Author: Jonathan Losos Page 37 of 130

Anlolis meridionalis. Photo from the Reptile Database

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.

I suppose we should be glad that Antiguan racer is back from the brink of extinction, even if it’s bad news for this Antiguan anole.

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.

Photo by Manuel Leal in the New York Times

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!

Photo by Karen Cusick

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.”

Photo by Rube Irizarry

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.

Lizard watching in Puerto Rico

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.

Racetrack for studying the sprint speed of hybrid lizards.

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…”

In English:

“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.