Author: Jonathan Losos Page 71 of 129

Professor of Biology and Director of the Living Earth Collaborative at Washington University in Saint Louis. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.

Sex and Battle in Puerto Rican Green Giants

Anolis cuvieri. Photo by J. Losos.

Anolis cuvieri. Photo by J. Losos.

Several days ago, Manuel Leal, Liam Revell and I went to Cambalache State Forest in Puerto Rico, west of San Juan. We were there to search for anoles, particularly–the giant Puerto Rican anole, Anolis cuvieri—and other fauna and flora. The trip was a great success, culminating in an action-packed interaction between three—count ‘em, three!—A. cuvieri. Manuel has already posted some observations over on Chipojolab, but Rashomon-style, I’ll present my take on what went down.

At about 2 p.m., we were walking along when a female—our fourth cuvieri of the day—was spotted head down at a height of about six feet on a tree trunk. After observing it for a few minutes, we noticed that there was a male about four feet above her on the same trunk. We watched them do nothing for a while, the inactivity perhaps caused in part by our peering and approaching for photographs.

Manuel Leal photographing two Puerto Rican giant anoles.

Manuel Leal photographing two Puerto Rican giant anoles.

IMG_1416xAfter a while, the female walked across a narrow branch to the next tree, performing some small headbobs as she did so. After a while more, the male started displaying (see photo), but the female studiously ignored him. Finally, the male came over to the female, who immediately ran away, up the tree. The male ran after her and caught up with her. She seemed to be playing hard to get—if she’d really wanted to get away, why did she stop and let the male get to her? He then approached her from behind in typical male fashion and grabbed onto her by biting the back of her neck. She, however, would not allow him to mate, keeping her body pressed firmly to the branch.

Attempted mating, with female not being cooperative. Photo by Manuel Leal from Chipojolab

After this went on for a while, another male comes tearing over through the canopy from another tree and chases the first male down to the ground, where he runs to a nearby tree. The female takes off and disappears up the tree. The second male then goes back up the tree. After a while, the first male—who had turned very brown—moves over to a nearby tree, slowly resumes his green color, and starts nodding. The two males bob and look menacingly at each other, but they are separated by a distance too great to jump across. At the beginning, the second male flashed his dewlap a lot and presented an open mouth tongue display, but as time went on and the old male regained his greenness, these behaviors waned. Both males continually moved up their respective trees, neither seeming to want to let the other be higher. As the trees bent in opposite directions, moving up caused the males to become further and further apart. After a while, male #2 turned dark and seemed to adopt a submissive pose, whereas male #1, who had been chased off, had a victorious pose. How the two of them had decided that #1 had won is a mystery.

Males posturing at each other from a distance. Photo by M. Leal at Chipojolab

So, what went on? Was the female being unreceptive because #1 was an interloper and she was waiting for her guy to come by? Given that #2 started from another tree and eventually retreated back to it, that doesn’t seem to be the case. Was she mating publicly and prominently to attempt to attract other males, as Trivers suggested for the Jamaican giant A. garmani? Another point is that the interaction, although aggressive, involved little or no physical contact (couldn’t quite tell what happened when the second male rushed the first one at the outset); these two males may be old acquaintances and were simply reminding each other of where their territory boundaries lies. Notably, as well, when the two males were displaying back and forth, it seemed at times like one or the other was thinking about attacking, but the distance between the trees was too great to bridge in a jump. The only other avenue would have been to go to the ground and run over to the other tree, and then attack from below, which would seem to put that male at a disadvantage according to the laws of gravity.

I am unaware of any reports in the literature on A. cuvieri territorial or mating behavior, so these observations are interesting and perplexing. As Manuel states, this shows the importance of getting out and observing animals in their natural habitats—we’ve got a lot left to learn.

Snake Tries To Eat Lizard; Lizard Bites Back

Photo by Manuel Leal

Another anole bites the dust. Or does it? Over at Chipojolab,  Manuel Leal reports the observation of a Puerto Rico racer apparently in the process of ingesting an Anolis krugi. But if you look carefully, the krugi is giving as good as he gets. Or at least doing his darned best. Will it be enough to fend off his demise? Seems unlikely given the size difference, but in lab trials, Leal and Javier Rodríguez-Robles showed that Anolis cristatellus often bites attacking racers on the snout and can hang on for as long as 20 minutes; in 37% of the trials, the lizard actually escaped. Admittedly, cristatellus is bigger and beefier than krugi, but who knows–maybe this guy lived to see another day.

More On Global Warming, Lizards And Extinction

Anolis cristatellus basking in the sun. Photo by Janson Jones.

In recent years, concern has arisen about how tropical ectotherms will cope with rising temperatures. For a variety of reasons, tropical species are considered particularly vulnerable, and coarse scale modelling exercises suggest that many populations and species may face extinction in the near future. Some of the most influential studies, such as Sinervo et al.’s mammoth 2010 paper (already cited more than 200 times!), have focused on lizards.

The field of thermal ecological physiology made great advances in the 1970’s and 80’s and a, perhaps the, major player in the work was research on lizards. And amongst this work, studies on Anolis played a particularly prominent role (reviewed in Chapter 10 of Lizards in an Evolutionary Tree). Hence, it is no surprise that a reconsideration of lacertilian prospects, based on detailed understanding of how lizards interact physiologically with their environment, is stemming from in-depth studies on anoles.

Most modelling studies are based on a coarse-grained (1 km2 resolution), remote sensing scale analysis of global temperature variation, with the assumption that relatively little variation in thermal environment occurs within each block. Recent papers focusing on anoles in Puerto Rico (Leal and Gunderson, 2012) and offshore islands in Honduras (Logan et al., 2013) have tested this idea and found it wanting–in open areas and, to a lesser extent, within forests–considerable thermal heterogeneity occurs. Moreover, many anole species thermoregulate behaviorally–i.e., they aren’t passive samplers of the environment, their body temperature a simple reflection of the ambient, but rather they move in and out of sun and shade, and thus can determine their temperature, mediating what is available in the environment. Thus, even if the environment gets warmer, lizards may have the option simply to switch to increased use of the cooler micro-environments, maintaining the same body temperature.

Plateau in peak sprinting performance in relation to body temperature in Anolis cristatellus. Increases in body temperature over the range of ca. 31-36 C will have little effect. Figure from Gunderson and Leal (2012).

A third point is relevant as well. Physiological performance is generally temperature-dependent, but often a broad plateau exists in which maximal performance varies over a broad range of body temperatures. Hence, populations may be buffered from effects of increased temperatures if the resulting increase in body temperature does not push them off the plateau.

Both studies ask the simple question: if global temperatures go up, will lizards in open and forested habitats experience an increase or a decrease in the quality of the thermal environment, quantified in terms of how readily they are able to achieve their optimal temperature (using sprint speed as a proxy).

Anolis bicaorum from Utila, one of the forest species in the Logan et al. study. Photo by J. Losos.

Anolis bicaorum from Utila, one of the forest species in the Logan et al. study. Photo by J. Losos.

The results show interesting similarities and differences.

New Journal Will Focus On Caribbean Natural History

A new journal focused on the natural history of Caribbean fauna and flora has just been announced. As the sample cover to the left illustrates, it might be a great place to publish observations on our favorite critters. The journal has a distinguished board of editors and the webpage states:

The Caribbean Naturalist is a peer-reviewed journal that publishes original articles focused on field research of all aspects of the biology and ecology of terrestrial, freshwater, and marine organisms and the environments of the Caribbean region. The journal offers:

• over 15 years experience of consistently providing timely publication of high-quality peer-reviewed research

• article-by-article online publication for prompt distribution to a global audience

• an efficient and responsive review process

• the expertise to bring to rapid fruition proposals for Special Issues based on a series of invitational articles or conference proceedings

• the capability to accommodate publication of a wide range of supplemental files in association with journal articles

As is the case with Eagle Hill’s other natural history journals, the Caribbean Naturalist is expected to be fully indexed in Elsevier, Thomson Reuters, Proquest, EBSCO, Google Scholar, and other databases.

Check out the details at their website.

All About Blue Animals

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Anolis allisoni, the green lizard wearing a blue jumper. Photo by J. Losos.

 

Female A. gorgonae. Photo by Joe Burgess.

Two of the world’s coolest lizards are blue anoles, male A. allisoni from Cuba and both sexes of the fabled blue anole of Gorgona (A. gorgonae). Why the blue? Heck if I know. You can see a male allisoni on a palm from a great distance, so it amazes me that they can survive. Seems clear that they must be trying to advertise their presence. On the other hand, I’m told that A. gorgonae can be very hard to spot when one looks up toward the canopy, where the species hangs out. In this instance, the blue may actual serve for crypsis. Who knows?

Lets not forget the blue toes of Anolis bartschi! Photo by Joe Burgess.

Turns out that there are lots of blue animals and the reason for their blueness, as well as the mechanism by which it is produced, is not well known. Kate Umbers has just published a nice review in Journal of Zoology on all things blue, and it’s a worthwhile read, even if she didn’t mention anoles, or even hardly any lizards at all. Among other interesting tidbits, she points out that dichotomizing colors as structural or pigmentary is somewhat misleading, because both pigments and structure can work together to produce blue colors. Also, blue-footed boobies’ feet are bluer when they’re well-fed, and female boobies invest more in their offspring if they have brighter blue feet.  Who knows what interesting blue-related aspects of natural history remain to be uncovered in anoles?

Many anoles have blue eyes as well, and this is a trait that seems to pop up repeatedly throughout the clade, though I have no data on this. I wonder what’s up with that.

Anolis peraccae. Photo by Alejandro Arteaga.

As a final bonus, here’s a video of a blue knight anole! (and here’s a previous AA post on the same). The video itself isn’t so sharp, but it’s a blue knight anole!

httpv://www.youtube.com/watch?v=hwHhyqTmqrk&feature=youtu.be&a

Lizards Licking Leaves: Why?

Manuel Leal recently observed this A. stratulus in Puerto Rico licking a leaf high in the forest at El Verde. He describes his observation over at Chipojolab, and suggests that they are not drinking water, and that the behavior is very focused.

Recently in the Bahamas, we observed a female A. sagrei licking a leaf. It hadn’t rained in several days and there wasn’t any dew on the leaves. However, close inspection of the leaf after the leaf left indicated that it was covered with a sticky substance. Perhaps aphid honeydew?

What Goes Around Comes Around: Who’s Eating Curly-Tailed Lizards?

A curly-tailed lizards, sans business end.

We’ve written much about the voracious depredations of curly-tailed lizards on smaller folks, so turnabout’s fair play. But who’s the culprit? Sean Giery provides all the gories over at The Abaco Scientist.

Anole Annals Clearly A WordPress Favorite

Anole Annals publishes on the WordPress blogging platform and clearly they like us, as they’ve just created a “theme” named Anolis. Maybe it’s time for a blog makeover!

Anole Wallet In Product Development

Brother O’Mara has proposed producing a wallet emblazoned with green anoles. It’s on a website, Dynomighty, that appears to be similar to Kickstarter and he’s looking for funding to make the project a go.

American Society of Ichthyologists And Herpetologists Launches Revamped Website

Scarlet kingsnake feeding on a green anole. Photo by J.D. Willson.

New and spiffy! Among many other features, there is an image bank of great photos, including the one above.

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