All posts by Jonathan Losos

About Jonathan Losos

Professor and Curator of Herpetology at the Museum of Comparative Zoology at Harvard University. 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.

Rat and Goat Removal Gives Anolis nubilus Another Shot

Colin Donihue and Anthony Herrel just completed their trip to Redonda to study Anolis nubilus and no doubt they’ll report back to us shortly. Meanwhile, a tip of the hat to AA commenter Nathan Manwaring for pointing out this article posted on Fauna and Flora International’s website:

Redonda harbours a number of endemic species that occur nowhere else in the world, including the Redonda tree lizard (Anolis nubilus), Shown here. In 2015 all of the surviving reptile species were evaluated by IUCN as Critically Endangered. Credit: Jenny Daltry/FFI.

Captivating Caribbean island to be given a new lease of life

Posted on: 21.07.16 (Last edited) 5 August 2016

Starving goats and predatory rats to be removed from Redonda to restore this Caribbean island to its former glory.

The Government of Antigua and Barbuda has announced plans to remove goats and invasive rats from its most rugged and remote offshore island to allow endangered wildlife and their habitats to recover.

Redonda is home to a unique array of plants and animals, including rare lizards found nowhere else in the world. The uninhabited and seldom visited island is also formally recognised as an Important Bird Area, supporting globally-significant numbers of seabirds.

However, the island’s plant and animal populations are disappearing fast thanks in large part to its population of over 5,000 aggressive black rats (an invasive alien species) which prey heavily on the island’s wildlife. Together with the herd of long-horned goats that was brought to Redonda by humans more than a century ago, these mammals have transformed this once-forested island into a moonscape. So few plants survive that even the goats now face starvation.

Redonda from the air. The island, once forested, now looks like a lunar landscape. Credit: Jenny Daltry/FFI.

Redonda from the air. The island, once forested, now looks like a lunar landscape. Credit: Jenny Daltry/FFI.

Redonda is over 50 hectares in area and rises dramatically from the Caribbean Sea, 56 km south-west of Antigua. Goat skeletons litter the island, along with the relics of stone buildings from a guano mining community that lived here until the First World War. With few trees left to stabilise the ground, soil and rocks are crumbling into the sea, threatening nearshore coral reef in the waters below.

“We cannot stand by and watch as a part of our country, part of our history, disappears. We cannot be responsible for decimating animal populations on a regional scale,” says local conservationist Natalya Lawrence of the Environmental Awareness Group (EAG).

The Redonda Restoration Programme has been formed by the Antigua & Barbuda Government and EAG in collaboration with partners from the UK (Fauna & Flora International, British Mountaineering Council), USA (Island Conservation) and New Zealand (Wildlife Management International Ltd).

“I am immensely proud that my ministry has been a driving force in the development of this major initiative,” says Honourable Molwyn Joseph, Minister of Health and the Environment. “Restoring Redonda to its full glory will be a great achievement for our country.”

A new home for starving goats

One of the first steps will be to capture and move the remaining goats to Antigua, where they will be cared for by the Department of Agriculture.

The miners also left behind a herd of long herd goats. Together with the rats, these animals have transformed this once-forested island into a moonscape. So few plants survive that even the goats now face starvation. Credit: Jenny Daltry/FFI.

The miners also left behind a herd of long herd goats. Together with the rats, these animals have transformed this once-forested island into a moonscape. So few plants survive that even the goats now face starvation. Credit: Jenny Daltry/FFI.

“The goats are starving to death on Redonda and must be removed for their own sake,” explains Astley Joseph, Deputy Director of the Department of Agriculture. “We believe it is important to rescue this rare breed because it could have useful drought-adapted genes that would benefit other herds on Antigua and elsewhere.”

Rats will then be eradicated using a rodenticide bait that has previously been used to restore more than 20 other Caribbean islands without harming native wildlife. This is scheduled to be completed by mid-2017.

Black rats are omnivorous, and are known to attack native wildlife, such as ground-nesting birds and reptiles. Credit: Jenny Daltry/FFI/OICP.

Black rats are omnivorous, and are known to attack native wildlife, such as ground-nesting birds and reptiles. Credit: Jenny Daltry/FFI/OICP.

“We and other international organisations have offered our support because we recognise that this is a very challenging yet globally important initiative” says Sophia Steele, Eastern Caribbean Project Coordinator at Fauna & Flora International. “Recent studies have identified Redonda as the most important island to restore in the Eastern Caribbean due to its Critically Endangered wildlife and the high probability of lasting success.”

The new programme is funded by the UK Government’s Darwin Initiative, the National Fish and Wildlife Foundation, the Taurus Foundation and private sponsors. Additional technical and in-kind support is being provided by Caribbean Helicopters and Syngenta Crop Protection AG.

Dr Helena Jeffery Brown of the Department of the Environment says, “Antiguans and Barbudans will be proud as Redonda becomes a role model for regional biodiversity conservation. This will be yet another example of how this country is proactive in meeting the national and international commitments it has made to conserve biodiversity.”

Redonda is also an Important Bird Area thanks to its regionally- and globally-significant colonies of seabirds, including these brown boobies. Credit: Jenny Faltry/FFI/OICP.

Redonda is also an Important Bird Area thanks to its regionally- and globally-significant colonies of seabirds, including these brown boobies. Credit: Jenny Faltry/FFI/OICP.

Antigua and Barbuda has a wealth of experience and success under the ongoing Offshore Islands Conservation Programme which has, since 1995, removed rats and other invasive pests from 15 islets closer to Antigua in the North East Marine Management Area. This has saved the Antiguan racer – once the world’s rarest known snake – from extinction, and enabled an incredible recovery of other native animals and plants. Many tens of thousands of residents and tourists now visit and enjoy Antigua’s pest-free islands every year.

“I am most excited to see the progression of recovery on Redonda once the threat of invasive species is removed,” says local biologist Andrea Otto, who will be part of the research team documenting the recovery process. “I want to see which types of vegetation spring up first and which birds return. From what we have seen on the smaller islands we have restored, the transformation will be incredible.”

For more information, read the press release.

Please support this important work by donating today.

Anole Annals — Valentine’s Day Special


Peter Uetz of the Reptile Database fame sends the following Valentine’s Day greetings:

DSCN3297-2If you or your significant other loves anoles, you may want to show her/him this hearty Anolis distichus (Figure 2960, above) on occasion of today’s Valentine’s Day. It clearly shows a heart on it’s head. Some other specimens such as the couple in Figure 3297 (right, from locality 1 in the Google map), also show a heart although it’s not as pronounced. Also note their blunt coloration which doesn’t seem to affect their affection.

Anolis distichus is pretty variable and even within this subspecies, A. d. dominicensis Reinhardt & Lütken 1863, to which all these specimen belong, there is considerable variation. By the way, the guy with the heart (Figure 2960) is from the same locality 3 as two other specimens which do not have a heart (Figures 2948 and 2968) although they display a similar shape on their heads. Figure 3087 shows yet another specimen for comparison, this time from locality 2.







Various authors have described a dozen subspecies from Hispaniola (reviewed in Schwartz 1971, see map 2 from that paper). The northern half of Hispaniola is almost entirely in the hands of A. d. dominicensis, hence the specimens on the photos have been assigned to that subspecies.

Hispaniola terrain map-2

Note that Glor & Laport 2012 elevated several Dominican subspecies of A. distichus to full species level, namely A. dominicensis, A. favillarum, A. ignigularis, A. properus, and A. ravitergum. The Reptile Database hasn’t followed this yet because their geographic sampling was limited to relatively few localities and they did not provide any updated diagnoses (but their recommendations have been recorded in the database). Also, there seems to be hybridization among several of these populations.

Photo localities:

2948: 3

2960: 3

2968: 3

3087: 2

3297: 1


Thanks to Miguel Landestoy and Luke Mahler who helped with the IDs.


Glor, Richard E.; Robert G. Laport 2012. Are subspecies of Anolis lizards that differ in dewlap color and pattern also genetically distinct? A mitochondrial analysis. Molecular Phylogenetics and Evolution 64 (2): 255-260.

Schwartz, A. 1968. Geographic variation in Anolis distichus Cope (Lacertilia, Iguanidae) in the Bahama Islands and Hispaniola. Bull. Mus. comp. Zool. Harvard 137 (2): 255- 309.

Schwartz, A. 1971. Anolis distichusCatalogue of American Amphibians and Reptiles (108)

(used to be available online at ZenScientist, and maybe soon at the SSAR website again).

Anolis distichus in the Reptile Database

(an extended synonymy and distribution section will appear in the next database release)

The database entry also has another 43 references most of which are available online.

Where Is the Type Locality of Anolis aequatorialis?

A new paper in Zootaxa aims to figure it out, based on the travel journals of its describer, Franz Werner. Here’s the paper’s abstract:

The eminent Austrian zoologist Franz Werner described several new species of amphibians and reptiles from America, including Anolis aequatorialis Werner, 1894 and Hylodes appendiculatus Werner, 1894. Both species were described based on single specimens, with no more specific type localities than “Ecuador” (Werner 1894a,b). After its description, A. aequatorialis remained unreported until Peters (1967) and Fitch et al. (1976) published information on its distribution and natural history. Anolis aequatorialis is currently known to inhabit low montane and cloud forest on the western slopes of the Andes from extreme southern Colombia to central Ecuador, between 1300 and 2300 m elevation (Ayala-Varela & Velasco 2010; Ayala-Varela et al. 2014; Lynch et al. 2014; D.F. Cisneros-Heredia pers. obs.). Likewise, Hylodes appendiculatus (now Pristimantis appendiculatus) remained only known from its type description until Lynch (1971) and Miyata (1980) provided certain localities and information on its natural history. Pristimantis appendiculatus is currently known to occur in low montane, cloud, and high montane forests on the western slopes of the Andes from extreme southern Colombia to northern Ecuador between 1460 and 2800 m elevation (Lynch 1971; Miyata 1980; Lynch & Burrowes 1990; Lynch & Duellman 1997; Frost 2016). To this date, the type localities of both species remain obscure. The purpose of this paper is to restrict the type localities of Hylodes appendiculatus Werner, 1894 and Anolis aequatorialis Werner, 1894 based on analyses of the travel journals of their original collector.

Great New Video on Anole Dewlaps: How Can Species with Identical Dewlaps Coexist?

Day’s Edge Productions has produced a great new video about how two species with seemingly identical dewlaps manage to coexist. Manuel Leal explains what’s really going on.

This video originally appeared in bioGraphic, an online magazine from the California Academy of Sciences that features beautiful and surprising stories about nature and sustainability. 

What is bioGraphic, you ask? Here’s what it’s webpage says:

A multimedia magazine powered by the California Academy of Sciences, bioGraphic was created to showcase both the wonder of nature and the most promising approaches to sustaining life on Earth. We hope our stories will spark conversations, shift perspectives, and inspire new ideas, helping not only to shed new light on our planet’s most pressing environmental challenges, but also—ultimately—to solve them.

Through an ever-evolving array of storytelling tools and techniques, we will introduce you to some of the world’s most intriguing creatures and inspiring people. We’ll also transport you to faraway places, enabling you to experience what it’s like to be there and what’s at stake for those involved. Along the way, we’ll take a critical look at the environmental issues that pose the greatest threats to our future—and the most promising ideas for addressing them.

So please come along—and come back often—as we travel the globe in search of stories that inspire both awe and hope for a more sustainable future.

Aquatic Anole Forages Underwater

I’ve recently learned that famous nature micro-photographer Piotr Naskrecki observed an aquatic anole catching prey underwater. Here’s what he had to say on his blog, The Smaller Majority:

The other aquatic iguana

Aquatic iguana (Norops aquaticus) on rocks in a rainforest stream in Costa Rica [Canon 1Ds MkII, Canon 24-105mm]

In a couple of days I am heading off to the Galapagos Islands, where I hope to be able to see the incredible marine iguanas, the world’s only truly marine lizards. Other lizards enter water occasionally, but aquatic lifestyle is quite rare among these reptiles, and few species live and feed under water. But in rainforest streams of Central America there is one little known species of iguana that does just that.I first saw the aquatic iguana (Norops aquaticus) in the southern part of Costa Rica in 1994. These lizards swam and dove in a fast-flowing stream, catching water insects. But when I told a herpetologist friend about it, she refused to believe me.

It took me 13 years to find the aquatic iguana again, and this time I had a camera with me. It was in a different part of Costa Rica (Est. Pitilla in Guanacaste), but the animal and its habitat were the same. I watched it for a couple of hours, following the lizard among slippery boulders, hoping to document its hunting behavior. Eventually I got lucky, but alas, the actual catching of the prey happened underwater, when the iguana cornered a nymph of an aquatic blattodean (a yet undescribed species.) Next time I will definitely try to get a photo of the underwater action.

Update (2 Sept 12): Turns out that the aquatic Norops iguanas that I saw in southern Costa Rica and those from the northern part of the country, shown here, are different species. The animal in the photos is Norops oxylophus, not N. aquaticus. You can read more about the amazing aquatic behavior of N. oxylophus here. (Thanks to Annemare Rijnbeek for pointing me in the right direction regarding the ID of these animals.)
Incidentally, it appears that these lizards are once again being placed in the genus Anolis, where they historically belonged.

Aquatic iguana with a freshly caught aquatic blattodean [Canon 1Ds MkII, Canon 100mm macro]

Aquatic iguana swallowing its prey [Canon 1Ds MkII, Canon 24-105mm]

Nice New Article on Anoles in The Scientist


Caribbean Anoles Function as Model Organisms for Evolutionary Dynamics

The small lizards adapted to unique niches among dozens of isles.

By Amber Dance | January 1, 2017

NOTICE ME!: A male Anolis stratulus (barred anole) extending his dewlap in Puerto RicoPHOTO BY MICHELE JOHNSON

It’s not easy to snare a lizard. Evolutionary biologist Michele Johnson affixes a noose made of dental floss to a telescopic fishing rod to reach into the bushes and tree canopies where Caribbean anoles live. By the end of the summer field season, her students from Trinity University in San Antonio, Texas, develop a knack for it. “We almost always catch our lizards,” says Johnson.

She doesn’t just collect field measurements and observations; she’s taken 30 different species of anoles back to her lab to analyze their physiology. Anoles have become a favorite model for evolutionary biologists because of their extraordinary diversity—there are more than 400 species in genus Anolis—and because of how they originally populated the Caribbean islands. The relative scarcity of mammals, snakes, or birds on the islands left many niches open for the lizards to occupy.

As anoles—which also inhabit Central and South America—reached individual islands, their populations diversified into island-specific forms that occupy certain niches. For example, each of the four largest islands in the Greater Antilles (Hispaniola, Cuba, Puerto Rico, and Jamaica) hosts one or more species that are green lizards hanging out in the lower canopies of trees, and another group of short-limbed, slow-moving reptiles that perch on twigs. These are two of the six “ecomorphs” that scientists who study Caribbean anole species have defined. To be considered an ecomorph, a set of habitat specialists must exist on more than one island, though the species in each group differ between islands. And yet, other anole species belong to no particular ecomorph class.

Caribbean anoles offer scientists a sort of “natural experiment,” explains Luke Mahler, an evolutionary biologist and herpetologist at the University of Toronto. Each isle, with similar environments, acts as a replicate for how anoles underwent convergent evolution into ecomorphs. As a result, evolutionary studies of anoles have flourished in the past couple of decades—think Darwin’s finches, but scalier.

“They really are a good model system for lots of questions, from very small-scale molecular work all the way up to adaptive radiation,” says Jerry Husak, a physiologist at the University of St. Thomas in St. Paul, Minnesota.

The basic anole ecomorphs go way back in evolutionary history, found Jonathan Losos, an evolutionary ecologist at Harvard University. Emma Sherratt, now at Australian National University in Canberra, got a hold of 20 fossil anoles while a postdoc in Losos’s lab. The fossils dated back 15 million to 20 million years, when the lizards were preserved in amber on the island of Hispaniola. Some were in museums, others in private collections. Using CT scans, the Losos team examined anatomy to confidently assign these fossils to four of today’s ecomorphs; a couple other fossils might be part of a fifth (PNAS, 112:9961-66, 2015). “At least several of the habitat specialist types already existed,” concludes Losos.

Despite the countless hours biologists have spent studying Caribbean anoles, the genus seems to have plenty of surprises still in store. In addition to her ongoing studies of physiology and behavior in diverse anole species, Johnson has recently focused on how her local Texan anole, Anolis carolinensis, determines dominance. A. carolinensis, like many other anole species, adopts a strict mating hierarchy in captivity, with males battling each other for access to prime habitat and to females. In the field, the hierarchy is more complicated—a lizard defending his own territory is more likely to win a fight, she thinks. She figured the biggest males would also be more likely to triumph, either in the lab or the field, and thus achieve larger territory and more females to court.

In order to correlate body characteristics and behaviors with dominance, Johnson’s group set up a sort of lizard fight club, pitting anoles against each other in one-on-one cage matches, with a single perch to battle over. Winners tended to execute more visual displays, performing push-ups and head-bobs and expanding the showy throat skin known as a dewlap. They also chased and bit the losers, who tended to back away and to hide in a corner.

But larger anoles weren’t always the winners in captivity or in the field. “Body size doesn’t predict who wins these fights at all,” says Johnson. Instead, behaviors made a huge difference—the most aggressive lizards won their matches. A longer head also helped, perhaps because it looked to opponents like a serious biting weapon. In the field, animals with a wider head and powerful jaws occupied larger territories with more females present (Anim Behav, 118:65-74, 2016).

Body size still probably matters, Johnson says. She has not yet tested in field studies whether size might help an A. carolinensis male establish his territory or take over a vacated area. And at least in other anole species, bigger males sire more offspring.

Mahler also got a surprise from the anoles when, in 2010, he received an email from Miguel Landestoy, a Dominican naturalist who claimed he’d seen a new species. Mahler was initially skeptical. “Everybody thinks they’ve got a new species,” he says, yet “the Caribbean anoles are the best known anoles, by a long shot.”

Then Mahler opened Landestoy’s pictures. “Holy crap,” he said. “That doesn’t look like anything we’ve seen on Hispaniola.” The critter was huge, by anole standards—about a foot from nose to tail tip. It had short legs, a short tail, and a mottled greenish-gray pattern that suggested it could easily blend into a mossy or lichen-covered branch. “I bought the first cheap flight I could find,” recalls Mahler.

The other thing that struck Mahler about the new species—which he and his colleagues dubbed A. landestoyi—was that it looked similar to anoles found in Cuba. Their clade is called chamaeleonides for their creeping, chameleon-like movements and camouflage prowess. These particular kinds of anoles, scientists had assumed, were unique to Cuba. But here was another species, making its living in many of the same ways, on Hispaniola (Am Nat, 188:357-64, 2016). “This is an example of what might be a seventh ecomorph. . . . Evolution is more predictable than we have yet given it credit for,” says Johnson, who was not involved in the project.

“It’s amazing, in part, that anything new there could be found after all these years,” adds Losos, a coauthor on the study. “The age of discovery is not yet over.”

An Unusual Color Pattern in Anolis roquet


As Skip Lazell showed nearly a half century agoAnolis roquet on Martinique is extraordinarily variable in color across its range. This variation has been the subject of much recent work by Roger Thorpe’s lab.

In a recent paper in Herpetological Review, Anderson et al. report on finding an unusual color variant during their recent fieldwork on Martinique.

The Anoles of Bermuda and Evidence for Interspecific Competition


Bermuda only has one native lizard, a skink. However, during the first half of the 20th century, three anole species were introduced.  The first, the beautiful Anolis grahami from Jamaica, quickly spread over most of the archipelago, as David Wingate reported in 1965. However, Wingate noted that the subsequent two species, A. leachi from Antigua and A. extremus from Barbados achieved only more localized distributions.

Thirty-one years later, I published a follow-up survey. By that time, A. grahami had conquered the entire entire and A. leachi had greatly increased its range, but A. extremus was still limited to a far corner on the west end of Bermuda.

Joe Macedonia and colleagues have now returned for a 20-year follow-up, now 51 years after Wingate’s paper. In a paper just published in Herpetological Review, hey find that A. leachi is now also found throughout the Bermudian archipelago. Curiously, however, A. extremus has not advanced at all, with still a very small distribution in the west (see map below). The explanation doesn’t seem to be habitat availability, because there is no obvious difference between where A. extremus occurs and where it doesn’t. Macedonia et al. conclude, as I did, that it is competition from the very similar A. grahami that is preventing A. extremus from expanding its range.

Macedonia et al. also provide a wealth of information on the habitat use of all three species. And there’s a kicker–A. sagrei  has recently been introduced to Bermuda. Will it expand its range and, if so, how quickly. Notably, A. sagrei is considerably more terrestrial than the other anoles on Bermuda, so the opportunity seems to exist.


Anole Toepads Not as Good as Those of Geckos


The truth must be told.

Previous work by Anthony Russell has demonstrated that geckos have a sophisticated vascular system  and connective tissues that allows the toepad of geckos to be molded to the surface with great precision, enhancing the contact between the setal hairs on the pad and the surface. It had been speculated that a similar system existed in anoles, but no one had looked carefully. Now, Russell has, and he reports in Acta Zoologica that previous statements were mistaken: anoles lack what most pad-bearing geckos have. Here’s what the abstract says:

Adhesive toe pads of geckos house modified components of vascular and/or connective tissues that promote conformity of the setal fields with the locomotor substratum. Similar modifications have been claimed for the digits of Anolis, but evidence for them is not compelling. Angiographic and histological investigations of Anolis failed to identify any evidence of either an intralamellar vascular reticular network or a central sinus. Instead, their vascularity more closely resembles that of lizards in general than that of pad-bearing geckos. The loose connective tissue of the toe pads likely contributes to their general pliability and flexibility, promoting localized compliance with the substratum. Through the shedding cycle, the lamellae change shape as the replacing setae elongate. The outer epidermal generation lacunar cells on the inner lamellar faces simultaneously hypertrophy, providing for compatibility between overlapping lamellae, enabling reciprocity between them. This contributes to continuing compliance of the setal fields with the substratum. Overall, digital structure and attachment and release kinematics of the toe pads of Anolis are very similar to those of geckos exhibiting an incipient adhesive mechanism. Both lack major anatomical specializations for promoting conformity of the setae with the locomotor substratum beyond those of the seta-bearing portions of the epidermis.