During a field survey in Muelas (21-08-2011; 21:07), buffer zone of the Santa Fe National Park in central Panama, an A. lionotus was captured in its sleeping posture on the river bank. Interestingly, they seem to “mimic” the dead tree branch, but being cryptic at night does not make much sense to me; even if the predator is capable of night vision, being perched on a tree without leaves does not seem to be an advantage.
Anolis lionotus
Earlier this year, we mentioned a paper by Juli Wade reviewing research on the green anole, which has become a model organism for integrative studies of reproductive behavior in vertebrates. One example of such research is a paper recently published in her laboratory by Cohen and Wade in which levels of testosterone were experimentally manipulated to see the effect of this hormone on gene expression in different regions of the brain. The abstract gives the details better than I could:
“Aromatase and 5alpha-reductase (5-alpha-R) catalyze the synthesis of testosterone (T) metabolites: estradiol and 5-alpha-dihydrotestosterone, respectively. These enzymes are important in controlling sexual behaviors in male and female vertebrates. To investigate factors contributing to their regulation in reptiles, male and female green anole lizards were gonadectomized during the breeding and non-breeding seasons and treated with a T-filled or blank capsule. In situ hybridization was used to examine main effects of and interactions among sex, season, and T on expression of aromatase and one isozyme of 5-alpha-R (5-alpha-R2) in three brain regions that control reproductive behaviors: the preoptic area, ventromedial nucleus of the amygdala and ventromedial hypothalamus (VMH). Patterns of mRNA generally paralleled previous evaluations of intact animals. Although no main effects of T were detected, interactions were present in the VMH. Specifically, the density of 5-alpha-R2 expressing cells was greater in T-treated than control females in this region, regardless of season. Among breeding males, blank-treated males had a denser population of 5-alpha-R2 positive cells than T-treated males. Overall, T appears to have less of a role in the regulation of these enzymes than in other vertebrate groups, which is consistent with the primary role of T (rather than its metabolites) in regulation of reproductive behaviors in lizards. However, further investigation of protein and enzyme activity levels are needed before specific conclusions can be drawn.”
Here at the Glor Lab we’re in the second year of a major anole breeding experiment. Specifically, PhD student Anthony Geneva is completing the second generation of an experimental study of reproductive isolation that was the subject of his poster at the Evolution meetings this past summer (see this previous post on Anole Annals for more on this poster). I’m happy to report that egg production thus far has been steady and that the we’ve had hatchling emerging for a few weeks now. In the photo above, you can see a baby just emerging from an egg in the foreground and other eggs individually incubating in vermiculite in the background. We’ll have more to report on this experiment in the coming weeks. We’re particularly interested in sharing information on how we’ve encouraged breeding this year by manipulating light and humidity, and in learning how others might have tried to do the same.
Anolis maynardi confrontation. Photo by Pat Shipman
AA‘s correspondent in the Little Cayman bureau, Pat Shipman, reports:
We are in Little Cayman, greatly enjoying our anoles (maynardi & sagrei). This morning we observed an interesting confrontation between two large, presumed male maynardi. Not only were they head bobbing and flashing their dewlaps at each other, but they put their tails UP and pivoted their whole bodies forwards & back. The lower one in this snap is showing the tail up posture with dewlap. Unfortunately it doesn’t show the rocking motion. We had not seen this rocking or pivoting posture before.
The second snap is a maynardi showing its ability to go dark.
Does anyone know how large a territory A. maynardihas? We see them quite regularly in the same places, day after day.
Dark A. maynardi. Photo by Pat Shipman
Anolis sagrei nelsoni. Photo by Steve Busack.
Bob Powell raises an important point in a recent comment, concluding “So, at what point does a differentiated isolate cease to be a subspecies and become a species?” In other words, how do we decide whether to recognize a distinctive population as a different species? I’m not talking about the situation where somebody goes out and comprehensively samples a clade and then uses the latest fancy-pants statistical wizardry to decide how to “delimit” taxa into one or multiple species. Rather, I’m going old school, focusing simply on the situation in which one has a population that is distinctive from other populations. Should we recognize that population as a different species? What kind of evidence is sufficient?
The context is the population discussed last week, Anolis sagrei nelsoni, from the remote Swan Islands 90 miles off the coast of Honduras. This isolated population is morphologically distinctive in many ways from other sagrei. It’s larger, has more lamellae on its toes, and, at least in the photograph above, has a very dark dewlap. Very likely, when Randy McCranie is done examining their scalation, he’ll document other peculiarities. Is this enough to decide to recognize Anolis nelsoni? Certainly, in recent years the same approach has been taken to recognize a number of other Central American anole populations as distinct species.
One problem with this approach is that nelsoni probably lies phylogenetically somewhere within what is currently recognized as A. sagrei (just my guess, but the only phylogeographic study on sagrei to date placed Belize populations in the middle of sagrei). Hence, raising nelsoni to species status would render the rest of sagrei paraphyletic, which bothers some people more than others.
Another option is to name the population (or in this case, retain the population) as a subspecies. I recently semi-seriously suggested to a collaborator that we name two subspecies for populations of a species found on two islands. He just laughed.
The answer, of course, is to conduct a detailed systematic study of the entire A. sagrei clade, using both molecular and morphological data. The problem is that this is a huge undertaking. Even Al Schwartz didn’t tackle variation in sagrei! So, it may be a while before this gets done. What do we do in the meantime? Is it A. sagrei nelsoni or A. nelsoni? Good question, Bob!
Update on Expedition to Swan Islands
While we’re on the topic of A. sagrei nelsoni,
Albert Schwartz, longtime professor of biology at Miami Dade Community College, was one of the most important figures in anole biology. Schwartz co-authored the authoritative account of West Indian reptiles and amphibians with Robert Henderson, described at least 8 anole species (in addition to many other reptile and amphibian species), authored dozens of reports on anole taxonomy and biogeography (see previous reviews on Anole Annals of his reports on Hispaniolan giant anoles and Hispaniolan trunk anoles for examples of this work), and amassed a collection that would ultimately include over 15,000 anole specimens. Most of Schwartz’s West Indian collection can now be found in the collections of the University of Kansas, including 15,511 anoles. When Schwartz completed his work on the vast collections he had accumulated over decades of intense field sampling, he reached an agreement with KU that would, in 1987, have Bill Duellman and Linda Trueb driving a 38′ U-Haul truck full of over 60,000 reptile and amphibian specimens of from Florida to Kansas. In addition to acquiring Schwartz’s preserved material, KU also acquired Schwartz’s original notebooks.
These notebooks are housed in KU Herpetology’s library and I had a chance to check them out during a recent visit. There are more than 40 notebooks in total, and they extend across Schwartz’s career in the West Indies. He kept his fieldnotes primarily in student composition books (some of which actually bear the title “SCHOOLTIME Compositions”). For the most part, Schwartz’s notebooks are simple catalogues of specimens that include a field series number, the species name, and the date and location of the collection. Although he provides color notes on most specimens, he rarely comments on natural history or other aspects of a particular specimen’s biology.
I’d like to get all of these notebooks digitized and transcribed so that the information they contain can be made available to anyone who’s interested. I’ve been thinking that it might be fun to crowd source the transcription of these notebooks once they’re scanned. For those who aren’t familiar with crowd-sourced transcription, this process permits large numbers of internet users to transcribe old texts that cannot easily be digitized via optical character recognition. Today, this approach is widely used by folks interested in transcribing handwritten documents and numerous software applications have been developed to facilitate the process. It’s already being used to transcribe some historical field notes, including an effort by The San Diego Natural History Museum to transcribe the field notebooks of the herpetologist Lawrence Klauber.
What do you think? Are there readers of Anole Annals who would be interested in helping transcribe Schwartz’s notebooks? Does anybody have past experience coordinating such efforts that they’d be willing to share?
Anolis gingivinus. From http://wordpress.iworklab.com/dcna/bush-and-tree-anoles/
Read all about them in this post from the Dutch Caribbean Nature Alliance (whose logo features an anole!).
Anole holiday shopping season is now officially open! What could be better than a Christmas tree festooned with ecomorphs?
Dickerson’s collared lizards. Photo from http://www.herpnation.com/wp-content/uploads/2012/05/Dickersons-Collared-Lizard-Crotaphytus-dickersonae-700×466.jpg
What the heck gives with blue lizards? Collared lizards, geckos, lacertids, teids, anoles—there’s more blue lizards than you can shake a stick at. And they stand out like a sore thumb. How can they possibly survive? And in those species in which only the males are blue, do the lady lizards really have an azure fixation?
Male Anolis allisoni from Atkins Botanical Garden, Cienfuegos, Cuba. Photo by J. Losos.
Male Anolis allisoni from Cuba are famous as the day-glo green lizard with a blue jumper. But their Honduran descendants are much less cerulean—indeed, here on Roatan, they barely have a hint of the cobalt (see below). What’s going on? It would seem that whatever has favored blueness in Cuba is not favoring it here. Do the ladies out here swoon not as much for indigo? Are the predators tougher? Is the environment different? Who knows. And has the population here reached a new, less blue, stable-state, or is it in the process of losing its turquoise entirely, returning to its verdant roots. At this point, we don’t have a good time estimate for how long allisoni has been here—if it’s a recent arrival, it would certainly be a reasonable hypothesis that the blue wash is on its way out entirely.
Male Anolis allisoni from Roatan. Photo by J. Losos
See if you can spot the lizard.
But while we’re on the topic of color craziness, here’s another question: how come green anoles can’t—or don’t—match their background? Color mavens may be offended at my non-analytic assertions, but I insist that green anoles often are conspicuous. On white tree trunks (much less brown or red ones), a green anole stands out a mile away.
How about this one?
Sure, green’s great for camouflage when you’re in the vegetation, but if you could change colors, wouldn’t you do so when on non-green backgrounds. Octopi can do it, why not anoles? Or, at least, why don’t they stay on green surfaces when they don’t want to be detected. Although, truth be told, not all greens are the same, and the bright green of these species often stands out against darker green vegetation (check out the anole in the grass in yesterday’s post, reprinted to the left).
Green lizard in the grass: not so cryptic
Now, some contrarians may claim that they’re actually trying to be conspicuous—Bob Trivers, for one, suggested that the beautiful green A. garmani intentionally perched in conspicuous sites in order to be seen. Maybe that’s so, but most of the time, anoles don’t seem like they’re trying to be seen, especially the females. And, yet, you can’t miss them.
Finally, of course, I have to acknowledge that it’s possible that I failed to spot one or two green anoles in green vegetation, especially high in trees. So, it may be that green is the color that camouflages them most effectively. Still, they could do better by changing color to match where they’re sitting, or by only sitting where they don’t stand out.
A female Anolis allisoni, no worse for the wear, from Roatan, Honduras
In advance of our trip out to Swan Island, I’ve come to Roatan, one of the Bay Islands just off the coast of Honduras, to check out its anole fauna. Of particular interest is the mixture of island and mainland faunas: A. allisoni¸ a trunk-crown member of the carolinensis group, somehow found its way here from Cuba, whereas A. roatensis (nee lemurinus) represents the mainlanders. And, as a bonus, A. sagrei is here, too, apparently introduced. I’m looking forward to seeing how they mix it up.
Things didn’t get off to a good start yesterday when I arrived mid-afternoon. It was very overcast and drizzly, and the temperature probably barely topped 70. Brrr! With more of the same forecast for today, I was not optimistic.
But although it looked like it was on the verge of raining all day, it held off until after dark. The sun was in and out, and so were the lizards. My expectation was that the balance of color would be like it is in other places where carolinensis and sagrei group anoles co-occur: lots of brown anoles on the ground and low on trees, bushes and buildings, and a small to moderate number of greens at eye level up to the treetops.
I couldn’t have been more mistaken. Green anoles were seemingly everywhere—as thick as anywhere I’ve ever been. And the browns? I saw three. The greens were on the buildings, on the fences, in the bushes up the trees, even doing their best grass-bush anole imitation along the roadside. They were everywhere, except one place: the ground. And therein lies the explanation for this green:brown inversion. There were brown lizards in great abundance—at least in open sunny localities—but although they skittered about and occupied the same place, they weren’t anoles. Rather, they were these fellows.
Brown basilisk on Roatan
Brown basilisks, Basiliscus vittatus. Many of them were sagrei-sized, and if you weren’t paying attention, their abundance might have convinced you they were anoles. But then there were the bigger fellows, not as abundant, but plenty of them. My hunch is that they’re why brown anoles haven’t gotten much of a foothold. The little guys compete with the sagrei, and the bigger ones eat ‘em. I speculated earlier this year about interactions between basilisks and introduced A. cristatellus in Costa Rica—there, they seemed to coexist and cristatellus was doing fine. Here, I think the story is different. Of course, brown basilisks have also been introduced to Miami, where they coexist with sagrei, so maybe I’m barking up the wrong tree, but the great abundance of basilisks, living exactly where you’d expect to see the sagrei, seems too much of a coincidence to me.
The proverbial lizard in the grass
Whatever the cause, the absence of sagrei seems to have given allisoni the green light to go crazy. They’re enormously abundant and use many off-the-ground habitats—fences, buildings, etc.—where you’d expect to see sagrei. At least in open places, like hotels, they are very common from 1-2 meters in height, or even lower. In more forested areas (and remember, this is based on one day’s observations, and the forested areas were visited in the afternoon), they seem mostly high up, generally in sunny spots. I was particularly struck that they were very common in the thick grass, while at the same time as high up in the tree as I could see them. Those of you who live with green anoles in other places (I’m thinking of certain Georgians and Little Caymanians), I’d appreciate your thoughts. Does this seem different from your abundant greens?
Now, as for the other native anole, A. roatensis, today I was shut out. They’re supposed to be in forested areas, and I have a hot lead for a spot tomorrow, so hopefully will have more to report then.
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