Author: Chris Thawley Page 2 of 3

NSF Postdoctoral Fellow at University of Rhode Island; evolutionary ecologist, herper, lizard lasso-er, cookie monster, discslinger

Measuring the swelling induced in anole feet during the PHA assay may result in swelling in one’s own fingers.

The immune system is critical to the survival of animals, including anoles, which are faced with an environment full of potential pathogens and toxins. Ecoimmunologists have developed a myriad of assays to measure various aspects of the immune system and its function in a variety of species, but these assays are often applied to organisms without fully validating them. This issue can prevent a full and accurate interpretation of the results obtained. The PHA skin test is widely used in lizards, including anoles, to test immune function, but has exactly this problem: it has only been validated in cane toads and a crocodile…a large oversight!

Caty Tylan, a PhD candidate and DVM at Penn State University in Tracy Langkilde’s lab, set about rectifying this situation by validating the PHA assay in our favorite squamate lab “rat,” the green anole, Anolis carolinensis. To conduct the PHA test, Caty injected two different types of phytohemagglutinin (PHA-L and PHA-P) into the footpads of green anoles and compared the swelling produced to that of control injections. She also measured types of white blood cells in the blood and foot tissue at regular intervals after injections. Caty found that both types of PHA work well and induce similar levels of swelling with a standard assay protocol in green anoles, but that they induce different types of immune responses. PHA-P elicits a broader response with different types of immune function that varies with time after injection, meaning that the outcomes of this test may be harder to interpret. PHA-L on the other hand, induces higher concentrations of T-lymphocytes, a specific type of white blood cell. As a result, using PHA-L for PHA assays may lead to a test that is more interpretable, especially in studies looking at how the stress response affects immune function.

PHA-L injections result in a clear peak in lymphocytes at the injection site after 24 hrs., an ideal response for a test of immune function.

The research represents the completion of work Caty first presented at SICB 2017 and has now been published!:

Tylan C, Langkilde T. Local and systemic immune responses to different types of phytohemagglutinin in the green anole: Lessons for field ecoimmunologists. J Exp Zool. 2017; 327:322–332.

JMIH 2018: Does the Bluefields Anole (A. opalinus) Contain a Cryptic Species?

By Chris Thawley

On July 14, 2018

In New Research

Kiyomi Johnson (L) and Marina Carbi (R) presenting their poster, “Speciation and Phylogeography of Anolis opalinus on Jamaica,” at JMIH 2018.

Caribbean anoles have been studied extensively, with researchers examining their evolution, ecology, physiology, morphology, and behavior in many different contexts. In some respects, they are one of the best known groups of organisms in the world. But are there still unique species “hidden” within the diversity of anoles we already know? Some papers suggest just that. In 2002, Jackman et al. examined the mitochondrial DNA of Jamaican anoles and found evidence that several species contained deeply diverged clades, indicating the potential presence of cryptic species.

Enter Marina Carbi and Kiyomi Johnson, two public high school students with a drive to dig into the biological sciences and a budding curiosity about all things Anolis. Ms. Carbi, a recent high school graduate, and Ms. Johnson, a rising senior at Fiorello H. LaGuardia public high school, began an internship specifically for high school students at the American Museum of Natural History. Working with Dr. Ed Myers, they set out to investigate the phylogenetic diversity in A. opalinus, the Bluefields anole, by sequencing a combination of mitochondrial and nuclear DNA from a series of 22 specimens of Jamaican anoles.

Mss. Carbi and Johnson found that both the mitochondrial data and combined species tree support the existence of a cryptic species within what is currently considered A. opalinus. Populations of the Bluefields anole found in the Blue Mountains area are monophyletic and sister to A. valencienni, indicating a potentially deep divergence from A. opalinus. Todd Jackman, whose initial work inspired this research, dropped by to check out Kiyomi and Marina’s follow up to his paper and was impressed. “Hopefully, they can go to Jamaica themselves,” Todd remarked, before adding as an aside, “I’m glad that their results match ours.”

The authors presented strong evidence that A. opalinus contains a cryptic species. Pic via Twitter.

Looking forward, Ms. Carbi has plans to attend Cornell University in the future, while Ms. Johnson is completing her high school degree. Both expressed interest in continuing to work in biology, with Ms. Carbi noting that she was excited to have had the opportunity to interact with researchers from Cornell at JMIH. The Society for the Study of Amphibians and Reptiles provided support for Mss. Johnson and Carbi to attend the meeting. More extensive sequencing is ongoing in order to further elucidate the phylogeography of what is currently known as Anolis opalinus. Stay tuned!

Sometimes Knights Eat Dragons (Dragonflies, That Is!)

By Chris Thawley

On June 4, 2018

In Introduced Anoles, Natural History Observations

One of the loudest anole meals I’ve witnessed.

During one recent afternoon’s field work, I heard an unusual noise in the botanical garden I was working in: a sound like someone crunching and crinkling a foil potato chip bag. Tracing the sound from about 20 feet away, I did not find a snacking plant enthusiast, but rather a young Knight Anole (Anolis equestris) in survey posture who had apparently just snagged a large dragonfly out of mid-air. The anole chowed down on its prey while keeping a weather eye on me and conducting a few half-hearted displays to let me know it was aware of my presence. As the anole continued to masticate its rather large afternoon meal, it moved to a higher perch away from the prying eyes of this anolologist.

The dragonfly, a Regal Darner (Coryphaeschna ingens), is a common species in the southeastern United States and an accomplished aerial predator. It was also more than a mouthful for this young knight, which had to chew with its mouth open for over four minutes (and still wasn’t finished when it escaped my view); quite the prey handling time! And yet more evidence that this largest of anole species is willing to take a chance on any prey item that might fit into its maw even if it takes a little work.

An impressive snag for such a young anole.

A Case of Matestaken Identity: Hybrid Mating between Crested and Brown Anoles!

By Chris Thawley

On March 13, 2018

In Natural History Observations

Somebody needs to work on their anole species identification skills.

Breeding season is heating up for anoles in Miami, and at least one male crested anole (A. cristatellus) is a little…confused. While collecting some baseline data for my post-doc work looking at impacts of artificial light at night (ALAN) on brown and crested anoles, I noticed a commotion on a nearby cycad. Upon closer inspection, I realized that a male crested anole was pursuing and subsequently mating with a female brown anole (A. sagrei) who was decidedly unhappy about the situation.

In case you’re wondering about the colorful jewelry at the base of their tails, both of the anoles in the photo/video are bead-tagged to allow me to reidentify them from a distance. The copulation here lasted 3-4 minutes a portion of which I managed to capture on video.

While previous reports on AA have documented coupling between A. carolinensis and A. sagrei, I haven’t seen any reports of interspecific mating between A. cristatellus and A. sagrei. Has anyone else observed this phenomenon? The two species do encounter each other quite frequently in the Miami area, so this might not be a rare occurrence. Hybridization seems unlikely given the divergence between these two species, but you never know!

SICB 2018 – Are Anoles Adapting to Hot City Environments?

By Chris Thawley

On January 6, 2018

In New Research

Urbanization, the creation and spread of urban habitats, is increasing across the world. Species that live in these urban habitats are subject to many alterations in their environment, including changes in food, predators, noise, and light among others. One of the most well-known changes associated with cities is the “Urban Heat Island” effect, where city habitats are hotter than surrounding areas due to increases in pavement and other heat-absorbing materials. For lizards such as anoles, living in this hotter environment could be challenging, as increased heat could reduce time available for foraging for food or defending territories, or, in more serious cases, might even lead to death. Shane Campbell-Staton, a postdoctoral researcher at the University of Illinois and the University of Montana, decided to test if anoles were adapting to these hot urban environments, and, if so, what mechanisms were driving this adaptation.

Credit: http://www.ecology.com/2013/07/01/summertime-hot-time-in-the-city/

Cities are hotter than the surrounding landscape.

Shane worked with crested anoles (Anolis cristatellus) from four different areas of Puerto Rico that had both urban and nearby natural environments. He and Kristin Winchell, his coauthor, verified that anoles in these urban habitats did indeed experience hotter conditions, and that, as a result, their body temperatures were also higher than anoles from nearby natural areas. In the lab, Shane found that these city anoles were capable of tolerating higher temperatures than their counterparts from natural areas as well. However, after 8 weeks in the lab, anoles from both types of habitats had similar temperature tolerances. Shane also raised offspring from these anoles under common conditions in the lab and found that these offspring had similar temperature tolerances (thermal limits), regardless of whether they came from urban or natural environments. These results show that anoles can have a plastic response to the thermal conditions in their environment, meaning that the differences Shane and Kristin saw in Puerto Rico are induced by an anole’s exposure to temperatures and are not completely determined by their genes.

Crested anoles (Anolis cristatellus) make use of many human-altered habitats. Photo by Andrew Battles.

Shane, however, continued to explore this question: he wanted to know if the ability, or plasticity, of an anole to alter its thermal tolerance in response to exposure to high urban temperatures was due to changes in its genetic structure. In essence, he wanted to know if anoles had evolved a higher responsiveness (or plasticity) in response to inhabiting hotter, city habitats. To get at this, Shane exposed anoles to both hot and normal temperatures in the lab and looked at their levels of gene expression. Using a transcriptomics approach, Shane could see which genes were activated differently when lizards were exposed to temperatures indicative of city and natural habitats. Shane observed differences in variation in the genes in use at these temperatures. He also found higher levels of differentiation between genes involved in thermal adaptation between lizards from city and natural environments. These exciting results show that living in hotter city environments has selected for lizards which are more able to respond to these hot temperatures when they experience them. Shane is continuing to dig deeper into these data to determine which specific genes may have been altered to understand the mechanisms by which lizards are able to alter their heat tolerances. We’re looking forward to seeing these results at a future conference!

On a side note, Shane will be setting up his own lab at UCLA this year, and he’ll be looking for talented graduate students interested in physiology, adaptation, and genomics. Don’t hesitate to look him up!

When a Meal Can Bite Back

By Chris Thawley

On December 9, 2017

In Natural History Observations

A Brown Anole (Anolis sagrei) attempts to make a meal of a large centipede.

Anoles eat a wide variety of food items present in their environments, including all sorts of arthropods, and, occasionally, smaller anoles! We might expect that anoles would choose safe, appropriately-sized prey that would reduce chances of injury and guarantee a meal. However, some anoles, including brown anoles (Anolis sagrei), have been seen taking on potential prey that are either quite large (enough that we might foresee trouble actually swallowing the prey item) or poisonous or venomous, such as caterpillars and centipedes.

Another attempt at subduing the centipede.

Margaret Griffis O’Brien, a contributor to iNaturalist, recently observed just such a showdown on the mean streets of Miami between a brown anole and a centipede nearly its own body size. The anole made repeated attempts to take down the centipede before it was scared away from its potential meal by an intervening automobile. The centipede was injured enough from the battle that it was unable to leave the road and later in the day was found flattened by the continued traffic. The centipede, either an eastern bark centipede or the invasive Rhysida longipes, was a member of the family Scolopendridae, a group of centipedes known to possess powerful and painful (to humans, at least!) venoms.

The anole’s predation attempt was characterized by a lot of waiting for opportune moments to attack followed by quick strikes at the centipede.

Given that large, venomous centipedes have been documented in the diet of A. sagrei previously, it would be interesting to know if anoles are able to consume centipedes without being envenomated, how susceptible they are to centipede venom, and whether consuming these large, potentially dangerous prey items is advantageous for these lizards.

All photos by Margaret Griffis O’Brien.

JMIH 2017: Anole Morphology Round-up: Comparing Gecko and Anole Toepads and Patterns of Embryonic Limb Development in Diverse Lizards

By Chris Thawley

On July 21, 2017

In All Posts

Travis in the Dominican Republic with Anolis fowleri. Photo by Luke Mahler.

Two recent talks at JMIH 2017 shed light on key morphological characters in anoles: toe pad shape and limb length. Travis Hagey presented his work which looks to shed light on why lizard toe pads are shaped the way that they are and addresses whether gecko and anole toe pads are convergent structures. Working with a team of undergraduates, Travis used geometric morphometrics to analyze the structure of toepads in a diverse group of geckos and anoles. Travis found that anole and gecko toe pads have a similar range of values for traits such as the placement of pads on the toes and the shape of the toes (skinny or fat) in relation to claws. However, anole toe pads formed a distinct cluster indicating that they occupy a unique area of trait space not used by geckos. This finding suggests that the divergent evolutionary history of anoles and geckos has resulted in independent evolutionary explorations of toe pad shape.

Immediately following Travis’ talk, Robin Andrews presented work investigating the embryological development of morphological characters in diverse lizard species. In anoles, consistent differences in the morphology of divergent species support the existence of different anole ecomorphs. Previous research by Sanger and colleagues has shown that the differences in limb-length between anoles of different ecomorphs have their origins early in embryonic development. These early differences in limb length continue throughout the development of anoles into hatchlings and adult forms, a pattern known as transpositional allometry.

Robin compared patterns of limb, tail, and head growth in early stage embryos of four different lizard species, including a chameleon, two geckos, and the brown anole (Anolis sagrei). She found that species-specific differences in limb and tail lengths were exhibited as soon as limb and tail buds emerged from the body and were both best characterized by the same pattern, transpositional allometry. Embryonic head growth, however, showed no specific pattern. Robin’s findings suggest that the adaptive evolution of adult morphology in anole ecomorphs as well as other diverse lizard species is underpinned by developmental reprogramming.

Travis Hagey, Jordan Garcia, Oacia Fair, Nikki Cavalieri, and Barb Lundrigan: Variation in Lizard Adhesive Toe Pad Shape
Robin Andrews: Developmental Origin of Limb Size Variation in Lizards

JMIH 2017: Removal of Curly-tailed Lizards Increases Survival of Urban Brown Anoles

By Chris Thawley

On July 16, 2017

In New Research

Interspecific Interactions Between Two Species of Invasive Lizards in an Urban Environment; Camila Rodriguez-Barbosa and Steve Johnson

An extensive body of work has addressed the eco-evolutionary impacts of the Northern Curly-tailed Lizard (Leiocephalus carinatus) on Brown Anoles (Anolis sagrei) (much of it receiving coverage right here, here, and here on Anole Annals!). These species co-occur not only on many Caribbean islands where much of this research has taken place, but also within the urban matrix of southern Florida, where both species are introduced.

Camila Rodriguez-Barbosa and Steve Johnson investigated the impacts of curlies on brown anoles in shopping centers in southern Florida where both species were plentiful. Camila first collected baseline data on anole and curly populations at eight sites before embarking on a quest to eliminate curlies from four of her sites. Over the next four months, she removed over 300 (!) curlies from these sites, many of which had brown anole remains in their stomachs.

She found that this removal had serious consequences for brown anoles. Compared to anoles from shopping centers where curlies were unchanged, A. sagrei at removal sites experienced higher survival and consequently greater abundances. These anoles also shifted to lower perches once curlies were removed, mirroring results from previous work which show that the introduction of curlies leads to brown anoles occupying higher perches to escape this dangerous predator. Camila’s work suggests that brown anole/curly-tailed lizard interactions may be similar even in very different habitats and provides a fascinating look at lizard life (and death) in the urban sprawl of southern Florida.

JMIH 2017: Brown Anole Reproductive Output Varies Seasonally

By Chris Thawley

On July 16, 2017

In New Research

Tim Mitchell, Josh Hall, and Daniel Warner: Seasonal Shifts in Anolis sagrei Reproduction Invoke Challenges for Scientific Reproducibility

Sometimes a scientist just needs hundreds of hatchling anoles for an experiment. Tim Mitchell found himself in this position recently, and, like a good lizard ecologist, he started breeding colonies of anoles in the lab to produce eggs to incubate until hatching. As he created three different breeding colonies from brown anoles (Anolis sagrei) in central Florida, one each in February, June, and September, Tim found that he had also created an ideal situation in which to examine how the reproductive condition and output of brown anoles varies across the breeding season.

Tim, along with his coauthors Josh Hall and Dan Warner, found that females produced eggs with significantly greater mass later in the breeding season. These eggs took longer to produce than those earlier in the year (a greater interclutch interval), and the eggs resulted in hatchlings that had higher mass in relation to the weight of their eggs. These reproductive differences remained even after accounting for the fact that female anoles were also larger and heavier later in the year.

These findings suggest that female A. sagrei may shift their reproductive effort from producing a higher quantity of eggs (i.e., more, smaller eggs resulting in smaller hatchlings) in the beginning of the breeding season, to producing higher quality eggs (i.e., fewer, larger eggs resulting in larger offspring) later in the breeding season. Tim’s findings also stress the importance of investigating and accounting for seasonal differences when examining reproductive output in lizards.

SICB 2017: Homeward Bound: An Incredible Anole Journey

By Chris Thawley

On January 8, 2017

In New Research

(c) OwenMartin12, some rights reserved (CC BY-NC)

The abilities of certain animals to navigate and home on a specific location over long distances are some of the most fascinating behaviors that scientists study. However, studying homing behavior, especially experimentally, can be a major challenge, as many animals home over long distances (thousands of miles), in difficult-to-study environments (underwater, high in the sky), on in ways that are technically difficult or very expensive to monitor. As we know, anoles can be relatively simple (and cheap!) to study. So what if anoles could be developed as a model system for studying homing behavior?

On the surface, the presence of homing behavior in anoles might seem unlikely, as many species are highly territorial and may not travel long distances during their lifetimes. David Steinberg and Manuel Leal showed that, while seeming unlikely at first glance, at least one species of anole, Anolis gundlachi, does indeed show strong homing behavior.

Anolis gundlachi, the yellow-chinned anole, is a denizen of cool, closed forests in Puerto Rico. Because these lizards stick close to their small territories, they likely have little specific knowledge of their surrounding habitats, potentially making navigation through unfamiliar areas difficult. Steinberg displaced anoles 40 and 80 meters from their home territories and then monitored their territories to see how many anoles returned. Surprisingly, 40-60% of females returned and 80% of males returned, even when taken 80 meters from their homes. Simulations of these movements show that it is highly unlikely anoles would be able to return to their territories in this way via random searching. Steinberg then tested whether two common mechanisms that support homing, use of magnet fields and visual detection of polarized light, were responsible for homing, but found that the homing abilities of these anoles do not depend on either of these two senses.

Finally, Steinberg tracked anoles through the Puerto Rican forest using radio transmitters, and found that anoles returned to their home territories with a high degree of accuracy, in some cases making a beeline home within 24 hours! These results suggest that homing ability may be more common in anoles than has previously been considered, and that strong selection for territory ownership in anoles may support spatial memory and navigation in these animals.