Anole Photo Contest Is Back!

Lucas Bustamante-Enríquez’s Grand Prize-winning photo of A. chrysolepis from the 2013 contest (© Lucas M. Bustamante-Enríquez/TROPICAL HERPING)

We know you’ve all been waiting, so here it is! Anole Annals is pleased to announce the return of the Anole Photo Contest, 2015 edition! We’re closing in on November, which means it’s time to gather the best anole photographs for our 2016 calendar. As with previous contests, the goal is to identify 12 winning photos. The grand prize winner will have his/her photo featured on the front cover of the 2016 Anole Annals calendar, second place winner will have his/her photo featured on the back cover, and they’ll  both win a free calendar! (Check out the 2013 and 2012 winners). We’re a bit late getting things going this year, so get your photos in as soon as you can!

The rules: submit your photos (as many as you’d like) as email attachments to anoleannals@gmail.com. To make sure that your submissions arrive, please send an accompanying email without any attachments to confirm that we’ve received them. Photos must be at least 150 dpi and print to a size of 11 x 17 inches. If you are unsure how to resize your images, the simplest thing to do is to submit the raw image files produced by your digital camera (or if you must, a high quality scan of a printed image).  If you elect to alter your own images, don’t forget that it’s always better to resize than to resample. Images with watermarks or other digital alterations that extend beyond color correction, sharpening and other basic editing will not be accepted. We are not going to deal with formal copyright law and ask only your permission to use your image for the calendar and related content on Anole Annals (more specifically, by submitting your photos, you are agreeing to allow us to use them in the calendar). We, in turn, agree that your images will never be used without attribution and that we will not profit financially from their use (nobody is going to make any money from the sale of these calendars because they’ll be available directly from the vendor).

Please provide a short description of the photo that includes: (1) the species name, (2) the location where the photo was taken, and (3) any other relevant information. Twelve winning photos will be selected by readers of Anole Annals from a set of 28 finalists chosen by the editors of Anole Annals.  The grand prize winning and runner-up photos will be chosen by a panel of anole photography experts. Deadline for submission is November 21, 2015.

Good luck, and we look forward to seeing your submissions!

 

A Few Meters Matter–Landscale Thermal Heterogeneity and Reproductive Output in a Puerto Rican Anole

Anolis cristatellus. Photo by Janson Jones.

If you ever come to Puerto Rico, the first thing you’ll probably notice is the warmth. Yet, for an anole, things are not that simple. Different habitats can have different thermal regimes that potentially influence the lizard’s biology and natural history in different ways. What might be a hot and humid urban park for us can be a heterogeneous thermal landscape for a small lizard.

This is the case for Anolis cristatellus, a lizard common in most parts of Puerto Rico. Back in the early70’s, Ray Huey (1974) studied how habitat influenced this anole’s thermal biology. He found that in open and sunny habitats, this lizard actively thermoregulates and has relatively high and stable body temperatures, but that in shaded forests it is a thermoconformer and has relatively low and variable body temperatures.

Also back in the early ’70s, George Gorman and Paul Licht (1974) found that altitudinal and seasonal variation in temperature had major effects on reproductive cycles of Puerto Rican anoles. So, do reproductive cycles differ between lizards living in thermally distinct — but contiguous — habitats? Ray Huey, George Gorman and I teamed up to find out, and you can find the answer in our recent paper just published in The American Naturalist.

We studied seasonal reproductive cycles of this lizard in two localities in lowland Puerto Rico. Both localities have contiguous but thermally distinctive habitats: open parks and forests, separated by only a few meters. We caught female lizards every month for more than two years and palpated their bellies to establish reproductive condition. At both localities, lizards living in open habitats were more often gravid than were those in the forest. This difference was especially marked during winter months (of course… in a tropical sense). During these cooler months, more than 20% of open lizards were gravid, while essentially none of the forests ones were.

Large-scale geographic variation in reproductive cycles has been described in many taxa, but this is one of the few examples on a micro-geographic scale. Very likely these difference will have significant effects on the population ecology of the species, and these will be reported on soon. But in the meantime, we can say that at least for the reproductive output of Anolis cristatellus, a few meters matter!

 

Brown Anole with a Busted Dewlap

Photo by Karen Cusick

From Daffodill’s Photo Blog.

You’re Never Going to Guess Who’s a Big Anole Lover

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Rush Limbaugh, that’s who! To wit: “But I love those little lizards.  They’re anoles, actually.  I love ’em.  They’re our buddies. They eat insects and all that.”

And it turns out that Jeb Bush is just like a cat chasing an anole. Read all about it here (or listen to it here), skipping to paragraph four if you want to get to the important, mostly non-political stuff.

The Incredible Shrinking Dewlap!

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Photo by Bonnie Kircher

Here in north-central Florida, summer is giving way to fabulous fall weather. While this change means an infinitely more comfortable bike commute, it also means that the anoles which were abundant throughout the summer are starting to disappear. Although pedestrians can still find lizards basking in the afternoon sun, Floridians are much less likely to see anoles at every turn. The lizards that are still out and about are also far less likely to be strutting their stuff, keeping their dewlaps tucked away, as they are not needed for mating or competition until the next breeding season. When the dewlap is little used for such an extended period of time during the non-breeding season, could the morphology of this structure be altered?

Indeed, studies have demonstrated that there are marked changes in dewlap size between breeding and non-breeding seasons. Specifically, this already amazing structure seems to change in size, being larger in the summer when it gets the most use, and smaller in the non-breeding season! Simon Lailvaux and colleagues first hypothesized that changes in dewlap size might be correlated with variation in resource availability throughout the year. However, the group found that changes in dewlap size do not correlate with resource availability at all! Recently, following the results of the dietary restriction study, Simon Lailvaux et al. (including yours truly) again asked the question, “Why?” More specifically, are there instead physiological changes that cause dewlap size to expand in the summer and shrink in the non-breeding season?

Lailvaux et al. first asked whether dewlap size was changing because of inherent changes in lizard physiology between seasons or, instead, if changes were due to the extensive use of the dewlap during the breeding season. The authors captured male A. carolinensis lizards before the onset of breeding season and constrained the dewlap in half of the lizards so that the lizards could not extend their throat fan. They found that lizards with unconstrained dewlaps had larger dewlaps in the summer that shrunk again in the fall. The constrained males, on the other hand, had smaller dewlaps in each consecutive season. These data suggest that changes in dewlap size stem from the behavioral use of the dewlap – when a dewlap is extended more often, it gets bigger!

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Apparatus for measuring skin elasticity. Photo from Ecology and Evolution. Volume 5, Issue 19, pages 4400-4409, 19 SEP 2015 DOI: 10.1002/ece3.1690

Next, the authors tested the hypothesis that dewlaps change in size due to seasonal changes in skin elasticity that correlate with the increased seasonal behavioral use. One of the authors, materials engineer Jack Leifer, developed a novel technique for measuring skin elasticity that involved pulling a piece of lizard skin on a machine that measures force until the skin sample sheared (see picture).The authors compared the force it took to break pre-breeding, breeding, and post-breeding dewlap skin, using measurements taken from belly skin as a control. They found that dewlap skin is more elastic than belly skin and that both belly skin and dewlap skin are more elastic in the summer. These results support the idea that dewlap skin is inherently stretchier than other skin!

Thus, it seems that changes in dewlap usage, coupled with changes in skin elasticity across the year, make the dewlap a dynamic signal. This work does not demonstrate any mechanism for these changes and leaves the door open for many exciting follow-up studies. Why is dewlap skin more elastic than belly skin overall? How are changes in skin elasticity regulated between breeding and non-breeding season? What are the ecological implications of a dewlap that changes in size over the course of the breeding season?

Redundancy in Communication Signals: Work on Anoles Anticipated Current Research Decades Ago

eew and asrIn anticipation of its sesquicentennial in 2017, The American Naturalist has solicited essays commenting on overlooked or underappreciated articles published in the journal during the past 150 years. In this month’s issue, Manuel Leal and I comment on a 1970 paper by Stan Rand and Ernest Williams on how differences among anole species in their dewlap and display behavior contain multiple signals for species-recognition. Several decades later, the importance of redundancy in communication signals has become an important area of research, but years before, Rand and Williams sketched out the important issues, as well as identifying some still-unresolved questions.

Here’s the introduction to our essay:

“Why are animal signals so complex? This question continues to attract the interest of behavioral and evolutionary ecologists. In this Countdown article, we revisit a littlea ppreciated article in The American Naturalist published in 1970: “ An Estimation of Redundancy and Information Content of Anole Dewlaps” by A. Stanley Rand and Ernest E. Williams. As part of this piece, Rand and Williams argued that signal complexity can be explained by redundancy, a mechanism by which multiple components of the signals have evolved to increase the probability of eliciting a response from an intended receiver. We highlight this work because it presents one of the earliest demonstrations of the potential benefits of applying information theory to animal communication. In addition, the study demonstrates the insights that can be gained by evaluating signal evolution at the level of the community. Even today, when both theoretical and empirical studies evaluating the potential forces leading to signal diversity have fl ourished, evaluations at the community level are extremely rare.

More generally, in the spirit of the American Society of Naturalists, we wish to emphasize that the perspicacity of Rand and Williams resulted from the fact that their ideas were ultimately derived from a deep understanding of the natural history of their study organism. In particular, Stan Rand spent substantial time in the fi eld observing lizards, including 10 months studying the ecology and social dynamics of the Jamaican lizard Anolis lineatopus. This study reported detailed observations of many aspects of behavior, including detailed descriptions of the signaling displays used during intra- and interspecific interactions (A. S. Rand, 1967, “ Ecology and Social Organization in the Iguanid Lizard Anolis lineatopus,” Proceedings of the United States National Museum 122:1– 79). It was this familiarity with what animals actually do in nature—when and where they do it, interacting in which ways with what other individuals—that formed the basis of the theoretical constructs put forth in Rand and Williams’ s article. At its core, Rand and Williams (1970) is an elegant illustration of the art of being a naturalist, demonstrating how an intimate knowledge of the organism can serve as the building blocks for the formulation of new conceptual approaches (see H. W. Greene, 2005, “ Organisms in Nature as a Central Focus for Biology,” Trends in Ecology and Evolution 20:23– 27, and references therein).”

You’ll have to read the essay to get the full details, but here’s the conclusion:

“By detailed field study of the morphology and behavior of sympatric lizards, Rand and Williams (1970) were able to outline the applicability of information theory to lizard signaling behavior and species recognition two decades before those ideas became widely accepted. Moreover, they proposed important hypotheses yet to be investigated. This article demonstrates the key role that natural history plays, and will continue to play, in the conceptual development of animal behavior, evolutionary biology, and many other fields. Although the tools available for technological advancement in these fields are unparalleled, Rand and Williams’ s work demonstrates that observing animals in the wild and developing an intimate knowledge of their ecology serves as the raw material for the development of new and exciting areas of research. Thus, as we move into new frontiers, the appreciation of natural history must be an integral component of our approach and should be encouraged to a new generation of behavioral and evolutionary ecologists.”

Where Did the Dewlap Come From?

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There’s been no shortage of enthusiasm when it comes to thinking about the anoline dewlap. From the recent findings that dewlaps are highly functional in low light environments to large scale characterization of dewlap diversity, these charismatic ornaments are captivating to biologists from many fields. However, they are also proving to be amazingly dynamic and difficult to functionally characterize universally. What we know definitively is that dewlaps in anoles are used during territorial and mating interactions. There is some evidence to support a correlation between dewlap morphology and a lizard’s physiological characteristics  or body condition. Dewlaps are highly diverse in both size and color; some species having enormous dewlaps that extend from snout to vent and some having virtually no extendable dewlap at all. Dewlaps also differ between the sexes. In most, but not all, species, males have a larger dewlap than females, but the degree of sexual dimorphism is highly variable across the genus. Strikingly, dewlaps are not unique to anoles! Within iguanid lizards, dewlaps have evolved at least twice, in anoles and Polychrus. Ambika Kamath has done extensive work on the Indian lizard genus Sitana, a dewlap sporting agamid genus. Going a step further, lizards such as Pogona, bearded dragons, and Chlamydosaurus, the frilled lizards, also have elaborate throat ornamentation that develops from similar throat structures as the dewlap (the hyoid apparatus).

While the ecology and diversity of the “dewlap” have been studied in a variety of contexts, the evolution of its underlying skeletal structure is a black box. Questions ranging from, “How many times has the dewlap evolved among lizards?”, “Do the same skeletal structures support an extensible throat in different groups?”, to “What selective forces are driving dewlap diversification?” have yet to be answered systematically. Recently, Ord et al. examined the factors influencing throat morphology diversification and systematically describe throat morphology evolution across iguanid and agamid lizards. They conducted a comparative phylogenetic study, first asking if the diversity in elaborate throat ornamentation across lizards can be explained either by the influence of male-male competition or by the need to signal in visually complex environments. They found that there are more species with colorful dewlaps or throat appendages in forested environments, suggesting selection for conspicuousness in visually complex environments.

Looking at the evolution of colorful and elaborate throat morphologies more broadly, the authors found a single origin of a colorful throat ≥ 110 MYA for agamid lizard. From there, throat morphologies took one of two evolutionary routes, either being modified to include a large appendage or reverting to a non-ornamented/non-colorful state. Following from their previous result, they hypothesize that the loss of a throat ornamentation is due to historical transitions into more open habitats where displays are less constrained.

Anolis is characterized by their large moving dewlaps because the skeletal elements that support the dewlap are highly specialized for rapid extension. However, both iguanids and agamids have a hyoid apparatus, and distinct skeletal elements support the extensible throat skin in each group. The dewlap of anoles is supported by the second ceratobranchial cartilage in the hyoid apparatus and is extended by the contraction of muscles attached to the front end of the hyoid system, causing the second ceratobranchials to rotate downward from the throat of the lizard. Most iguanid lizards exhibit a similar, conserved hyoid morphology, but typically with a smaller second ceratobranchials and no dewlap compared to anoles. Alternatively, across agamids, the authors found amazing diversity in hyoid morphology. While some agamids have a strikingly iguanid-like hyoid, others demonstrate extreme reduction in the length of the second ceratobranchials and extension of other elements of the hyoid system. For example, the beard of a bearded dragon results from the loss of second ceratobranchials altogether coupled with an extension of the first ceratobranchials to support the charismatic lateral frills. When mapped on a phylogeny, hyoid morphological diversity supports a single origin of a movable dewlap with extended second ceratobranchials in iguanid lizards (in Anolis) and two independent origins of a moveable dewlap with extended second ceratobranchials in agamids. Including throat fans that are supported by alternative hyoid modifications, as seen in the bearded dragon, there are another two origins of moveable throat morphologies in agamids (see Figure 3 from Ord et al below).Screen Shot 2015-10-13 at 5.44.22 PM

There is much more work to be done to further understand the specific environmental factors influencing the evolution of elaborate throat morphologies in lizards. However, this study strongly suggests that there are many factors at play. Also, the extensive characterization of hyoid morphology across agamid and iguanid lizards in this study sets up many questions about the physiological processes driving the diversification. What processes cause hyoid morphology to vary so dramatically across a group of closely related groups?

Is It Possible to Distinguish A. carolinensis from A. porcatus

Name that lizard (this one from Miami, not Grand Cayman). Photo by J. Losos

Tennessee lizard guru Sandy Echternacht writes in to AA about the green anoles that have shown up on Grand Cayman, in response to a post from several years ago:

I also think that it is difficult or impossible to distinguish U.S. Anolis carolinensis from U.S. A. porcatus in the field since you typically don’t have live, known A. porcatus for comparison. I think that Wes Chun is correct. Fully adult male A. porcatus are bulkier than A. carolinensis and I’ve seen some with what appear to be large bilateral calcium (?) deposits between the jaw and the neck that give them a bit of the look of a bulldog. I haven’t a clue how, for these two species, to distinguish subadult males and females in general. That shoulder bar (black; often with turquoise blue spots around the edges) is present in many populations of A. carolinensis in the Florida and further north and west, so it can’t be a reliable indicator of A. porcatus.

In addition, most of the relevant research on these issues today concentrates on spectral analyses of skin and dewlap colors, sometimes comparing these to spectral characteristics of the habitat which the lizards occupy. It’s time for a little old school field work. We need detailed narrative descriptions of color AND pattern of live A. carolinensis obtained under controlled conditions of light and temperature and in the maximum green and maximum dark color phases, and of patterning in both color phases, and these data need to be representative of populations across the entire mainland range of the species. If done by multiple investigators, these studies need to employ the same methods and standards. Geographic variation is obvious. Most A. carolinensis have pink to reddish dewlaps but those in southwestern Florida are grayish or greenish, I found a small population between Corkscrew Swamp Sanctuary and Immokalee, FL with pale orange dewlaps, and some males on Oahu, HI have lilac-colored dewlaps. As noted above, the shoulder patch can be entirely absent in a population or present but in frequencies that differ among populations. In East Tennessee, animals in the maximal dark phase are very dark brown to nearly black with no patterning (except a pale venter) whereas those near Gainesville, FL are a gray with a filigree pattern that is whitish in color. The frequency of females with pale middorsal stripes varies among populations. In a part of Withlacoochee State Forest, FL and in the green phase, the color is “chalky” green, along the coast near Ft. Myers it is a beautiful emerald green, further north, as far as Tennessee, it is more of a leafy green. As important as they are, spectral studies usually don’t mention pattern at all, and are carried out only in the green phase. Further, spectral values are of little value to someone working in the field not well versed in visualizing what they mean in the context of the lizard they are holding. I say all of this despite having a friend who is heavily invested in spectral studies. With all of this variation, and without having comparable data for A. porcatus, I’m not sure that we will ever be able to identify in the field with 100% certainty whether a green anole in South Florida (or the Cayman Islands) is A. carolinensis or A. porcatus with the possible exception of a large male A. porcatus with “calcium” deposits.

But I guess I could be wrong.

Video of Anolis proboscis Walking

 

Video Of A Beating Embryonic Anole Heart

Vimeo user “Ectopher” posted a beautiful video of beating embryonic anole hearts. You can even see the blood flow through the branchial arches at one point. Check it out here.

Beating anole hearts

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