Author: Colin Donihue

Back in 2014, collaborators Panayiotis Pafilis, Anthony Herrel, Johannes Foufopoulos and I initiated a multi-island lizard introduction experiment, inspired by the foundational anole evolutionary ecology work of Losos, Schoener, and Spiller. Our twist: we were going to do it in Greece, with a different genus of lizard – Podarcis. Wall lizards haven’t radiated like anoles, but there is fascinating work demonstrating rapid evolution in the genus and a large descriptive literature documenting the phenotypic differences of populations living on mainland, large islands, and small islands.

We introduced 20 marked individuals from the large, predator-rich island of Naxos to each of five Podarcis-free islets, and revisited the populations annually (up until pandemic), censusing each island. Each year we gathered new morphology, performance, behavior, and diet data, and released the lizards back to the experimental islets. We’ve just published a new paper showing that the traits that best predicted initial survival were not all the ones we’d expected. Body condition – sure – lizards with a higher body condition probably have the reserves that enable them to weather the stressful introduction. Bite force? Not so much. We’d expected bite force to be an important predictor of survival because lizards with harder bites would be more competitively dominant and also have access to defended prey items like gastropods. Contrary to our expectation, bite force was not a predictor of survival (but stay tuned, bite force has become more and more important as the experiment has continued).

If you’re interested, I’ve written lots more about the experiment on my blog over the years. We also have photos and videos from the islets:

Finally, a quick call to the community: I have six years of tissue samples from the five islet populations, but don’t have the molecular chops to ask any of the fantastically interesting questions we might be able to with paired survival, phenotype, and molecular data. If you’re interested in a collaboration, let me know!

New Literature Alert:

Colin M Donihue, Anthony Herrel, Johannes Foufopoulos, Panayiotis Pafilis, Body condition and jumping predict initial survival in a replicated island introduction experiment, Biological Journal of the Linnean Society, 2022;, blab172, https://doi.org/10.1093/biolinnean/blab172

Abstract: Over-water dispersal to small islets is an important eco-evolutionary process. Most often, new arrivals on islets find the environment harsh or mate-less, making their footholds on these islets fleeting. Occasionally, introduced animals are able to survive the strong selection following their arrival, leading to subsequent propagation and, in several famous cases, adaptive radiation. What traits predict that initial survival? We established a replicated island introduction experiment to investigate this process in lizards. In 2014, we introduced 20 Podarcis erhardii lizards to each of five small islets in the Greek Cyclades Islands. We found that the lizards that survived were those with better initial body condition, longer distal portions of their limbs and a greater propensity for jumping. Contrary to our expectations, neither body size nor the strength of the lizards’ bite – two traits positively related to competitive ability, which becomes important later in the colonization process in lizards – predicted survival. This is the first selection study of its kind investigating an experimental introduction of Podarcis, and whether the traits that determined initial survival are important in driving the future evolutionary trajectories of these populations remains to be determined.

Anoles in the Hot Seat on the Ologies Podcast

By Colin Donihue

On March 1, 2019

In Anole Art, Literature, and Humor, Anoles and Anolologists in the News

UCLA professor Shane Campbell-Staton was recently interviewed on the science podcast Ologies, hosted by Alie Ward. Shane is a thermophysiologist and anolologist (you may remember the stories about A. carolinensis and the polar vortex on AA a couple of years ago (here, here, and here). That’s not all Shane has going on though; his lab is branching out in lots of different directions (listen to learn about some cool/hot new projects) and he’s also hosting The Biology of Superheroes Podcast. As per usual, Shane’s interview is filled with jaw-dropping factoids (bees that cook their wasp predators), words of wisdom (write tomorrow’s to-do list every night before bed), lots of lizards, and many an endearing anecdote (though we never did find out who wins Superman vs. Ali).

You can listen to the full interview here, or on iTunes, Spotify, or wherever you get your podcasts.

Hold Tight Little Lizards! StoryMap Science Communication

By Colin Donihue

On December 16, 2018

In All Posts

Last year, just days after my team and I finished surveying two populations of Anolis scriptus in Turks and Caicos, the islands took a direct hit from Hurricane Irma. Shortly after that, Hurricane Maria barreled through. We realized that we had a serendipitous opportunity to investigate natural selection, and so Anthony Herrel and I returned to the islands, measured the survivors and, well, you’ll just have to keep scrolling…

I recently heard about ESRI StoryMaps for the first time. They’re a great, free online platform for using maps, pictures, and videos to tell a compelling story. I think they make for a great science communication tool. I put together a StoryMap about our project in Turks and Caicos and thought I’d share it here. I’d definitely recommend anyone interested to take a shot at making one, too. (Click here if the embed doesn’t work for you – it’s prettier full screen anyway).

Evolution 2018: Selection on Thermal Plasticity in City Lizards

By Colin Donihue

On August 24, 2018

In All Posts

Cities were hot at this year’s Evolution meeting because they provide valuable petri dishes for asking myriad evolutionary questions. For example, cityscapes tend to create and retain heat–the so-called urban heat island effect–resulting in significantly elevated temperatures in urban areas relative to nearby undeveloped landscapes. Hot cities thus provide scientists an opportunity for asking questions about how plants and animals adapt to tolerate high temperatures. These questions are especially relevant as the built landscape continues to creep into less-developed surroundings and the globe as a whole experiences year after year of record temperatures.

Dr. Shane Campbell-Staton and colleagues used steep thermal differences between cities and nearby forests in four municipalities in Puerto Rico to determine whether, and to what extent, lizards may have adapted to warmer temperatures in the city. First, they found that operative temperature does change: lizards in cities use warmer perches and they operate at higher body temperatures than their forest counterparts. When brought back to the lab, however, those city lizards did not continue to function better at higher temperatures than their forest counterparts.

So what might be underlying this thermal plasticity?

Campbell-Staton and his collaborators then brought lizards back to the U.S., bred them, and raised the offspring in common conditions. Surprisingly, they found that the differences they observed in the wild populations disappeared in the next generation, an indication that this thermal ability is a plastic response to the thermal environment.

This thermal plasticity observation generated another question: Is thermal plasticity the target of natural selection in urban heat islands? To investigate this, Campbell-Staton isolated and analyzed transcriptomes of skeletal muscles in lizards from the hot city and cool(er) forests. Indeed, after the lizards were subjected to controlled heat treatments in the lab, they found a suite of candidate genes that were expressed at different levels between the populations. More genomic wizardry is planned for the very near future.

The work is ongoing and a very exciting paper is coming together. Keep your eyes peeled because it will certainly make a splash. Additionally, if you’re interested in this kind of work, Campbell-Staton has just started a lab at UCLA and is actively recruiting new lab members. Shoot him an email here.

An Update on Taking Toepad Pictures

By Colin Donihue

On August 24, 2017

In Research Methods

I’ve taken more than four hundred toepad pictures using the new macro photography technique I introduced in an earlier post and I’ve learned a few tricks that I want to share in this update.

First and foremost, I highly recommend this approach. For those of you looking to capture a lot of toepad data, particularly in the field, this kit is way faster and more portable than using a flatbed scanner and the images I’m getting are at least as sharp.

A few tips:

Petri dishes work great as a clear platform to place the lizard feet on. I found that the 60 mm diameter dishes were much easier to balance atop the lens (~40 mm in diameter) than the larger dishes I’d originally shown.
I cut and taped a scale bar to one edge of the petri dish so I wouldn’t have to worry about juggling a lizard and a tape measure.
Make sure you have several petri dishes – they scratch fast – and keep some ethanol and a kimwipe close at hand.

The app that lets you remotely trigger your iPhone is absolutely maddening. Do not download it. I’m not even going to relink the name. Instead, I suggest a much more stable alternative: connect your phone to your computer with the USB cable, open QuickTime Player, select File > New Movie Recording and click the down arrow next to the record button. This will give you the option to select your attached iPhone as a recording device. This live-view is far more stable and less frustrating. *Windows and android users I’m afraid I haven’t had an opportunity to sort out a solution for those platforms. If you know of something that works, please include in the comments!

Unfortunately, through the live view all you can see is whether the lizard is in position. You cannot remotely trigger the shutter this way. That means you’ll need a second pair of hands to help. I found it worked best when my partner was in charge of putting the ID tag in the frame after I’d placed the lizard foot and then pushing the volume button on the side of the phone to trigger the camera shutter.

Lighting is really important. I suggested a headlamp in the previous post providing an oblique light source through the diffuser around the lens. I tried using a microscope fiber optic light source but I was really unhappy with the “warmth” of the light. I found that the white-LEDs in my headlamp produced a much more realistic looking image (see above). Also, make sure you don’t have any light sources above/behind the subject. Backlighting confuses the camera’s auto-contrasting and results in dark and sometimes unfocused images.

A New Method for Taking Toepad Pictures in the Field

By Colin Donihue

On August 8, 2017

In Research Methods

Getting good pictures of lizard toepads in the field can be tricky. Flatbed scanners are heavy and don’t take well to transit bumps and bruises, and getting a digital camera to focus on the toe, not the glass, requires surgical precision on the manual focus ring. I’ve just found a new solution for an iPhone (or GooglePixel, if that’s how you roll), and I’m eager to share.

Here’s what you need:

An iPhone 6 or 7 series or a GooglePixel, the Moment Lens mounting case ($29.99) with the Moment Macro Lens ($89.99), a clear surface, a scale bar, your headlamp, and a laptop.

Here’s the setup in action (and, by the way, this particular lizard’s bite force was classified as medium-ouch):

You’ll notice that when the camera is facing up the iPhone screen is facing down. Obviously this makes it difficult to snap the photo—enter the app WiFiCam. This app enables you to type the phone’s IP address into your web browser and remotely trigger the camera, as long as both devices are on the same wifi. It’s very simple, and the price was right (free!).

And so here’s the whole shebang:

(Don’t forget to keep a tissue handy for wiping up lizard poop!)

And not to bury the lede, but the results are fantastic (see above).

A few things to note:

The white plastic platform around the lens ensures perfect focal distance so getting your lizard as close to that plane as possible is ideal. I tried a square of single pane glass but wasn’t tremendously pleased with the results. The above is taken with a cheap plastic petri dish, which works great but scratches quickly. Another option I’m going to look into is a glass microscope slide. (The biggest drawback to the slide is that it’s smaller than the camera lens platform… meaning that the lizard can actually poop ON YOUR PHONE. And believe me, they will.)
The app works fine for controlling the shutter, but it’d be nice to be able to also control other camera settings like focus point and brightness or contrast. There might be other apps out there that do all of that; I just haven’t tried to find them yet. If you’re taking photos of lizard toepads in a place without wifi (as you most likely are), you can use your computer to create a local network and pair the camera to the computer that way.
I found that the sidelight was really helpful to get good illumination on the toes. Without the sidelight the camera sometimes adjusts for ambient light behind the foot, making the lamellae hard to see. My headlamp was the perfect size and brightness and worked great.

One last thought: Moment also has a fisheye lens that might do a really nice job of canopy cover photos in the field. That’s on my short list of things to experiment with in the near future!

I’d love to hear your thoughts on how to improve the system in the comments.

Reporting on the Reptiles of Redonda

By Colin Donihue

On March 22, 2017

In All Posts

I’m back from Redonda and the expedition was a great success! I’m happy to report there were many Anolis nubilus boulder-hopping out of the way of the black rats and even blacker ground lizards on the island. In many ways the trip was even more challenging than expected but we came out with quite a lot of data so we have a great sense of the current status of the reptiles on the island and a baseline for comparisons into the future. I have even more stories and some videos going up on my blog to keep watch over there if you want even more details about Redonda.

To refresh your memories, Redonda is an island of Antigua and Barbuda and was completely denuded by rats and goats over the last century. Despite the dearth of vegetation, three endemic reptiles had been hanging on: Anolis nubilus, Ameiva (Pholidoscelis) atrata, and an as-yet unnamed Sphaerodactylus dwarf gecko. The government of Antigua and Barbuda, in collaboration with Fauna & Flora International and local NGO the Environmental Awareness Group, has decided to undertake a massive restoration effort by eradicating the rats and relocating the goats. My job was to get some baseline data on the current lizard populations so we can figure out how they change into the future.

Helicoptering to the island was every bit as exciting as I’d hoped. The Jurassic Park theme was playing through my head the whole way down. See that grassy patch with slightly fewer large rocks – that was the little tiny helipad, but our pilot was a pro and set us down perfectly. Almost as soon as we were out of the helicopter, we deposited our bags by our tents and set about catching Anoles.

Anolis nubilus is at first blush a relatively innocuous member of the genus. They’re perfectly camouflaged in this environment, which is to say they’re drab gray and brown. Their dewlaps are cream-colored (which is really just my nice way to say drab gray-yellow) and the most decorated of the females sport faint dorsal stripes. Males did fairly regularly display impressive crests behind their heads, but nonetheless, the species at first and second glance is considerably less flashy than many of their cousins on nearby islands.

Photo: Geoffrey Giller

All that said, there’s still a lot of cool stuff going on with nubilus. As Skip mentioned in his article 45 years ago, there’s a casuarina tree right next to the remains of the mine manager’s house that hosts an abundance of the few Redonda tree lizards living up to their name. The tree is still there and the lizards are still eagerly defending their precious few branches (see above).

There are actually quite a few trees still on Redonda, some of which are native Ficus trees. For the most part they’re in fairly inaccessible areas, but that really just means you need to bring a longer noose pole and don’t look down. I caught a lizard on this tree below with a perch height of approximately 350 meters (that’s really going to mess with the averages). Truth be told, after catching the lizard my knees were so wobbly I had to go find a nice big boulder and just had Geoff and Anthony shout me data for a while.

After a week on the island and many, many Anoles, we got morphometric and performance data, diet data, extended focal-animal behavior videos, two mark-recapture density studies and two permanent transects established, thermal ecology data, habitat use data, and flight behavior data. We even exhaustively determined whether nubilus likes Chuckles! (But that’s a story for another post).

I know this is an Anole blog, but there were some pretty cool things going on with the other reptiles on the island, too. The ground lizards were jet black and really big. Here’s a picture of Anthony Herrel trying to get a tail measurement:

Photo: Geoffrey Giller

The atrata spent their days cruising around scavenging. We saw one eating a hermit crab, and we heard rumor of another that managed to get a sardine away from one of the crew working on the eradication effort! Analyzing the stomach contents of these guys is going to take quite a lot of detective work.

We also were able to gather the first natural history data on this unnamed dwarf gecko species. They’re strangely beautiful with an unlovely shovel-face and semi-transparent, too-squishy, gelatinous body. You wouldn’t guess it but they’re quick!

Photo: Geoffrey Giller

In all, the reptiles of Redonda were fascinating and getting to explore the island was a unique privilege. I can hardly wait to return next year, and many years after, to see how the lizards change with the island.

“What about us?” Technically these guys are reptiles too, but c’mon, the lizards are so much cooler. Photo: Geoffrey Giller

Of Rats and Reptiles: An Expedition to Redonda

By Colin Donihue

On February 21, 2017

In New Research

Anolis nubilus male and female from The Anoles of the Lesser Antilles.

In 1972, James “Skip” Lazell published a monograph on the Anoles of the Lesser Antilles including the species description of Anolis nubilus, an endemic anole restricted to the island of Redonda. His description of the animal and island, like the rest of the monograph, is colorful and evocative:

“The tiny islet is exceedingly steep-to, and rises nearly 1000 feet out of the sea. There is virtually no surrounding bank, and the full swell of the western North Atlantic pounds Redonda’s cliffs. A tiny, nearly vertical gut on the leeward side provides the only access to the top of the islet up the cliffs; great blocks of basalt lie at the foot of this gut and one’s original entrance to Redonda is made by jumping onto these blocks as the boat goes past them. It is about like jumping from a moving elevator onto a card table, except that elevators give more notice of directional reversals… but getting on is just the beginning. …

The top of Redonda is a rolling wold and a favorite place of innumerable nesting sea birds; the gut provides a route for their guano to descend the cliffs, and it dries to a thick powder there. Because of its lee-ward location, a chimney effect is produced in the gut, and the guano dust, mixed with the volcanic sand weathered from the parent rock, tends to rise when disturbed. As one toils up the gut under the tropical sun, one is accompanied by a cloud of this dust, which soon mingles with one’s own sweat to produce a wondrously aromatic and abrasive, though rather gluey, bath. At the top, jumbles of rocks and clumps of prickly pear rise gently to the old ruins, complete with a hedge of bougainvillea and a single tree. This is the home of Anolis nubilus. …

Surely Redonda once supported more vegetation, and presumably Anolis nubilus then had an easier life. The feral goats should be extirpated on this remarkable island, whose only known nonflying vertebrates are species found nowhere else on earth.”

Now, 45 years, 1 week, and 4 days later, I’m headed to Redonda to gather baseline lizard data on exactly such a goat extirpation.

Skip did miss one nonflying vertebrate in his account; Rattus rattus has taken up residence en masse on Redonda. The black rats are so plentiful now that they’ve taken to stalking the lizards on the island in daytime—“tiger rats,” according to Dr. Jenny Daltry, one of the researchers leading the island restoration effort. And so, the government of Antigua and Barbuda, in conjunction with numerous conservation NGOs including Flora and Fauna International, has decided to remove the goats and rats from Redonda in an attempt to restore the island and help its three endemic lizard species to recover.

Redonda is home to not just A. nubilus but also a jet black ground lizard, Ameiva atrata and an as-yet unnamed dwarf gecko, Sphaerodactylus sp. Presumably, A. nubilus would be perched high in vegetation avoiding the roving A. atrata; however, after centuries of goat grazing on Redonda, that vegetation has been reduced to a single Cassuarina tree. So, while that tree is likely swarming with anoles, most of the A. nubilus are spending their time hopping around the boulders of Redonda. Normally this would put them in range of the roving ground lizards, but it sounds as though both lizards should be more worried about those hungry black rats.

Fortunately for all of Redonda’s reptiles, as of a few weeks ago the goats on the island took a one-way ferry ride to new pastures (not a euphemism) and, well, starting soon the rats will be making their way to the great big garbage heap in the sky (definitely a euphemism). My goal is to get to Redonda and gather as much baseline data on the lizards as possible to see whether and how the lizard community changes on a goat-less, rat-free Redonda.

That’s no easy task, though. Here’s a picture of Redonda:

Photo credit: Dr. Jenny Daltry. I’m reasonably sure that’s the gut there, in the foreground of the image.

Believe it or not, that’s the pleasant side of the island. Here’s the other:

Photo credit: TopTenz.net

We decided that hauling a week’s worth of research and camping gear up Lazell’s gut (let alone jumping to that card-table basalt) was out of the question, so I’m going to be arriving by helicopter. As if the rats weren’t enough, Redonda has no source of fresh water so we’ll be carrying in food and drink for the 8 days on the island. No power either, so I’ve been putting together solar kits to try to get enough juice to run a computer and spectrophotometer.

All in all, it’s going to be an adventure! I’ll update Anole Annals when I return, but I’ll also be posting more frequent updates to my personal blog and twitter. I’d love to hear from you, especially if you have any tips for rat-proofing tents (seems more efficient to just bait the other ones, right?).

Citation: Lazell, J.D. 1972. The Anoles (Sauria, Iguanidae) of the Lesser Antilles. Bulletin of the Museum of Comparative Zoology. 143(1).

Happy Birthday, Festive Anole!

By Colin Donihue

On January 30, 2017

In All Posts

I got up early this morning to put a video camera on one of our A. sagrei eggs that was looking particularly ripe. About two hours later, this little hatchling crawled out. The whole hatching process took about 25 minutes, and I’ve sped up the video by 30x. The video is much more compelling with sound. I personally like “Also Sprach Zarathustra,” though “Ranz des Vaches” by Rossini had some enthusiastic support in lab. If you have other music suggestions, add them to the comments!

Happy birthday, little one!

Feed or Fight: Lizard Bite Force on Islands

By Colin Donihue

On October 1, 2015

In New Research

I’m a bit of an impostor here on Anole Annals, but I’m spending the year in the Losos lab writing up my dissertation and thinking about lizard evolution, so I wanted to share stories from some other island lizards “across the pond.

My dissertation work has focused on the Aegean Wall Lizard, Podarcis erhardii, common through much of the Greek archipelago. I’ve been surveying and experimenting with these lizards in different biogeographic and human contexts to connect trait changes to ecological surroundings. I recently published a paper looking specifically at lizard bite force. Since it comes with pretty pictures and is relevant to anoles, I want to share it here with you all.

For lizards, bite force is often important for determining what you can eat and how well you can fight off competitors. On small islands where food is often scarce, a proportionally stronger bite force might enable a lizard to access hard food items (like snails or beetles) or fight off other lizards, protecting access to mates, food, or prime nesting sites. Both explanations have been demonstrated in anoles: bite force has been closely tied to diet hardness (Herrel et al. 2006), and fighting success (Lailvaux et al. 2004).

I surveyed lizards on a dozen islands in the Cyclades. First, I found that lizards on small islands in the Greek Cyclades had significantly stronger bite forces relative to their body size. I then decided to try to untangle these two potential drivers (diet and aggression) and determine which better explained inter-island variability in bite force.

By looking at proxies of competition including bite scars and missing toes, and lizard diets across islands ranging over five orders of magnitude in size, I found that, in general, it was the competitive environment that was driving the trend in P. erhardii bite force.

I’ve put together a short video about the findings for Functional Ecology (see above). For the full paper, please see:

Donihue, C.M., K.M. Brock, J. Foufopoulos and A. Herrel. 2015. Feed or fight: What drives bite force differences in the Aegean Wall Lizard, Podarcis erhardii, across the Greek Cyclades? Functional Ecology. doi: 10.1111/1365-2435.12550 Full text

Papers Cited:

Herrel, A., R. Joachim, B. Vanhooydonck, and D.J. Irschick. 2006. Ecological consequences of ontogenetic changes in head shape and bite performance in the Jamaican lizard Anolis lineatopus. Biological Journal of the Linnean Society 89: 443-454.

Lailvaux, S.P., A. Herrel, B. Vanhooydonck, J.J. Meyers, and D.J. Irschick. 2004. Performance capacity, fighting tactics and the evolution of life-stage male morphs in the green anole lizard (Anolis carolinensis). Proceedings of the Royal Society B: Biological Sciences 271: 2501-2508.