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from the pages of The Washington Post:
Scientists are studying natural selection in real time on a small Florida island.
Our research takes place on a South Florida island roughly the size of an American football field — assuming we are successful in sidestepping the American crocodiles that bask in the surrounding lake. We call it Lizard Island, and it’s a special place.
Since 2015, we have been conducting evolutionary research here on five species of remarkable lizards called anoles. Our team is working to understand one of biology’s most fundamental questions: How does natural selection drive evolution in real time?
Each May, coinciding with the start of the breeding season, we visit Lizard Island to capture, study and release all adult anoles — a population that fluctuates between 600 to 1,000. Through the summer, female anoles lay a single egg every seven to 10 days. By October, a whole new generation has emerged.
Anoles aren’t early risers, so we don’t expect much activity until the sun strengthens about 9:30 a.m., giving us time to prepare our equipment. Our team catches anoles with telescopic fishing poles fitted with little lassos, which we use to gently pluck the lizards off branches and tree trunks.
Picture yourself as an anole on Lizard Island. Your life is short — typically one year — and filled with daily challenges. You need to warm up in the sun, find enough food to survive, search for a mate, guard your favorite branch from other lizards and avoid being eaten by a predator.
Like human beings, each lizard is unique. Some have longer legs, others stronger jaws, and all behave slightly differently. These differences could determine who survives and who doesn’t, as well as who has the most babies and who doesn’t.
These outcomes drive evolution by natural selection, the process in which organisms with traits better suited to their environment tend to survive and reproduce more. These advantageous traits are then passed on to future generations, gradually changing the species over time. However, scientists have an incomplete understanding of exactly how each of these features predicts life’s winners and losers in the wild.
To understand how species evolve, researchers need to crack open this black box of evolution and investigate natural selection in wild populations. My colleagues and I are doing this by studying the anoles in exquisite detail. Last year was especially exciting: We ran what we called the Lizard Olympics.
As the morning heat builds, we spot our first lizards: Cuban brown anoles near to the ground, and the mottled scales of Hispaniolan bark anoles just above them. Farther up, in the leafy tree canopies, are American green anoles and the largest species, the Cuban knight anole, about the size of a newborn kitten.
In 2018, a new challenger entered the arena — the Puerto Rican crested anole, a species present in Miami that hadn’t yet made it to Lizard Island. Its arrival provided us with an unexpected opportunity to study how species may evolve in real time in response to a new neighbor.
Catching these agile athletes requires patience and precision. With our modified fishing poles, we carefully loop dental floss over their heads. Each capture site is marked with bright pink tape and a unique ID number; all lizards are then transported to our field laboratory a short walk away.
Here, the real Olympic trials begin. Every athlete goes through a comprehensive evaluation. Our portable X-ray machine reveals their skeletal structure, and high-resolution scans capture the intricate details of their feet. This is particularly critical: Like their gecko cousins, anoles possess sticky toes that allow them to cling to smooth surfaces such as leaves and maybe even to survive hurricanes.
We also measure the shape and sharpness of their claws, as both features are crucial for these tree climbers. DNA samples provide a genetic fingerprint for each individual, allowing us to map family relationships across the island and see which is the most reproductively successful.
The performance trials are where things get interesting. Imagine a tiny track meet for lizards. Using high-speed video cameras, we test how fast each lizard runs, and using specialist equipment, we measure how hard it bites and how strong it grips rough branches and smooth leaves.
These aren’t arbitrary measurements — each represents a potential evolutionary advantage. Fast lizards might better escape predators. Strong bites might determine winners in territorial disputes. Excellent grip is crucial for tree canopy acrobatics.
Each measurement helps us answer fundamental questions about evolution: Do faster lizards live longer? Do stronger biters produce more offspring? These are the essential metrics of evolution by natural selection.
As afternoon approaches, the team relocates each piece of bright pink tape and returns the corresponding lizard to the exact branch on which it was caught. The anoles now sport two 3-millimeter tags with a unique code that lets us identify it when we recapture it in future research trips, along with a small dot of white nail polish so we know not to catch it immediately after we let it go.
At 8:30 p.m., with the Lizard Olympics done for the day, we return to the island with headlamps. Night brings a different perspective. Some of the most wily lizards are difficult to catch when fully charged by the midday sun, so our nocturnal jaunts allow us to find them while they sleep. However, it’s often a race against time. Lizard-eating corn snakes are also out hunting, trying to find the anoles before we do. As we wrap up another 16-hour day at about 11:30 p.m., the team shares stories of the night.
Now spanning 10 years, 10 generations and five species, our Lizard Island dataset represents one of the longest-running active studies of its kind in evolutionary biology. Such long-term studies are fundamental to our understanding of evolution. By tracking which individuals survive and reproduce, and linking their success to specific physical traits and performance abilities, we are documenting natural selection with unprecedented detail.
So far we have uncovered two fascinating patterns. Initially, it did not pay to be different on Lizard Island. Anoles with very average shapes and sizes lived longer than those with features that are slightly different. But when the crested anoles arrived, everything changed: Suddenly, brown anoles with longer legs had a survival advantage.
The Lizard Olympics is helping us understand why. The larger, more aggressive crested anoles are forcing brown anoles to spend more time on the ground, where those with longer legs might run faster to escape predators — allowing them to better survive and pass on their long-leg genes, while shorter-legged anoles might be eaten before they can reproduce.
By watching natural selection unfold in response to environmental changes, rather than inferring it from fossil records, we are providing cutting-edge evidence for evolutionary processes about which Charles Darwin could only theorize.
These long days of observation are slowly revealing one of biology’s most fundamental processes. Every lizard we catch, every measurement we take adds another piece to our understanding of how species adapt and evolve in an ever-changing world.
James T. Stroud is an assistant professor of ecology and evolution at the Georgia Institute of Technology.
This article was produced in collaboration with theconversation.com.
Turns out that for anoles, predation by spiders is a very real threat. What a horrible way to go! We’ve reported on this phenomenon many times in the past. Here’s another example.
from the pages of Louisiana Illuminator:
Green anoles are less frequently seen near the ground as brown anoles become more prolific, instead evolving to a better suited life in the tree canopy. (Augustus Hoff/WUFT News)
She sits, her sleek, green body invisible in the tangle of leaves, and waits.
High up in the trees, in her favorite hunting spot, the green anole is patient, her bright, black eyes swiveling independently of each other, searching for the smallest flicker of movement. The green anole isn’t picky when it comes to food. Special sensors on her tongue will let her know if what she catches is edible, and most anything able to fit in her mouth will do just fine as a meal.
A slight rustle of branches dissolves the silence of her vigil. Her eyes pause their scanning, then snap in tandem to the roach that has just landed on a branch about 10 inches from her face. The bug is oblivious to the silent, scaled creature that could spell its demise. Now 3 inches away, 2 inches…
The anole strikes forward, breaching through her protective canopy of leaves towards the roach. She crunches her mouth down around the roach, its struggle to escape ceasing as she swallows it whole. Satisfied, she climbs up once again to her favorite spot, a cleverly camouflaged crusader among the leaves.
Green anole lizards, the only anole native to North America, stalk the treetops across the southeastern United States. Many Southerners witness these friendly creatures hunting for moths near the porch light. They might remember summertime stretches of childhood boredom spent catching green anoles and coaxing them to bite down on the soft flesh of their earlobes, wearing the live green earrings with pride, always a nice shock to the grown-ups.
Anoles display their own fanciful adornment. Males have bright red neck flaps known as dewlaps that puff out from under their chin in a crimson crest when calling for a mate or challenging another anole to a duel. They pump their bodies up and down in an impressive show of their pushup abilities, like middle-school boys in a gym-class contest. They “drop” their tails to distract a predator, or mischievous child, the detached appendage wiggling with a life of its own, allowing the crafty crawler to slip away.
But today, the green anole faces a more dire threat. Its new competitor is none other than its own cousin: the brown anole. Since the 1940s, the brown anole, otherwise known as the Cuban or Caribbean anole, found its way to Miami and has since spread rapidly across the South. As climate change expands its warm, habitable range northward, the prolific nonnative lizard is spreading further across the American South.
“It’s really good at traveling with humans,” said Yoel Stuart, an assistant professor and evolutionary ecologist at the University of Loyola Chicago who specializes in evolutionary biology through the study of the green anole.
The brown anole is not picky about its mode of transport. It travels in the wheel wells of cars, in the hidden crevices of boats and shipping containers, tucked away in bundles of firewood and, most frequently, in exotic plants, carted from lands afar and put up for sale at garden centers across the U.S.
The brown anoles are much more aggressive than the greens. They outcompete green anoles for food on the ground, fight even harder for territory and have even been known to prey on green anoles.
Plus, they’re everywhere. In Florida, brown anoles are now the most abundant vertebrate, according to Stuart. Researchers there put their numbers at 10,000 per hectare, or more than 5,000 lizards in a single acre.
Anoles lay eggs every four to six days during the spring and summer, and it takes only a little more than a month for baby anoles to emerge.
But the story of the anoles is more than just a lizard battle royale.
Their story of survival is also the story of human survival. Biodiversity supports the stability of food chains and ecosystems, which provide sustenance and income for people and protect the built environment from natural disasters. The introduction of species to an environment can have complex, unintended consequences that impact people, animals, plants and the landscape itself.
The case of the anoles is one small instance of how something as simple as a stowaway lizard can have a massive effect on ecosystems. The brown anoles were not necessarily spread with intention by humans like other invasive species such as kudzu, nutria or Burmese pythons. But negligence and willful ignorance can have just as powerful an effect.
Green anoles, previously left undisturbed on the entire continent, have never faced pressure like they do from brown anoles today. In a turn of events that intrigues evolutionary biologists, the presence of the brown anole on the ground has pushed the green anole from the lower parts of trees upwards, climbing skyward for a new chance at survival. There in the canopy, something extraordinary happened.
“As anoles moved up into the trees, they tended to have larger toe pads,” Stuart said. “The exciting bit about that is, it happened quite fast,” he said.
Evolutionary change typically happens on a timescale of hundreds of years, if not thousands. This 5% increase in toepad size for green anoles happened over the course of only 20 generations. This means that, with an average life span in the wild of 5.5 years, this evolution is happening on a fast track within the last century.
That’s like seeing the average height of humans going from 5-foot-9 to the size of “NBA players,” according to Stuart. It’s a brown anole world in the modern-day South, and the greens are changing in order to survive.
These little green lizards show remarkable resilience. Faced with the options of total domination or change, they’ve adapted to the new world they find themselves in, those larger, grippier toes learning to climb on ever more delicate branches high up above the ground because they have to. Change is the only option for them.
But a new home higher up in the canopy isn’t necessarily what will save the green anole.
Martin Main, professor of wildlife ecology and conservation at the University of Florida, said the knight anole — another invasive, even more aggressive, predatory lizard from Cuba, also poses a serious threat to the green anole. They eat the same food as the green anole, prey on adult green anoles and live mostly an “arboreal” lifestyle, according to Main.
Knight anoles are also huge by comparison, at 13-20 inches in length and weighing in at close to 5 ounces at their largest — or about 21 times the size of the green anole.
The potential loss of the green anole comes with the potential for biodiversity losses, too.
Lots of species diversity means better chances of survival against diseases, severe heat and changes to the environment; all features associated with a warming global average temperature. A loss of biodiversity can lead to a “homogenization” of species in that niche of the food web, meaning only one species is occupying that space. This can have unintended consequences.
“If everything is exactly the same, there’s going to be very little of that variety that provides us resistant individuals that allow a particular species to continue,” Main said.
One study from The Royal Society Publishing found that brown anoles as more vulnerable to extreme temperatures caused by climate change than green anoles. The loss of brown anoles to extreme heat after after out-competing green anoles could result in the spread of diseases, with fewer creatures to eat pests like mosquitoes and attract their bite. This disruption of the food chain could lead to the spread of insect-borne diseases such as West Nile virus.
Lawrence Reeves, entomologist, assistant professor and researcher at the Florida Medical Entomology Laboratory, described how lizards are “dead-end hosts” for the West Nile virus, meaning that lizards cannot pass on the virus when bitten by an infected mosquito, unlike other animals that harbor West Nile.
“Every bite that goes toward a lizard is a bite that goes away from a bird or a mammal,” Reeves said.
This is just one instance of how life could be affected by the loss of a species. Ecosystems are so complex and delicately balanced that it can be hard to determine what impact an introduced species will have, experts say.
“By introducing new species and causing native species to disappear, we’re fooling with stuff that we don’t really understand,” Main said. “You never really know what’s going to happen when things change in an environment. It’s so complicated.”
Consider the green anole roach hunter who used the structures available to her: green leaves, brown stems and extra grippy toes. She took advantage of her natural surroundings rather than seeking to become dominant over them.
The idea that humans better connect with their environment when viewing their place on the planet as part of a system isn’t new. In Rachel Carson’s iconic environmental book ”Silent Spring,” she argues that “man is a part of nature, and his war against nature is inevitably a war against himself.”
Jennifer Skene, clinical lecturer at Yale Law School and the natural climate solutions policy manager with the Natural Resource Defense Council, describes how that shift in thinking can allow humans to adapt just as the green anoles have.
“I think conceptually, the way that conversations are moving gives me a lot of hope,” Skene said. “The rights of nature, conversations about rights of animals and animal welfare, and the way that we think about all of these is interconnected.”
Hello fellow anole enthusiasts!
Last year I marked Green Anoles (Anolis carolinensis) in my backyard using a permanent marker to chart their population size. I’m looking to do a similar thing this summer and was wondering if anyone has any marking tools they recommend. I’ve heard about methods like toe clipping, or giving them a micro chip, but I’m not qualified for those sorts of methods and I’d rather do something simple.
If you have any recommendations, please email me at millicent.smalley@gmail.com.
Thank you,
Millie
Editor’s Note: This post from 14 years ago might be a place to start, but 2011 was a long time ago and surely new methods have arisen!
from the pages of Phys.org:
Mosquitoes might be the bane of a summer barbecue in Kendall or a stroll on Miami Beach, but researchers in Florida are now also looking at the insects’ more obscure targets—and how even a tiny, orange-flapped lizard could play a role in protecting our health.
While itchy bumps might make us feel like mosquitoes solely target humans, most of the world’s 3,600 mosquito species don’t specifically target humans, and the ones known in Florida bite humans, birds, amphibians, and reptiles like the brown anole, a pencil-sized lizard with a signature orange gullet.
Though these lizards are fast and feisty when they’re out hunting for insects, they rest on branches and leaves through the evenings and nights, making them an easy target for mosquitoes.
Brown anoles, said Melissa Miller, an invasion ecologist at the University of Florida, “may unwittingly be helping humans by absorbing the mosquito bites, and decreasing the transmission of serious pathogens to humans.”
The bad news for human health, Miller and her colleagues believe, is that the anole population is being squeezed out.
A couple of decades ago, reptile collectors inadvertently started a turf war by releasing Peter’s rock agamas they’d kept as pets into the wild.
No matter how much the male anoles spread their gullet, technically called a dewlap, to make themselves appear bigger and more
dangerous, the agamas—up to three times the size of the little anoles—were unimpressed. The agamas quickly spread, ate the anoles’ food and, sometimes, their little cousins themselves.
In many areas, the anole has disappeared, and the redheaded agama are now basking in the sun. While neither lizard is known to carry disease that mosquitoes can contract and then pass on to humans, the issue, Miller says, is the change in the mosquitoes’ diet.
In the early evening hours and throughout the night, mosquitoes can no longer feast on anoles, which typically sleep out in the open. Nor can they bite the agama, which hides in cracks and crevices as soon as the sun begins to set.
With less lizard blood on the menu, Miller and her colleagues theorized, mosquitoes could be biting birds more often. At least from a human-health point of view, that’s arguably the worst meal a mosquito could pick: Birds are some of the best hosts and multipliers of disease.
“And the more often they bite birds, the higher the chances that the mosquito picks up a pathogen” that they can then pass on to humans, Miller said.
To test their hypothesis, the UF team caught mosquitoes at three specific sites where the agama has taken over, then used DNA analysis to show which animals the insects had feasted on.
Next, Miller and her colleagues had to become experts at catching the agile reptiles with sticks, nets and even their bare hands. When the anoles returned to their original habitat, the team again caught mosquitoes. With the anoles back on the menu, the researchers believe that this second batch of mosquitoes would have drawn more blood from anoles, not from disease-riddled birds.
In theory, that would also mean that fewer mosquitoes carry viruses that could harm humans.
The researchers are still waiting for results, but in a few months, they’ll know exactly how the mosquito-bird-lizard-human transmission works. That, they hope, will add to our understanding of the unintended, often damaging consequences of human changes to the environment—like the introduction of non-native species like the agama, and the more notorious Burmese python, which has devastated the small mammal populations in the Everglades.
That the large-scale burning of fossil fuels has warmed the planet by 2 degrees Fahrenheit, on average, is another factor. Whether any of the mosquito-borne diseases become endemic in Florida isn’t just tied to the anoles, of course, but “will depend on global warming, and whether we start seeing more and more mosquitoes that stay year-round,” said Dr. Joyti Somani, an infectious disease specialist who used to treat malaria, dengue and other mosquito-transmitted diseases in Singapore before joining Miami-Dade’s Jackson Memorial Hospital last year.
At Miami-Dade’s Mosquito Control, division chief Dr. John-Paul Mutebi also said he worries that a warmer climate enables some mosquito species to spread to regions that were previously too cold, and that the season they’re most active is getting longer. Within the next 25 years, researchers project that the US mosquito season will last two months longer than today.
“That is really, really dangerous, because towards the end of the transmission period, that is when most of these mosquitoes are infected,” Dr. Mutebi told the Herald. “They keep on picking up the pathogens as the season goes,” he said.
Dengue, Chikungunya, Zika, and West Nile virus are among the diseases Dr. Mutebi lists as worrisome, as is eastern equine encephalitis. Also known as Triple E, the virus swells the brain and kills about one in three patients.
“If you don’t die from it, you’re going to end up with some long-lasting effects,” Dr. Mutebi said, including permanent blindness, loss of hearing, or other physical and mental impairments.
Right now, the odds of contracting Triple E are almost trivially low. In 2023, Florida reported only two cases in humans. But contracting any mosquito-transmitted disease is a numbers game.
The more mosquitoes there are, the longer they stay active, and which species they bite all matters. With Florida under attack by invasive species, from Burmese python to lionfish, the UF researchers hope that their results could help authorities direct resources to fighting the agama—and protecting the anoles.
“Brown anoles seem like such a small component of the ecosystem,” Miller said, “but even removing that can have impacts that are felt much higher up the food chain, all the way to humans.”
Anolis chloris, image courtesy Felipe Barrera Ocampo, https://www.inaturalist.org/observations/253195032
Now that I have reviewed the diversity of South American anoles north and south of the Andes, I will discuss conservation issues in this region. I will start by identifying some of the major threats to anoles, attempt to identify what makes particular anole species vulnerable, and conclude with discussion of the path forward for work with these species.
Threats
As pointed out in the review of introduced species, the general lack of invasive species means that invasives are of relatively low concern at this time, though this could change if more introduced species become invasive. Rather, the major threats to anoles in South America are probably habitat loss and climate change.
Given that one can fly for several hours and seemingly pass over nothing but intact tracts of Amazonian forest, habitat loss seems like it should be a low concern. However, recall in previous entries in this miniseries I pointed out that many species of anoles are range restricted to just a few areas geographically. Hence, the loss of habitat in just the wrong place could wipe out an entire species in one clearcut or fire event. This is especially true for species close to or adjacent to areas with large human populations, such as southeastern Brazil or around other urban centers. For example, species occurring in the Atlantic rainforest of South America, such as Anolis neglectus, A. pseudotigrinus, A. nasofrontalis, and A. phyllorhinus, are known from only a handful a specimens and only from a handful of localities. Together, these four species have been observed a total of eight times on iNaturalist.org (n = 2, 1, 1, and 4 observations, respectively) indicating just how uncommonly encountered they are in the field.
Beyond the Atlantic Rainforest region of Brazil, another area of concern becomes the valleys coming off the Andes mountains in countries like Peru, Ecuador, Colombia, and Venezuela. Many of the species in mountain valleys only occur in one or a few places as the mountain ridges have created barriers to dispersal both enhancing speciation as well as risk of extinction. For example, a recent paper by Moreno-Arias and colleagues (2023) split Anolis heterodermus into eight separate species all occurring in different parts of the cis-Andean valleys of Colombia. Some of the ranges of these species comprise only a few hundred square kilometers in areas not far from population centers such as Bogotá, Cali, and Medellín and most of these species are only known from a handful of observations. For example, Anolis inderenae near Bogotá has only five observations on iNaturalist while Anolis vanzolini slightly to the south has only three. Even species that are seemingly more abundant are often range limited. For example Anolis chloris has nearly 200 observations on iNaturalist but only occurs in the lowland forests along the Pacific coast of Colombia and Ecuador.
Hence, range-restricted species are probably at greatest risk throughout South America. However, small geographic distribution is not the only thing that threatens lizards of South America. Other factors such as governmental policy can either protect or threaten species.
Policy changes and their impact on local diversity has been well documented including in South America. For example, in the late 1970’s the Brazilian state of Rondonia was opened to colonization for the development of new farmland. As such, deforestation there occurred at an accelerating rate (see data and imagery). The deforestation in the western Amazon dramatically impacted natural environments on which many anole species depend (Fearnside 1982, Fearnside and de Lima Ferreira 1984). This is especially important given the enhanced extinction risk associated with forest-dwelling species (e.g., Cox et al. 2022), which describes many, if not most, anole species. So clearly, establishing protected areas can be of value as well as generally trying to reduce habitat loss.
Another major issue that is only going to grow in importance in future years is climate change. In recent years numerous papers have pointed out the risk of a changing thermal environment on lizards as regions experience both increased temperatures and variation in temperatures. Several papers stand out for discussion (e.g., Huey et al. 2009, Sinervo et al. 2010, Caetano et al. 2022, Cox et al. 2022). For example, in 2020, Diele-Viegas and colleagues pointed out that most lizard clades are vulnerable to extinction despite associated geographic distributions or local climate conditions. Their meta-analysis revealed that Neotropical regions of South and Central America were most at risk of climate-related extinctions. Given that tropical regions have the highest species diversity in general, this is not too surprising. However, vulnerability is hard to assess given that not every species was evaluated for risk. For anoles, only 98 of 427 species were evaluated as part of Diele-Viegas et al. (2010), yet their larger taxonomic clade (Iguania) was considered to be vulnerable in the Neotropical biogeographic realm unlike the Anguimorpha and Gekkota.
So at least some recent meta-analyses suggest anoles are at risk. However, some of the projections from other studies differ slightly with regards to when or where risk will occur. For example, many of the most vulnerable species or clades of lizard occur in low latitudes (Ceballos et al. 2017). However, extreme temperatures are most expected in mid-latitude regions, not the tropics (Murali et al. 2023). Murali and colleagues (2023) reported that 11.9% of environments were predicted to experience extreme thermal conditions for half the year by 2099. Another study (Cosendey et al. 2023) identified species as most at risk if they were tropical, viviparous, thermo-conformers. While not viviparous, the tropical thermo-conforming anoles (which pretty much describes all anoles in South America) are among the clades that are likely at greater risk than, say, desert reptiles. This is because desert reptiles are thought to be pre-adapted to thermal stress (Murali et al. 2023). Though not without controversy, some early projections indicate that by 2080 lizard extinction could reach 20% of all species globally (Sinervo et al. 2010), which would easily qualify as a mass extinction event.
The Path Forward
Green anoles usually perch high in the vegetation, especially in the presence of brown anoles. But here one female braved the brown bullies, presumably to prey on mosquitoes lured to the trap.
Hurricanes and anoles often go hand in hand. You’ve likely come across reports of the infamous wind tunnel experiments mimicking hurricane-force winds or stories about anoles surviving—or not surviving—these intense storms. But what do hurricanes and the environmental matching hypothesis (EMH) have to do with each other? In this case, they’re not directly linked, but they leave room for an intriguing story.
When a lizard lays an egg, it has no control over how the embryo will develop in response to environmental conditions. This lack of control can make survival tricky if conditions are not ideal. However, some animals can adapt their development before hatching to better suit the environment they will encounter later. The “environment-matching” hypothesis (EMH) suggests that the match between developmental and adult environments is a key factor influencing performance.
Chris Norris, a current PhD candidate in the Warner Lab, tested this hypothesis using a population of brown anoles (Anolis sagrei) on two small islands in Eastern Florida. More than 3,000 eggs were collected from wild lizards and incubated under two conditions: warm and sunny or cool and shady. After hatching, the baby lizards were released onto two islands—one sunny and open, the other shady and forested. Over five months, their survival and growth were tracked. Early results show that lizards incubated in sunny conditions had higher survival rates on the sunny island compared to those incubated in shady conditions. In both habitats, selection on body size was stronger on the open island that experienced more flooding and had less structure, and, on both islands, larger body size was selected for. While the developmental environment had no effect on survival from the storm .This suggests that the environment they develop in before hatching plays a crucial role in their later survival, especially when their early and later environments align.
During the course of the experiment, the islands were submerged by not one, not two, but three hurricanes: Ian (2022), Helen (2024), and Milton (2024). While these storms caused significant disruptions (Fig 1), they also underscored the resilience of these tiny reptiles. This work highlights not only the importance of developmental environments, but also the remarkable ability of anoles to endure extreme weather events. As climate change leads to more frequent and severe storms, studies like this provide valuable insight into how animals might adapt—or fail to adapt—to rapidly changing environments. The resilience of these anoles serves as a testament to nature’s capacity to surprise us, even in the face of seemingly insurmountable odds.
Figure 1. Shaded habitat before hurricane impact
Figure 2. Shaded habitat after hurricane impact
Photos provide by Chris Norris
Chris is currently seeking postdoc positions this year. He will be completing his PhD in December 2026 and can be reached at mcn0018@auburn.edu.
Green anoles (Anolis carolinensis) are known for their bold visual displays—vibrant dewlaps and dramatic head bobs dominate their social interactions. But at SICB 2025, Dr. Stephanie Campos highlighted an overlooked aspect of their behavior: chemical communication. Her research explores how the hormone arginine vasotocin (AVT) influences the production and interpretation of chemical signals, revealing a fascinating layer of complexity in how these lizards interact.
Dr. Campos’s work focuses on how AVT alters both the creation of chemical signals and the way they are perceived. To investigate, her team treated male anoles with AVT or a saline control and observed how untreated “receiver” males responded to these “signalers.” The researchers tracked receiver behaviors like tongue flicking—a chemosensory behavior—and analyzed their forebrain neurochemistry, specifically dopamine, norepinephrine, and epinephrine, which are linked to motivation and social behavior.
The findings revealed something remarkable: receivers interacting with AVT-treated males responded more frequently with tongue flicks and lip smacks, suggesting AVT makes chemical signals more prominent or engaging. Additionally, dopamine levels in the receivers’ forebrain typically influenced how quickly they tongue flicked in response to saline-treated males. However, when interacting with AVT-treated males, this relationship disappeared, suggesting that AVT doesn’t just enhance the chemical signals—it changes how they’re processed by receivers.
This study has big implications for understanding anoles. While their visual displays have been studied extensively, chemical communication has often been overlooked. Dr. Campos’s work suggests that AVT modulates territorial behavior by enhancing chemical signals and shaping how social information is interpreted. It highlights the need for further research into the neuroendocrine system’s role in communication, especially in animals like anoles, which rely on multiple sensory modalities to interact.
Chemical signaling in anoles, long underappreciated, is a promising area for uncovering new insights into the complexities of their social lives. This research reminds us that even subtle behaviors—like a flick of the tongue—can reveal the sophisticated ways animals navigate their social environments. As anoles continue to surprise us, it’s clear there’s much more to learn about these charismatic lizards!
For more on Dr. Campos’s work, check out her publications:
• Campos, S. M., et al. (2020). Arginine vasotocin impacts chemosensory behavior during social interactions of Anolis carolinensis. Hormones and Behavior, 124, 104772.
• Campos, S. M., et al. (2022). Signaler’s vasotocin alters the relationship between responder’s forebrain catecholamines and communication behavior in lizards (Anolis carolinensis). Brain Behavior and Evolution, 97(3-4), 184–196 .
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