While no one was looking, AA welcome it’s one millionth page view last Thursday, four years in the making. Here’s to the next million!
Martin Whiting’s lab at the University of Macquarie has been very busy of late. In a single day, I received notice of two new, fascinating papers.
First, Whiting and colleagues described a gorgeous new species of flat lizard (Platysaurus) after Sir David Attenborough. Enough said. Read all about it in Zootaxa or on the Whiting Lab website, The LIzard Lab.
The second paper, available online in Biological Journal of the Linnean Society, concerns a topic near and dear to Anole Annals: lizards with projections on their noses. We’re particularly hung up on horns (1,2), but some species have rostral blobs. Like the Sri Lankan Ceratophora tennentii. Whiting and colleagues examined this species, finding very little difference between the sexes, although males did have longer heads and bigger nasal projections. However, bite force did not correlate with nose size. What’s going on with the rostral appendages, as well as the color on the throat. labials, and inside the mouth, is unknown. A fascinating lizard worth more study!
Here’s the paper’s abstract:
Measures of physiological performance capacity, such as bite force, form the functional basis of sexual selection. Information about fighting ability may be conveyed through a structural feature such as a rostrum (i.e. horn) or a colour signal and thereby help reduce costly conflict. We quantified sexual dimorphism in key traits likely to be the targets of sexual selection in Tennent’s leaf-nosed lizard (Ceratophora tennentii) from Sri Lanka, and examined their relationship to bite force and body condition. We found body length and bite force to be similar for males and females. However, head length was significantly greater in males and they had significantly more conspicuous throats and labials (chromatic contrast and luminance) than females. Males also had a proportionally larger rostrum, which we predicted could be an important source of information about male quality for both sexes. Rostrum length was correlated with throat chromatic contrast in males but not females. Nonetheless, the rostrum and aspects of coloration did not correlate with bite force or body condition as we predicted. We have no information on contest escalation in this species but if they rarely bite, as suggested by a lack of difference in bite force between males and females, then bite force and any associated signals would not be a target of selection. Finally, males and females had similar spectral reflectance of the mouth and tongue and both had a peak in the ultra-violet, and were conspicuous to birds. Lizards only gaped their mouths during capture and not when threatened by a potential predator (hand waving). We hypothesize that conspicuous mouth colour may act as a deimatic signal, startling a potential predator, although this will need careful experimental testing in the future.
AA‘s correspondent in the West Coast Bureau, Alexis Harrison, just filed this report from Reno:
At the Joint Meeting of Ichthyologists and Herpetologists in Reno, Nevada this week, the most surprising news for an anolologist may be the lack of presentations focusing on anoles. Given the ubiquity of anoles in ecology and evolutionary studies, I’ve come to expect a steady stream of anole presentations and posters, anole discussions, anole-themed paraphernalia and other anole-centric events. Maybe I’ve been living too much in an anole-shaped bubble.
The sole anole-focused talk was a presentation by Kirsten Nicholson (with co-authors Craig Guyer and John Phillips) entitled “Biogeography of Central American anoles in the genus Norops”. In this talk, Nicholson et al. explore biogeographic hypotheses developed in their 2012 paper in greater detail, with a particular focus on the timing and geographic context of diversification in the Norops clade. Current and ongoing work incorporates the addition of several new species and greater sampling of widespread species into the phylogeny. Although the results presented were preliminary (mitochondrial sequences are already available, with nuclear sequence data to come), the broad patterns in the data appear to be consistent with the conclusions from the 2012 paper: the estimated divergence times among three subclades of the Norops group are ancient, in the range of 40-50mya, while a reconstruction of the ancestral range of the Norops group suggests an early colonization of South America followed by re-expansion northward and then back south.
Regular readers of Anole Annals will probably remember the vigorous debate occasioned by the publication of Nicholson et al 2012. Based on this latest research, I think we can expect further provocative papers and ensuing discussion in the near future. Let’s hope this will stimulate more Anolis talks at next years JMIH meeting in New Orleans!
Recently, Kristin Winchell reported on the 2015 Evolution meetings in Guarujá, Brazil. Kristin noted: “Fernanda de Pinho Werneck gave a lightning talk titled “Cryptic lineages and diversification of an endemic Anole lizard (Squamata, Dactyloidae) of the Cerrado hotspot” that I am sad to have missed. If anyone did catch it, please let us know in the comments.”
Well, Fernanda herself responded and summarized her talk: “Hi Kristin, really cool summary of the Anole talks! Here is what I presented at the meetings for Norops meridionalis lighting talk: we found five highly divergent lineages, confirmed by multiple phylogenetic and species delimitation methods. These lineages (potential candidate species) diverged in the early-mid Miocene, when most of the geophysical activity of the Cerrado took place. Population-level analysis for the broader distributed lineages showed evidence for non-stationary isolation by distance, when the rate at which genetic differentiation between individuals accumulates with distance depends on space. Finally, niche conservatism, rather than niche divergence, seems to be the main mechanism that promoted the fragmentation of main populations across the Cerrado. Cheers!”
Fernanda also pointed out that the work is the basis of a paper by Carlos Guarnizo et al. that is in revision at Molecular Phylogenetics and Evolution. We’ll hear more when the paper appears!
Researchers have previously shown that anoles and other lizards will respond to moving robot lizards. In a recent elegant study in Herpetologica, Joe Macedonia and colleagues have used such robots to investigate what aspects of a lizard’s body or behavior are most important in eliciting responses. The work was conducted in Bermuda, where A. grahami and A. extremus were introduced from Jamaica and Barbados, respectively, in the first half of the last century.
Macedonia and team built robots to look like these two species. It’s worth reading the details of how they built these realistic looking models: “We constructed a conspecific robot body and dewlap to resemble our study species, A. grahami, as well as a heterospecific robot body and dewlap to resemble A. extremus. Excluding the hind limbs and tail of each robot, which were made of airbrushed latex cast from lizard specimens (see Macedonia et al. 2013), each robot body was carved from a thick wooden dowel and attached to a servomotor pushrod. Anterior to the hind limbs, robots were covered with an image created in Adobe PhotoshopH from photos of the study species (Fig. 1). These images were mirrored and joined together at the body midline. Final images were printed onto adhesive-backed fabric and molded around the wooden body, which, together with the latex hindquarters, was attached to the polyvinyl chloride (PVC) perch. Dewlaps were fashioned from white, semitransparent guitar picks that fit into a slot carved in the neck of the robot body. A small hole that was drilled into the guitar pick was secured to a hinge pin that allowed it to pivot and extend. A second small hole in the pick allowed insertion of a thin wire that was attached to the pushrod, which in turn was attached to a servomotor.” The researchers were able to tune two servomotors to produce dewlap extension and head-bobbing patterns similar to those produced by each species. The following movies illustrate what the robots looked like.
In the first experiment, wild A. grahami were presented with robots in the following four treatments: grahami color and grahami display patterns; grahami color and extremus display patterns; extremus color and grahami display patterns; and extremus color and display patterns.
Sixty-seven of 145 lizards responded to the displaying robots, and the strongest response was to the normal-looking grahami. In addition, the lizards dewlapped more to the robot with grahami color but extremus display pattern than they did to either of the robot treatments with extremus coloration; however, in terms of head-bobbing, the grahami did not distinguish between the three other treatments, responding similarly to all three at a lower headbobbing rate than to the normal- looking and behaving grahami robot.
In a second experiment, wild grahami were exposed to robots that looked like grahami and that: bobbed and dewlapped; only bobbed; or only dewlapped. Unexpectedly, they dewlapped the most to the robots that only dewlapped, and headbobbed the most to the robots that only headbobbed.
Macedonia et al. conclude the paper by suggesting that in the future, the best way to further this line of research will be to develop robots that can be controlled in real-time such that the robot’s behavior can be responsive to what the subject lizard does.
An article in Oryx recently trumpeted the successful elimination of rats and mongooses from the 15th Antiguan offshore island. Once these invasive depredators have been removed, local species, including the endangered Antiguan racer have thrived, increasing in population over the last 20 years from ca. 50 to over 1,000. Though not endangered, anoles have benefited as well, with three-fold higher densities on islands on which the invaders have been removed compared to those on which they remain.
The New York Times yesterday had a long article on Manuel Leal’s research on the homing ability of Anolis gundlachi. Manuel has discovered that if you catch a gundlachi and let it go somewhere else in the forest, it will very quickly find its way back to its tree. He’s done a number of experiments to see if they’re using magnetic sense, polarizing light or telepathy (ok, maybe not the last one), but so far has been unable to figure out how they manage to get home. In fact, as the article states, he’s looking for suggestions. Read the article and give him such much-needed help!
Karen Cusick keeps a close eye on her backyard anoles and reports her observations–with lovely photos–on her blog, Daffodil’s Photo Blog. Recently, she described a brown anole that has a penchant for eating spiders, and she told us how it does it: “It sits very still and carefully watches the grass near the back door, and then suddenly sprints over to a spot in the grass and comes up with a spider in its mouth. It must really like spiders! Ants, on the other hand, are pretty much ignored by anoles. I’ve watched ants walk right past anoles, even walking over their feet or tails, and the anoles don’t even seemed tempted.”
Rube Irizarry posted the photo on Facebook’s Biodiversidad de Puerto Rico page. I’m guessing it’s an Anolis cristatellus eating a hapless Hemidactylus, whose tail was previously nabbed by who knows what.
The Leal Lab is hard at work in Puerto Rico this summer, and they’re reporting all about it on Chipojo Lab.
Ellee Cook, who recently graced these pages with a report on fever in anoles, is studying the behavior of female A. gundlachi and is reporting on the trials and tribulations of behavioral field work.
Meanwhile, Edward Ramirez is studying the physiology of hybrids between the grass anoles A. pulchellus and A. krugi.
Check out the details over at their site.
Liam Revell has kindly pointed out this awesome song from the Puerto Rican children’s show Atencion Atencion.
Here’s Liam’s translation:
“Un lagartijo se metió en la cueva,
de pronto asomó la cabeza,
miró para un lado y al otro,
y que pasó, y que pasó…”
“An anole went into the cave,
suddenly he poked out his head,
he looked to one side and the other,
and what happened, and what happened…”
Heidi Fagerberg, a children’s book writer, is in the middle of writing a book featuring the green anole of St. Kitts. Photos below. Can anyone confirm that these are Anolis bimaculatus? More importantly, does anyone know about their color-changing abilities and proclivities? Under what conditions does color change occur?
One of our favorite topics here at Anole Annals is adaptive radiation. Don’t believe me? Just type adaptive radiation into the search bar on the right and see all the interesting posts that come up. And why shouldn’t we be interested in AR? After all, anoles are one the great examples of the phenomenon.
So, it seems relevant to notice that two new review papers just appeared on the topic, both of which mention anoles at least in passing. Tom Givnish, in a paper in New Phytologist stemming from a conference on plant radiations last year, provides the most convincing analysis to date about why the term “adaptive radiation” should be reserved for clades that have diversified to occupy a wide range of ecological niches, regardless of how fast they have done so and how many species the clade contains (title of paper: Adaptive radiation versus ‘radiation’ and ‘explosive diversification’: why conceptual distinctions are fundamental to understanding evolution).
Some pithy quotes encapsulate his points:
“Of the early writers on adaptive radiation (Osborn, 1902; Huxley, 1942; Lack, 1947; Simpson, 1953; Carlquist, 1965; Mayr, 1970; Stebbins, 1974), only Simpson included what we might term explosive speciation in his concept of the process.”
“Definitions of adaptive radiation that require accelerations of species diversification relative to sister groups will thus fail to identify Darwin’s finches and Brocchinia as adaptive radiations; excluding such iconic examples of adaptive radiation makes such diversification-based definitions untenable.”
“Why should we care about this distinction? Nothing could be more pointless than a pedantic debate about definitions that goes nowhere. I would argue, however, that making a distinction between adaptive radiation and explosive diversification is fundamental to understanding evolution, and that failure to make such distinctions can blur such understanding and hinder progress.”
Givnish goes on to suggest that “we might consider re-defining adaptive radiation as ‘the rise of a diversity of ecological roles and associated adaptations within a lineage, accompanied by an unusually high level or rate of accumulation of morphological/physiological/behavioral disparity and ecological divergence compared with sister taxa or groups with similar body plans and life histories.’ Such a definition would retain traditional components of adaptive radiation, while suggesting a way forward that includes tempo, not in species diversification, but in the rate of accumulation of disparity.”
Meanwhile, Soulebeau et al., in a new “Forum Paper” in Organisms Diversity & Evolution, conduct a review of the use of the term “adaptive radiation” in the period of 2003-2012 (title: The hypothesis of adaptive radiation in evolutionary biology: hard facts about a hazy concept). Givnish would say that it is hard to draw conclusions from a meta-analysis that lumps different concepts all under one name, but the review does show some patterns in how research is trending. If nothing else, the number of papers purporting to study adaptive radiation doubled over the time period. Moreover, the paper makes an important point that the number of studies that investigate whether adaptive evolution has occurred in a putative adaptive radiation is very low.
The California Academy of Sciences in San Francisco has just opened a new exhibit, The Color of Life. You can read more about it at their website. Naturally, anoles played a prominent role in the exhibit, as the panel above attests. The small print says: “Anole lizards regularly advertise their ownership of their territories. They bob their heads and extend a colorful flap of skin called a dewlap, just in case another male is watching.”
Notably, the anole gets much more prominent billing than frogs, which are relegated to a panel further back in the exhibit, as the photo to the right illustrates. Perhaps it’s not surprising, then, that Cal Acad Herpetology Curator Dave Blackburn has just inked a deal to move to the University of Florida where, sources say, he will not only become the Curator of Herpetology at the UF Museum of Natural History, but will also switch his research program from frogs to the local anoles. A wise move, indeed, and we look forward to his further explanation in the Comments section.
Two days ago, Ambika Kamath posted an entry in which she observed that the green anoles in her study site in Gainesville are doing just fine, they’re just high up in the trees and harder to spot than the abundant browns. She concluded that, contrary to what many think, brown anoles are not threatening greens in Florida with extinction.
I’d like to add to Ambika’s conclusion by pointing out how browns and greens interact throughout the natural range. Both species evolved in Cuba. There members of the sagrei group coexist widely with carolinensis’s relatives. Where they co-occur, brown anoles are very abundant and are found on the ground and low in vegetation. Greens, primarily A. allisoni and A. porcatus are seemingly less abundant (population estimates are not available) and they occur on tree trunks on up into the canopy.
This mostly peaceful coexistence is repeated in other places the two species co-occur. In the Bahamas, it’s A. smaragdinus and A. sagrei, on Little Cayman, it’s A. maynardi and A. sagrei. In both cases, sagrei is apparently much more abundant, and the two species occupy different parts of the habitat.
Some time ago (possibly several million years, according to genetic data), green anoles colonized Florida from Cuba. In the absence of browns, the greens took the arboreal to increase their habitat use, a phenomenon termed “ecological release.” Then the browns arrived, thanks to us. They have moved into their ancestral niche and the ancient order has been restored. Greens have moved back up in the trees and, yes, their populations are probably now smaller, because some of the resources they were using are now taken by browns. But they’re not going extinct. Greens and browns stably coexist throughout their range. That’s what they’ll do in Florida, too, as long as all the trees aren’t cut down for shopping malls and parking lots.
And you’ll never guess what happened next! Something that I’ve never experienced in all my years. But I don’t know how to paste a video from Twitter into WordPress, so you’ll have to go to casa martin’s Twitter page to find out.
People pay a lot of attention to the color of a anole’s dewlap, but it’s often forgotten that the perceived color of the dewlap is not just a function of the light that reflects off of it, but also the light that at least sometimes shines through it!
These are two views of the brown anole taken minutes apart from opposite sides of the tree (the lizard was in the same spot, the photographer (me) moved.
For more on this topic, see what Manuel Leal had to say a while back on Chipojolab.
Jill Davidson-Guillen of Boca Raton, Florida, had an unexpected guest when she went swimming in her backyard pool last week. She said that she routinely finds curly-tailed lizards in the pool, but this was the first knight anole.
“The Wild Amelia Facebook page has photos and some info on a lot of the activities–releasing sea turtles, ecotours on foot, by kayak, and by segway, learning about bats with the Bat Lady, sunrise yoga on the beach, etc., so I hope that helped.
Although the green anole was the Critter of the Year, the main things specifically related to green anoles were: the green anole presentation by the people from the zoo (along with the person in the anole suit); a couple of booths at the expo that featured some pictures and books about anoles and other lizards; the kids’ activity where they got prizes for going around answering questions about anoles; and the festival tee shirts with the anole logo. I noticed that the person in the anole costume was also on hand to congratulate two children for becoming Seashore Junior Naturalists.”
Karen also nabbed two photography awards for the photos below. Congratulations, Karen!