How The Bearded Anole Got Its Name

Anolis pogus. Photo from Wildlife of St. Martin.

The resemblance is uncanny

The diminutive A. pogus of St. Martin is sometimes referred to as the bearded anole. Since anoles lack hair, facial or otherwise, one might wonder where the name comes from. In fact, Mark Yokoyama explains on his Wildlife of St. Martin site, the name is a misnomer, a misguided translation of the specific epithet pogus. Rather than being derived from the Greek pogos, the name is a reference to the cartoon character Pogo the possum! Who else would be behind this than AA faithful Skip Lazell? Anyone have any other favorite anole scientific names?

Anoles And Other Biodiversity Of Haiti: A Calendar

Calendar_June
Haiti has some spectacular anoles found nowhere else. For example, if you go to CaribHerp and click on “Haiti” in left toolbar, you see the 176 species of herps in the country. Then click filter by “Dactyloidae” and you see the 32 recognized anole species.

13 of those are endemic to the country, but there are quite a few in the works (not yet described). One beautiful endemic Haitian species, Anolis monticola, is on the cover of Jonathan’s book “Lizards in an evolutionary tree.” Deforestation continues, with only 1% forest cover remaining, so almost everything will be disappearing soon.

For several years I’ve been doing some intense field work in Haiti, and professional photographers have joined on the trips. In collaboration with the Audubon Society of Haiti (Philippe Bayard, president), we put together a large biodiversity calendar for this year, with text translated in 3 languages. It opens into a 24″ x 12″ poster. Anoles are on the cover and a month is mostly devoted to anoles. After some unexpected delay they have arrived and we’re happy to give them away, for cost of shipping/packing. If interested, see Caribnature for images of the calendar, and instructions to order:

Adventures With Phenacosaurus

Anolis heterodermus. Photo by J. Losos.

Anolis heterodermus. Photo by J. Losos.

Although many generic names have been proposed for species within the anole clade, traditionally only three other than Anolis were widely used: Chamaeleolis, Chamaelinorops and Phenacosaurus. Each of these clades—which at one time were thought to represent early, pre-Anolis derivations from the anoline line—are morphologically distinctive. The former two, Chamaeleolis and Chamaelinorops, need no introduction—they are oddball species that at first pass might not even be recognized as anoles, and that have received a modicum of scientific study. The third clade, Phenacosaurus, by contrast, has been mostly ignored. This is surprising, because at least some species are quite notable morphologically, with head casques, heterogeneous scalation, wild colors, and an all-over prehistoric appearance. Moreover, they live at remarkably high altitudes, at least by anole standards, and have a passing resemblance—some species more than others—to Caribbean twig anoles. Nonetheless, there is almost no literature on the natural history or evolution of these anoles.

Ken Miyata’s 1983 Journal of Herpetology paper is the one exception. In it, he describes the habitat use of A. heterodermus in areas near Bogotá, Colombia. His description paints the species as one that uses narrow perches on bushes and other vegetation, and that is especially plentiful in blackberry bushes. Combined with its short legs, heterogeneous body and head scalation and elongate and compressed body, reminiscent of twig anoles like A. valencienni, one might entertain the possibility that it is in functional terms a mainland twig anole.

A year and a half ago, we reported in AA on our studies of another phenacosaur, the much smaller A. orcesi from Ecuador. Our studies conclusively demonstrated that it is in all respects like a twig anole—behaviorally, it moves extremely slow; ecologically, it is found almost entirely on narrow surfaces; and morphologically, it is a Caribbean twig anole doppelgänger. But in one respect, A. orcesi was a disappointment—it looks just like any old anole, without the wildly prehistoric aspect for which the larger phenacosaurs are renowned. For this reason, it was time to examine another phenac, and what better choice could there be than A. heterodermus, the subject of Miyata’s study, supposedly common near Bogotá, and appropriately wild in appearance?

And so Rosario Castañeda, Anthony Herrel and I converged on Bogotá in late February for just this purpose, joined by Rafael Moreno, a graduate student at Universidad Nacional de Colombia, who has just completed his masters degree research on this species, with one fine paper out and more in the works. Our plan was simple: go to appropriate spots on the outskirts of Bogotá, locate lizards in the vegetation, watch them and record habitat use and behavior, then capture them and bring them back to the field lab to measure sprinting and biting capabilities and to examine their stomach contents. Continue reading

Dewlap Research On Grand Cayman

Tess Driessens, but that’s no lizard

Channel 27 in Grand Cayman has just aired a report on the doctoral work of Tess Driessens (co-winner of the 2012 Anole Photo contest!) and Simon Baeckens (actually, from their webpages, this seems like Tess’s project). They’re studying the diversity of dewlap color in Anolis sagrei by looking at brown anoles throughout their range.

Female Green Anoles Exhibit Limb Length Plasticity In Natural Habitats

carolinensis by michele johnsonMuch has been written about how differences in relative limb length allow anoles to successfully occupy distinct portions of the arboreal habitat. Most research has focused on large-scale patterns of diversity, which are presumably the result of natural selection. But limb length could also be more finely tuned using an alternative process, whereby an individual’s morphology responds to environmental cues experienced throughout development. This process is known as phenotypic plasticity. We already know that anole limbs exhibit plasticity in the lab (e.g., Losos et al. 2000, 2001 – A. sagrei; Kolbe and Losos 2005 – A. carolinensis), with lizards raised on narrow perches having shorter limbs than those raised on broad perches.  But what about lizards in their natural environments; could plasticity in limb length allow lizards to become more specialized to their particular microhabitat in the wild?  This was the question that Trinity University (San Antonio) undergraduate Alisa Dill asked in summer 2010, working with fellow undergraduate Andrew Battles, regular AA contributor Thom Sanger, and me.

We studied green anole lizards in three plots in Palmetto State Park, in southeastern Texas (Figure 1).

Figure 1 from Dill et al. In press. Study plots in Palmetto State Park. The star on the small map of Texas (bottom left) indicates the location of the park.

Figure 1 from Dill et al. In press. Study plots in Palmetto State Park. The star on the small
map of Texas (bottom left) indicates the location of the park.

The three plots differed dramatically in perch availability – one was in a dense dwarf palmetto stand in a closed forest, another was trees and bushes surrounding an open field, and the third was in a light forest with many small vines and twigs. We found that female lizards in the third plot (with the narrowest perches) had significantly shorter hindlimbs than females in the other two plots, although males did not differ in limb length among the plots.  Juveniles also did not differ in limb length across the three plots, consistent with the idea that the female’s developmental experience on varying perches may influence their adult limb length.

Why this difference between the sexes?  (This difference is also consistent with results from the laboratory studies mentioned above.)  We also observed where males and females were found in their habitat and how they locomoted through it to determine if differences in behavior between the sexes could affect the way the developing lizards interact with their environment. We found that females performed fewer locomotor behaviors, spending more time on particular perches; thus, perhaps the perches had a stronger influence on female limb length than on males, who used many more perches as they move through their environment.

There is much more work to be done to further test the hypothesis of plasticity in a natural environment. After all, the previous lab experiments were performed by growing lizards on either a wooden 2×4 or a small dowel, a much simpler environment than a forest with many perch options. It would be ideal to perform a “common-garden” experiment where juvenile lizards are transplanted between environments with different perch diameters. We also don’t yet understand the developmental mechanisms that cause limb plasticity in anoles, but more information about those mechanisms will help determine why the sexes respond differently to differences in their microhabitat.

You can read more about our study in our recent publication in the Journal of Zoology, available online now in Early View.

References:

Dill, A.K., T.J. Sanger, A.C. Battles and M.A. Johnson. In press. Sexually dimorphisms in habitat-specific morphology and behavior in the green anole lizard. Journal of Zoology.

Kolbe, J.J. & Losos, J.B. (2005). Hind-limb length plasticity in Anolis carolinensis. J. Herpetol. 39, 674–678.

Losos, J.B., Creer, D.A., Glossip, D., Goellner, R., Hampton, A., Roberts, G., Haskell, N., Taylor, T. & Ettling, J. (2000). Evolutionary implications of phenotypic plasticity in the hindlimb of the lizard Anolis sagrei. Evolution 54,301–305.

Losos, J.B., Schoener, T.W., Warheit, K.I. & Creer, D. (2001). Experimental studies of adaptive differentiation in Bahamian Anolis lizards. Genetica 112-113, 399–415.

Advice Needed: GPS Tags For Giant Bronze Geckos?

Here’s a question for AA readers from Nancy Bunbury, from the Seychelles Island Foundation, who is conducting some exciting work on large gecko interactions, ecological roles, and niche separation in the palm forests of the Seychelles:

Giant-bronze-gecko-on-tree“The main species in question is Ailuronyx trachygaster (first field study on this amazing species) and one thing we would love to do is look at movements and territory size (also because we suspect it’s the main pollinator for the coco de mer which has huge conservation and inevitably commercial value). We are looking into GPS tags for the geckos (which are about 150g in weight) but it seems the technology for such a small tag requiring GPS and remote downloading is not yet available. Do you happen to know if such tags have yet been developed and who I might be able to contact for them (I’ve tried the standard larger companies for animal tracking devices)?”

Any suggestions?

Four Weeks Later, the CBS Sunday Morning Anole-Gecko Episode Now On Youtube

On February 17th, CBS Sunday Morning’s wonderful Nature Moment featured footage of brown anoles…but called them geckos. After we pointed this out, they took down the video from their website, but now it’s up on Youtube. You still have to watch the commercial first, though.

 

Do Bats Eat Anoles? Yes!

Fringe-lipped bat chows on a frog. Apparently, they take lizards, too. Photo from Smithsonian Science.

A quick answer to my question posed a few days ago. Some bats do, indeed, eat anoles. In particular, the fringe-lipped bat Trachops cirrhosus has been reported to do so a number of times, I now know thanks to avid anolologist and zoological polymath Anthony Herrel. Try googling “anole” and “trachops.” One hit with several references comes from the entry in Mammalian Species for Trachops, although only one paper specifically identifies anoles (A. lemurinus being the victim), as opposed to “lizards” or geckos.

Habitat Fragmentation And Population Biology Of A High Andean Lizard

Anolis heterodermus. Photo by J. Losos.

Anolis heterodermus. Photo by J. Losos.

We all know that habitat fragmentation and destruction have devastating consequences on biodiversity. Yet, one of the reasons that Caribbean anoles have been so intensively studied is that some species do extremely well in human-disturbed habitats and, because they have become so ubiquitous, they are extremely good subjects for ecological and behavioral studies.

In fact, it gives pause to realize that Caribbean islands were mostly cloaked in forest before the arrival of man, and thus many of the common anole species which are abundant in open, disturbed habitats–brown anoles, for example–were probably much less abundant in pre-historic times. In other words, it seems likely that some species are actually doing better today than in the past, but there are very few relevant data.

Anolis (Phenacosaurus) heterodermus probably occurs at higher altitudes than any other anole and has a very large altitudinal range. It’s natural history is almost unknown, and until recently, nothing had been published on its ecology and behavior since Miyata’s J. Herp. paper 30 years ago. However, that has now changed. Rafael A. Moreno-Arias has just completed his master’s degree at Universidad Nacional de Colombia on populations of this species near Bogotá, and the first paper from this work was recently published in Biotropica.

The habitat near one of the study sites in Tabio, Colombia. Photo by J. Losos.

The habitat near one of the study sites in Tabio, Colombia. Photo by J. Losos.

In that paper, Moreno looked at six habitat patches, differing in size and degree of fragmentation. By conducting a mark-recapture study,  he found that populations seemed to be increasing in all populations. Moreover, survival and growth rates were calculated to be highest in the most disturbed habitats, perhaps reflecting this species’ adaptation to edge habitats. Although too much habitat destruction is obviously detrimental–without any bushes, the species will not be able to survive–it seems that the species, perhaps like its Caribbean cousins, does just fine in fragmented landscapes. However, Moreno and Urbina-Cardona take a different, more nuanced, view on their findings, as their abstract below indicates.

Abstract:

Habitat fragmentation and loss affect population stability and demographic processes, increasing the extinction risk of species. We studied Anolis heterodermus populations inhabiting large and small Andean scrubland patches in three fragmented landscapes in the Sabana de Bogotá (Colombia) to determine the effect of habitat fragmentation and loss on population dynamics. We used the capture-mark-recapture method and multistate models to estimate vital rates for each population. We estimated growth population rate and the most important processes that affect k by elasticity analysis of vital rates. We tested the effects of habitat fragmentation and loss on vital rates of lizard populations. All six isolated populations showed a positive or an equilibrium growth rate (k = 1), and the most important demographic process affecting k was the growth to first reproduction. Populations from landscapes with less scrubland natural cover showed higher stasis of young adults. Populations in highly fragmented landscapes showed highest juvenile survival and growth population rates. Independent of the landscape’s habitat configuration and connectivity, populations from larger scrubland patches showed low adult survivorship, but high transition rates. Populations varied from a slow strategy with low growth and delayed maturation in smaller patches to a fast strategy with high growth and early maturation in large patches. This variation was congruent with the fast-slow continuum hypothesis and has serious implications for Andean lizard conservation and management strategies. We suggest that more stable lizard populations will be maintained if different management strategies are adopted according to patch area and habitat structure.

Two New Papers Criticize Proposal To Split Anolis

Last year, Nicholson et al. proposed splitting Anolis into eight genera in a paper in Zootaxa.  This idea was extensively debated in AA’s pages (e.g., 1,2,3 and links therein). Now, two papers have been published criticizing the methods and conclusions of Nicholson et al. and suggesting that the generic name Anolis be retained for the entire clade.

In a paper just published two days ago in Zootaxa, Steve Poe argues strongly against Nicholson et al.’s proposal on multiple grounds, primarily on the lack of demonstrated monophyly of most of the proposed genera. Poe concludes at the end of the introduction of the paper: “Nicholson et al. (2012) selectively adopted results of their own flawed, unstable, and conflicting analyses, selectively incorporated pertinent published data and results, and changed names for over 100 species that have never been included in a phylogenetic analysis. The proposed taxonomy is unnecessary and unwarranted according to standard taxonomic practice. It should not be adopted by the scientific or nonacademic communities.” The paper is only five pages long and is readily downloaded.

Meanwhile, within the past month, Castañeda and de Queiroz published a paper in the Bulletin of the Museum of Comparative Zoology on phylogenetic relationships within the Dactyloa clade of anoles (pdf, supplementary material). The paper is a follow-up to their 2011 paper on Dactyloa, adding morphological data to the molecular dataset analyzed previously. We’ll have more on this paper soon, but the pertinent part for today is the “Note added in Proof” appended to the beginning of the paper. The authors explain “Shortly after our paper was accepted, Nicholson and colleagues published a phylogenetic analysis of anoles and a proposal to divide Anolis into eight genera… Here, we comment briefly on their study as it pertains to the phylogeny and taxonomy of the Dactyloa clade,” and then go on to criticize Nicholson et al.’s recognition of genera (in this case, Dactyloa) and species groups that are not monophyletic in their own analyses. Moreover, like Poe, Castañeda and de Queiroz present strong critiques of the Nicholson et al. methodology and analyses, concluding “Because our results are based on larger samples of Dactyloa species (for both molecular and morphological data), as well as larger samples of molecular data (with respect to both numbers of bases and numbers of gene fragments, and including both mitochondrial and nuclear genes), and because many of their taxonomic conclusions that differ from ours are either contradicted by their own results or unsubstantiated, we do not consider any of the differences between our phylogenetic results and taxonomic conclusions compared with those in the study by Nicholson et al. (2012) to warrant changes to our proposed taxonomy. In contrast to Nicholson et al. (2012), we refrain from assigning some species to series and treat some taxonomic assignments as tentative because of contradictory results or poorly supported inferences, and we present justifications for all taxonomic decisions pertaining to species not included in our analyses.”

The Castañeda and de Queiroz critique is only two pages long. Read ‘em both and decide for yourself.

Do Bats Eat Anoles?

Micronycteris microtis. Photo from http://www.chiroping.org/images/bats/microtis2.jpg

A question that comes up from time to time is whether bats are among the panoply of species that munch on anoles, particularly in the mainland neotropics. As we all know, some bats are renowned for catching and eating frogs, but will they also sup on our little friends? As far as I’m aware, there are no records in the literature of anolivory in bats, but perhaps a reader can correct me on this point. One can imagine two scenarios: first, bats active at dusk or dawn might nab anoles while still active. Alternatively, second, perhaps bats can use their sonar to locate sleeping anoles on leaves. This latter point has generally been considered unlikely because the acoustic clutter in a thick vegetational matrix has been thought to be make it difficult for bats to identify and locate non-moving objects in the vegetation.

A recent study shows that this is not so. Studying the insectivorous bat Micronycteris microtis from Panama, Geipel et al. have just shown that bats can use echolocation to find and capture non-moving prey, in this case dragonflies. More details are provided in the abstract pasted below. It would seem to follow, then, that bats may, indeed, prey on sleeping anoles, but in a critical oversight, the authors fail to comment on this pressing issue.

Abstract: “Gleaning insectivorous bats that forage by using echolocation within dense forest vegetation face the sensorial challenge of acoustic masking effects. Active perception of silent and motionless prey in acoustically cluttered environments by echolocation alone has thus been regarded impossible. The gleaning insectivorous bat Micronycteris microtis however, forages in dense understory vegetation and preys on insects, including dragonflies, which rest silent and motionless on vegetation. From behavioural experiments, we show that M. microtis uses echolocation as the sole sensorial modality for successful prey perception within a complex acoustic environment. All individuals performed a stereotypical three-dimensional hovering flight in front of prey items, while continuously emitting short, multiharmonic, broadband echolocation calls. We observed a high precision in target localization which suggests that M. microtis perceives a detailed acoustic image of the prey based on shape, surface structure and material. Our experiments provide, to our knowledge, the first evidence that a gleaning bat uses echolocation alone for successful detection, classification and precise localization of silent and motionless prey in acoustic clutter. Overall, we conclude that the three-dimensional hovering flight of M. microtisin combination with a frequent emission of short, high-frequency echolocation calls is the key for active prey perception in acoustically highly cluttered environments.”

Mentally put an anole in there, and you can see we’ve got trouble!

In The South American Footsteps Of Ken Miyata

Anthony Herrel, Rosario Castañeda and I are just back from a three-week trip to Colombia and Venezuela to collect data on the natural history of several little-known anole species. Unbeknownst to us, we were retracing the work of Harvard graduate student and naturalist extraordinaire Ken Miyata, who conducted similar—though more extensive, fieldwork on two of our focal species—A. (Phenacosaurus) heterodermus and A. onca in the 1970’s.

Fortunately, our South American colleagues were more knowledgeable than we are and pointed us to contributions in Anolis Newsletter II and III in which Miyata and Ross Kiester detailed their work and findings, which, alas, were never formally published. I’ll be reporting on what we saw, both here and in the Scientist at Work blog of the New York Times (first post this morning), but if you want to get up to speed, check out these reports. And, more generally, this indicates the wealth of important information available in the Anolis Newsletters, all six of which are available.

Lastly, a teaser: we’ll be hearing more about Ken Miyata in the next few months.

Anolis Fuscoauratus Displaying

 

Anolis fuscoauratus. Photo by Roberto Langstroth

AA reader Roberto Langstroth writes:

Perhaps Anole Annals readers would enjoy these shots of a displaying A. fuscoauratus on the Nassau Plateau of Suriname.  The second photo shows some interesting behavior, e.g., the tail curling and the tongue protrusion.  There were two individuals involved in vigorous displays…as the third blurry “artistic shot” shows…  They were on a vertical trunk of a large tree about 6 meters above ground on a steep slope on the plateau in March 2010.

Diet Overlap Between Brown Anoles And A Native Lizard In Taiwan

Large prey taken by brown anoles (top two photos) and Swinhoe’s tree lizard (bottom two).

Starting in the 1970s, Caribbean anoles became a model system for studying community ecology, especially interspecific competition. Such studies generally focused only on anole species. Though seemingly chauvinistic, this anolocentrism is reasonable in many localities, where resource competition probably is primarily between anole species (although there was a boisterous debate in the 1980s on the extent to which anoles and insectivorous birds might compete).

However, this is not always the case. In Central and South America, for example, the much greater non-anole saurifauna than on Caribbean islands makes it likely that anoles may experience much greater resource competition with non-anole lizards, as well as other taxa. And the same may be true for anoles introduced to far-flung regions.

Take, for example, the brown anole in Taiwan, which occurs with the native Swinhoe’s tree lizard. Like brown anoles, the agamid is found on the ground and low on tree trunks, and thus might be considered a trunk-ground anole. Being only slightly larger than brown anoles, the tree lizard probably eats much the same food. Gerrut Norval posted a while back on the amazingly large prey that brown anoles and tree lizards eat in Taiwan, and now he and colleagues have published a paper documenting the extensive diet overlap between the species (Gerrut previously provided a post on the background to this study, including some interesting information and photographs on the research methods). Very likely they are strong competitors, although Norval et al. argue that the size discrepancy means that the effect is asymmetric. However, at least in some areas, brown anoles have much higher densities, meaning that their aggregate effect on tree lizards may be just as great as the reverse.

Brown anoles are most dense in hot, open areas, whereas the tree lizards reign supreme in shaded habitats, suggesting that environmental effects mediate the outcome of interspecific interactions between the two species. In addition, this difference indicates that reforestation efforts would be a good conservation move to stem the effect of the brown anole invasion.

Did the Adaptive Radiation of Anoles Happen in Stages?

Do events unfold in a predictable sequence when organisms undergo adaptive radiation? Anoles have diversified in many ecologically important characteristics as they have radiated both in the Caribbean and on the mainland. As one of our best-understood cases of extraordinary evolutionary diversification, they make a great system in which to ask how ecological diversity builds up during adaptive radiation.

The idea that anoles radiated in stages dates to at least 1972, when Ernest Williams derived some hypotheses from his observations of Puerto Rican Anolis in particular, drawing upon earlier work by Stanley Rand and Rodolfo Ruibal. Williams noticed that the most closely related species on Puerto Rico tend to belong to the same ecomorph class and occupy similar structural habitats (e.g. branches, trunks or twigs), but occur in different thermal habitats (e.g. closed forests or hot open areas). He proposed that anoles on Puerto Rico diversified first in structural habitat, and later in thermal habitat, a pattern that might scale up to the entire adaptive radiation of Anolis. While this idea has been discussed many times, and helped to inspire more general hypotheses about stages of radiation (e.g. Streelman and Danly 2003), until now it had not been tested using modern analytic techniques that incorporate phylogenetic information for many species.

Figure 11 from Williams (1972), modified to show only the 8 species in the main Puerto Rico radiation.

Figure 11 from Williams (1972), modified to show only the 8 species in the main Puerto Rico radiation.

Continue reading

The Passing Of A Legendary Herpetologist

17d6112f7c32f26ae9515d4fd15f4bbf.jpgTwo days ago, Hobart Smith died at the age of 100. Hobart was among the most prolific herpetologists of all time, with more than 1,500 publications to his name. Included among his publications are several classic monographs such as the Handbook of Lizards (1946) and the Checklist and Key to Amphibians of Mexico (1948). Hobart is the namesake for numerous species of reptiles and amphibians, including Anolis hobartsmithi, an endangered species endemic to the highlands of Chiapas, Mexico. May he rest in peace.

Axolotl and Curt Coonors research

The Dream Of Curt Connors Could Become Real Thanks To A Mexican God

Axolotl and Curt Coonors researchI read a recent news about “The secret to running repairs” and I remembered an older AA post about a hypothetical genetic biologist who researched the ability of certain reptiles to regrow missing limbs, partially to find a way to regrow his own missing arm.

Today, his noble research could be real thanks to a Mexican god. Yeah, the Axolotl, who according to the Aztec myth is a god transformed on a neotenic salamander with the hope that their ability to regenerate body parts will one day help people with amputations.

The Axolotl has become the amphibian prefered by many scientists around the world thanks to its capacity to regenerate both their hurt limbs as well as its jaw, skin, organs and even parts of the brain and the spinal cord. And to top things off, it doesn’t get cancer.

Scientists believe that it will only take a decade or two before the dream of Curt Connors could became a reality: the human limbs could regenerate like the axolotl.

I’m very excited for this news that I believe I forgot the anoles for a little moment.

Jumping Anole Video Goes Viral

Who wouldn’t want to see a lizard do a face plant? Apparently tens of thousands couldn’t pass this one up. It’s all part of Chi-Yun Kuo’s research in the Duncan Irschick Lab; Chi-Yun provided a first-hand account of the research when the paper was published last year.

Editor’s Correction: Chi-Yun’s paper is fabulous, but this video actually comes from Casey Gilman’s also wonderful research. See her original paper in the lab that produced this video and the recent field follow-up.

Flexible Perches… Who Cares?

I had spent a summer in Florida watching green and brown anoles jump around on trunks and branches, and I was amazed by how well they appeared to navigate their habitat, despite the variable flexibility and complexity of the habitat. Many anole species jump. They jump to move around their habitat, to forage, to fight, to chase (or be chased by) potential mates, and to avoid predators. If you have observed anoles jumping in the wild, you might notice that some species jump a lot, and they jump to and from a lot of different types of structures (the ground, trunks, branches, leaves). While the diameter of different types of structures has been shown to affect running speed and surefootedness, it has also been shown to have little impact on jumping, at least in the lab. But what about the flexibility (compliance) of the structures they are jumping to and from? Will a narrow branch in the wild affect jumping performance, not because of its diameter, but because narrow branches tend to be flexible? What about other flexible structures in nature, such as leaves, which tend to be wide and highly flexible? And, are anoles choosy about where, and from what, they jump?

It turns out, when it comes to jumping, perch flexibility is quite important.

With the help of my advisor, an engineer, and a generous collaborator who gave me guidance and let me use his specially-designed anole jumping tank, we conducted a lab study to to determine if and how perch flexibility affects jump performance in green anoles. We found that the  more flexible a perch was, the more it negatively affected jump distance and jump speed. We also observed that the recoiling perches whacked the anoles in the tail as they were jumping, which caused many anoles to do an impressive faceplant (this part of the story has received a bit of notoriety, both in the Annals (twice) and elsewhere). So, increased perch flexibility decreases jumping performance in the lab. But what does this mean for those anoles I’ve seen jumping from leaves and twigs in their natural habitat?

Male green anole perched on a flexible palm leaflet

Male green anole perched on a flexible palm leaflet

To answer this question, I headed back down to Florida and spent a little over a month filming green anole jumping behavior. The green anoles I observed in the wild appeared to be extremely choosy about which structures they jump from. While I found them basking and foraging on a range of perches, from stiff trunks to highly flexible leaves, the lizards would generally jump from the sturdiest perches in the habitat. If they were on a thin and flexible palm leaflet, they would move closer to the base of the leaflet to a stiffer spot before jumping. And when they did jump from highly flexible perches, they jumped to another perch that was just a short distance away. The longest jumps we observed were from the most sturdy (and low-lying) perches.

The green anoles I observed appeared to be so good at choosing perches to jump from, that over the course of my study I only noted two failed jumps from flexible perches. In one instance, a male was perching near the end of a leaflet, then moved to a sturdier part of the leaflet to jump onto a perch above him. Although this part of the leaflet was sturdy, it was not sturdy enough. The force of the jump pushed the jump perch down away from him, and he was unable to jump high enough to reach his intended perch. Luckily, he was able to catch onto another leaflet before he hit the ground. In the other instance, another male attempted a jump to a far perch and landed on the ground instead, then quickly climbed back up the palm. However, because I documented undisturbed behavior, many of the jumps I witnessed were sub-maximal. The lizards were jumping as far as they needed to at the time to get to another perch, but were not attempting to flee and therefore may not have been jumping as far as they might otherwise been able to. I wonder how my observations of how choosy they are with jump perches would change if they were in situations where they needed to escape quickly. Continue reading