Eye of the /Tiger Green Anole

In that classic of American cinema, Rocky III, Rocky Balboa (Sylvester Stallone) employed a particularly cunning strategy during the climactic fight with the younger, stronger Clubber Lang (Mr. T): he used his face to repeatedly absorb all of Clubber’s most powerful blows until Clubber grew very tired. Rocky’s strategy worked, and Clubber, fatigued from what seemed like hours of savagely beating Rocky in the head, ultimately succumbed to one of the relatively few punches Rocky managed to land.

Repeat until World Champion

Repeat until World Champion

Now one might suspect that Rocky III’s inspiring message of never giving up being punched in the face would have few adherents in the animal world, and this is indeed what we find. In most cases of male-male combat, combatants are reluctant to enter into escalated physical altercations because the risk of injury to themselves is too high. Instead, males of many animal species have evolved ritualized aggressive signals or displays aimed at intimidating their opponents into withdrawing, and will turn to violence only as a last resort when all else has failed. But some species have adopted the spirit of Rocky’s strategy, if not the letter, and rely on persistence to outlast as opposed to outfight their opponents.

A new study by Wilczynski et al. shows that Anolis carolinensis (the undisputed greatest study organism in the world) may use persistence as part of its fighting strategy as well. Adult male green anoles establish dominance hierarchies initially through aggressive interactions, and the outcomes of these interactions are affected by a variety of behavioural, physiological and morphological factors, many of which are likely reflected in the pattern and intensity of their ritualized aggressive displays. Wilczynski et al. set up staged aggressive interactions between pairs of adult males in the laboratory and tested whether males that responded faster or for longer to behavioural challenges were more likely to win fights. They also noted the colour state, as well as the presence of post-orbital eyespots, of winners and losers, both of which have been the subject of previous discussion on Anole Annals. figure 2The authors found that for the measured types of display, future dominant individuals generally displayed more frequently, and continued to display for longer than future subordinate individuals, whereas the effects of latency to display on competitive outcomes is less clear. With regard to colour, despite some intriguing trends, there were no significant differences between dominants and subordinates in any aspect of post-orbital eyespot expression. However, future dominant individuals did remain bright green for longer throughout the interactions than did future subordinates, supporting earlier suggestions that dark brown colouration is linked to subordinate social status and/or stress.

While persistence is a key component of contest behaviour in many animal species, the apparent importance of persistence in display duration in particular is especially interesting within the context of lizard displays. For example, duration of sagittal compression has previously been suggested as a handicap display in Uta stansburiana lizards, and previous studies have also suggested that persistence, perhaps related to accumulation of metabolic costs (paper here), might also dictate male contest outcomes in green anoles. Despite the wealth of knowledge regarding male green anole displays, studies such as Wilcynski et al.’s show that we still have much to learn regarding the behavioural aspects of male combat in this species, not to mention the likely relationships between behaviour and physiology.

Rocky III was unjustly spurned by the Academy of Motion Picture Arts and Sciences in 1983, not even receiving a nomination in the category of best picture (Ghandi won that year for some reason). Even more outrageous, it didn’t win the Best Original Song category it was nominated in! (Would anyone seriously argue that “Up Where We Belong” is a better song than “Eye of the Tiger”? Because it isn’t, and you are wrong). In retrospect, the reason for this travesty is clear: persistence is an important part of animal fighting strategies, and Rocky III was actually a nature documentary.

Anoles Moving North, Way North

A recent paper by Matt Helmus, Luke Mahler, and Jonathan Losos highlighted the ways in which globalization has influenced the distribution of Caribbean Anolis lizards. At the heart of this research was the relationship between commercial shipping traffic and lizard biogeography. Two more recent observations can now extend these findings well beyond the Caribbean, much, much farther north.

First, Twitter user  recently posted a story about a stow away green anole that he found on pallet in Edmonton, Canada. This was a shipment of oil field supplies that originated in Houston, TX and that took ten days to reach its destination. This male green anole survived the trip all the way to Canada and is now housed in a new terrarium. The tweet originally posted October 16th and since then the anole has shed and appears to have adapted well to its new home.

An anole in the great white north.

The Canadien green anole.

Photo by Randi Duun

In separate case of stowaway lizards, another anole survived a transatlantic journey to Denmark in a shipment of bananas and was discovered incapacitated on the floor of the stockroom where incoming bananas are fumigated. The photo is too small for me to be certain, but this appears to be an Anolis cybotes female. According to the original post by Randi Duun in the “Anoles” Facebook group, the shipment originated in Colombia, Costa Rica, or the Dominican Republic so this would be consistent with an A. cybotes hitchhiker. It would be interesting to know how long a shipment like this takes, but I bet that it is longer than ten days port-to-port. Regardless, just like the globetrotting green anole, this anole is healthy following its journey, housed in a terrarium and enjoying Danish mealworms.

In contrast to the research described by Helmus et al, it is probably safe to assume that despite the perseverance of these anoles, and any others that make their way towards the arctic circle in subsequent shipments, escapees will not be establishing viable introduced populations.

 

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

Find the Anole: Squamates Versus Archosaurs

Regular readers of Anole Annals may remember the “Find the Anole” series that has been popular over the last few years. It has been a while since we enjoyed such fun times, so I wanted to breathe new life into this classic challenge.

Earlier today I visited Dinosaur World in Plant City, Fl. and enjoyed the contrast between Mesozoic and Cenozoic  reptile diversity. It was very exciting. Below are two images from their grounds for your enjoyment. Can you find and identify the anoles in these photos? A far bigger challenge may be to identify the dinosaurs illustrated by these statues.

Find the anole 1

Find and identify the anole.

On a separate note, if you are ever passing through central Florida with your families, stop by Dinosaur World. The interpreters were quite good with our kids, there are over 200 life-sized (and colorful) dinosaur statues, they clearly state that the earth is 4.5 billion years old, and there are no humans riding dinosaurs. I was pleasantly surprised by all of this in this part of the country. Its worth a few hours of your time!

Find the anole and identify the species.

Communal Nesting in Anolis angusticeps

Previous posts have discussed communal nesting behavior among a number of anole species, whereby females deposit eggs in the same cavity. A new paper by AA‘s own Michele Johnson and friends extends this growing body of observations, stretching all the way back to Stan Rand’s 1967 work. This behavior has been previously reported for the Cuban Twig Anole (Anolis angusticeps) in Cuba, though apparently not in the Bahamas. According to Robinson et al. (2014), at least nine West Indian anole species are now known to engage in communal nesting, with others potentially to be added. AA has also called attention to a tenth mainland species (A. lionotus), described in Montgomery et al. (2011). So these observations bring to mind some questions: what intrinsic factors of a nest cavity draw multiple females to oviposit there? Are female offspring returning to the site in subsequent years to lay their own eggs? Does this behavior vary individually or regionally? Let us know if you have some of your own observations.

Untitled-1

Communal nest of Anolis angusticeps on South Bimini. Figure 2 from Robinson et al. 2014, photo by B. Kircher.

 

Survey: How Many Lamellae Are on This Toepad?

Hi everyone, I apologise for the repeat post. As mentioned by Martha, it may not have been obvious from the initial post that there was a survey inside!

So, please forgive me while I repost with an amended title in the hope of getting a few more poll participants. We are only just into double figures (including only 3 of you who have previously published on the subject) – surely we can do better than that! Thank you to everyone that has already contributed. I will present the results in a follow up post in week or so depending on participant activity.

****

One of the age old questions in anole morphology is at what point do you stop counting lamellae on the toepad?

Without giving any more information on various techniques or methods, I thought it would be interesting to ask the AA community their personal opinions. Below I have attached a flatbed scan of a toepad. Could people please fill out the corresponding poll below, and I will present the results in a follow up post!

alt text

Lamellae numbered 1-51 on the 4th digit of an Anolis lizard hindfoot

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

How Many Lamellae Are on this Toepad?

One of the age old questions in anole morphology is at what point do you stop counting lamellae on the toepad?

Without giving any more information on various techniques or methods, I thought it would be interesting to ask the AA community their personal opinions. Below I have attached a flatbed scan of a toepad. Could people please fill out the corresponding poll below, and I will present the results in a follow up post!

alt text

Lamellae numbered 1-51 on the 4th digit of an Anolis lizard hindfoot

Finding the “Rare” Anolis duellmani

Like many quests to find rare herps, this is a story of courage, persistence, and strength. Just kidding; it was a piece of cake.

Anolis duellmani was described by Fitch and Henderson (1973) based on four specimens from the southern slope of the Volcán San Martín Tuxtla, Veracruz, Mexico. Even though the phylogenetic position of A. duellmani is uncertain, no additional morphological variation had been described for the species. As part of a major effort led by Dr. Adrián Nieto-Montes de Oca and Dr. Steven Poe to untangle the systematics of Mesoamerican anoles, Israel Solano-Zavaleta, Levi N. Gray, and I went to Los Tuxtlas to search for the elusive species.

Continue reading

Registro de Copula de Anolis huilae

Copula de Anolis huilae en Ibagué (Colombia).

Copula de Anolis huilae.

En el marco de mi tesis de maestría sobre la Ecofisiología térmica de Anolis huilae tuve la oportunidad de observar, creería que sería el primer registro, una pareja de ésta especie copulando en el tronco de un árbol. Evento que lo considero relevante por la falta de información acerca de ésta especie.

El estudio lo estoy desarrollando en el Corregimiento de Juntas, Ibagué (Colombia). Mi objetivo es conocer aspectos de la fisiología térmica de A. huilae y relacionarla con las temperaturas ambientales y microambietales de su hábitat.  Para la colecta de datos me estoy apoyando con una cámara termográfica infrarroja (metodología no invasiva) y modelos de cobre con data loggers insertos en ellos.

Imagen termográfica de copula de Anolis huilae.

Imagen termográfica de copula de Anolis huilae.

En una primera etapa del estudio estoy averiguando si A. huilae es una especie heliotérmica o tigmotérmica; como también, si es termoconformadora activa o termoconformadora pasiva. Datos que próximamente los compartiré.

Observaciones comportamentales, no registradas,  ayudarán a conocer más aspectos de la biología y ecología de ésta especie, de la que aún falta mucho por descubrir. Así mismo, he observado en esta localidad la simpatría con otro anolis, Anolis antonii.

*****

English translation via the internet:

Record of Copulation of Anolis Huilae

In the framework of my master’s thesis on the thermal ecophysiology of Anolis huilae, I had the opportunity to observe, you would not believe that would be the first record, a couple of this species copulating in the trunk of a tree. Event that is considered relevant by the lack of information about this species.

The study, I am developing in the Corregimiento of seals, Ibagué (Colombia). My goal is to understand aspects of the thermal physiology of A. huilae and relate it to the ambient temperatures and microenvironments of its habitat. For the collection of data I am supporting with a infrared thermal imager (non-invasive methods) and copper models with data loggers inserts in them.

In the first stage of the study, I am enquiring whether A. huilae thermoregulation is a species or is thigmothermic; also, whether it is an active or passive thermoregulator. I will share the data soon.

Behavioral observations, unregistered, help you learn more aspects of the biology and ecology of this species, which still lack much to discover. Also, I’ve seen in this locality the sympatry with another anole, Anolis antonii.

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.

More Morphological Oddities in Anolis sagrei

A few months ago, I shared with you some of the odder morphological variations my field assistants and I encountered while measuring Anolis sagrei in Gainesville, FL. We went on to measure quite a few more lizards, and saw quite a few more oddities, as well as some fairly gruesome injuries. Here are some of my favourite examples:

1. A far better picture of a doubly-regenerated tail.

double regeneration

2. A jaw injury that resulted in the left and right sides of the jaws being dissociated from each other.

jaw injury

3. A cut hyoid. I imagine this lizard was no longer able to extend his dewlap.

hyoid

4. A nasty head injury. We saw this lizard three or four more times after we measured him, and his wound seemed to have healed up completely.

head injury

5. A brutal leg injury.

IMG_0430

6. A male with not only an impressive tail crest but also some nice red tail coloration.

tail crest

 

The Dewlap of Cophosaurus texanus

_1070960

Here at Anole Annals, we can appreciate a good dewlap. In particular, a pair of agamid clades, namely the genera Draco and Sitana + Otocryptis, arguably do extensible throat fans even better than Anolis. But dewlaps are actually found in many other iguanian lizards, covered by AA posts here and here.

Today I thought I’d share a lesser-known dewlap, that of Cophosaurus texanus, known as the greater (greatest?) earless lizard, and a legitimate candidate for best lizard coloration if you ask me. In my experience, these lizards don’t often dewlap, but will occasionally hit you with a few push-ups, and reliably wag their striped tails at you before darting away — though they are upstaged in this latter respect by Callisaurus draconoides. On a recent walk in the Rincon mountains near Tucson, Arizona, I encountered a particularly saucy individual, and thought I would share.

Here’s a series of photos showing a pushup/dewlap combo being delivered. By the way, Cophosaurus texanus are known to display at potential predators (see Dial 1986, American Naturalist 127:1).

_1070980
_1070979
_1070978

Another shot, the dewlap is being retracted here:

_1070973-2

As far as dewlaps go, its not the most impressive, but there certainly looks to be some cartilaginous rod action involved, as in Anolis. But wait – notice anything unusual in the above photos? Yes, there looks to be a parasite peeking out through the lizard’s nostril. Here’s a closer look:

_1070972

Pretty gnarly. I’m not sure what the parasite is, it looks to me like it could be a maggot (hey, speaking of maggots, remember anole throat maggots?). Hope I didn’t just ruin anyone’s lunch!

Anyway, if you’re interested in learning more about Cophosaurus, here is an excellent write-up written by Robert Bezy and provided by the Tucson Herp Society.

Globalization and the 50-Year-Old Predicted Reorganization of Anole Biogeography

helmus_etal_fig2I caught an anole lizard and tossed it ten feet or so out into the water. To my dismay, it popped to the surface, swam expertly back to the shelter of the trees, and climbed up a mangrove trunk. Well, I continued, suppose a full hurricane blew an anole so far away on open water it couldn’t get back. Our little experiment shows that it could swim to the nearest islet if it were not too far away.

So wrote E.O. Wilson (1995 p. 271, Warner Books, NY) in his autobiography, Naturalist, reflecting on his island defaunation work with Daniel Simberloff. From his ‘little experiment’ (I can hear animal care committees cringing), Wilson postulated that anoles could, if they had to, disperse from island to island across open water. Whether anoles can cross water, however, isn’t that important. Rather, what’s important is that they rarely do. Anoles’ status as a symbol of island biogeography and adaptive radiation is largely due to the fact that isolation and the resulting low gene flow among islands set the stage for in situ speciation and adaptive radiation. In fact, much of what we (and island biogeography in general) owe to anoles, we owe because they don’t swim so well. And they don’t colonize new islands very often.

Or rather, they didn’t.

A new paper in Nature by Matt Helmus, with AA stalwarts Luke Mahler and Jonathan Losos, shows how human-mediated dispersal of anoles among Caribbean islands is reorganizing anole biogeography in a very predictable way. I suspect many who have worked on anole island biogeography, me included, have considered what to do about recent introductions and have often, like me, dropped them out of a dateset with the goal of trying to discern the ‘natural’ pattern. Helmus et al., however, saw the spate of recent anole introductions across the Caribbean as an opportunity, rather than a nuisance. Their great leap came from realizing that this reorganization of anole Caribbean biogeography should be predictable from the basic tenets of island biogeography theory.

Based on MacArthur and Wilson’s equilibrium theory, adaptive radiation theory and drawing on Losos and colleagues’ past work from 1993 and 2000, Helmus et al. predicted three patterns: 1) Species-impoverished islands (for their size) should have more exotics than more saturated islands, 2) The phylogenetic diversity of islands should increase due to exotic establishment, and 3) Human-mediated introductions should degrade richness–(geographic) isolation relationships. In short, they found evidence consistent with all of these patterns. Furthermore, they showed that economics that has replaced distance as the key determinant of island isolation. Needless to say, these are very exciting results that have supplied a key test, at biogeographic scales, of some classic theory*. It’s a must read.

This paper is also important because it shows how ‘blue skies’, curiosity-driven science can help us understand and, most importantly, predict how human activity will impact ecological systems. Did MacArthur and Wilson know, more than half a century ago, that their work would predict how increasing globalization and trade embargoes would affect modern biodiversity? I doubt it (cue someone pointing out in the Comments the exact line in the ETIB where they do predict this). However, regardless of whether they knew it at the time, this is exactly what their theory has done. As Helmus et al. state (p. 545): “Our results support the theory that it is the influence of geographic area and isolation on … speciation and colonization that fundamentally determine island biodiversity”. However, as they crucially find, what we now need to do is rethink how we define ‘isolation’. We can’t leave ourselves out of the equation any more. It’s economics, not geography, that matters now. Thus, not only does Helmus et al.’s paper test a long-standing theory, but it provides a clear example of the importance of fundamental scientific theory for understanding and predicting ecological dynamics in the ‘Anthropocene’.

In conclusion, the observation that humans are moving anoles — and other taxa — around faster than they could make their own way will come as a surprise to no one. But finding that the subsequent reorganization of life can be predicted by island biogeographic theory is fantastic (it should be pretty clear by this point that I like this paper. A lot). So if you haven’t read the paper, you should. I know it’s a terrible cliché to call a study ‘elegant’. So I won’t. I’ll call it damn elegant.

*I can’t help but mention that Helmus et al.’s findings were mostly based on good old-fashion OLS regression and ANOVA, and visualized using simple scatterplots – No fancy-shmancy statistical machismo here (phylogenetics aside). Just a clear set of predictions that could be parsimoniously tested. Chapeau.

Editor’s note #1: nice summaries of this paper have been written by Ed Yong’s Phenomena: Not Exactly Rocket Science blog and by Emily Singer in the new online Science magazine Quanta.

Editor’s note #2: The paper grabbed the cover of Nature.

Helmus et al. cover

This, in turn, joins a long list of recent science journal covers sporting an anole:

covers