Feed or Fight: Lizard Bite Force on Islands

Colin_With_LizardI’m a bit of an impostor here on Anole Annals, but I’m spending the year in the Losos lab writing up my dissertation and thinking about lizard evolution, so I wanted to share stories from some other island lizards “across the pond.

My dissertation work has focused on the Aegean Wall Lizard, Podarcis erhardii, common through much of the Greek archipelago. I’ve been surveying and experimenting with these lizards in different biogeographic and human contexts to connect trait changes to ecological surroundings. I recently published a paper looking specifically at lizard bite force. Since it comes with pretty pictures and is relevant to anoles, I want to share it here with you all.

For lizards, bite force is often important for determining what you can eat and how well you can fight off competitors. On small islands where food is often scarce, a proportionally stronger bite force might enable a lizard to access hard food items (like snails or beetles) or fight off other lizards, protecting access to mates, food, or prime nesting sites. Both explanations have been demonstrated in anoles: bite force has been closely tied to diet hardness (Herrel et al. 2006), and fighting success (Lailvaux et al. 2004).

I surveyed lizards on a dozen islands in the Cyclades. First, I found that lizards on small islands in the Greek Cyclades had significantly stronger bite forces relative to their body size. I then decided to try to untangle these two potential drivers (diet and aggression) and determine which better explained inter-island variability in bite force.


By looking at proxies of competition including bite scars and missing toes, and lizard diets across islands ranging over five orders of magnitude in size, I found that, in general, it was the competitive environment that was driving the trend in P. erhardii bite force.

I’ve put together a short video about the findings for Functional Ecology (see above). For the full paper, please see:

Donihue, C.M., K.M. Brock, J. Foufopoulos and A. Herrel. 2015. Feed or fight: What drives bite force differences in the Aegean Wall Lizard, Podarcis erhardii, across the Greek Cyclades? Functional Ecology. doi: 10.1111/1365-2435.12550 Full text

Papers Cited:

Herrel, A., R. Joachim, B. Vanhooydonck, and D.J. Irschick. 2006. Ecological consequences of ontogenetic changes in head shape and bite performance in the Jamaican lizard Anolis lineatopus. Biological Journal of the Linnean Society 89: 443-454.

Lailvaux, S.P., A. Herrel, B. Vanhooydonck, J.J. Meyers, and D.J. Irschick. 2004. Performance capacity, fighting tactics and the evolution of life-stage male morphs in the green anole lizard (Anolis carolinensis). Proceedings of the Royal Society B: Biological Sciences 271: 2501-2508.

Lizard Playground Dedicated to Anole Happiness and Fitness

News-Journal/Mark Lane

The Daytona Beach News-Journal recently reported on a couple that has built an anole playground. Here’s the article:

The sign says “Lizard Land.” It’s a little sign. A lizard-sized sign, in fact. A sign marking a kind of lizard playground that Carol and Gary Mueller created in front of their home in Ormond by the Sea.

Anoles, small lizards that live around trees and eat insects, are a common sight in Florida yards. If you have enough time to sit very still outside, you’ve noticed their furtive movements up trees, down the side of the house and around the mailbox stand.

The Muellers have the time. “We’re totally retired,” laughs Gary, 70, a retired electrician. “Our biggest decision each day is whether to go to the ocean and fish or go to the river on the boat.”

One day they were sitting on the porch and noticed a particularly determined anole trying to make it to the top of a lawn ornament with a shiny globe on top.

“We were out there one time watching this little guy and he was trying like a dozen times to get up there,” recalled Gary. “So I thought, ‘I’ll make him a little bridge to get up there.’ ”

The little PVC ramp led to a more elaborate little lighthouse Gary made out of scrap wood laying around the garage. And that led to the miniature boathouse along with toy boats the couple found on the beach. And that led to the slide and the slide led to the little castle. It all turned into quite a little spread.

“The boathouse is their favorite part,” Carol. “It’s something to watch. They’re very smart little creatures.”

She said they now have a lizard population of about 15, “eight babies and seven big ones.”

It’s easy to tell them apart. “They’re very territorial, so each one sticks to its own part of the playground,” she said. Sometimes birds eat them but the local cats have mostly left them alone.

The current group of lizards are brown anoles, Anolis sagrei, a non-native lizard first noticed in the Florida Keys in 1887, according to the Florida Fish and Wildlife Conservation Commission, but not recorded in Volusia County until the 1980s.

The couple said they sometimes get green anoles, too, Anolis carolinensis, which are native to Florida. Their numbers are down because of competition from the brown anoles, but they’re holding on. And occasionally, the Muellers spot a third kind. “They look like little dinosaurs, I don’t know what they’re called,” Carol said.

Carol used to be a tram driver at Fort Wilderness at Disney World. “Casting felt I looked rugged,” she said. She liked the job and the people and being outdoors. She met her husband in the 1980s on New Year’s Eve. Both moved here from Orlando. They’ve been at their current home for two years.

“I don’t go there to Orlando anymore,” Gary said. “You need a helicopter to get there anymore.”

“Everything we need is in Ormond Beach,” agreed Carol.

Including the pleasures of sitting on the porch in the evening just watching lizards scamper around the garden.

Caption from article: A brown anole checks out a PVC ramp at Lizard Land in the yard of Ormond-by-the-Sea residents Carol and Gary Mueller. News-Journal/Mark Lane

Caption from article: Lizard tower is seen with an anole holding onto its side in the Lizard Land area of the yard of Ormond-by-the-Sea residents Carol and Gary Mueller. Photo courtesy Carol Mueller


Anoles’ Namesake Salamander Rediscovered After 30 Years

Nyctanolis pernix. Photo by Robin Moore

The Amphibian Survival Alliance reports: “Two rare salamander species lost to science for nearly 40 years have not only been recently rediscovered, but a consortium of international groups has protected some of the last remaining forest home of the salamanders just in the nick of time.”

One of these salamanders is Nyctanolis pernix, a long-limbed, arboreal salamander. Paul Elias and Dave Wake described the species in 1983 in the festschrift for Ernest Williams, Advances in Herpetology and Evolutionary Biology (in fact, it was the first article in the volume). The authors explained the species name as follows: “We name the new genus for its anoline apsect and nocturnal habitats (Gr., nyktos, night) and the species (L., quick agile) for its gymnastic behavior.

Read all about it on the ASA webpage.

Anolis Entertainment Scores with The Reptile: “Bloody Disgusting”

anolis ent

A movie production company in Germany is named Anolis Entertainment. We’ve mentioned them previously in these pages. What I believe is their latest project, The Reptile, is described by as “Horror at its finest,” winning the coveted “bloody disgusting” rating. Oops. My mistake. The blog is called Bloody Disgusting, but the review substantiates the name. For Anolis Entertainment’s other films, go to their website which, oddly, features an iguana at the top. Be forewarned: the site is in German. I suspect there’s an English version out there, but I can’t find it.

It’s Twins! Two Embryos in One Anolis sagrei Egg

For the last several months, I’ve been collecting eggs from 36 female Anolis sagrei from Gainesville, FL. This is for a project on linking the movement patterns and mating patterns of brown anoles. To be able to assess which males have mated with each of these females, I’ll be sequencing the DNA from the mothers, their offspring, and potential fathers, and then trying to figure out which males have fathered each female’s offspring. All this is to say that what I want from the eggs I’ve been collecting is the offspring’s DNA. To this end, I’ve been dissecting out embryos from eggs about ten days after laying, and storing the tissue for future genetic work.

So far, the females have laid over 300 eggs, and dissecting embryos out of them has gotten a little monotonous. So I didn’t pay any special attention to an egg that looked perhaps a bit bigger than normal. I was shocked, though, when two seemingly healthy embryos popped out of it!

Two embryos from a single brown anole egg

Two embryos from a single brown anole egg

My initial excitement waned when I realised that twins are not that rare in humans, but returned when two anole breeding experts (AA correspondents Thom Sanger and Anthony Geneva) said that they haven’t seen anything quite like this before. In Thom’s words, “I’ve only found two [twins] in over a decade of dissecting eggs, both were conjoined and inviable. I think you have something special.”

Have any of you seen anything like this before?


Anolis garmani, the Green Venus

While canoodling about on the internet, I came across this delightful drawing of a green guana (Anolis garmani), which in turn led me to its source, Naturalist’s Sojourn in Jamaicapublished in 1851. Here’s the charming description of the species, including evidence that the art of lizard noosing has a long history. The description starts here:


It then continues:


and concludes:


And here’s the title page:


Are Green Anoles Attracted to Bait?

A green anole on the Ogasawara Islands. Photot from Alamy

Anolis carolinensis is an invasive pest in the Ogasawara Islands near Japan, and the Japanese are trying hard to get rid of it. Do you think green anoles can be lured by bait–in this case a cricket–so they’ll approach and stuck in a sticky trap? Apparently they will, as Mitani et al. report in the latest edition of Current Herpetology. Here’s the abstract:

A non-native insectivorous lizard, the green anole (Anolis carolinensis), is causing a severe negative impact on the insect fauna of the Ogasawara Islands of Japan, a UNESCO World Natural Heritage site. A common method to capture anoles is to use adhesive traps. We tested if attracting the lizard by bait improves the effectiveness of these traps. We examined the effects of a lizard’s (1) length of fasting period, (2) distance to the bait, and (3) access to the bait on feeding attempts in a laboratory experiment using 15 lizards collected from Chichi-jima Island. Responses to the baits were also observed in the field, and stomach contents of the trapped lizards were analyzed to assess fasting level in a natural population. The number of lizards that reached the bait was positively correlated with increased fasting days. With a smaller number of days of fasting, the number of lizards that reached the bait was significantly higher when the bait was 50 cm away than 195 cm. Based on the stomach contents of wild A. carolinensis on Chichi-jima, the fasting period of invasive A. carolinensis was typically short, with 92% of the lizards foraging at least every other day. Both laboratory and field experiments indicate the bait must be less than ca. 2 m away to effectively attract the lizard. There is no clear difference between a lizard’s attraction to crickets tethered to a line and those housed in a transparent cup. Therefore, whether the lizard could physically capture the prey did not alter the effectiveness of the bait. This suggests that using an artificial bait simulating prey movement may also be effective.

Climate Niche Evolution in Anoles – New Research by Adam Algar and Luke Mahler

Anolis shrevei, a species inhabiting extreme cold environments on Hispaniola.

Anolis shrevei, a species inhabiting extreme cold environments on Hispaniola.

Caribbean anoles are widely recognized as a key example of “adaptive radiation,” or the diversification of a group of organisms into different ecological niches*. Anoles in the Greater Antilles (Cuba, Hispaniola, Jamaica, and Puerto Rico) diversified into multiple types of habitat specialists, or “ecomorphs,” so-named for the portion of the structural habitat that they most often occupy. For example, “twig” anoles are found on the distal ends of branches. They have relatively short limbs (and, often, prehensile tails) for navigating their spindly habitat. The ecomorphs have evolved a myriad of morphological features suited to their microhabitat use. But diversification into different structural niches comprises only one dimension of their radiation across the Caribbean. Anoles have also diverged into distinct climatic habitats in the Greater Antilles, such as Anolis shrevei (pictured above), a montane species found at high elevation in the Cordillera Central mountain chain of the Dominican Republic. Some anoles are restricted to desert scrub habitats, others to cloud forests, and others to warm lowland environments. The list goes on!

But how does climatic evolution fit into the bigger picture of the Anolis adaptive radiation across the Caribbean? In a previous study, Mahler et al. (2010) suggested that “ecological opportunity” (roughly, the lack of competitors for ecological niche space) influences rates of morphological diversification into different portions of the structural habitat. In a study just published in Global Ecology and Biogeography, Adam Algar (University of Nottingham) and Luke Mahler (University of Toronto) sought to test the idea that ecological opportunity also influences rates of climatic niche evolution in Caribbean anoles. Although they are tropical, several of the Caribbean islands possess considerable elevational variation , which has created substantial thermal variation and the potential for climatic niche evolution in anoles (See Figure 1 below).

Portion of Figure 1 from Algar and Mahler (in press) showing temperature variation in the Greater Antilles (a) and the Lesser Antilles (b)

Portion of Figure 1 from Algar and Mahler (in press) showing temperature variation in the Greater Antilles (a) and the Lesser Antilles (b).

Algar and Mahler first quantified two temperature axes (mean temperature and temperature seasonality of species’ localities) of the climate niche for 130 Anolis species on each of the islands in the Greater Antilles, as well as from the northern and southern Lesser Antilles (i.e., the series of small, volcanic islands that dot the eastern Caribbean Sea). The first temperature axis (PC 1) correlated with thermal  minima and maxima and the second temperature axis (PC 2) correlated with temperature seasonality.

Figure 2 from Algar and Mahler showing how rates of thermal PC 1 relates to climate heterogeneity (a), and geographic area (b). (c) shows how rates of thermal PC 1 evolution correlate with climatic heterogeneity after correcting for geographic area. Relationships depicted in (b) and (c) are statistically significant.

Figure 2 from Algar and Mahler showing how rates of thermal PC 1 relates to climate heterogeneity (a), and geographic area (b). (c) shows how rates of thermal PC 1 evolution correlate with climatic heterogeneity after correcting for geographic area. Relationships depicted in (b) and (c) are statistically significant.

They showed that rates of niche evolution for thermal PC 1 was significantly higher in geographically larger regions (Fig. 2b). Thermal PC 1 was, however, unrelated to climatic heterogeneity (Fig. 2a). But, when the residuals of the relationship between thermal PC 1 and geographic area were regressed against climatic heterogeneity, they did recover a significant positive relationship (Fig. 2c), indicating that, over a given area, thermal niche evolution is faster in regions with greater climatic heterogeneity. They conducted the same analyses for thermal PC 2 (temperature seasonality) and, as with PC 1, found no relationship between evolutionary rate and climate heterogeneity and a positive relationship with area. However, in contrast to their results with PC 1, even after controlling for geographic area, they did not recover a significant relationship between evolutionary rate and climatic heterogeneity.

To determine whether the relationships between evolutionary rate and island area could be due to the higher species numbers found on larger islands, they regressed the evolutionary rate against species number. They did find a strong relationship between species number and evolutionary rate. However, given that island area and species number are highly correlated, this result was not unexpected. Thus, they were unable to fully disentangle how island area and species might interact to influence rates of the climatic niche evolution.

In short, Algar and Mahler found that island area greatly influenced the rate of climatic niche evolution. It has long been recognized that island area is a major determinant of species richness and species diversification on islands – on islands above a certain threshold size, in situ speciation can occur. In this study, Algar and Mahler add climate niche radiation to the list – on islands above a certain size, climatic niches can diverge considerably. But how, specifically, does island area contribute to rates of climatic niche evolution? The authors suggest that larger islands allow more speciation along elevational gradients, such as mountains, which can result in climatic specialization (either during the process of speciation or post-speciation). On small islands, they argue, high gene flow may swamp out the effects of climatic divergence even where climatic thermal heterogeneity exists and, when such specialization does occur, those species may be susceptible to higher extinction rates (due to their smaller geographic ranges). In short, climatic niche evolution presents an equally important (though relatively understudied) aspect of the Anolis adaptive radiation in the Caribeean.


*Scientists differ in their definition of adaptive radiation, though most can agree with the idea that it involves adaptive diversification. Here I follow the definition of Losos and Mahler (2010).

Works Cited

Algar, A. C., and D. L. Mahler. In press. Area, climate heterogeneity, and the response of climate niches to ecological opportunity in island radiations of Anolis lizards. Global Ecology and Biogeography.

Losos, J. B., and D. L. Mahler. 2010. Adaptive radiation: the interaction of ecological opportunity, adaptation, and speciation. Pp. 381-420 in M. A. Bell, D. J. Futuyma, W. F. Eanes, and J. S. Levinton, Eds. Evolution Since Darwin: The First 150 Years. Sinauer Associates, Sunderland, MA.

Mahler, D. L., L. J. Revell, R. E. Glor, and J. B. Losos. 2010. Ecological opportunity and the rate of morphological evolution in the diversification of Greater Antillean anoles. Evolution 64:2731-2745.

What Color Are Green Anoles When They Die?

Mr. Cricketts, the anole in question, in her prime

Mr. Cricketts, the anole in question, in her prime

Can any reader help with this question that came in to the AA offices?

“I found the Anole Annals website but I really would just like an answer to one question.  Can you help me?  My daughter wanted an anole and we bought one in May of 2012.  Well, she passed away last night and I didn’t realize the extent of my love for her because I’ve been miserable all night.  She would be brown and turn green when she slept or when she was alone.  I found her at 10 PM hanging out of her log and I believe she had just expired because she was still all soft and lovely.  The main thing is she was her beautiful green color and in death she remained green.  Is it normal for an anole to be green when they die? Would she have turned green before or after her death?  Could she have felt a feeling of calm or been sleeping in her green color when she died?  I really am just hoping she died in her sleep.  She was an old lady and her habits changed.  She used to always be vertical in her greenery, but the last 2 months I think it was too hard for her to grasp and she spent more time on her log or on the slanted jutouts on her log as that was easier for her to hold on to but still be a little bit vertical.  I am just trying to come to grips with her death and hoping she was OK at the very end.  I was probably in the same room as I was on the computer but not paying attention to her right then, really hoping she wasn’t reaching out of the log to try and get my attention and I didn’t know.”

New Paper Supports Proposal to Split Anoles into Eight Genera


We had plenty of discussion a couple years back about the proposal to divide Anolis into eight genera. The debate seems to have quieted down without clear resolution. Now, in a new paper on Mesoamerican herp conservation, Johnson and colleagues come out in favor of the Nicholson et al. proposal. I’ll place their commentary below, but I want to address a point they raise at the end of their discussion.

Johnson et al. conclude: “We agree that Nicholson and her coauthors provided a perceptive set of reasons why their classification will be accepted in time, just as with other classifications that sought to make sense of formerly unmanageable genera, such as Eleutherodactylus , which now not only is segmented into a number of genera, but also a number of families.”

This is not the place to discuss or debate these points, which have been thoroughly aired in previous commentary in these pages [e.g., 1,2]. But what about the authors’ suggestion that this new classification will be accepted in time? Is that happening?

It’s hard to assess how the winds of systematic practice blow, but I took a crack using Google Scholar, restricting my search to the years 2014 and 2015. When I queried how many hits there were for “Anolis,” GS returned (searched on August 14, 2015): “about 2600.” For Norops,  “about 110.” Can we conclude that represents a 24-fold preference for the old taxonomy over the new one? Of course not. For one thing, some of those Anolis papers may have been referring to species that would still be Anolis in the new classification, most notably A. carolinensis.

I then tried again, focusing on probably the most studied species that would change its name in the new classification, Anolis (Noropssagrei. In this case, for the same 2014-2015 period,  GS located 16 hits for Norops sagrei vs. 270 for Anolis sagrei. These results would seem to indicate that the new classification system hasn’t penetrated very far into the broader scientific community.

One clear schism in the anole community is between those scientists who work in the West Indies, who overwhelmingly use the name Anolis, versus those in Central and South America, who are more split. So, as a second test, I looked at what I think may be the most frequently referred to mainland anole, A. limifrons. The GS search in this case yielded six hits for N. limifrons and 22 for A. limifrons. Searching on the species chrysolepis gave a comparable result, 29-8 in favor of Anolis (and proving that my guess was wrong about which species is most discussed in the literature). Still a large preference for the established taxonomy, but only a 4:1 ratio compared to sagrei‘s 17:1 ratio.

Of course, there are much more sophisticated ways of addressing their question, but they would take a lot more time. Anyone want to dig further?


Here’s what the authors have to say (broken into paragraphs for easier reading): Continue reading

New Conservation Asssessment of Central America Herps Finds Most Anoles Need Help

conservation anoles

The IUCN (International Union for the Conservation of Nature) has a detailed protocol for assessing the conservation status of species. A report on the world’s reptiles was published in 2013. Now, a paper by Johnson and colleagues in Amphibian & Reptile Conservation complains that the IUCN’s methods are not efficient and proposes a simpler, faster method.

Their abstract explains:

“Mesoamerica, the area composed of Mexico and Central America, is the third largest of the world’s biodiversity hotspots. The Central American herpetofauna currently consists of 493 species of amphibians and 559 species of crocodylians, squamates, and turtles. In this paper, we use a revised EVS measure to reexamine the conservation status of the native herpetofauna of this region, utilize the General Lineage Concept of Species to recognize species-level taxa, and employ phylogenetic concepts to determine evolutionary relationships among the taxa. Since the publication of Conservation of Mesoamerican Amphibians and Reptiles , in 2010, 92 species of amphibians and squamates have been described, resurrected, or elevated from subspecies to species level, and one species of anuran has been synonymized. The herpetofaunal diversity of Central America is comparable to that of Mexico, an especially significant finding because the land area of Mexico is 3.75 times larger. The number of amphibian species is 1.3 times greater in Central America, whereas the number of species of turtles, crocodylians, and squamates is 1.5 times greater in Mexico. Endemicity also is significant in Central America (65.6% among amphibians, 46.5% among turtles, crocodylians, and squamates), with a combined average of 55.6%. We regard the IUCN system as expensive, time-consuming, tending to fall behind systematic advances, and over-dependent on the Data Deficient and Least Concern categories. Conversely, the EVS measure is economical, can be applied when species are described, is predictive, simple to calculate, and does not “penalize” poorly known species. Our EVS analysis of amphibians demonstrates that on average salamanders are more susceptible to environmental deterioration, followed by caecilians, and anurans. Among the remainder of the herpetofauna, crocodylians are the most susceptible and snakes the least, with turtles and lizards in between. We compared the EVS results for the Central American herpetofauna with those reported for Mexico; the results from those regions show an increase in numbers and percentages from low through medium to high. Arguably, attempting to conserve biodiversity is one of the most important and intransigent issues facing humanity, a situation partially due to humanity’s lack of appreciation for its most serious concerns, and brought about by its anthropocentric focus.”

But what about anoles, you are no doubt thinking? In Johnson et al.’s EVS classification, all Central American anole species are rated as medium or high vulnerabilty, except the following species that are rated as low vulnerability: Anolis biporcatus, A. crassulus, A. laeviventris, A. lemurinus, A. petersi, A. sericeus, A. tropidonotus, and A. unilobatus.

More Red-Headed Brown Anoles, This Time From Gulf States

Photo by Patricia Sanders.

Photo by Patricia Sander from New Orleans, LA.

We’ve had reports of red-headed and orange-headed A. sagrei previously, but here are some new records. Bob Thomas, Director of the Center for Environmental Communication at Loyola University in New Orleans, sent along photos of red heads from both New Orleans (above) and Mississippi (below). If you click on the links to the previous posts, you’ll see that these have been reported far and wide, but we have no idea whether there is any adaptive significance to this stylish look.

Photo by Brad Glorioso from Hancock Co., MS

Photo by Brad Glorioso from Hancock Co., MS