Anole Annals

Reports Pat Shipman in Little Cayman, adding “Notice the difference between her expression and his.  Anolis maynardi on Little Cayman, just after a nice rain.”

And notice that sexual dimorphism in snout length!

Find this week’s anole!

Before leaving for Cuba, Martha and I discussed our anole wish-list. Figuring prominently were Cuba’s legendary sister-species, A. bartschi and A. vermiculatus. Also swiftly declared were the beautiful A. allisoni and anything in the erstwhile genus Chamaeleolis (alas, we found none of the snail-eating giants). However, I must admit — I had no idea A. lucius existed until I first laid eyes on it!

After encountering A. lucius in a patch of mature forest along a slow-moving stream, my first impression was that it looked and behaved like a trunk anole, if trunk anoles were 150% bigger and had zebra stripes on their heads. Indeed, at the first locality we encountered them, they seemed to favor perching head-down on trunks 1-3m high (with one individual spotted almost 5m high.)

Although I’m still fond of my initial diagnosis of “giant zebra-headed A. distichus,” we proceeded to encounter A. lucius in a variety of other habitats. For instance, we found them scrambling over limestone karst and taking refuge in sea cliff caves on Cuba’s southern coast, a habit described in Schwartz & Henderson’s Amphibians and Reptiles of the West Indies. Later I would wonder what A. bartschi, were it to occur syntopically, would have to say about that.

~5m up a tree

~2m below ground

We also found A. lucius near human habitation, on the streets of Trinidad and the home of a coffee farmer in Cuba’s Topes de Collantes nature reserve park.

So it seems clear that this anole is jack of at least a few trades. But wait, there’s more!

A. lucius has a bizarre trait, one that’s shared with a close relative already featured on Anole Annals, A. argenteolus. Can you guess what it is? If you guessed translucent scales on the lower eyelid, you win! The function of these “shades” is not entirely clear, with one obvious idea being that they block harsh sunlight. For what it’s worth, we almost never saw A. lucius close its eyes during the day.

Anolis lucius: pretty much obligated to wear its sunglasses at night

A. lucius was, dare I say, a dark-horse third-place finisher on the list of coolest species we managed to see. I’ll (probably) finish off the top three next time with A. vermiculatus!

PS
Anoles with sunglasses…just stop, evolution.

Photo by Jake Scott

Some people think so, such as this posting on the Association of South Eastern Herpetogists website. I have my doubts about the presence of porcatus in Florida. Anolis carolinensis, after all, is derived from A. porcatus. In reality, it is simply a population of A. porcatus, perhaps smaller than most of their Cuban comrades. Suppose for some reason A. carolinensis started growing larger–wouldn’t they look like the green anoles on Cuba? Anyone have thoughts on whether Cuban porcatus are really in Florida and, if so, how easy it is to identify them?

Photo by Christopher Kirby

Here’s another putative porcatus, this one photographed by Christopher Kirby. Those heads are pretty mean looking, I’ll grant that. Several other photos are also on the ASEH website.

Anolis cybotes, one of the species included in Husak and Lovern’s study, still showing its dewlap during copulation.

If I were to take survey of Anole Annals readers regarding the factors that regulate aggressive and showy behaviors, I suspect that the vast majority of you would implicate testosterone as the primary culprit. Whether we are discussing humans or nearly any other vertebrate, there is a common societal notion that testosterone fuels these behaviors like oxygen fuels fire. The widespread belief is simple: individuals with more testosterone tend to exhibit more aggressive, ostentatious, and risky behaviors.

For decades researchers have investigated the link between testosterone and behavior in a variety of biological contexts – including different behaviors, experimental manipulations, environmental conditions, and life history parameters – but rarely in wild animals or within an evolutionary context. If the supposed testosterone-behavior correlation is extended to a broader, comparative context, it would suggest that aggressive species should also have higher levels of circulating testosterone than more placid species. But, in an upcoming paper, Husak and Lovern test the testosterone-behavior supposition among Anolis lizards and, quite frankly, turn it right on its head. To give away their conclusion at the outset, three of the four “aggressive” anole lineages examined have evolved this behavior without a clear correlation with circulating levels of testosterone.

Anolis lizards are renowned for their convergent anatomical evolution (reviewed in Lizards in an Evolutionary Tree), but these species have also independently evolved similar behaviors. In a study that was one of the first of its kind, Johnson et al. showed that the Anolis ecomorphs exhibit evolutionary convergence towards similar patterns of aggressive display and territorial behaviors. Trunk-ground anoles tended to be the most “aggressive” ecomorphs, consistently exhibiting higher display rates and  territoriality than the trunk-crown, grass-bush, or twig ecomorphs. Twig species tended to exhibit the least aggressive behavior in the analysis. (Also see Ord et al. 2013 for a more fine-scale dissection of display behavior.) Using this pattern of convergent behavior as a foundation, Husak and Lovern predicted that trunk-ground anoles would have higher levels of circulating testosterone than other ecomorphs from the same island, twig anoles the least. The absolute levels of testosterone might vary depending on the specific lineage in question, but they predicted that the rank-order of testosterone on each island would follow the behavioral continuum described in Johnson et al. In total the authors surveyed circulating levels of testosterone and corticosterone, an adrenal steroid hormone associated with stress, in 18 Anolis species!

Figure 1 from Husak and Lovern 2014: Circulating testosterone levels in 18 species of Caribbean Anolis lizards. Bars group by ecomorph classification (CG= crown giant, GB= grass-bush, T= trunk,
TC = trunk-crown, TG = trunk-ground, TW= twig) and color coded by island (white = Bahamas, light gray = Jamaica, dark gray = Dominican Republic, black = Puerto Rico).

As I already stated, the authors found no support for the idea that elevated levels of circulating testosterone consistently drive aggressive behavior in Anolis lizards. Instead they found that three out of the four clades of trunk-ground anoles had the lowest levels of testosterone, the opposite pattern than would be predicted based on their behavior.

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Check out this green anole photographed at the Archbold Biological Station in Florida by Nick Fletcher, participating in a Cornell University field trip led by Harry Greene.

Green anole. Photo by Nick Fletcher.

Photo by Nick Fletcher.

And here’s one more by Nick, taken a day later.

Photo by Nick Fletcher.

St.Lucian Anole

I was recently in St.lucia travelling around photo-documenting the local Anolis luciae which seem to be rapidly being displaced by the invasive A. wattsi from Antigua. While exploring the southwestern town of Soufriere, I came upon a few specimens of this species in the backyard workshop of the sculptor host of mine.
I have showed the photos to a few herpetologists at UWI (St. Augustine) and they are as baffled as I am; for the closest-looking possibility, A. richardi, native to Grenada and the Grenadines, is not noted to have migrated this far north.
Any takes on what species it could possibly be?

From the pages of Sports Illustrated, 25 years ago today

That’s my thumb! Ain’t she a beauty?

A few months ago, I ran into Nicholas Dawidoff, the author of the fabulous new book Collision Low Crossers: A Year Inside the Turbulent World of NFL Football. Seeing Nicholas reminded me of the article he wrote for Sports Illustrated at the very dawn of his writing career, 25 years ago today. The article was on the then developing field of performance studies, measuring the sprinting, jumping, clinging and other capabilities of small ectotherms, and featuring none other than yours truly, as well as Ray Huey, Al Bennett, and Sharon Emerson. Written tongue-in-cheek, but accurately and respectfully, the article was a very nice overview of that emerging field of study. It’s worth checking out the article just to see the wacky pictures taken by the SI photographer sent out on assignment to Seattle and Berkeley.

Inexplicably, the article didn’t make the cover

If you followed the barrage of blogposts we wrote from SICB 2014, you might recall some discussion of the information actually conveyed by anole displays and dewlaps (1, 2). The upshot of these studies is that anole displays are complex. We see unexpected relationships between various traits and the probability of success in male-male competition, and different traits correlate with different measures of male success. A recent study by Steffen and Guyer (2014) adds to our growing knowledge of the information conveyed by different dimensions of multimodal anole displays. When viewed together with previous research, this study presents us with an even messier picture than before of how Anolis lizards communicate with each other.

Steffen and Guyer (2014) set up paired competitions between size-matched male Anolis sagrei in a lab setting, implementing two treatments–males either compete for access to a single perch, or for mating access to a single female. All interactions were recorded, and display behaviours–headbobs, push-ups, dewlap extensions–were quantified. Further, the spectral reflectance of both the centre and the margin of the dewlap (which can be strikingly different in A. sagrei) was also measured. The question asked by the paper was straighforward: which display and dewlap traits are related to an individual lizard’s status as a winner or loser of competitions?

In both competitive contexts, only two traits seem to be important–a composite axis of behavioural variation, and one of three composite axes describing the colour of the margin of the dewlap. Lizards who headbob, push-up, and extend their dewlaps more during competitive interactions are more likely to win than lizards who display less. Curiously, lizards with lower UV reflectance of the dewlap margin are more likely to win than lizards with brightly UV-reflecting dewlap margins.

Of the two variables, display behaviour was more highly correlated with the probability of success than dewlap margin UV-reflectiveness. I’m curious about how the two variables are themselves related–do lizards  that display more also have less bright dewlap margins? The authors propose that a dewlap’s reflectance might relate to its conspicuousness, and it would be interesting to know if different individuals are conspicuous in different ways.

Each of the studies conducted so far on how anoles convey information to each other has examined different dewlap and display variables, studied different competitive contexts, and used different measures of male quality. It therefore isn’t surprising that we seem far from reaching a consensus on what the dewlap says.

Book cover from the Animorphs series book 1, The Invasion by K.A.Applegate.Published 1996
Photo from wikipedia

Recognize that Lizard?

I actually read this book a long time ago, I loved the series; basically the premise was that a bunch of children were given a space cube by an alien that allowed them to change into any animal for two hours. The kids would then use the abilities of these animals to thwart the various plans of a race of alien, mind-controlling parasitic slugs.The idea was original and the books were an interesting read too.

The picture on the cover is of one of the main characters morphing into a Cuban (specifically mentioned) green anole; unfortunately, I don’t remember what it was that he did with this morph.