It’s amazing the size of prey that some anoles will try to get down their throats (and who could blame them?). Here’s an example from Daffodil’s Photo Blog. And here’s another example from the same source.
AA stalwart Tony Gamble has provided these two photos from exhibits at the Milwaukee Public Museum. The one above is a knight anole, whereas below, an Archaeopteryx appears to be dining on a green anole, significantly increasing our understanding of the age of the anole radiation.
AA’s other Wisconsin stalward, Greg Mayer, provides the low-down: “The equestris is from the Rain Forest exhibit. This is a fabulous exhibit based mostly on the Costa Rican rain forest, but including some other tropical/rain forest elements. I take my vert. zool. class there every year, and have used it as part of the pre-trip preparation for Costa Rican field classes. It was funded in part by the NSF, and involved lots of field work–they did latex casts of trees to get the bark right for life size models of them! The Milwaukee Public Museum was much involved in making Costa Rica the center of tropical studies for US-based scientists. The MPM was slightly independent of OTS. They had their own field station, La Tirimbina, which is very nice–I’ve taken students there 2 or 3 times.
Allen Young, the MPM lepidopterist, was the driving force for Milwaukee’s tropical studies. He wrote about his work at Tirimbina in Sarapiqui Chronicle (Smithsonian Institution Press, Wash. DC, 1991). Young first went to Costa Rica in 1968 with OTS, then focused his work at Tirimbina. (Bob Hunter, who owned Tirimbina at the time, also owned part of La Selva, and was involved in getting both places established as field stations.) MPM’s stake in Tirimbina was sold off by then Milwaukee county executive (now governor) Scott Walker, who couldn’t imagine why a natural history museum in Wisconsin could be interested in Costa Rica. Fortunately, another conservation organization bought MPM’s share.
Others were involved in the exhibit creation as well, and though I’ve never asked him, I’ve always thought the Anolis equestris behavior display in the rain forest exhibit may have been a contribution of Bob Henderson. There are several males and females (not sure if they’re freeze-dried, or some kind of model), showing various levels of agonistic display– fans, nuchal crests, open mouth, raised posture– set out on vines/branches. A question I ask vert. zool. students about this display case is how could they tell the lizards are arboreal, even if they were not posed on branches.”
And with regard to the photo below: “The other picture is from the Third Planet exhibit (I’m always tempted to write Third Rock!), from a section of that very good exhibit on the Hell Creek Formation and the end Cretaceous vertebrate extinctions. The MPM has two Archaeopteryx models made up with feathers, and the one in the pic has a dried or model Anolis carolinensis in its mouth, painted a fairly bright green. The other Archaeopteryx model is better done, and that one goes out on loan periodically to other museums (I think I’ve seen it at the Field Museum).
A recent paper in the Caribbean Journal of Science on the diet of the Lesser Antillean barn owl on Dominica revealed that anoles, specifically the native species A. oculatus, are a very frequent prey item, constituting 193 of the 517 prey items. The authors note that owls are nocturnal and anoles are diurnal and proffer three explanations: 1. the predation occurs at dawn and dusk, when both species are normally active; 2. the anoles are active around lights at night; 3. the owls are catching the anoles while they sleep. We’ve discussed this topic before: owls are known to eat anoles in Cuba and many other places in the neotropics, and there’s the great photo re-posted below (original post here). As far as I’m aware, that’s the only direct observation of an anole being preyed upon by an owl (although a quick search on Google Images will yield many photos like the one at right). We’ve also discussed the parallel issue of bat predation on anoles in these pages. Clearly, more data are needed!
I was recently doing some anole field work in the Gulfo Dulce area of Costa Rica, and I came across a lizard that has me stumped. Perhaps some more experienced AA readers have some insight – any idea what species this little guy is? To me, it looks a bit like A. limifrons and a bit like A. carpenteri, but not completely like either (and carpenteri isn’t supposed to occur in the Gulfo Dulce area). It was in an area of pretty thick primary forest, perched about 6 ft or so up a tree trunk, and it ran quite high when I pursued it. I’d appreciate any tips!
Although camera traps have historically been used to study endotherms, particularly mammals, recent studies have found them to also be effective for reptile research, given proper conditions. Indeed, Welbourne and colleagues (2015) found them to be as effective as complementary methods for detecting reptiles.
We conducted a study in the Lower Urubamba Region of the Peruvian Amazon using camera traps to monitor mammal use of natural canopy bridges for crossing over a pipeline road between September 2012 and October 2013 (see Gregory et al. 2014 for further description). Unexpectedly, we ended up with numerous records of reptiles, including many of Uracentron flaviceps, which is easy to identify because if its large body size, and records of 17 individuals we have not been able to identify. We suspect many of them to be Anolis species, but they are very difficult to see. We would be grateful for identification assistance from the Anolis researcher community. Below we show pairs of images for each individual: the full camera trap photo and then a cropped image of just the individual. Please e-mail me (GregoryT@si.edu) with the individual number (listed above each photo pair) and any thoughts you have about identifications. Thank you Anolis research community!
Gregory, T., Carrasco-Rueda, F., Deichmann, J.L., Kolowski, J., and Alonso, A. (2014). Arboreal camera trapping: taking a proven method to new heights. Methods in Ecology and Evolution 5:443-451.
Welbourne, D.J., MacGregor, C., Paull, D., and Lindenmayer, D.B. (2015). The effectiveness and cost of camera traps for surveying small reptiles and critical weight range mammals: A comparison with labour-intensive complementary methods. 42:414-425.
Unknown sp. 17
Unknown sp. 16
Unknown sp. 15
Unknown sp. 14
Unknown sp. 13
Unknown sp. 12
Unknown sp. 11
Anolis cf. punctatus (#10)
Unknown sp. 9
Unknown sp. 8
Unknown sp. 7
Unknown sp. 6
Unknown sp. 5
Anolis sp. 4
Anolis sp. 3
Anolis sp. 2
Anolis sp. 1
Maintaining an already-impressive 2016 conference tour de force which included presentations at both JMIH and Evolution, Kristin Winchell presented a broad summary of her urban anole research in an invite-only Urban Ecology session at ESA 2016.
This presentation provided a synthesis of two large research projects both independently reviewed on Anole Annals (1,2), and so I will provide only a brief summary here. Kristin began by presenting an over-arching question in modern ecology: how is urbanisation going to affect biodiversity? While many may intuitively think of the process negatively, there is a large (and growing) body of research suggesting that many species are able to behaviourally respond to these novel environments and persist. So what about anoles? Kristin focuses her research on two Puerto Rican species: the crested anole (Anolis cristatellus) and the barred anole (A. stratulus).
To do this, Kristin and her team employed multiple methods to explore if a) these two species have differences in their ecology in urban vs. natural areas, b) if differences in ecology are observed, does this lead to differences in morphology, and c) if differences in morphology are observed, is this related to performance? Firstly, niche partitioning between these two species in natural vs. urban areas was investigated (more details here).
This niche partitioning research is new and will be the main body of a manuscript currently in prep so I will keep discussions brief. One species, A. cristatellus, was observed to significantly shift its microhabitat use, which resulted in adaptive shifts in morphology. This research was documented in Winchell et al.’s recent Evolution paper and reviewed previously on AA (1,2,3). Specifically, urban lizards have longer limbs and stickier toepads (higher number of subdigital lamellae) in response to perching on broader, slippier substrates.
This research has now developed on to the next stage of performance-related investigations. Kristin is asking the question of whether these observed morphological shifts lead to better performance (and therefore, presumably, higher fitness). Kristin presented some preliminary results, but keep your eye out for more developments!
As anole enthusiasts, most of you have probably seen anoles engage in lock-jawed fights, where two rival males grab onto each other’s jaws and try to throw their opponent off a contested perch. These encounters are extremely physical, often leaving one or both contestants injured. While these fights are exciting to watch, they are relatively rare in nature. Most contests between anoles are resolved without fighting using stereotypical display behaviors, where the two lizards head bob and dewlap at each other until one anole submits. In these cases, dominance is conveyed not through physical defeat, but from the animals’ perceptions of their opponents.
This of course begs the question, what criteria do anoles use to evaluate their rivals? How do they decide if they should keep pushing or if they should back down during a fight? A lot of research has attempted to answer this question. Many of these studies are performed in the lab using staged contests between two individuals, called arena trials. These studies generally look for differences between the “winners” and the “losers” of each trial to identify potential dominance signals.
When I was an undergraduate in Dr. Michele Johnson’s lab at Trinity University, we ran a lot of arena trials to understand how lizards interact. At the same time, I was part of a collaborative biomath team that included McKenzie Quinn (another undergrad) and me, and our advisors Michele and mathematician Dr. Cabral Balreira. We had been working together to develop a mathematical model of lizard energy use, and as that project was wrapping up, we were considering other directions our team might pursue. We came up with the exciting idea that we might be able to use those arena trials we’d been doing in combination with Cabral’s area of expertise –the development of ranking algorithms, usually applied in sports. In Cabral’s work with sports ranking algorithms, he summarizes the win-loss results of a sports tournament to identify the overall best and worst teams. These rankings allow you to incorporate how each team performed against teams of varying skill levels, providing a more holistic metric of their abilities than individual game results would. This led us to a “light bulb” moment. By applying a sports tournament framework to a lizard population, we could see how individuals compete against different opponents to determine what traits are associated with social dominance. This also allows us to evaluate lizard dominance using quantifiable metrics instead of qualitative metrics.
We first created a tournament in which each lizard in our population (n=18) competed in six arena trials. We then used sports ranking algorithms to generate a dominance hierarchy for the population and used stepwise linear regressions to compare rank (y variable) to morphological and behavioral traits (x variables) of each lizard. We found that rank was highly predicted by aggressive behavior, indicating that lizards that displayed more during the tournament tended to be more dominant (surprisingly, body size didn’t predict dominance in our trials!). We then applied this same logic to a natural system (studying the green anoles in Palmetto State Park in Gonzales, Texas) to see if “dominant” anoles in the wild had the same characteristics as “dominant” anoles in the lab. In the wild, male anoles fight over territories, because controlling a territory gives owners uncontested access to the food and potential mates within it. Therefore we can “rank” males based on the size (bigger = better) and quality (more females = better) of their territories. When we compared territory size and quality (y variables) to morphological and behavioral traits (x variables) as before, we found that traits related to fighting ability, such as head width (a proxy for bite strength), were the best predictors of dominance in the natural system (but again, body size was not predictive of territorial success).
Together, our results indicate that dominance cues in anole contests are often context specific. In brief arena trials between unknown males, signals that reveal immediate intentions (i.e., display behaviors) are especially important. In contrast, males in the wild have to back up their bluster, and thus actual fighting ability is more highly favored in the long run. If you are interested in this study, we hope that you check out our recent paper to view the details of our results and methods.
The following appeared in the spring/summer 2016 issue of the University of Missouri publication Illumination.
By Melody Kroll
Photos by Manuel Leal
These are the “cold-blooded” animals, the millions of amphibians, fish, insects and reptiles, collectively known to scientists as ectotherms. Together these species make up the vast majority of the world’s biodiversity.
Ectotherms are found all over the world, but most make their homes in the tropics, where, obviously, it is warm already. Being used to the heat, one might assume that an extra degree or two wouldn’t make much difference. Wrong. Scientists have recently determined that many tropical ectotherms are already surviving at their upper temperature limits. Even a modest rise may, in fact, be enough to push them into extinction. Consider the plight of tropical lizards, an animal that MU’s Manuel Leal, an evolutionary biologist and associate professor, has spent two decades observing. Studies have predicted that about 6 percent of tropical lizard species will be extinct by the year 2050. A full 20 percent of the world’s lizard species, one study predicts, could be gone by the year 2080.
Consider the plight of tropical lizards, an animal that MU’s Manuel Leal, an evolutionary biologist and associate professor, has spent two decades observing. Studies have predicted that about 6 percent of tropical lizard species will be extinct by the year 2050. A full 20 percent of the world’s lizard species, one study predicts, could be gone by the year 2080.
Because many Anolis species, commonly known as anoles, have evolved over long periods of time in isolated island habitats, their study has become profoundly important in ecological and evolutionary scholarship.
Leal says there is little doubt that anoles are in trouble and that warming is the primary reason. But, despite all the attention they’ve received over the years, he argues that scientists have largely failed to grasp the complicated means by which climate change may be contributing to the lizards’ survival struggles, a failure that could make understanding their vulnerabilities much more difficult.
“We’ve done very well at saying climate change will have an impact on ectotherms, but we don’t know how,” says Leal. “We have painted with a broad brush already; now we have to take the pencil and try to say, ‘Ok, how is this going to happen?’”
An A. acutus observed in Saint Croix, U.S. Virgin Islands.
With his former graduate student, Alex Gunderson, Leal recently proposed a new conceptual framework aimed at re-thinking how scientists model the effects of climate change on lizards specifically, and ectotherms in general.
The problem, Leal explains, is that previous studies have treated “optimal body temperature” as the primary or only driver of activity.
“Activity time is treated as an on-off switch — a lizard is either active or it isn’t. But, it’s not that way,” says Leal. “We have shown that the effect of temperature on activity is continuous. We have observed lizards engage in all types of activities – eating, mating, fighting — at temperatures outside their optimal body temperatures. Activity is more like a dimmer switch.”
The strength of the new framework, he says, is its organism-centered approach. “The framework nicely illustrates the importance of measuring variables at scales relevant to the species in question or, in other words, of doing natural history work in order to inform climate-change models.”
Leal believes obtaining lizard-level results is critical. “I tell my students that we are the boots on the ground,” he says. “Theoretical predictions need to be tested. In order to be tested, you need somebody that is willing to do the dirty work, somebody that wants to be working at the scale that really represents the organism and to ask, ‘okay, does this really matter?’”
For Leal’s team, this means hours of filming anoles in the field, coupled with even more hours re-watching and transcribing these videos back in the lab. A big chunk of time is also spent catching anoles and collecting morphological data such as body length, weight, and dewlap color (the characteristic fold of skin hanging from anoles’ throats). They also document aspects of the lizards’ subtropical habitats.
This last point is particularly attractive to Leal, because anoles are abundant in Puerto Rico, the place where Leal spent his childhood catching all sorts of critters, anoles among them.
“I just grew up catching everything that moves, from spiders to big things to little things,” says Leal.
Manuel Leal collects data on light levels in a wooded area near Barahona, Dominican Republic.
His lizard-catching abilities paid off when his biology professor at the University of Puerto Rico one day invited students to help him collect blind snakes. Leal jumped at the chance. “I said, I’ll go! That’s what I like to do. Then I started working with him and eventually did my master’s degree with him.”
Leal started observing anole behavior in earnest while pursuing his master’s degree in Puerto Rico. His thesis involved looking at how anoles signal their physiological condition to lizard-eating snakes. He showed that the number of push-ups a lizard does is correlated with the lizard’s running endurance. “Basically, the lizard is saying, don’t waste your time attacking me because I’ll run away very fast and if you catch me I’ll bite you really hard,” says Leal.
His research provided one of the first demonstrations under natural conditions that prey can honestly advertise their escape abilities, that is, physiological conditions to predators. It has since become a staple study mentioned in the seminal animal behavior textbook.
While a master’s student, Leal met Jonathan B. Losos, a world leader in evolutionary ecology, who was in Puerto Rico on a collecting trip. Leal says, only half joking, that it was his unrivaled lizard-catching ability that impressed Losos to the point that the senior scientist invited him to join his lab and pursue a doctorate at Washington University in St. Louis. “He promised me that as long as I was able to catch more lizards than him, I would be successful at getting a Ph.D.,” Leal says with a laugh. “I had no idea you could make a living studying lizards. Even to this day, I often stop and think how amazing it is that someone pays me for being dirty and catching lizards. That’s cool.”
“That is not why I selected him,” says Losos, now a professor of organismic and evolutionary biology and Curator in Herpetology at Harvard University. “I took Manuel as a student because it was obvious that he really understood the biology of these animals at a very deep level. But, yes, it’s true that Manuel can walk up to a lizard and just catch it with his bare hands. I still don’t know how he does it.”
Leal with one of his many lab lizards.
By way of example, Losos recalls a field trip they made shortly after Leal arrived in St. Louis. “We came across some local fence lizards. Manuel approached one, and it ran away. I said something like, ‘Hah! Manuel. Not so easy as in the tropics, is it?’ Well, he disappeared, and 10 minutes later, he came back holding two lizards in his hand. I have no idea how he does it. I’ve watched him do it. I tried to figure out what he’s doing that I’m not. I don’t know, but he can do it.”
At Washington University, Leal continued his investigation of anole signaling behavior. After earning his doctorate in 2000, he followed up on these behavioral studies with Leo J. Fleishman at Union College in New York. In 2003, he joined the faculty at Vanderbilt University, moving to Duke University three years later. He joined MU’s faculty in 2014. Over the years, his studies have appeared in top scientific journals, includingScience, Nature, Proceedings of the National Academy of Sciences, Proceedings of the Royal Society of London B, The American Naturalist, as well as commercial publications such as the New York Times, The Economist, National Geographic, El Pais and Der Spiegel.
Leal’s most recent work seeks to advance scientists’ understanding of how temperature affects anoles’ behaviors. Along with Gunderson, he has proposed that temperature differentially affects four elements of activity that the researchers define as thresholds, probabilities, modes and vigor.
Thresholds, they explain, are the temperatures below and above which animals are inactive. Probability involves evaluating whether an animal will engage in activity when its body temperature is between the lower and upper temperature ranges. Mode is about activity, for example feeding, mating, fighting. Mode of activity is important because different modes have their own temperature-dependent probabilities. Finally, the researchers seek to determine the vigor with which an animal engages in an activity.
“Each of these components has been studied to some extent previously, but it was always only one of them,” says Gunderson, who is currently completing his postdoctoral work at San Francisco State University’s Romberg Tiburon Center. “In order to get a comprehensive understanding of how temperature is going to influence activity, you really need to know how all of these components are interacting simultaneously.”
A. bahorucoensis is of one of almost 400 lizard species from the genus Anolis.
The authors have applied their framework to document the consequences of climate warming on Anolis cristatellus, a tree-dwelling lizard found in both dry and wet habitats on the island of Puerto Rico. In the case of A. cristatellus, they sought to learn how the lizards’ overall health affected crucial behavioral characteristics.
Their findings showed that behaviors such as eating and mating are extremely sensitive to thermal change, especially compared to sprinting speed, the physiological trait typically used to measure climate-change effects.
“For example, our analyses show that the physiological performance of A. cristatellus in dry habitats will decrease by about 25 percent under future warming, but their activity budgets will decrease by 50 percent. Furthermore, the habitat will become much less suitable for reproductive behaviors, which are, of course, critically important for the viability of populations,” says Leal.
In other words, adds Gunderson, physiological traits alone may not be the best way to estimate the consequences of climate change. What we really need, he says, is to integrate both the physiological and behavioral.
“Even though organisms might have relatively high physiological health, if they’re not eating or reproducing then there are going to be big population consequences,” Gunderson says.
“If anything,” Leal adds, “what we have done is taken all these data and put them at the scale of the lizard and asked, can we predict what the lizard will do when we have the interactions of the temperature of the environment, body temperature, and sprint speed, which is basically the curve on which behaviors will happen.”
‘The habitat will become much less suitable for reproductive behaviors, which are, of course, critically important for the viability of populations.’
“Previously, we could say, yes, they can live in place A or place B and that is true. Now, we can say, when they are in place A, they will not be able to mate as often as they would if they were in Place B or they will not be able to defend their territory as often if they were in this environment. So it’s more at the scale of the individual.”
Harvard’s Losos calls Leal’s conceptual framework “a major step forward” in our understanding of how global warming will affect all ectothermic animals.
“Previous work has recognized the importance of changing temperatures but hasn’t been very sophisticated in trying to evaluate how global warming might affect the biology of the species,” he says. “What Gunderson and Leal do is take a much more in-depth examination of the biology of the species and how temperature really affects what they do and when they do it or how much they do it to present a framework to understand whether species will be able to cope with changing climates.”
A. cristatellus asserting his dominance, with “dewlap” flared.
Such insights don’t come by accident, Losos says. They happen because scientists like Leal and his graduate students spend a “huge amount of time out in nature actually studying animals and what they do. There is simply no substitute for understanding the biology of animals in their natural environment. Nonetheless it takes a huge amount of effort to collect those sorts of data: time, money, and being out in uncomfortable situations often. Most scientists don’t do that. What Manuel has shown is that this sort of data, what we call natural history, is critical in understanding how animals interact with their environment, and how, as the environment changes, animals will be able to respond. What is really unusual about their approach is that they are not sitting in a lab and making a bunch of assumptions and running data through computers. They’re out in nature getting the data we really need to have.”
The hope, Gunderson says, is that these “natural history” data, coupled with the revised conceptual framework he and Leal developed, can help scientists develop strategies to better predict and, one day perhaps, mitigate the effects of climate change on these vulnerable animals.
“Everything we talk about in this paper is relatable to other cold-blooded animals. That was something we really wanted, to make sure that what we were presenting, even though we were using lizards as a model, was applicable to a wide range of animals.” The types of animals, Leal would hasten to add, that can best be understood by “thinking outside the lab.”
“While laboratory studies of the effect of temperature on the physiology and behavior have provided significant insights into thermal ecology of ectotherms,” says Leal, “the time is ripe to take this knowledge outside the lab to further develop climate-change models.”
A year ago, McCranie and Kohler published The Anoles of Honduras: Systematics, Distribution, and Conservation (available on Amazon for under twenty bucks and downloadable for free on the Museum of Comparative Zoology website).
In case you missed them, we thought we’d provide copies of some recent reviews of the book–in the last year, two favorable book reviews have appeared by Levi Gray in Herpetological Review and by Steve Poe in Quarterly Review of Biology.
In one of the few anole talks here at the annual Ecology meeting in Ft. Lauderdale, Florida, James Stroud presented on a project he conducted with the Fairchild Tropical Botanical Garden, Jason Kolbe, and others. Together, they organized a large citizen science project engaging middle-school aged students to collect distribution and abundance data about anoles in the Southern Miami region in a program they call “Lizards on the Loose.”
In this outreach project, James and colleagues had 101 schools participate in collecting data. Armed with a handy anole ID guide created by Jason Kolbe and a video by James explaining anole biology and species differences, students and teachers set out to conduct 15 minute visual surveys. On these surveys, they recorded how many animals they encountered, the species ID, and the approximate body size using a provided standardized collection protocol and entering data into a Google forms site.
The results were overwhelming: more than 1,000 students conducted a total of 1,356 surveys resulting in 12,000+ lizard observations! This project produced massive amounts of data on very short time frames. In general, distribution patterns fell as they were expected to, although some records certainly hint at some mis-identification (e.g. some A. cristatellus locations). Unsurprisingly, the least abundant lizards were those that were hardest to detect: the species typically found high in trees.
While the resulting dataset is impressively large, James admits that there are data quality issues with collecting data in this manner and asked for input on how to improve data collection. Specifically, he suggested that in the future they would like to incorporate photographic and smartphone GPS information, perhaps via an app. Does anyone have any suggestions for James on implementing such an app or otherwise improving the design?
James emphasized that providing meaningful natural experiences with wildlife for kids is good for conservation, fosters an appreciation for nature and helps inspire the next generation of scientists. Many of our readers may find inspiration from the success of this program and we would love to hear about it if you implement similar types of citizen science projects with anoles!
From time to time, people find anoles with broken dewlaps. Here’s an extreme example, found by Bob Powell and Rich Sajdak on the island of Grenada. Years ago, Richard Tokarz reported a lab study that showed that males with non-functional dewlaps mated as frequently as intact males, and a follow-up study with Ann Paterson and Steve McMann showed no difference in the field between males with and without working dewlaps. Makes you wonder what the dewlap is needed for.
Bob points out that brown anoles have spread widely in disturbed lowland habitats since first discovered on Grenada in 2002, when they were restricted to intensely disturbed urban habitats and decorative plantings in a few resorts.
All evolutionary biologists are familiar with Robert Trivers, but many do not know that some of his most important work was conducted on Anolis lizards. This work–as well as the rest of Trivers’ life–is featured in his just-published memoirs, Wild Life: Adventures of an Evolutionary Biologist. I had the good fortune to review the book for Current Biology. You can read my review, but the short story is: a fascinating book about one of the great figures–and characters–of modern evolutionary biology. And in case you’re wondering, it was the publishers who put a collared lizard, instead of an anole, on the cover. Available on Amazon for $12.99!
Competition for perches has been an important factor in the diversification of anoles. Yet, we know little about the influence of perch availability on reproduction. To address this, Dan Warner, Matt Lovern, and I housed male / female pairs of brown anoles (Anolis sagrei) in treatments with either high- or low-availability of perches (Fig. 1).
We found that females reduced how often they used perches when perches were limited. More interestingly, though, when perches were limited, females tended to take longer to begin laying eggs (for the first time in a season; p = 0.063, Fig. 2A) and allocated more corticosterone to egg yolk (p = 0.069, Fig. 2B), although these findings were not statistically significant.
In many habitats in which brown anoles occur, organic perches are abundant and not likely to be limited. However, in urban areas or on some islands anoles have colonized, perches can be limited. Our study suggests that such habitats may have consequences for reproduction.
Citation for the full paper:
Delaney, DM, MB Lovern, and DA Warner. 2016. Does reduced perch availability affect reproduction in the brown anole? An experimental test in the laboratory. Journal of Herpetology 50:227-232.
Remarkably little is known about the natural history of the Puerto Rican twig anole, Anolis occultus, except where it sleeps. The reason is simple: the animal is small, moves slowly, is highly cryptic and probably spends a lot of its time amidst the twigs high in the canopy. As a result, there have been reports of only a handful of animals located while they are active.
In a just published paper, Ríos-López and colleagues report two new observations of these charming little lizards, one of nectarivory (above) and the other, sadly, of predation by a kingbird (right). In addition, the paper presents a comprehensive review of what we know about this species and its conservation prospects.
Every summer, a group of students heads down to the Dominican Republic to take the Harvard summer course on biodiversity of the country. As a teaching assistant, I often watch unsuccessful attempts of students trying to catch the abundant fast-moving lizards. Sometimes I also participate, usually resulting in the same outcome. Last week, we were climbing an observation tower in Punta Cana to spot Ridgway’s hawks (Buteo ridgwayi) when Ryan Friedman, a student taking the course, noticed a Hispaniolan green anole (Anolis chlorocyanus) perched on the side of the tower. We thought we would finally outsmart an anole and catch it with our hands. However, the lizard apparently preferred to jump to certain death rather than being handled by us. We watched it falling down about 10 meters, but, instead of going straight down and hitting the ground, it followed a curved trajectory that safely brought it back to the tower (and enabled Brian Farrell, the course instructor, to take a picture after the fact).
This observation seemed remarkable enough for Jonathan Losos to allow this entomologist to report it here, and also made me very curious. Are some anoles able to direct their fall, or maybe to glide with the wind while they go down? Hopefully someone will have the chance to do a controlled trial and figure it out!
Editor’s Note: Such behavior has been noted for Anolis pentaprion.
Alberto Puente-Rolon (Universidad Interamericana de Puerto Rico, Recinto de Arecibo) and I were incredibly fortunate to spend a week on the Cay Sal Bank, Bahamas. Cay Sal is a partially emergent island bank situated about 100 km south of Islamorada in the Florida Keys and about 50 km north of the Cuban Bank in the vicinity of Sagua la Grande. Politically part of the Commonwealth of the Bahamas, the bank is separated from the Great Bahama Bank by the 47 km-wide Santarem Channel, and is about 175 km west of the southern tip of Andros Island. Cay Sal Bank is a shallow carbonate platform with dozens of small emergent islands around the edges of the roughly triangular-shaped bank.
A note before we launch into the narrative of our trip. The Cay Sal Bank is an area known for a significant amount of illegal activity. This largely involves illegal fishing fleets and human trafficking. While a typical visitor to the area would not likely be in great danger from these activities, there is always the possibility that you might run into the wrong people at the wrong time. Illegal fishing vessels have been known to harass, intimidate, and attempt to board cruising vessels on Cay Sal, while happening upon a human or drug trafficking exchange could be extremely dangerous. We saw evidence of all of these activities during our cruise, and mention some specifics in the narrative below. In addition, the Cay Sal Bank is remote. There are occasional Coast Guard planes in the area, but keep in mind that there might not be many vessels able to monitor emergency radio channels (channel 16) or respond quickly to an emergency. We cruised to the region with a highly experienced crew and a very well maintained and outfitted vessel, and we recommend anyone else planning to visit do the same, as well as consider taking all available safety precautions. I am happy to discuss my experiences in detail with researchers interested in visiting the area.
We arrived on the bank at dawn after an overnight cruise from Bimini, where we had cleared Bahamas customs and immigration. Our first stop was Dog Rocks, where we were able to disembark and swim ashore for a short walkabout on the largest of the small rocks jutting out of the ocean. The Dog Rocks mark the eastern edge of the Cay Sal Bank, and as far as we were aware there were no herpetofaunal records from these islands. Most are rocky and jagged, likely washed over during hurricanes and largely devoid of vegetation. Great Dog Rock is quite small, with a patchy covering of ground vegetation. There is a single large, pyramid shaped stand of Cocoloba uvifera near the center of the island-
approximately 5 meters high and 10 meters wide. Quite a few Sooty Terns (Onychoprion fuscatus) and Brown Noddies (Anous stolidus) nest here. Even in this very isolated and largely barren stretch of rocks, we managed to locate Anolis sagrei. The large males and robust females were mostly occupying the Cocoloba stand, though we did find juveniles, young males, and females on the ground near the scrub vegetation. We even located a juvenile underneath a discarded conch (Strombus gigas) shell. We spent about two hours here, plenty of time to survey the entire island. We did not find evidence of any other terrestrial reptiles, and it is quite remarkable that even A. sagrei could persist there.
Our next stop was at the Damas Cays, a small group of narrow, high-walled islets jutting out along the spine of the eastern Cay Sal Bank. Like Dog Rocks, we are unaware of any herpetofaunal records from Damas, and for good reason. We took a rigid inflatable boat out for a brief survey of the largest of the Damas Cays. There are no easy landing spots on the island, so landing would require a swim. There was very little vegetation, we spotted a single small shrub and some very sparse groundcover. As we approached the island to land, we lost power on our outboard engine and were losing daylight, so we opted to repair the engine and not to clamber ashore.
We then cruised across the bank to the southwestern edge, about 80 km from Cuba. Continue reading Anole Surveys on the Cay Sal Bank, Bahamas
In a recent paper, Hagman and Ord discussed how dewlaps have evolved multiple times, often with different underlying anatomy. This is an excellent paper, but I was intrigued that Polychrus, sometimes considered the sister taxon to anoles, in part because of its apparently anole-like dewlap (see above), was not considered to have a dewlap.
I wrote Terry Ord, asking “I didn’t understand one thing. You seem to say there is no evidence for extendible dewlaps in several species of Polychrus, but a quick Google reveals plenty of images of these species with dewlaps extended. I take your point in the previous sentence that actual observations of the dewlap being used are rare, but did you really mean to say that they don’t exist at all?”
Terry responded: “What I found when attempting the first paper of this series (Ord et al. 2015, Journal of Evolutionary Biology) is that relying on photos alone is really problematic for identifying a moveable dewlap (a.k.a., a dewlap like anoles or Draco or Sitana).
For example, if you google Sceloporus — who definitely don’t have dewlaps — you’ll find photos where species do appear to have something like a small dewlap. In fact, I found an image of what was clearly a Sceloporus that looked to have an engorged throat that was remarkably similar to your Polychrus photo… All the google images I’ve found so far that are obviously Polychrus (and not anoles) could quite easily be engorged throats akin to Sceloporus and other non-dewlaped iguanids/agamids.
But the clincher for me is that all the hyoids we’ve looked at so far for both Sceloporus and multiple species of Polychrus (and other non-dewlaped iguanids/agamids) all look very similar (e.g., see Fig 5a in the JEB paper and supplementary info). The point being, the mechanics of the hyoid simply isn’t functional in the capacity of extending a dewlap like in anoles and others.
Of course, while the mechanics of the hyoid in extending the dewlap in anoles is well described, how Draco do it and some other genera is unclear. I’m hoping someone will look into detail on the biomechanics of the dewlap extension in non-anole groups because it can clearly be very different to anoles — e.g., the attachment points for key muscles for the anole dewlap are absent in Draco, so they’re sticking that dewlap out using a very different mechanism. Regardless, there are still key signs in the hyoid that point to a moveable dewlap in Draco (and other genera) that are not present in Polychrus.
Proof of a Polychrus dewlap would have to be a video of a Polychrus extending the dewlap because videos of Sceloporus quickly reveal that its an engorging (“puffing”) of the throat, so direct observation is a solid alternative to looking at the hyoid.
The taxonomy of “Polychrus” is potentially sketchy and not all species really are of that genus. Which means I also wouldn’t be surprised to see a species that has been classified Polychrus, but really isn’t related to all the Polychrus species we’ve examined the hyoids of, actually having a convincing moveable dewlap.
But at the moment, Polychrus = a moveable dewlap, all the evidence says otherwise. I also wonder whether the historical association of Polychrus as basal to anoles resulted in reaffirming wishful thinking field observations into the current myth.”
Terry’s next email made the distinction clear (as well as his unwarranted agama-philia): “If your notion of a dewlap is a prominent ornament that is dynamic in some sense (becomes extended through puffing out the hyoid in general or pushing out the CII in particular), then there are many many examples in agamids, and a handful in iguanids. I would definitely include Sceloporus, too.
If your notion of a dewlap is more specific to something that is part of a complex behaviojral display and involves rapid extension of a structure that is complex in temporal and amplitude characteristics, then it’s basically anoles, Sitana/Otocryptis, Draco and possibly one or two other agamids.
Agamids still clinch the diversity stacks in all regards – ha!”