, Spain. On Tuesday night, July 9th, a colleague and I were walking through the Plaza de Cervantes at about eight PM (Spanish time) when I noticed an <i>A. sagrei</i> sitting on the rim of a cement planter displaying its dewlap. This is such a common sight to me, it took a second for it to sink in that I was not at home but in the middle of Spain.  As I approached for a closer look the lizard darted into the shrubs and disappeared, but there’s no doubt about what I saw.
The question, of course, is whether the little feller was an escaped pet or indicative of yet another feral population of this ubiquitous species. I suspect the former, since during Madrid area winters the nighttime temperature drops into the mid-thirties F. Even so, I’d be curious if anyone else knows of reported sightings of brown anoles on the Iberian peninsula.

PS – I should add that even if central Spain is too cold from late October – April to support a feral population of sagrei, southern coastal Spain from Isla Cristina, around the coast past Cadiz to Gibraltar and then back northward maybe halfway to Barcelona, is much warmer and would support them handily.

Just a thought.

Another Newspaper Article Talks about Brown Anoles Replacing Green Anoles

Yet another newspaper article on brown anoles supplanting green anoles. This one from The Times of Apalachicola and  Carabelle in Florida. The text of the article is reprinted below, but it contains maps and other figures that you’ll have to go to the original to see. Also, the article included the video above.

Cuban anoles at war with native Carolinians

The Forgotten Coast is being invaded by an exotic lizard called the Cuban brown anole. This may not be a crisis unless you are a native green anole, in which case, raise the alarm because the newly-arrived brown anoles really are eating your young. And once invasive brown anoles are established, there is no way of removing them.

For the past 10 years, most of the anoles in local yards were the little green natives called Carolina anoles. They are not true chameleons, but some people call them that because they can change their color from brown to green. As every child knows, the males climb up tree trunks and flower stems and flash their rosy pink throat pouches, called dewlaps, to let females know they are interested.

But this year, green anoles have become scarce. Most of the anoles in my yard are now brown to black, with a light stripe down the back, and their throat pouch is bright orange rather than pink. Some of the males also have a raised crest from head to tail like a mini-dragon. Unlike Carolina anoles, brown anoles cannot change color, so no one will mistake them for chameleons.

When brown anoles appear, green anoles take to the treetops and become scarcer. Green anoles also adapt to their new situation by becoming even better tree climbers. Scientists have shown that the foot pads on green anoles become larger over time when brown anoles force them into tree canopies. This change is said to be a case of rapid genetic adaptation going on before our eyes.

Naturally, two similar species that are competing for food and territory will fight each other. Island resident Kimberly Alexis recently took a video of green and brown anoles fighting on a fence in her yard. Although the green lizard attacked the brown one, the brown anole quickly got a good bite on the green anole’s head. It surely would have won the contest if Kimberly had not broken up the fight. (See photo)

At first, I thought the brown anoles were merely green ones changing their color. Then a friend said, no, it is actually a different species that is creating havoc among the local lizards. It turns out that we humans accidentally imported the lizards with cargo coming from Cuba and the Bahama Islands. The brown anole first arrived on a ship that was unloaded on the Florida peninsula or the Keys around 1887 and began spreading north, (See map)

A map from 2004 that depicts the distribution of brown anoles does not show them in the Florida Panhandle, but not only are they in Franklin County, they are already on the barrier islands. Clearly, their range is expanding. How a land-loving lizard got to the barrier islands is anybody’s guess. One possibility is that they arrived as eggs in the roots of potted house plants.

Like a lot of other lizards in Florida, brown anoles are also kept as pets, and some of the feral population probably escaped into the wild. The Florida Fish and Wildlife Conservation Commission compiled a list of non-native reptiles that are now established in Florida, and they list 20 kinds of exotic anoles and their relatives that now live here.

The brown anole is hardly alone. Over 170 different reptiles have been introduced into Florida from imported cargo, from release of pets, or from zoos and research facilities after hurricanes. FWC lists 54 exotic reptiles that now have established breeding populations in the state, meaning that they have been present for 10 years. For example, Alexis mentioned that she also finds Mediterranean house geckos in her yard. Like most lizards, house geckos were brought here as pets but escaped and quickly became established.

The best known and most destructive escaped reptile in Florida is the Burmese python, which eats any native bird, mammal or even alligator it can wrap its coils around. Except for humans, mature alligators are the only animal large enough to return the favor and eat pythons.

I may be the last person in Franklin County to have noticed brown anoles, partly because there are many kinds of small lizards in the county. We have blue-tailed skinks, red skinks, Mediterranean house geckos, and legless Eastern glass lizards that many people mistake for snakes. Glass lizards have a checkered diamond pattern on their body that makes them look like a men’s tie, so my wife calls them “menswear lizards.”

From the standpoint of homeowners and gardeners, brown anoles are beneficial. Although they do eat the eggs of green anoles, they also eat flying insects, grasshoppers, spiders and even cockroaches. One can only hope that they will also dine on gnats and mosquitoes!

James Hargrove, a retired university professor who now lives on St. George Island, is a regular contributor to the Times on subjects of history and science. He can be reached at jhargrov@gmail.com

Are Brown Anoles Pushing Greens to Extinction in Louisiana?

Festive Anoles in Panama

The brown (a.k.a. “festive”) anole, A. sagrei, is slowly making its way around the world. Latest report: Panama City, Panama!

New Records of Festive Anole Populations on Pacific Coast of Mexico and in Panama

Anolis sagrei now established on the Pacific coast of Mexico.

Anolis sagrei, the brown or festive anole, continues its march through Central America (see previous posts on the species elsewhere in Mexico and in Costa Rica, not to mention South America). New reports reveal populations on the Pacific coast of Mexico (figures above and below) and in Panama City. Where next?

Weird Lizard with Three-and-a-Half Legs

stumpy in bag

Periodically here on Anole Annals, we have posts about three-legged lizards. The most recent such post was last year from Miami. Here’s another lizard, with a twist: it’s got four legs, sort of. Looking at the floppy left hindleg of this lizard, caught in the Bahamas two years ago. An x-ray confirms that this is odd–there’s no bone in most of that limb! I’ve never seen anything like it, and wonder how it happened.

xxx

Despite this seeming impediment, the lizard looked quite healthy, and as the video shows, could run quite adeptly up a note pad.

And here she is when we released her back at the place where we caught her. Pretty nimble!

Video courtesy Buddy and Cindy Pinder.

Anoles in the New Yorker!

The Behind-the-Scenes Story of the Recent Nature Paper on Lizard Competition and Predation

In the most recent issue of Nature Ecology & Evolution, first-author Rob Pringle gives the inside skinny on the recent paper about the interaction of predation and competition among lizards (see the video description of the study).

Herewith, the essay:

I was heavily influenced by a handful of papers that were published during my first few years of graduate school. Some of these — Fine et al. (2004) on how herbivores promote habitat specialization in trees, Rooney et al. (2006) on food-web structure and stability — resonated because I could connect them to problems that I was working on. Others, such as Schmitz et al. (2004) on the ecological importance of predator-avoidance behavior, made an impression because they seemed to herald seismic shifts in the outlook of community ecology. And then there was a set of papers that captivated me with their sheer elegance: beautifully designed and executed field experiments that inspired me and made me jealous.

A string of papers by Tom Schoener, Dave Spiller, and Jonathan Losos belonged to this last category. There was a new one each year, with titles like “Predator-induced behaviour shifts and natural selection in field-experimental lizard populations” (2004) and “Island biogeography of populations: an introduced species transforms survival patterns” (2005). These studies used tiny cays in the Bahamas as arenas for a simple yet powerful experiment. On some islands, the investigators had introduced top predators — curly-tailed lizards (Leiocephalus carinatus), which occurred naturally on larger islands just a few stone-throws away from the experimental islands. A major aim of this work was to understand how the introduced predators affected populations of brown anoles (Anolis sagrei), which were native to the experimental islands.

The results were dramatic. Curly-tailed lizards are stocky, ground-dwelling animals, and they devastated brown-anole populations. The brown anoles that survived did so by climbing into the vegetation, beyond the reach of the curly-tails, and this behavioral shift was associated with  natural selection on hindlimb length — an evolutionary consequence of predator-avoidance behavior. When I was a kid, we used to play a game called ‘the floor is lava’; if your feet touched the ground, you were dead. It seemed kind of like that for the brown anoles on these islands.

Brown anole and curly-tail
Left: Brown anole. Right: curly-tailed lizard. Photos: Jonathan Losos and Kiyoko Gotanda.

When I started a post-doc at the Harvard Society of Fellows in 2009, I met Losos and we started discussing ideas for a new experiment. I thought that a minor innovation on the earlier experiments could open up new conceptual territory. Losos said that he’d been wanting to do the same thing for years. To wit: if we introduced not just curly-tailed lizards, but also a second species of anole — green anoles (Anolis smaragdinus) — then we could ask questions about predation, competition, and the interaction between the two. Among other things, this design would enable us to test classic ideas about how predators affect the ability of competing prey species to coexist.

Green anole
Green anole, characteristically perched on a thin branch in the canopy.

The risky thing about this idea was that so much of it had already been done to one degree or another. Previous work had painted a rich picture of the interaction between curly-tailed lizards and brown anoles — our odds of discovering something new on that front were low. And there were dozens of studies about competition between sympatric Anolis lizards. The novelty of our approach hinged on the interaction between predation and competition, which was a thin thread on which to hang such a massive undertaking. But I felt supremely confident that the experiment would work. Todd Palmer, Rowan Barrett, and a raft of other collaborators must have been confident too, because they joined me in setting up and monitoring the experiment.

Islands
Left: Aerial view of island 926; at left is a larger island, similar to those where we collected green anoles and curly-tailed lizards for introduction onto the experimental cays. Right: Naomi Man in ‘t Veld conducts a population census; squirt guns with water-soluble paint were used to mark lizards from a distance. Photos: Day’s Edge Productions and Kiyoko Gotanda.

By 2013, two full years into the study, my confidence was giving way to panic. I had started a job as an assistant professor in 2012; I was anxious about my professional survival, and I had ploughed large amounts of time and money into an experiment that did not seem to be working after all. The introduced curly-tailed lizards were firmly established in their new homes, and the brown anoles were responding by becoming more arboreal, as previous work had indicated they would. But the introduced green-anole populations seemed to be struggling. It looked as if they might die out, in which case our experiment would amount to a very expensive confirmation of the earlier work by Schoener, Spiller, and Losos. Our project had some original twists — Tyler Kartzinel was spearheading an effort to monitor the lizards’ diets using DNA metabarcoding — but it wasn’t at all clear that we would discover anything new or noteworthy.

Our break came in 2014, when it became clear that the green-anole populations were indeed thriving on some islands — just not on any of the islands with curly-tailed lizards. When we returned to the Bahamas in 2015, buoyed by the emerging results and freshly funded by the US National Science Foundation, we found that green anoles had disappeared on one island with curly-tailed lizards (the largest such island). Sometime during 2016, a second green-anole population vanished, this time from the smallest island with curly-tailed lizards. That left just two islands where green anoles still persisted in the presence of curly-tails, and one of those populations looked like it might soon join the list of casualties. Was this because the curly-tailed lizards were simply eating the green anoles to extinction on those islands? Probably not. The green anoles were highly arboreal; they rarely descended to the ground and instead moved by scampering through the twigs and leaves in the canopy. The chunky curly-tailed lizards, by contrast, lumbered across the ground, rarely climbing higher than 50 centimeters — and then only on the thickest of tree trunks. Indeed, the curly-tails didn’t seem to be eating many lizards of any kind. We saw them feasting on cockroaches, and occasionally snacking on fallen fruits and dead hermit crabs, but it wasn’t until 2016 that we finally saw one eat a small female brown anole. Isotopic analysis revealed that curly-tailed lizards actually occupied a slightly lower trophic position than did either anole species, which suggested that the top predator was subsisting more on insects than on other lizards.

Curly-tail and green anoles
Left: Curly-tailed lizard eating a cockroach; the lizard’s paint marks signify that it had been seen on the first two days of the three-day population census. Center: Mating green anoles were a welcome sight in 2013. Right: Green anole clinging to a thin twig, where we often found them, especially on islands with curly-tails. Photos: Kiyoko Gotanda and Rowan Barrett.

The more plausible explanation for our results was that the presence of curly-tailed lizards intensified competition between the two anole species within the predator-free arboreal refuges, and that this competition — not direct predation — was the primary reason why the introduced green-anole populations failed to increase on islands with curly-tailed lizards. Molecular analysis of fecal samples subsequently reinforced this impression. DNA metabarcoding produced evidence that curly-tailed lizards exacerbated the competition between brown and green anoles for insect prey. And a quantitative PCR assay — conducted by Charles Xu at the behest of one of the four very thoughtful reviewers for Nature — detected the DNA of brown and green anoles in just 4% of the curly-tailed lizards that we sampled. Curly-tailed lizards really were the top predators; they just didn’t catch anoles very often.

We concluded that indirect effects of the top predator destabilized the coexistence of competing prey species. In the landscapes of fear created by curly-tailed lizards, the clear niche partitioning exhibited by brown and green anoles on predator-free islands — a product of adaptive radiation — was no longer evident. Instead, these species were trapped together in the top story of the small islands, competing for the same space and food, afraid of getting burned by the hungry predators on the ground. Green anoles, despite being better adapted to arboreal life, got the shorter end of the stick (both literally and figuratively). This might be because brown anoles, as the incumbents on the islands, had greater strength in numbers. If we had introduced both brown and green anoles at identical starting numbers, would the green anoles have come out on top? Or, now that the combination of competition and predation has greatly diminished brown-anole populations, might green anoles stage a comeback? In 2018, we reintroduced green anoles on the two islands where they had been extirpated, with the hope of answering this question.

In any event, our findings ran counter to one of the motivating hypotheses of the project. Early studies, notably Bob Paine’s classic experiment in the rocky intertidal habitats of Makah Bay, suggested that predators tend to ameliorate competition between species at lower trophic levels by preventing any one species from becoming too abundant and excluding the others. Many ecologists, myself included, love this idea of ‘keystone predation’. Not only is it an elegant concept, but it also validates top predators as linchpins of ecological integrity. But when can we expect predators to play this role? In rocky intertidal communities, where keystone predation is a powerful force, sea stars feed on sessile invertebrates; but prey that are attached to the substrate have a limited ability to escape predators in space. In predator-prey interactions involving fast-moving prey that can rapidly adjust their behavior to avoid predators, I would expect keystone predation (sensu stricto, as opposed to the broader concept of ‘keystone species’) to be infrequent, and competition for enemy-free space to be both frequent and strong.

Boating
Left: The crew of the Sand Crab prepares to disembark on an island (from left: Naomi Man in ‘t Veld, Todd Palmer, Rowan Barrett, Tim Thurman). Center: When the Sand Crab got stuck at low tide, we had to walk (from left: Palmer, Pringle). Right: When the seas were rough, we contemplated our own mortality (from left: Palmer, Man in ‘t Veld, Pringle, Thurman). Photos: Kiyoko Gotanda and Rowan Barrett.

It has now been almost a decade from the conception to the publication of this work. What started out as a post-doc project has become an enduring annual ritual, and one that I have (usually) been able to enjoy thanks to a talented group of collaborator-friends: Palmer, Barrett, Kartzinel, and Xu, along with Tim Thurman, Kena Fox-Dobbs, Matt Hutchinson, Tyler Coverdale, Josh Daskin, Dominic Evangelista, Kiyoko Gotanda, Naomi Man in ‘t Veld, Hanna Wegener, and Jason Kolbe — and, of course, Schoener, Spiller, and Losos.

Fieldwork
The research team left it all on the field. Tim Thurman (left) required stitches after one nasty fall; later (center), he was possibly sick (or simply didn’t want anybody to steal his water). Todd Palmer (right) was forced to become arboreal in his search for green anoles. Photos: Rowan Barrett and Kiyoko Gotanda.

The interdisciplinarity of this team enabled what is to me the most satisfying feature of our work. We were fortunate to have access to a replicated set of small cays on which to manipulate species composition. That is a rare opportunity and would have made for a nice study in itself. But by also integrating molecular assays (to quantify diet composition and intraguild predation) and stable-isotope analyses (to quantify trophic position and food-chain length), we were able to gain deeper insight into the mechanisms underlying the population dynamics. Indeed, without these additional assays, our suppositions about the relative importance of consumptive and non-consumptive effects would have been equivocal at best. Molecular techniques have fully entered the mainstream of ecology over the past decade, yet they are still rarely paired with the kind of manipulative field experiments that so inspired me as a first-year graduate student. The fusion of sound natural history, rigorous experimentation, and forensic mechanistic exploration offers tremendous power to resolve the kind of messy complexity that has long frustrated ecologists.

Predators Alter Interactions between Green and Brown Anoles: an Experimental Study

New paper in Nature examines the interaction between green anoles and brown anoles, and how the presence of the predatory curly-tailed lizard changes the balance.  See also the commentary by Os Schmitz.

Anatoly the Anole: A Lizard-Themed Children’s Book

 

Another great anole book for kids! Author Adi Schneider summarizes it:

This colorful story in rhyme, for both children and adults, will put a smile on your face.  You will observe the flamboyant Anatoly flaunting his magnificent dewlap to his female fan club and learn lots of solid facts about these fascinating and abundant little Floridian lizards.

When showing off, with his push-ups and head nodding, there is a crisis when he hits his dewlap on a rock.  That red and yellow dewlap of his is now black and blue and he is more than depressed about it.   His chance encounter with a Monarch butterfly sets him on the right path toward improving his character and not relying on looks for his popularity.

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