Author: Jonathan Losos Page 60 of 133

Let’s face it, “squamate” doesn’t work. It’s an ugly word, and most people don’t know what it means–if anything, it conjures up “squamous cell carcinoma,” a type of skin cancer.

More importantly, the term is not needed. Squamate comes from the scientific order Squamata, the lizards and snakes. But we know that snakes evolved from lizards–they are one type of lizard. In other words, lizards do not form a monophyletic group; they are paraphyletic with respect to snakes.

Does this remind you of any other major group of vertebrate? Say, birds and dinosaurs? We all know that birds evolved from dinosaurs, they are a type of dinosaur; dinosaurs are paraphyletic with respect to birds. And so, what is the solution to this problem? We now realize that birds are dinosaurs, members of the Dinosauria. Indeed, failing to recognize birds as a type of dinosaur commits the sin of paraphyly, obscuring the fact that some dinosaurs (in the old sense) are more closely related to birds than they are to some other dinosaurs.

And so, for the same reason, we should start referring to snakes as one type of lizards and, in turn, when we use the term “lizard,” we should understand that we are referring to snakes as well. In other words “Lizard” = Squamata. And, hence, we have no need to use the term “squamate” in common discourse.

Ahh, that warmth feels good.

We all know that many anoles species are very good at behaviorally regulating their body temperature by moving from an area that is too hot or too cold to another area that is just right. But how do they actually judge the thermal properties of a particular microsite? There’s been a lot of work on the sensation of temperature in mammals, but not so much in reptiles.

Recently, Erkin Kurganov and colleagues at the National Institutes of Natural Sciences, in Okazaki, Japan began to rectify this shortcoming, and their paper has just been published in Pflügers Archiv – European Journal of Physiology. Here’s the abstract: 

Transient receptor potential ankyrin 1 (TRPA1) is a member of the large TRP super family of ion channels and functions as a Ca2+-permeable nonselective cation channel that is activated by various noxious stimuli. TRPA1 was initially identified as a potential mediator of noxious cold stimuli in mammalian nociceptive sensory neurons, while TRPA1s from nonmammalian vertebrates (snakes, green anole lizards, and frogs) were recently reported to be activated by heat, but not cold stimulus. In this study, we examined detailed properties of the green anole TRPA1 channel (gaTRPA1) related to thermal and chemical stimulation in whole-cell and single-channel recordings. Heat activates gaTRPA1 with a temperature threshold for activation of 35.8 °C, while heat together with allyl isothiocyanate (AITC), a chemical agonist, had synergistic effects on gaTRPA1 channel activation in that either the temperature threshold or activating AITC concentration was reduced in the presence of the other stimulus. Significant heat-evoked gaTRPA1 activation was observed in the presence but not absence of extracellular Ca2+. gaTRPA1 channels were also activated by heat and AITC in excised membrane patches with an inside-out configuration. By comparing the kinetics of heat- and AITC-evoked singlechannel currents, we defined similarities and differences of gaTRPA1 channel responses to heat and AITC. We observed similar current-voltage relationship and unitary amplitudes for heat- and AITC-evoked currents and found that heat-activated currents showed shorter durations of both open and closed times. Our results suggest that the gaTRPA1 channel is directly activated by heat and chemical stimuli.

Ron Savage, who works for USAID and is currently posted in Haiti, reports “I haven’t been getting out herping in Haiti much since I sold my car but today I managed to go out and check out some relictual forest (at about 2,700 ft elev.) not too far from Port au Prince and photographed these two anoles. This is the first time that I’ve seen this species in Haiti or the DR come to think of it. They were both up a tree about 15-20 feet and I would say that they were both about 8-9” long including their tails. As you can see, one has a stump tail. He was higher in the tree keeping his eye on the greener one. I honestly don’t know what these are, do you have any idea? It could actually be two species. I’m not familiar with A. ricordii, but I suppose this could be one.”

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!

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.

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.

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

Blurb: “This guide will allow nearly everyone with an interest in amphibians and reptiles to collect and store samples for genetic analyses. It is written at a level appropriate for people with a basic background in biology, including professional scientists moving into a new project as well as wildlife managers, conservation biologists, ecologists, and others working on herpetological projects. The book should also be useful for advanced undergraduates and graduate students just starting their research careers.”

See more at the SSAR book website.

Price: $11

Anolis pentaprion taxiing down the runway on a canopy tower at the La Selva Biological Station in Costa Rica. Photo by Vinicio Paniagua.

Draco, the flying dragon, has borrowed an anole dewlap, so it’s only proper that anoles return the favor by developing gliding capabilities. It’s been long rumored that Anolis pentaprion, a twig anole from Central America, will launch itself off of perches in canopy and glide away, but now Steve Overbauer, Vinicio Paniagua, Craig Guyer and Mo Donnelly have documented just that in an interesting herpetological natural history note that appeared in the last issue of last year’s volume of Herp Review (Vol. 44, pp. 677-678).  Here’s what they have to say:

“Lizards with gliding or directed aerial descent behaviors are well known from the Old World Tropics (e.g., Draco, Ptychozoon), and snakes and frogs exhibiting these behaviors are found both in the Old and New World Tropics (Dudley et al. 2007. Annu. Rev. Ecol. Evol. Syst. 38:179–201). However, lizards showing directed aerial descent have not been reported from the New World Tropics. Here we report on directed aerial descent capability and behavior in Norops pentaprion, a canopy lizard from eastern Costa Rica, southern Nicaragua, and western Panama (Köhler 2010. Zootaxa 2354:1–18).

The initial discovery of this behavior in N. pentaprion was serendipitous in July 2001 when an individual was captured on a walk-up meteorological tower at canopy level (~ 25 m) at La Selva Biological Station in the Atlantic lowlands of Costa Rica. After identification, the animal was returned to the original location on the tower, but upon release to a horizontal tower brace, it executed a controlled aerial descent to a tree in the distance below. Individuals of N. pentaprion have been occasionally observed on our meteorological towers subsequent to our first observation of directed aerial descent. The lizards are typically at canopy level but are sometimes found well above the canopy on the highest levels of the towers (up to 42 m). While the typical response of N. pentaprion to the presence of personnel on the tower is to race down the tower or hide on the opposite side of vertical supports, the animals will occasionally jump from the tower to escape when approached. Since 2001 we have observed directed aerial descent by N. pentaprion from canopy towers on several occasions. In at least two instances the lizard landed at lower levels on the tower, but in other occurrences they covered substantial distance to adjacent trees including aerial rotations of near 180º. During more than one observation, animals appeared to glide with near-horizontal trajectories towards termination of the descent. Similar to some snakes, frogs, lizards, and ants showing directed aerial descent, N. pentaprion does not have strongly specialized features associated with gliding behavior such as skin flaps, skin extensions, or webbed feet. Norops pentaprion has a relatively flattened head and wide body. During aerial descent this lizard proceeds headfirst, with limbs partially extended and the body strongly flattened, a position that may take advantage of regions of relatively loose skin along the sides of the body (Guyer and Donnelly 2005. Amphibians and Reptiles of La Selva, Costa Rica, and the Caribbean Slope, Univ. California Press, Berkeley, California. 299 pp.).

At La Selva Biological Station this species is uncommon in the understory and is usually found on trees limbs. Norops pentaprion is a member of a closely-related group of anoline lizards subjected to a recent analysis of morphology and morphometrics (Köhler, op. cit.); these related taxa share similar body size characteristics with N. pentaprion and are frequently arboreal. Future observations of some of these species may result in the discovery of similar directed-aerial descent behavior. Canopy pioneer Donald Perry reported lizards with a rose dewlap parachuting between trees in the canopy in Costa Rican forests (Perry 1986. Life Above the Jungle Floor, Simon and Schuster, Inc. New York, New York. 170 pp.), but the species was not identified. In their description of Norops pentaprion, Guyer and Donnelly (op. cit.) indicated that parachuting behavior likely occurs in this species on the basis of our initial observations and those of Perry. Our repeated observations verify directed aerial descent in this species and confirm that the lizard observed by Perry was N. pentaprion, the only lizard in the region with magenta dewlap coloration.”