All posts by Jonathan Losos

About Jonathan Losos

Professor and Curator of Herpetology at the Museum of Comparative Zoology at Harvard University. 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.

Creationists on Lizard Evolution Study: “What’s the Big Deal?”

discovery institute

Last week, Yoel Stuart and colleagues (including me) published a paper demonstrating that green anoles had rapidly (ca. 20 years) evolved an increase in toepad size as a result of upward shifts in habitat use caused the presence of brown anoles.

The Discovery Institute, an organization devoted to the advocacy of creationist views, posted a blog yesterday saying, basically, “this is not news?” After summarizing the study, here’s what they have to say:

“….these scientists found that when a new species of lizards invaded another’s territory (in fact the new species was placed there intentionally by the researchers, meaning they weren’t quite studying “natural” selection), the old one sought higher ground. That seems like a smart thing to do. To go along with the new territory, they subsequently evolved “larger toepads (see here for a picture).

After reading this, what I really wanted to see was the precise sizes of the toepad and compare the changes. But alas that information is not in the paper. I tried downloading the supplemental materials but it’s not there either. So let’s assume that the toepad size changed a lot. What have we shown?

Not much. We’ve seen that the size of lizard feet can change in response to invaders’ driving a species to perch at higher levels in the trees. No new traits arose. Only the size of a pre-existing trait changed. Again, that’s interesting but such changes in the size of lizard feet do very little to explain the origin of lizards in the first place, even if these changes happen in just a few generations.

If we take seriously the statement from the authors that the modest results from this study can help test “evolutionary hypotheses about phenomena … on time scales too long for direct observation,” then that implies that over long periods you might be able to change the size of an organism or some of its body parts. Since when is that news?”

Where Do Anoles Lay Their Eggs?

Anole eggs found in a tomato pot. Photo by Karen Cusick.

The egg-laying habits of anoles are surprisingly little known. On Daffodil’s Photo Blog, Karen Cusick recently reported on the discovery of eight–count ‘em, eight!–anole eggs in a tomato plant pot. Readers, where else have you found anole eggs?

Also, whose eggs are these? Both green and brown’s occur in Karen’s backyard. In Anolis Newsletter V, Todd Vincent provided tips on how to tell them apart.

Brown and green anole eggs. Photo by Todd Vincent.

Brown and green anole eggs. Photo by Todd Vincent.

And for some delightful footage on baby anoles, let’s not forget this old post.

New Phylogeny for Amazonian Dactyloa Anoles: Multiple Evolution of Horns, Dewlap Color Evolution, New Divergence Time Estimates

Anolis phyllorhinus. Photo by Bret Whitney

Anolis phyllorhinus. Photo by Bret Whitney

Anolis dissimilis. Photo by Paulo Melo Sampaio

Anolis dissimilis. Photo by Paulo Melo Sampaio

In a fascinating new paper, Ivan Prates and colleagues report on a phylogenetic analysis of Amazonian Dactyloa clade anoles with implications for a number of important topics in anole evolution.

The authors generated new mitochondrial and nuclear gene data for many Amazonian Dactyloa and combined those data with existing data from previous studies. Of particular note was inclusion of Anolis dissimilis, until recently known from only a single locality, and the Amazonian horned anole, Anolis phyllorhinus.

The paper had four main results, which I’ll go through seriatim. First, the overall phylogeny is very much in accord with Castañeda and de Queiroz’s previous work. The biggest difference is that A. dissimilis occurs in a distinct clade with A. neblinus and A. calimae. A relationship between the latter two species had been suggested by the previous work; A. dissimilis had not been included in those studies. The three species have quite disjunct geographic distributions (Amazonia, western Colombia, and the tepuis of the Guiana Shield, so finding them to comprise a distinct clade is interesting.

phylogeny dissimilis

Anolis punctatus. You can almost see a horn ready to burst forth from the tip of that snout. Photo by Arthur Georges.

Second, as the figure below illustrates, A. phyllorhinus, as expected, groups with A. punctatus, whereas A. proboscis groups with the phenacosaurs (heterodermus group; though A. proboscis is not actually included in the analysis because genetic samples were not available; however, recent studies clearly indicate that A. proboscis belongs with this clade). Prates et al. note that, other than the horn, A. phyllorhinus and A. punctatus are morphologically very similar. I’ll take that one step further–you can almost imagine the antecedents of the horn as a swelling on the tip of the snout of A. punctatus. And, in addition, note that the horns of the two-horned species are very different-looking. Although Williams placed them in the species group, he did note that they actually didn’t look at that much alike. We now know that he was correct in this observation–hornedness is a convergent trait in anoles (no, I’m not calling it horniness).

horns

Third, Prates et al. calculated divergence times, calibrated with three fossils that can be confidently placed in iguanian phylogeny. Continue reading

Six New Mexican Anoles Described

nietoi

Gunther Kōhler and colleagues have just published in Zootaxa a new revision of some Mexican anoles, including the description of six new species and the sinking of one species. Rather than describing the work, I think it would be more effective to present the title and abstract:

A revision of the Mexican Anolis (Reptilia, Squamata, Dactyloidae) from the Pacific versant west of the Isthmus de Tehuantepec in the states of Oaxaca, Guerrero, and Puebla, with the description of six new species

GUNTHER KÖHLER1, RAÚL GÓMEZ TREJO PÉREZ, CLAUS BO P. PETERSEN & FAUSTO R. MÉNDEZ DE LA CRUZ

We revise the species of anoles occurring along the Pacific versant of Mexico west of the Isthmus de Tehuantepec in the states of Oaxaca, Guerrero, and Puebla. Based on our analyses of morphological and molecular genetic data, we recognize 21 species, six of which we describe as new (i.e., Anolis carlliebi sp. nov., A. immaculogularis sp. nov., A. nietoi sp. nov., A. sacamecatensis sp. nov., A. stevepoei sp. nov., and A. zapotecorum sp. nov.). Furthermore, we synonymize Anolis forbesi Smith & Van Gelder 1955 with Anolis microlepidotus Davis 1954. Of the recognized species, six have smooth ventral scales (i.e., Anolis dunni, A. gadovii, A. liogaster, A. omiltemanus, A. peucephilus, and A. taylori) and 14 have keeled ventral scales (i.e., A. boulengerianus, A. carlliebi, A. immaculogularis, A. megapholidotus, A. microlepidotus, A. nebuloides, A. nebulosus, A. nietoi, A. quercorum, A. sacamecatensis, A. stevepoei, A. subocularis, A. unilobatus, and A. zapotecorum). In one species, A. macrinii, the ventral scales vary from smooth to weakly keeled. For each species we provide color descriptions in life, color photographs in life, descriptions and illustration of hemipenis morphology (if available), descrip-tion of external morphology, distribution maps based on the specimens examined, comments on the conservation status, and natural history notes. Finally, we provide a dichotomous key for the identification of the 21 species of anoles occurring along the Pacific versant of Mexico west of the Isthmus de Tehuantepec in the states of Oaxaca, Guerrero, and Puebla.

Florida Festival Features Green Anole

Karen Cusick, author of  Lizards on the Fence and tender of Daffodil’s Photo Blog, writes:

You may remember that the Wild Amelia Nature Festival (Amelia Island, FL–just north of where I live) chose the green anole as their Critter of the Year for 2015. I was looking at the Wild Amelia website and they are already starting to gear up for the festival, which will be held May 15-17. They’ve designed a new website logo featuring a green anole, and there are going to be tee shirts with the logo. The website button to buy a tee shirt doesn’t work yet, but that should be fixed as the festival gets closer. I’m going to check on that.

There’s only a small size image of the logo so far, but I’m attaching it anyway. It looks like it’ll be a nice shirt.

They’ve scheduled a series of nature-based seminars in the months leading up to the festival, and the last one is May 12, when the director of the Jacksonville Zoo, Tony Vecchio, will give a presentation about the green anole and the Zoo.

I’ll let you know if I hear any more anole-related news about the festival!

Third Specimen of Anolis dissimilis Found in Brazil

dissimilisIn a recent paper in Herpetology Notes, de Freitas et al. report the third specimen of the species, the first from Brazil and the first in which a living specimen is illustrated.

Look at that schnoz! Reminiscent of some members of the carolinensis species group, such as AA regular A. maynardi from the Cayman Islands.

Here’s the illustration from Ernest Williams’ 1965 description in Breviora.

dissimilis williams

Anolis carolinensis BAC Library Available

Jessica Alfoldi of the Broad Institute writes:

“Matthew Breen from NCSU has a copy of the Anolis BAC library used in the sequencing and anchoring of the reference Anolis genome:CHORI-318: Green Anole Lizard . He unfortunately no longer has room for it, and will have to throw it out very soon unless someone else can give it a new home. If you would like to have a copy of this BAC library, please email me back as soon as possible.

Thank you,

Jessica”

Time to Plan the Next Anole Symposium: Input Needed

 

Lourdes Rodriguez Schettino speaking at the 2009 Anolis symposium

Symposia on anole biology have been held three times in the last 25 years. First, in 1989 as part of the ASIH meetings in San Francisco, then in 1999 in conjunction with the herpetology meetings at Penn State, and most recently as a stand-alone meeting at the Museum of Comparative Zoology at Harvard in 2009. These meetings have been a great success–the MCZ meeting was attended by more than 125 people (take a photographic trip down Memory Lane).

The time has come to think about the next Anolis Symposium. The meeting organizers have settled on 2016 in Miami. We’re considering a number of great venues there, so it should be a fun, anole-filled event, easily accessible for anole researchers from all over.

The question is: when should the symposium be held? In January, right after the holidays? February, in the heart of winter? August, right after the Ecological Society of America meeting in Fort Lauderdale? October, like the last meeting?

We’re going to try to pick the date that works best for most potential attendees, so please comment below and let us know which dates are good or bad, and why.

Can Lizards Adapt to a Warming World? An Experimental Study Demonstrates Natural Selection for Performance at Warmer Temperatures

Anolis sagrei in the Bahamas. Photo by Christian Cox from the Washington Post

In these times of rapidly changing climates, a major question is whether species will be able to survive. Essentially, they have two options: either shift their geographic ranges to stay within their ancestral niches, or adapt to new circumstances. Or, of course, go extinct. In recent years, evolutionary biologists have come to realize that evolutionary change can occur very rapidly when selective pressures are strong. The question is whether it can occur rapidly enough to accommodate quickly changing environments.

A recent study suggested that many tropical lizards are imperiled by a warming world. This study suggested that lizard populations would not be able to adapt rapidly to warmer conditions, but the analysis wasn’t very detailed.

First author Mike Logan hard at work at the field site. Photo reprinted from the Washington Post

In a study that is the first of its kind, Mike Logan and colleagues at Dartmouth have investigated the selective forces that may impinge on lizards as the world warms. The study was conducted on the old workhouse, the brown anole, Anolis sagrei. In essence, what the researchers did was calculate the extent to which sprinting capability was affected by temperature in two populations, one in an area in the Bahamas currently occupied by the anoles, and another in a population transplanted to a warmer era that served as a surrogate for conditions that will be experienced under global warming.

The study was gargantuan in its scope. Each lizard was put through its paces a number of times at each of a number of temperatures. From these data, the researchers could establish the temperature at which each lizard ran fastest and the breadth of temperatures at which they ran reasonably fast (compared to their maximum), which is termed performance breadth. They then marked the animals and returned them to their habitats. They then returned three months later to recapture the lizards to see which had survived and which hadn’t, allowing them to see whether their sprint capability measures were acted upon by natural selection.

It turns out that a fair amount of variation exists in the lizards in terms of both optimal temperature and performance breadth. In the natural habitat in Georgetown, Great Exuma, Bahamas, there was no evidence of selection operating on any of their measures.

The transplant experiment was conducted a year later on the Bahamian island of Eleuthera, which is not all that far from Great Exuma. In this case, the thermal characteristics of the habitat from which lizards were taken were very similar to the study site on Abaco. However, the more open, exposed area into which the lizards were transplanted was several degrees warmer, and also more variable in temperature.

Lizards in the transplanted population experienced body temperatures 1.5 C higher than those in the reference population. When the researchers recaptured the lizards on Eleuthera, they found strong evidence for natural selection, and in the direction expected: lizards that performed better at higher temperatures survived better than those with lower performance optima, and those with a broader thermal range survived better than those more narrowly adapted. In other words, there was strong selection for adaptation to warmer conditions.

The big question is whether populations can adapt to such strong selection pressures. The authors didn’t measure the heritability of the traits—that is, the extent to which adults with higher temperature optima produce offspring with similarly high optima, and such heritability is crucial to predicting evolutionary response. Nonetheless, if these traits have levels of heritability equivalent to that of other thermal performance traits in other species, the authors argue, then the brown anole may well be able to adapt evolutionarily to the warming predicted to occur in the next century.

This paper received a lot of attention in the press and blogosphere. For example, nice articles appeared in the Washington Post and on Scientific American‘s website.

Male Brown Anoles Disperse Farther than Females

sagrei dispersalUnderstanding dispersal—the extent to which organisms move from their place of birth—is of obvious importance in understanding many aspects of the natural history of a species, such as how related individuals are in a population or how genetically distinct one population is from another. Despite the intensive study on Anolis, however, very little is known about their dispersal. This is particularly surprising for species like the green and brown anoles, which are so common in so many places. Now, in a very nice experimental study in Behavioral Ecology, Calsbeek and colleagues have shed light on dispersal in the brown anole in the Bahamas.

Basically, the study went like this: the authors collected a bunch of gravid females from a variety of sites on a single, small island in the Bahamas. They got the lizards to lay eggs in the lab and hatched them out, then released them within three weeks of hatching back on their mom’s island. Each lizard was individually marked. The researchers then returned the following spring to find which animals had survived and how far they had moved. Then, they returned again in the fall to see how these survivors fared over the following summer and whether subsequent survival in this second period varied as a function of the distance they had dispersed in the first period.

There are a lot of interesting specific details and I encourage you to read the paper, but the broader story is this:

1. Males dispersed substantially further than females

2. Surviving males grew faster than surviving females

3. Survival of the lizards was low

4. Among females that survived the first period, those that had dispersed shorter distances survived better in the second period

Surprisingly little is known about the extent of anole dispersal, and so this paper is an important advance. As far as I’m aware, dispersal of only two other anoles have been studied. Here’s a summary from Lizards in an Evolutionary Tree:

“Little is known about the dispersal of anoles. One study of A. limifrons found that most lizards dispersed very little and that the home ranges of many individuals moved little from the juvenile to adult age. The maximum dispersal distance, measured as distance from the center of the juvenile home range to the center of the adult home range, based on 148 individuals, was 45 meters. Both the mean and extremes were greater for males than for females (Andrews and Rand, 1983). Anolis limifrons is a small and short-lived mainland species; it is always possible that larger, longer-lived species may disperse further.

The only other data come from Anolis aeneus, which moves as much as 150 meters or more after hatching to occupy open clearings (Stamps, 1983b, 1990). Ultimately, the lizards move back into shadier areas when they reach subadult size, although it is not known whether they return to the vicinity of their hatching site.

A number of arboreal species are known to disperse across open ground between trees (Trivers, 1976; Hicks and Trivers, 1983; Losos and Spiller, 2005).

How Anoles Respond to Toucans and Other Birds

James Christensen, a fabulous nature photographer and keen naturalist, made the following comment on the recent post about how anoles react to bird calls. However, the points are so important that they deserve a post of their own, so I’m reprinting them here:

I have spent many hours photographing wild anoles, especially here in Ecuador, and have learned a great deal about their behaviour while watching them through the viewfinder. When the wind picks up and begins to stir the surrounding foliage I can expect my subject to risk rapid movement – therefore, I probably won’t get a viable shot. Conversely, when toucans or furnarids become active in the vicinity I know that my anole will not venture an abrupt movement, so I squint through the viewfinder and start clicking the shutter. What I have noticed is that the anoles – e.g. Anolis gemmosus and A. proboscis – react not only to the calls of these birds, but also to the sound of their wingbeats. The usual response is a cessation of movement and an increased watchfulness; the anole sits very still and peers upward while discreetly swivelling its head. In the case of a very fit male A. gemmosus with whom I spent many hours – over a period of several weeks – upon the disappearance of avian predators he would begin to dewlap, frequently ‘emphatically’, seeming to reassert his local dominance in the wake of forced inactivity. It became clear to me that the sounds of nearby birds triggered a profound shift in behaviour, and that vision played a secondary role in the perception of avian threats – as every neotropical birder knows, foraging birds are heard more readily than seen.

Concerning the above study, it perhaps bears noting that the American Kestrel is not a highly vocal bird, and that it is likely to remain silent while hunting. I have frequently observed toucans apparently hunting in shrubby forest margins, where no fruit-bearing trees were evident and anoles were plentiful, and at such times the birds were always silent – only their deep wingbeats would betray them to a wary anole.

New Comprehensive Account of Everything about Tuatara

Alison Cree, one of the leading researchers on tuatara, has written a comprehensive account of everything we know–and would like to know–about toots. The book not only covers ecology, evolution, behavior, physiology and so on, but also the history of knowledge of tuatara as well as details on how they were perceived by the Maori. And, of course, the incredible conservation turnaround, which has led to reintroduction of tuatara to the New Zealand mainland after a half-millenium absence.

This fine volume can be purchased for a tad under US$75 plus shipping from the University of Canterbury Press.

Anole Apartment Invasion: What Can Be Done?

Anole in the house. Photo from Daffodil’s Photo Blog

AA reader Katharine from southern Florida writes:

“I live on the 4th floor of a 4-story concrete constructed condominium building (6 units to a floor) with catwalks in S.E. Fl.  In front of the ground floor walkway of our building there is landscaping & ligustrum trees that reach up to the 2nd floor with catwalks with overhead lights on in front of each doorway at night.

For some reason anole lizards seem to find their way more to my unit (when I open my entrance door they come in) than the others on the same floor all with the same ground floor foliage, trees & overhead lights. One also sees the feces they’ve left overnight in front of my unit and not the others.

It makes me wonder if these lizards travel as ants do, following a leader either by a scent or fluid left by the leader or previous lizard?  I’ve learned that these lizards are attracted both to light (obviously, the catwalk lights) & the greenery.  However,  the other units on the same floor under the same conditions don’t seem to have the same invasion.

I’ve done as much Google researching as I can but can’t seem to find an answer.  Do you have an answer or can you direct me where I can look.?  Obviously, I’m trying to find some way to deter or reroute their path.”

Geckos Eat Rats

gecko eating rat

As lizards go, it’s hard to beat an anole. But geckos come pretty close. Anole Annals, of course, is dedicated to reporting all things anole, but until Gecko Gossip debuts, we feel it’s only polite to occasionally comment on geckonid happenings.

In that light, we were impressed to see the culinary prowess of the Tokay gecko, which apparently quite regularly preys on small rats in the Philippines. Read all about it in Herpetology Notes.

Anole Foraging Mode: New Data

An actively foraging anole on the prowl (A. tigrinus; photo by J. Losos)

An actively foraging anole on the prowl (A. tigrinus; photo by J. Losos)

Nearly 50 years ago, Eric Pianka proposed the idea that hunting animals forage in one of two ways, either actively foraging for prey or sitting-and-waiting for food to wander by. These ideas were initially promulgated with lizards in mind, and much of the research in the last half century has involved lizards. Anoles haven’t been a major player in the work, but their certainly have been some studies conducted on anoles.

This post is motivated by a paper published by Cooper et al. in Herpetology Notes last year in which new data are presented on six anole species, as well as for a variety of other species. The anole data conform both to previous data on the same species and studies on anoles in general: as lizards go, anoles are on the sit-and-wait end of the spectrum, moving relatively little (think about the other end of the spectrum, species like whiptail lizards which seem to move almost non-stop).

I was surprised in looking through the archives to see that we haven’t previously had a post on AA about foraging mode. Now we do! And for some background: I reviewed what we know about anole foraging in a five-page section of Lizards in an Evolutionary Tree. The take-home messages:

1. By comparison to other lizards, anoles don’t move much and would be considered sit-and-wait foragers;

2. Nonetheless, among anoles, some are much more active foragers than others;

3. Caribbean anoles are much more active than mainland species;

4. Much remains to be learned about the specifics of anole foraging and how it differs among species

And here are some highlights, from the footnotes:

“Some of the danger inherent in an active foraging mode was apparent in another observation of a female [A. valencienni] moving upside down on a bromeliad, searching for prey (quoting from Trivers’ field notes, p. 575): “. . . it seems to spot something on a neighboring bromeliad, also upside down. I too spot something on the second bromeliad. Starts to dart the 5 cm to the neighboring bromeliad but—as if forgetting it is upside down—it steps into thin air and falls 6 m to the ground. It appears to be uninjured.”

“Examples of this prey-catching behavior were provided for the relatively short-limbed A. carolinensis (under the name A. principalis) by Lockwood (1876, p. 7): “I have just been watching Nolie eying a fly which was walking on one of the glass panes of his house. He made a noiseless advance of about three or four inches; then followed a spring, when he was seen cleaving to the glass by his feet, and champing the captured fly. I saw him once intently watching the movements of a fly which was walking on the glass. As seemed evident to me by an ominous twitch of that little head, his mind was made up for a spring; but lo, there was a simultaneous makeup of mind on the part of the fly, which at this juncture flew towards the other side of the case. Then came—and how promptly—mental act number two of Anolis, for he sprang as the after-thought directed, and caught the insect on the fly.” Dial and Roughgarden (1995) report an anole jumping from a branch one meter above a spider web, catching the spider as it passed by, before landing in the vegetation below.”