Does This Dewlap Go With My Signalling Environment?

Geographic variation in dewlap coloration in A. distichus on Hispaniola (from Ng et al.)

Animals regularly need to communicate with one another (both within and between species) and have developed a variety of signals, some quite elaborate, for doing so.  In some cases, we see extensive variation in these signals across the range of a species, raising the questions of how and why this occurs.  As Julienne Ng, Emily Landeen, Ryane Logsdon, and Rich Glor explain in a new Evolution paper, there are essentially three possible explanations.  Signals may diverge due to random drift, the pressures of sexual selection, or adaptation to local signaling conditions.  The latter possibility, in which signals evolve to match local habitat or environmental conditions, is a particularly interesting scenario.

In their study, Ng et al. examined geographic variation in the dewlaps of Anolis distichus, which vary from yellow to orange/red across Hispaniola.  They recorded reflectance spectra from the dewlaps of 36 different populations, extracted annual precipitation, surface temperature, and percent tree cover variables from GIS data layers, and tested for associations between dewlap and environmental variation.  Because dewlap variation could potentially be influenced by the relatedness of two populations in space or through shared ancestry, Ng et al. also corrected their data sets to remove the effects of spatial autocorrelation and phylogenetic relationships, important extra steps that will hopefully become commonplace in future studies.

It turns out that in drier habitats, A. distichus display smaller, brighter, yellow dewlaps, whereas in wetter habitats, they display larger, less bright, orange dewlaps.  Dewlaps also tended to be more orange in cooler environments with more tree cover.  Interestingly, this pattern is actually opposite that observed by Leal and Fleishman (2004) in A. cristatellus on Puerto Rico, which have brighter dewlaps in drier areas.  Thus, like any good study, this one raises a series of interesting new questions in the course of answering several others.  As Ng et al. point out, it will be interesting to see what future studies tell us about the mechanistic underpinnings of environmentally-associated dewlap divergence.

Finally, I think that the first line in Ng et al.’s paper is an especially good one: “Signals involved in sexual selection and species recognition – the peacock’s tail, the rhinoceros beetle’s horn, and the swordtail’s sword, to name just a few – are some of evolution’s most spectacular outcomes.”  Hopefully, with the impressive recent work done on its ecologically and evolutionarily important variation, researchers in other systems will take note that the anole’s dewlap clearly deserves to be added to this list too.

Ng, J., Landeen, E. L., Logsdon, R. M. and Glor, R. E. 2012. Correlation between Anolis lizard dewlap phenotype and environmental variation indicates adaptive divergence of a signal important to sexual selection and specie recognition. Evolution. doi: 10.1111/j.1558-5646.2012.01795.x

Leal, M., and Fleishman, L.J. 2002. Evidence for habitat partitioning based on adaptation to environmental light in a pair of sympatric lizard species. Proc. R. Soc. Lond. Ser. B 269:351–359.

 

Green Anole Stalking And Capturing A Butterfly: The Story In Photos

We’ve talked about anole predation on butterflies before, and now Karen Cusick has photo-documented the events leading up to it on Daffodil’s Photo Blog. This is the same green anole that Karen previously documented with an enormous moth in its mouth.

The moment before the attack was launched.

 

Feeling isolated? New Research by Wang et al. Shows You’re Not The Only Anole Feeling That Way

Proportion of population genetic divergence accounted for by isolation-by-environment and isolation-by-distance in 17 Anolis species (from Wang et al.)

Identifying the factors contributing to population genetic divergence is important for understanding how many evolutionary processes play out in geographical space. Plus, it’s just plain interesting. In a new paper in Ecology Letters, Ian Wang, with Anole Annals stalwarts Rich Glor and Jonathan Losos, tested the roles of environment and distance in determining spatial patterns of population genetic divergence of 17 anole species on the Greater Antilles. To give the game away (spoiler alert!), the short answer is that both play a role, with some interesting variations among islands and species. However, it’s not just Wang et al.’s results that are interesting (more on those later), but also how they went about getting them.

Wang et al. tested two (not mutually exclusive) hypotheses for population genetic divergence. The first was isolation-by-distance (IBD), where distance and dispersal barriers prevent gene flow among populations. The second was isolation-by-environment (IBE), where there is either selection against dispersers, or a preference to remain in the environment where individuals are locally adapted. To test these hypotheses for each species, the authors first quantified environmental dissimilarity among populations using the Worldclim dataset, MODIS vegetation data, and elevation. Next they measured geographic distances among populations, but with a twist. To incorporate the idea that certain environments will be easier to disperse through than others, Wang et al. constructed environmental niche models. They then used the resulting (reverse) suitability values as a proxy for the ‘resistance’ of an area to movement and calculated the weighted distance between populations using two methods: least-cost pathway and all-possible-paths (circuit distance).

Armed with these measures of environmental dissimilarity and geographic distance, Wang et al. used structural equation modeling to determine the contribution of IBE and IBD to genetic divergence (they redid the analysis a few other ways, to ensure their results were robust. Short answer: they were). They found that both IBE and IBD had a role, but that distance was of greater importance, with collinearity being much less of an issue than I, at least, initially guessed. Their results were relatively consistent across species and islands, though a few species, mostly Hispaniolan, were exceptions (you’ll have to read the paper to find out which ones). Regardless of whether you’re more interested in the general pattern across species (and islands), or in the exceptions, Wang et al.’s study will undoubtedly generate more research questions and spur future work.

Lastly, one of the paper’s aspects I liked best was how the authors used environmental niche models. Species distribution/environmental niche/ecological niche/spawns-of-hell models get a lot of flak from a lot of sources. Much of this is even deserved – however, this is often more the fault of the modeller than the model. As Wang et al. have shown, such models can still provide useful and interesting insights into ecological and evolutionary process. In fact, anole biologists are leaders in new and informative ways to exploit such models. Wang et al.’s paper certainly continues this (emerging) tradition.

Wang, IJ, Glor, RE & Losos, JB. 2012. Quantifying the roles of ecology and geography in spatial genetic divergence. Ecology Letters. doi: 10.1111/ele.12025

Doctor Anole – The Climb

Doctor Anole, Mt. Lemmon, AZ

Among biologists one of the greatest honors is having a species named after them. Among climbers one of the greatest honors is inspiring the name of a new climb. (In fact, much like biology, local ethics and traditions often govern route nomenclature.) It turns out that I have scarred my research has inspired an old friend to name a new route with reference of our favorite scaly beasts. Here I present you, “Doctor Anole” at the Lizard Boulders, Mt. Lemmon, AZ.

Because climbing can, to some, seem a bit esoteric let me take a moment to explain the photo. Unlike climbing mountains or large cliffs, “bouldering” is a form of climbing where a person attempts to climb for only a few moves, but where each move may be at the absolute limit of their ability. Bouldering can just be a single move or, to the most brave, reach death defying heights while rope-free. On Doctor Anole the goal is to climb to the top of this boulder using the small seam for handholds. A pad is also placed below the climb to cushion a potential fall. Hopefully the moderate grade of V2 does not directly reflect my friend’s opinion of my climbing abilities or research.

heatstack

Shelby Prindaville’s Anole Artwork

Watercolor drawing by Shelby Prindaville

Shelby Prindaville, Polychrotidae (Heatstack) detail, watercolor and pencil on paper, 30×22″, 2011

My watercolor drawings and figurative sculptures feature a variety of Anolis lizards.  The visually fascinating characteristics of anoles combined with their small size yet reptilian “otherness” (occupying a middle ground between too-easily-anthropomorphized mammals and too-alien fish or invertebrates) make anoles an ideal animal representative for my broader ecological interests.

Watercolor drawing by Shelby Prindaville

Shelby Prindaville, Anolis proboscis (Pair), watercolor, 3P art medium, and pencil on translucent paper, 16×24″, 2012

The drawings and sculptures I create with anoles use their innate character and abilities to explore a purgatorial space. The first drawing in the watercolor series puts anoles in place of rats in the rat king myth made famous in The Nutcracker; the use of anoles allows a way out of the diseased mass through voluntary autotomy and allegorically demonstrates that repairing environments requires sacrifice. Other drawings pull from subjects ranging from the Ouroboros to Terry Pratchett’s allegory of summer.

Watercolor drawing by Shelby Prindaville

Shelby Prindaville, Anolis carolinensis and Mimosa Pudica (Falling), watercolor and pencil on velvet paper, 27×19″, 2012

My desire to sculpt small yet still anatomically accurate anoles has actually led to the development of a new polymer medium: 3P QuickCure Clay.  I collaborate with LSU Chemistry Professor John Pojman and his company 3P, and my suggestion to create a clay and its subsequent development has allowed me to use a batch-curing process that achieves the intricately detailed results below.

Sculpture by Shelby Prindaville

Shelby Prindaville, Polychrotidae (Dive and Climb), 3P Clay, 4x8x2.5″, 2012

To see larger images or more of my artwork, please visit shelbyprindaville.com.

Physiological Adaptation On Ecological Timescales – New Research By Alex Gunderson And Manuel Leal

Anolis cristatellus from Puerto Rico. Photo taken by Liam Revell

Anolis lizards are a model system for studies of evolutionary ecology because they are remarkably adaptable creatures. We know from long-term studies conducted by Jonathan Losos, Dave Spiller, Tom Schoener, and others that anoles can rapidly adapt their behavior and morphology over ecological timescales. For example, the presence of a ground-dwelling predator (Leiocephalus carinatus) forged a strong selective gradient in favor of A. sagrei with longer hindlimbs within a single generation. Interestingly, in a follow-up study the long-term effect of this predator is that A. sagrei evolves shorter hindlimbs, as they will tend to perch higher off the ground, where the perch diameter is narrower than near the ground. These studies of rapid morphological evolution puts anoles in the a very exclusive club with the likes of stickleback fishes, Peromyscus beach mice, guppies from Trinidad, Galapagos finches, and few others, as vertebrate systems in which evolutionary change on ecological timescales has been confidently demonstrated.

A notable exception to Anolis ‘evolvability,’ however, is thermal physiology. The thermal physiology of reptiles is generally evolutionarily conserved – taxa separated by millions of years and found in very different thermal environments will often share similar physiological patterns. But recent research has suggested that some physiological metrics may not be as static as previously thought, and that Anolis invasions provide an excellent opportunity to see how labile physiology actually is.

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Are You Displaying At Me? There’s No One Else Here…

Three stereotyped head-bobbing patterns of A. carolinensis. The black area represents the amplitude of the head as it moves up and down. Although amplitude can vary within and among individuals, the cadence remains constant for each of the display types. The hatched area refers to times when the dewlap is displayed. Length and number of dewlap displays and associated headbobs at the end of the display can be quite variable. This figure is a modification from Jenssen et al. (2000) that appeared in Lizards in an Evolutionary Tree.

Anole displays have proven to be as frustrating as they are fascinating. These displays, which are species-specific and typically involve headbobs and/or pushups that may or may not be accompanied by dewlap extensions, are as varied as one might expect within a group as diverse as Anolis. However, despite concerted efforts by an energetic group of researchers aimed at understanding the form, context and meaning of these varied adult male displays, a complete understanding of this complex signal eludes us. The stereotyped displays exhibited by many anole species are of particular interest, and of these, arguably the best-studied are the A, B, and C displays of that lab rat of the anole world, Anolis carolinensis.

In a recent paper, Jenssen and collaborators report a characteristically detailed and rigorous field study on the use of such stereotyped displays in both breeding and postbreeding free-ranging A. carolinensis males. Through painstaking analysis of videotapes of thousands of undirected male displays in nature with no obvious receiver, they show, among other results, that breeding males in “monitor” mode (i.e. lizards that signal while stationary) used mostly C displays, but increased use of A and B displays while moving or “travelling.” Monitoring lizards also exhibited an overall lower display rate than travelling males, and used more and longer volleys of displays. Additionally, about a third of all displays had an extra “shudderbob” tacked on. These patterns held through the postbreeding season. Interestingly, Jenssen et al. note that these undirected displays aimed at no-one in particular are most similar to aggressive signals used by males engaged in contests. The implication is that these undirected displays are in fact directed at an unidentified (or undetected) rival male audience, rather than being for the benefit of any single lady lizards in the area.

The notion of males displaying aggressively just in case any rivals might be present makes sense for a species such as A. carolinensis that defends areas harbouring females, rather than trying to attract them. One wonders if this result would hold for species that place less emphasis on territory defense and that have been rumoured in the past to exhibit signs of female preferences (Anolis valencienni, anyone?).

Anolis Back In Strong Force At SICB 2013

Annual conferences are a major way for scientists to get their research out to a broad audience and to find out what is new and emerging in different fields. For those of us who study Anolis lizards, there are two annual conferences that are a major draw for our community – the Society for Integrative and Comparative Biology (SICB) meeting in January and the SSE/SSB Evolution meeting in June. There are other conferences, as well, that meet less often, such as the World Congress of Herpetology and the Anolis Symposium, which are also important gatherings for our growing community.

Last year, we were pleased to report that Anolis research was prominently featured throughout the SICB conference in Charleston, South Carolina. In addition to more than a dozen talks and posters, there was also an open forum on the Anolis genome and evo-devo research, in light of the publication of the A. carolinensis genome. The online schedule for SICB 2013 has just been published and a preliminary search using the keyword Anolis returns a list of 18 talks and posters. There is a great diversity of topics explored this year, including phylogenetic frameworks for evolutionary convergence, aggressive behavior, locomotion, thermal ecology, and parasitism, among others.

One of the cool things we did last year was blog live from SICB in Charleston (1, 2, 3). Because the conference was hosted in South Carolina, Marc Tollis shared some pictures of actual anoles at the conference center. We plan to blog live from the conference in San Francisco and provide you with information about all the interesting research being done on anoles. Stay tuned for more!

Anole Annals Photo Contest 2012: Judge’s Choice Winner

Anolis bartschi photograph by Steven De Decker.

[Editor’s Note: the person who took this photograph is Steven De Decker; see comments after the first paragraph for corrected information]

As one of the seven or eight folks who judged the photos in this year’s AA photo contest I want to give some recognition to an image that didn’t even make the list of finalists determined by popular vote.  My judge’s choice award winner is a striking photograph of a juvenile of the Cuban endemic Anolis bartschi that was taken by Joe Burgess at Cueva del Indio, Vinales, Cuba. Although observed most frequently on rocks in karstic regions, individuals like this one are also commonly seen on trunks and other broad perches emerging from the karst beneath. The quality and clarity of this image are superb. The subtle colors along the animals spine and the steely blue of the eye and surrounding region are beautiful under natural light (perhaps complemented with a tactfully subtle fill flash?). A catch-light in the black eye gives the lizard some personality, and makes me wonder what it might be thinking. The right front forelimb is lifted off the trunk and possibility somewhat blurred by motion, impressing me with the animals agility and suggesting that its ready to make a move. This photo that makes me want to get out and find some anoles.

[Note from Jonathan Losos: I screwed up! There were two photos of A. bartschi entered into the photo contest, and when Rich asked for information on the A. bartschi photo, I gave him the info for the wrong one. The photo above was taken by Steven De Decker (who also took the grand prize winning photograph of A. allisoni). Steven had this to say about the photograph of the juvenile: “It was in the proximity of the prehistoric wall at Vinales, Pinar Del Rio. We were there with 2 local biologists who told us A. bartschi was pretty common to be found at the wall 10 years ago. Great was our disappointment when we saw that [the curly tailed lizard] Leiocephalus carinatus had taken over habitat near the wall. When we went back we decided to investigate some semi caves at the border of the park, and that’s where we found A. bartschi sitting on a trunk near the caves. And to answer your question, no I didn’t use a flash for this particular photo. Using the flash here would have given me a black background.
Meanwhile, below I’ve pasted the photo of A. bartschi by Joe Burgess (whose photo of an A. gorgonae took second place in the contest); this is the photo for which Rich gave info in his post above.

Photo Guide To Mexican Anoles

Could this be the all-time coolest anole dewlap?

As we all know, even though the diversity of anoles is greater on mainland Central and South America, we know a lot more about the island species. This extends even to simple matters such as resources for learning about and identifying species–for many mainland areas, it is hard to get information on the species that occur there, although this has changed in recent years.

Nowhere is this more true than in Mexico, an anologically rich area for which information on the anolifauna has not been brought together into a single compendium. Into this breach step Levi Gray, Steve Poe, and Adrian Nieto Montes de Oca, who have just produced a photo guide to the anoles of Mexico.

They recognize 46 species of Mexican anoles.  Of these 46, the authors and collaborators in the Poe Lab have caught 40 of them, including approximately 21 from their type localities, and field work this month is targetting three of the others.  The photos in the key are all from the authors, except the carolinensis photo provided by Alexis Harrison.  The key includes all Mexican anoles that the authors recognize (leaving out forms they consider unlikely to be valid–e.g., cumingi–or that have questionable status–e.g., utowanae).  The authors report that the well-known species schmidti, simmonsi, breedlovei, polyrhachis, microlepis and adleri are junior synonyms of other forms; these points will be discussed in a paper currently in review in Zootaxa; unfamiliar names in the key (e.g., rubiginosus) will be explained in that paper as well.

Below are low-resolution pictures of the guides; larger, downloadable pdfs can be accessed here. And I can’t help but adding: isn’t the diversity of dewlap colors and patterns incredible? I vote for sericeus as one of the greatest ever!

Spend A Night At The Museum With Anolis Lizards

Darwin Day Herp Tour, Museum of Comparative Zoology, 2011

Attention Boston-area Anolophiles – This Friday, November 9th, the Harvard University Biological Sciences Society (HUBSS) is hosting its annual Night at the Museum event! This free and recurring event at the Harvard Museum of Natural History features plenty of tasty treats, exciting exhibits, and exclusive behind-the-scenes tours of the research collections in the Museum of Comparative Zoology. Although the event is sponsored and hosted by the undergraduate society, interested members of the public are welcome to participate.

As part of this event, I will be giving two free tours of the Herpetology collections. I love working for these events because I get to display my favorite pieces from our amazing collections, including enormous croc skulls, strange and rare reptiles, and, naturally, a dizzying array of anoles. Anoles will be featured prominently in my tours as I use them to illustrate the principles of convergent evolution and to talk about island biogeography. Visitors will get to participate in a team activity using Anolis specimens. If you’re in the area, how else would you rather spend a Friday night than learning about anoles?

Check out the HUBSS website for this event and I hope to see you there!

Electoral Map Awash In Blue In Anole Photo Contest

Well, the election is finally over, and the electoral results are awash with the color blue. More than 300 votes were cast in the semi-finals round, and then an all-star panel chose our winners from the top 12 in the popular vote. Perhaps surprisingly (perhaps not), the hoi polloi and the experts identified the same top three photos.

So now, with no further ado, the winner of the 2012 Anole Photo Contest is…

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Oliver The Over-Achieving Anole: The Book

Another entry into the ever-expanding genre of anole literature. Check out snippets of the book. Amazon.com describes the book thusly: “From the moment of his hatching, in a flowerpot high above the ground, Oliver Anole saw the world as a game and an adventure. His spirit of play and love of creating spreads through the anole world, as just by being himself, he is able to inspire others to be inventive and create the lives they enjoy. I wrote Oliver the Overachiever to encourage children to celebrate their individuality and sense of community. I wanted to illustrate, through story and pictures, that a small person can create great effects that can change his world for the better.” And as for the author, “Karin Mesa has worked for the past nineteen years as a designer of decorative glass. She lives on the west coast of Florida with her husband, glass artist, Julian Mesa. Their studio, located in a one acre garden, provides the inspiration of nature that Karin has always used for her illustrations. Throughout her life observing nature has been fuel for Karin s imagination. Jagged tree stumps in a snowy winter became elven castles. Tree frogs nestled among orchid roots whisper of their cozy hidden homes throughout a garden world. Small lives, out of sight to many, are brought to life in water color and pencil. Karin s stories about these small creatures can be applied to their own lives by children, in ways that are real to them as individuals. Karin has stated her purpose in writing and illustrating like this: I hope that in a light and playful way my stories and pictures will encourage children to develop their creativity and sense of adventure. I want them to know the power they have to change things for the better.”

Anole Research Featured In Animal Cognition Documentary

Manuel Leal’s fascinating studies showing that anoles have more going on than anyone would have expected is featured in a new Canadian TV documentary. The Nature of Things is a well known series hosted by the inimitable David Suzuki. This episode on the cognitive abilities is wide-ranging and has all the usual suspects (chimps, crows, etc.)…and anoles! Not to mention Manuel Leal. Unfortunately, the series can only be accessed online if you’re in Canada, but the rest of us can see a snippet on the post on Chipojolab, as well as a “behind-the-scenes” discussion of the film crew’s visit to Leal’s lab.

Filming in the Leal lab. From chipojolab post.

Documentary On Cuban Anoles

Watch the cuban documentary: ANOLIS: VIGILANTES DE DÍA

In the year 2010, a group of students from the International School of Film and Television from San Antonio de los Baños, Cuba, made a film: “Anolis: Vigilantes of the Day,” an excellent documentary of nine minutes about Cuban anoles. The documentary is narrated in Spanish and has the best aspects of the natural history of these lizards, including some ecomorphs and the use of the dewlap in displays.