Author: Jonathan Losos Page 1 of 133

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.

Why Green Anoles Change Color by Whit Gibbons

By Jonathan Losos

On May 3, 2026

In All Posts

Whit Gibbons

From the pages of Tuscaloosa News:

You’ve likely seen this common lizard. Why it changes color | ECOVIEWS

Whit Gibbons

Contributor

May 1, 2026, 3:45 a.m. CT

One of the most commonly seen lizards in the Southern states is the green anole, also known as the North American green anole or Carolina anole. (Its scientific name is Anolis carolinensis.) Although more than 400 species of anoles are known to science, the green anole is the only one native to the United States. Most people appreciate seeing them in their yards.

Q. A type of lizard we have in Birmingham, Alabama, is sometimes green and sometimes brown. I know it is not two different lizards because I have watched one change from brown to green. Are these a type of chameleon that can change skin color to match their surroundings?

A. No. Anoles are in a different family of lizards from Old World chameleons. Those are the ones famous for being able to change skin color based on the background, thus creating a true camouflage. In green anoles color change is a response to external factors, such as temperature and humidity. It may also be influenced by hormonal changes.

Whether lizards experience emotions comparable to humans remains a mystery. Researchers continue to investigate why anoles change color, as well as what purpose that change serves for the individual lizard. Most anoles found hidden under bark or leaves on cool days will be brown. If you pick up a brown one and hold it, it will usually turn green.

To learn more, I contacted Tom Jenssen, an expert on the subject of color-changing behavior in green anoles.

During his career as a professor at Virginia Tech, Tom observed thousands of green anoles while conducting research on the species. His observations confirmed categorically that the color of a green anole has nothing to do with what the lizard is standing on. One on a green leaf can be brown; one on dark soil can be green.

He indicated that factors causing a green anole to exhibit the brown color phase are not completely understood but he explained the biological mechanism.

A male green anole flashes its dewlap in a territorial display. Males flaunt the red throat fan to challenge other males.

“Color-shifting comes from melanophore activity over a subdermal layer whose structure reflects green wave lengths.” In other words, the concentration of black or brown pigment cells determines the color exhibited. If the pigment cells are large, they obscure a lower level in the skin that reflects green light. When the cells are concentrated, the lizard looks dark brown, mottled brown or even like a bad bruise of blotchy brown and olive-green. If the pigment cells contract in size, the lower level is exposed, and the lizard appears green.

He further noted that the activity of pigment cells and their concentration are controlled by the endocrine system, the glands that affect hormones and mood changes for many animals. The remaining biological mystery: What triggers the endocrine system to cause the pigment cells to contract or expand? Body color in anoles is highly complex, with no simple answer for why an individual is a particular color at any given time.

Social interactions with other lizards may be responsible in some cases. Brown coloration could possibly result in faster warming of the body on a cool sunny day.

Q. Why do these lizards that can change from brown to green sometimes have a bright red throat?

A. Male green anoles use the vivid red throat fan, or dewlap, to challenge other male anoles and sometimes even other animals. The dewlap display is often accompanied by push-ups and head-bobbing. An invasive species from Cuba, the brown anole, now found in Florida, Georgia and Alabama, has an orange dewlap.

Next time you see a green anole displaying a red throat, take a moment to watch its performance. Who is its audience? Is it another anole in the vicinity — or is it you?

Native green anoles are completely harmless and offer fun outdoor entertainment. Enjoy watching them stalk bugs and interact with each other. They are indicative of a healthy environment and deserve our appreciation wherever we find them.

Whit Gibbons is professor of zoology and senior biologist at the University of Georgia’s Savannah River Ecology Laboratory. If you have an environmental question or comment, email ecoviews@gmail.com.

Are Red Chili Pepper Anoles a Real Thing?

By Jonathan Losos

On April 23, 2026

In All Posts

From Cold Blooded Kingdom’s website

AA reader Steve Hopman writes:

My question is on genetics of the “Red Chili Pepper” anole being sold on Underground Reptiles.

Are they A. sagrei or a cross with another species?
How is the red transferred to offspring? Dominant or recessive trait or ?.

Red Chili Pepper Anoles For Sale - Underground Reptiles

And here’s one from Underground Reptiles.

Spring Time and the Green Anoles Are Back in Georgia

By Jonathan Losos

On April 21, 2026

In All Posts

From the pages of Vanguard, the student newspaper of the University of North Georgia:

The Green Anole is Back in Georgia

Riley Hansen, Staff Writer • April 9, 2026

Despite being misunderstood, Green Anoles remain adaptable and present in North Georgia. Photo by Riley Hansen.

With spring weather on the rise, green anoles, a small lizard species native to the southern portion of the United States, are returning to Georgia in large numbers. Anolis Carolinensis is known as a “trunk-crown ecomorph,” meaning they can change colors from shades of brown and green depending on their temperature and stress level.

Lily Grace Smith, a UNG freshman with a concentration in sustainability, said, “I have experience with green anoles because they like to hide in my house a lot. I live near a creek in a forested area, so I come into contact with them frequently. They are seen as scary because they like to jump around a lot to try to escape, but if you hold them by softly holding right under their head, you can release them.

“I’m glad I’m seeing them around because they regulate the insect population and also keep their predators around,” Smith said. “I wish people would save them and, if possible, make tiny habitats for them (keeping leaf litter, brushes, vertical spaces for them to bask on).” – Lily Grace Smith, UNG Freshmen Environmental Spatial Analysis Major

With limited research on the specific predators impacting the green anole populations, researchers are studying specific instances of predation that have appeared due to the introduction of other non-native species such as carnivorous plants.

In a publication from Herpetological Review, authors Daniel A. Warner and Patrick Thompson of Auburn University said, “Although Interactions between these two species are probably rare, the native ranges of ‘A. carolinensis and D. muscipula overlap in areas of North Carolina and South Carolina, USA, suggesting that A. carolinensis is a potential source of nutrients for this carnivorous plant. In addition, the small size of the D. muscipula restricts prey to relatively small individuals, and its small native range restricts the impact of this predator to a limited area.”

Despite these challenges, the green anoles’ adaptability and rapid evolution have assured their return to houses, schools and communities of the south this spring.

Anole Chocolate to Save Nature!

By Jonathan Losos

On April 19, 2026

In All Posts

Mashpi Chocolate sustainability farms chocolate to help preserve nature in Ecuador. And anoles are doing their part. As they say on their website: “All the ingredients we use in Mashpi Chocolate are grown in an agroecological and regenerative way, next to cocoa trees and within edible forests….We created this chocolate to preserve a native forest reserve, restore degraded areas and generate opportunities in the magical territory of the Andean Chocó….The beauty of coffee is that it is planted under the shade of other trees, providing a habitat for many other species. We use high-altitude coffee as it has a special set of aromas and a characteristic taste that makes me want more!”

As for anoles, decide for yourself which species! Perhaps the fabulous Reptiles of Ecuador‘s Anolis webpage can help!

And many thanks to the Missouri Botanical Garden’s Carmen Ulloa Ulloa for not only tipping AA off to this, but providing a delicious sample!

The History of Anole Annals According to ChatGPT

By Jonathan Losos

On March 16, 2026

In All Posts

The very first Anole Annals post in November 2009, a poem by AA stalwart Yoel Stuart.

This all started with an innocent query: how long has Anole Annals been around? This led to a series of questions answered–for the most part accurately–by chapgpt. Unfortunately, the links didn’t copy, but if you want to go to the posts mentioned below, look at Chatgpt’s transcript of our conversation.

So with that, here goes:

when did Anole Annals debut?

The blog Anole Annals effectively debuted on November 21, 2009. The first post—written by Jonathan Losos—contained several anole-themed haikus by Yoel Stuart.

A few additional details about the early history:

Nov 21, 2009: First post published (the haiku post).
2009–2010: Only a couple of posts appeared initially.
Late October 2010: The blog began posting regularly and “really got rolling.”
The site was created collaboratively by Losos and Richard Glor, with the goal of serving as a clearinghouse for research, news, and observations about Anolis lizards.

So the short answer:

Launch / first post: 21 November 2009
Regular activity: mostly from late 2010 onward

If you’d like, I can also reconstruct the very earliest posts and contributors from 2009–2011—they give a pretty fun picture of how the blog community got started.

please do

Knight Anoles Spreading through Florida–Will They Get to Georgia?

By Jonathan Losos

On March 4, 2026

In All Posts

Cuban knight anoles were introduced to Florida in the 1970s. Credit: Alexander Romer

from the Wildlife Society:

Florida towns facilitate spread of knight anoles

March 2, 2026

News, Wildlife News

by Joshua Rapp Learn

Giant Cuban anoles have found footholds in habitats across Florida thanks to expanding human development over the past decades.

But it’s unclear whether the reptiles can push into Georgia or if the introduced reptiles may be near the edge of their potential range.

“Jacksonville might be suitable, even though one might be surprised that they can get so far north,” said Alexander Romer, a quantitative ecologist at the University of Florida’s Fort Lauderdale Research and Education Center who works with the interagency Everglades Invasive Reptile and Amphibian Monitoring Program (EIRAMP).

A biology student was the culprit behind the first introduction of Cuban knight anoles in 1952 to the campus of the University of Miami’s north campus in Coral Gables. They have since spread throughout much of the state—especially in urban areas. These lizards are much larger than most anoles, stretching up to 20 inches long, including their tails. They are striking, with vibrant green bodies, yellow stripes with black speckles and baby-blue mascara-like eye shadowing.

Their ecological impact isn’t completely certain yet, but scientists have observed them eating some imperiled vertebrates, such as Florida tree snails (Liguus fasciatus). They also likely eat federally endangered Florida tiger beetles (Cicindelidia floridana) and Schaus’ swallowtail butterflies (Papilio aristodemus). “We know that they do eat butterflies,” Romer said. “They do eat beetles.”

In a study published recently in Ecology and Evolution, Romer and his colleagues examined the factors that characterized suitable habitat for knight anoles in Florida and compared them to the factors that predicted occupancy in their home range of Cuba.

Citizen scientists track anoles

To conduct the study, the team relied on citizen science reports gathered from the Global Biodiversity Information Facility, a database that corrals information from platforms like iNaturalist together with museum specimen data.

They also used data that EIRAMP collected during reptile surveys in southern Florida in the Everglades Cooperative Invasive Species Management Area.

The models that they developed predicted knight anoles gravitated toward different ecological factors in Florida as opposed to Cuba. In Florida, for example, urbanization was the strongest predictor of knight anole presence, which wasn’t the case in Cuba.

While their study didn’t examine why Florida knight anoles gravitate more toward human settlement, Romer said it might have to do with the novelty of the environments and the level of disturbance there compared to Cuba. “Disturbed habitats likely have more open niches,” he said. “There are [fewer] predators, less competition.” In Cuba, meanwhile, the ecosystems might function better, with more predators that control the expansion of knight anoles.

So far, knight anoles have been seen in most eastern coastal cities in Florida and some western coastal cities. They are found all the way north to St. Augustine, but the models predicted the heat island impact in Jacksonville has likely made that city warm enough for the lizards, though they haven’t yet spread there, according to records.

Romer still hesitates to call knight anoles invasive rather than just introduced at this point, despite their potentially negative impact on several imperiled invertebrates. But this research shows that developing or disturbing habitat only helps them spread.

“Conserved habitat is precious,” he said. “When you disturb habitat, you’re facilitating invasive species. When you protect it, you’re protecting native species.”

Article by Joshua Rapp Learn

Knight Anole Meets Cat

By Jonathan Losos

On February 1, 2026

In All Posts

Photo by Miriam Lipsky

Happy ending: they both lived to see another day thanks to the screen between them! Thanks to Miriam Lipsky for the photo from Miami.

Breaking News: Green Anole Savagely Bites Stephen Colbert

By Jonathan Losos

On January 29, 2026

In All Posts

Ok, not actually breaking news–occurred almost eight years ago, but somehow word never reached Anole Annals. People magazine tells the story:

Published on April 21, 2018 12:55PM EDT

Nearly three years after taking over The Late Show from David Letterman, Stephen Colbert finally welcomed the first animal expert back on the CBS program, Friday. But… he might regret that decision.

The 53-year-old talk show host sat down with Nathaniel “Coyote” Peterson, the animal expert and adventurer known for his popular YouTube show Brave Wilderness — for which he travels the globe letting animals and insects bite and sting him.

It was only fitting, then, that Peterson brought an animal along to bite Colbert. “I was told you wanted to enter the bite zone,” Peterson said, before pulling out the green anole lizard. “What we have here is…arguably one of the most painful lizards in the world. They can be found all throughout Florida and maybe even here in New York because they often times escape as people’s pets.”

He then asked Colbert, “If you’re brave enough, and I know you are, you’re actually going to be bitten by one of these anoles.”

Colbert was game, though he was nervous. “I wanted to do something that wasn’t very painful,” he said. “Lizards don’t really bother me but is it going to hurt?”

“That’s yet to be determined,” Peterson said. “How are you going to endure the pain. It’s all on you. You have to mentally prepare yourself. When I do this and I’m bit and stung by things, I kind of walk and pace behind the cameras before I actually go through with it.”

The former Colbert Report host didn’t do that. Instead, he stayed seated — looking directly into the camera before saying, “I’m Stephen Colbert and I’m about to enter the bite zone with the green anole.”

That’s when Peterson put the lizard up to Colbert’s ear — because “the ear is the best place to be bit by this thing, then it just kind of hangs there like an earring,” according to Peterson.

As for the bite, Colbert handled it well. “Well done. Well done,” Peterson said.

Invasive Brown Anoles More Aggressive to Native Greens at Higher Temperatures

By Jonathan Losos

On January 27, 2026

In All Posts

Tulane University reports:

Study: Invasive lizards’ tempers flare with the heat

Stacey Plaisance splaisance@tulane.edu

Turns out those New Orleans lizards with record levels of lead in their blood are also picking more fights — but heat, not heavy metal, may be driving their aggression.A new Tulane University study published in the Journal of Thermal Biology finds that invasive brown anoles become more aggressive toward native green anoles as temperatures rise, suggesting that warming conditions could tip the competitive balance between the two species.

Earlier Tulane research revealed record-high levels of lead in brown anoles collected in New Orleans, prompting questions about whether lead exposure could explain their feisty tendencies. While the team can’t rule out a connection, the evidence so far points elsewhere, said senior study author Alex Gunderson, assistant professor of ecology and evolutionary biology in Tulane’s School of Science and Engineering.

“We don’t yet know whether lead contributes to the brown anoles’ aggressive behavior,” Gunderson said. “But since we haven’t seen lead affecting them in other ways, my guess is that it’s probably not the cause. What we can say for certain is that their aggression increases with warmer temperatures.”

The research, led by Gunderson and PhD student Julie Rej, examined how temperature influences aggression between the two species, which compete for the same habitat in the southeastern United States. The invasive brown anoles displace the native green anoles from their preferred habitats in the wild, and behavioral aggression is one potential reason.

“Invasive species cause a lot of ecological and economic damage, so biologists are really interested in understanding what makes these species so successful,” Rej said.

The team found that brown anoles are consistently more aggressive than green anoles, and that their aggression increases as temperatures rise.

To measure aggression, Rej placed pairs of brown and green anoles together in controlled enclosures set to simulate different seasonal temperature ranges – from cool spring days to hotter summer conditions expected in the future. Across all tests, brown anoles displayed higher levels of aggression, and while rising temperature increased the aggression of green anoles somewhat, the gap between the two species’ aggression widened as the temperature increased.

The findings suggest that as the climate continues to warm, invasive brown anoles may become even more dominant competitors, further displacing native green anoles from their preferred habitats.

“Climate change can make invasive species more potent, and this study shows that heat-driven aggression could help explain why in some cases,” Gunderson said.

The study contributes to growing evidence that behavioral responses to temperature are an important, and often overlooked, factor in how species will interact and compete as global temperatures rise.

The research was supported by Tulane University and conducted at the Gunderson Lab, which studies how animals respond and adapt to environmental stressors such as temperature changes.

Hurricanes as a Source of Episodic Natural Selection on Lizards

By Jonathan Losos

On January 25, 2026

In All Posts

from the pages of Rhody Today:

URI’s Jason Kolbe studying hurricanes as a source of episodic natural selection

Storm study shows adaptive selection in southeast lizards

A new study led by URI’s Jason Kolbe examines adaptive selection in *Anolis* lizards in the southeastern U.S. (Photos / J. Kolbe)

KINGSTON, R.I. – Dec. 11, 2025 – How do intermittent events like hurricanes impact natural selection? How do animals adapt to challenging weather? A University of Rhode Island professor has set out to track natural selection in the Anolis lizard over time to see how the species has weathered hurricanes in the southeastern United States.

A new paper by Jason Kolbe and colleagues published in the P roceedings of the National Academy of Sciences finds hurricane-induced selection and responses to hurricanes in Anolis lizards. Chair of URI’s Department of Biological Sciences, Kolbe studies how human-mediated global change phenomena drive evolutionary change in the natural world.

High winds associated with hurricanes can result in natural selection on traits related to clinging performance in anole lizards.

If species’ mortality depends on specific traits, then hurricanes — extreme and intermittent in nature — provide a source of episodic natural selection on affected populations. The predicted increase in hurricane activity and strength in the North Atlantic has the potential to alter patterns of selection and evolution for populations, especially in coastal areas and islands.

The paper’s focus brought Kolbe back to the start of his professional research career. He has studied lizards for 25 years and used genetic markers to reconstruct the invasion histories of Anolis lizards introduced to Florida from the Caribbean for his dissertation.

As part of his Ph.D. research, Kolbe studied the ecology and evolution of anole populations on islands in the Bahamas. When Hurricane Sandy hit their study site there in 2012, he decided to use the devastating storm’s impact to compare lizards before and after impact.

The invasion of Anolis sagrei in the southeastern U.S. provided a rare opportunity to put a timestamp on the start of adaptive evolution for populations in this region, Kolbe says. Over 100 hurricanes have hit Florida since the start of the A. sagrei invasion.

Their results affirmed that hurricanes are a source of episodic selection with lasting evolutionary effects on lizard traits connected to weathering storms. Kolbe’s team’s preliminary analysis found lizards with longer limbs survived better during the hurricane and that lizards with longer limbs possessed greater clinging ability, supporting hurricanes as a source of natural selection for lizard populations.

“Our studies of the brown anole in Florida provided an excellent opportunity to test whether hurricane-induced selection could shape the morphology of lizards over the course of their invasion, around 100 years,” he says. “Because we have a good estimate of the time each brown anole population in our study was established and hurricane records go back to 1851, we were able to estimate the number of hurricanes impacting each population and test for an association with traits that increase clinging performance.”

Introduced lizard

The Anolis sagrei was introduced in Florida and Georgia beginning in 1887 in the Florida Keys. It showed up on the peninsula a half-century later. Kolbe’s team reconstructed a chronology of the A. sagrei invasion in Florida and Georgia using dates from published observations and museum specimen records.

Brown anoles were introduced to the U.S. from at least eight geographically and genetically distinct source populations in their native range, mostly from Cuba. These introductions likely occurred accidentally via shipping or intentional introductions (release of pets into the wild).

Kolbe and his colleagues found that brown anole populations experiencing more hurricanes had longer limbs and larger toepads, traits that help them hold on — both in the immediate sense of a single storm and in the long-term as well, in terms of natural selection. Their results confirm hurricanes as a major force shaping variation in Anolis lizards and highlight how the evolutionary trajectories of animal populations will be altered as climate change modifies historical patterns of natural selection, he says.

An evolutionary ecologist, Kolbe studies the evolutionary response of species adapting to rapid environmental shifts and says that biological invasions are useful scenarios to study rapid evolution.

Although there aren’t many good studies on the ecological impacts of this species, its high densities, rapid spread and generalist nature suggest potential impacts on other species, Kolbe says, noting that other species could be studied, as well.

“Lizards are surely not the only species potentially experiencing selection during hurricanes,” says Kolbe. “Our understanding of episodic selection may be enhanced by studies on the evolutionary effects of hurricanes on other species, not only lizards.”