Effect Of Brown Anoles On Behavior And Habitat Use Of Green Anoles

Up high displaying green anole. Photo from this website, which has some nice other reptile shots.

Many animals use different parts of their habitat for different activities–eating in one place, mating in another, and so on. This hasn’t been studied in many anoles, but has been documented in several. In addition, many species alter their habitat use in the presence of competitors, and this has been widely demonstrated in anoles. However, few have studied the interaction of the two phenomena: is the extent of behavioral partitioning among habitats affected by the presence of competitors?

To address this question, Ambika Kamath and colleagues studied green anoles on several islands in Mosquito Lagoon in the Intracoastal Waterway of Florida. In this area, a number of small “spoil” islands were created when the waterway was dredged half a century ago. These islands were quickly colonized by plants–and now are covered with very large trees–and then by green anoles. More recently, the invasive brown anoles have arrived on the scene on some of the islands.

Kamath et al., whose research was recently published in a paper in Breviora, chose four islands, two with brown anoles, two without (freely available, as are all MCZ publications, on the museum’s website). On these islands, they recorded habitat use and behavior. As predicted animals forage at lower heights than where they perch. One possible explanation is that they sit at vantage points looking for prey, then go down and catch them. And as predicted, males display at particularly high spots. The explanation here is not clear, but as reported recently for A. cuvieri, males seem to like to display higher than their rivals. Finally, once more as predicted, in the presence of brown anoles, green anoles shift upwards in all respects.

The interesting finding, however, is that the shift is essentially parallel for all activities. Animals move downward the same amount to capture prey and upward the same amount to display. This would suggest that there is not an optimal height for feeding or displaying, or perhaps that the optimal height changes in the presence of brown anoles. That would be readily understandable with regard to feeding–the voracious brown anoles probably vacuum up the low-lying food, so no point in dropping down as low to feed as in their absence. Why males continue to move up even higher is less obvious, though it may be just that competitors are now perching higher, so a male has to go higher yet to display above them.

This paper represents the sort of detailed behavioral study that is all too infrequent for anoles. How these lizards modulate their behavior in response to conditions is fascinating and often surprising. Much remains to be learned, and most anole species–well, at least in the Caribbean–are amenable to behavioral observation.

Ol’ Blue Eyes: Convergence In Frank Sinatra And Anoles

Anolis stratulus

Anolis stratulus

evermanni eyes

Anolis evermanni

Anolis gundlachi

Anolis gundlachi

Ok, this post has nothing to do with Frank Sinatra other than his nickname. But what about blue eyes in anoles? They seem to pop up all over anole phylogeny. For example, in my recent trip to Puerto Rico, three anoles had cerulean peepers–A. evermanni and A. stratulus, which are closely related, and A. gundlachi, which is more phylogenetically distant. And blue eyes occur in other anoles, such as A. etheridgei from Hispaniola.

The observation raises two questions:

1) Just how phylogenetically widespread is the occurrence of blue eyes in anoles? I know I’ve noted blue-eyedness from time to time, but I haven’t get tracked and can’t remember in which species. I propose the Anole Annals community take it upon itself to compile a list of blue-eyed anoles. If you know of one, please post a comment and, even better, add a photo.

2) Why? I can’t believe there is an adaptive significance to having blue eyes per se. Is it genetically linked to some other adaptive trait? Could sexual selection have a role (though I don’t know of sexual dichromatism in eye color)? Other animals exhibit interspecific variation in eye color and I bet there’s a literature trying to explain it, but I’m not familiar with it. Would make an interesting project!

Some quick googling reminded me of a few other examples, below. Who am I missing? And does anyone have a good photo of blue-eyed etheridgei?

Anolis transversalis

Anolis peraccae

Anolis oculatus

 

Name That Big Costa Rican Anole

 

Rick Stanley photo #2 of a large Costa Rican anole

Award-winning nature photographer, naturalist, and undergraduate Rick Stanley spied this large anole in Costa Rica. Is it A. microtus? A. insignis? Something else?

Photo #1

Here’s what Rick had to say: “I encountered these impressive lizards on the Pacific Slope of the Cordillera Talamanca, on the border of Chirripo National Park, in the summer (wet season). They were between 1500 and 1600m elevation, in secondary forest habitat. Although sightings were about a month apart, all of the animals observed were in the same general area near the cabins.

Photo #3

Images 2/3 are of the same individual. Image 1 was taken nearby at an earlier date, so it could be the same individual as well. Image 4 is of a different, slightly smaller individual seen along with 2/3 (perhaps the female?). The male(?) displayed his dewlap at me- I think it was an aggressive gesture, because the female was out of sight by then. When I first saw him, he had a large clump of moss in his mouth that he proceeded to devour (chances are there was an insect in there as well).

Photo #4

The lizards were over a foot long including the tail, although I didn’t catch them and measure svl. The first time I sighted 1 it was sunning. Later, it changed color and appeared more like the individual in photos 2 and 3. Didn’t move much, as I found him in the same place the next day, hanging head down on some vines.

There is also some damage to the animal’s dewlap that isn’t part of the pattern.”

Reproductive Character Displacement And Dewlap Color In Haitian Anoles

figure 1

Shea Lambert and colleagues have just published a fabulous paper in Molecular Ecology on dewlap color evolution and reproductive character displacement in species in the Anolis brevirostris species complex. Manuel Leal and I wrote a perspective piece accompanying the paper that goes something like this:

‘Sibling species’, an old term that has fallen out of use, refers to closely related species that are so similar that it is hard to tell them apart. The existence of such species raises the obvious question: How do the animals themselves tell one another apart? And indeed, this is an active area of research (Tibbetts & Dale 2007; Uy et al. 2009). Usually, the species differ in one or more traits (i.e. species recognition signals) detectable with the sensory modalities upon which they rely (e.g. raptors use visual signals, frogs use sound and electric fish use different patterns of electric discharge).

A more general question concerns how such differences evolve. Over the last decade, it has become increasingly evident that mating signals can evolve under simultaneous selection for two functions (Fleishman et al. 2009): (i) eliciting attention (i.e. detectability); and (ii) species identification (i.e. distinguishing conspecifics from non-conspecifics). Historically, species recognition has attracted a significant amount of research from evolutionary biologists based on the assumption that if hybrids suffer reduced fitness or cannot be produced at all, then natural selection should favour individuals bearing traits that prevent such matings. This idea—confusingly termed either reinforcement or reproductive character displacement—had a rocky time in the evolutionary literature for many years, though now it is widely accepted (Servedio & Noor 2003; Rundle and Nosil, 2005; Pfennig & Pfennig 2009).

Near the dawn of the era of molecular ecology, one of the first studies to employ molecular tools to study the evolution of species recognition signals was Webster & Burns’ (1973) study of the evolution of dewlap colour in Anolis lizards. Anoles possess a retractable flap of skin under the throat, termed as dewlap, that is used in courtship, aggressive interactions and even encounters with predators (reviewed in Losos 2009). Anoles can be found in communities of as many as 15 species, and sympatric species never have identical dewlaps, leading to the hypothesis that the dewlap is used in species identification (Rand & Williams 1970).

Webster and Burns studied a highly unusual pattern of dewlap distribution in the Hispaniolan bark anole, Anolis brevirostris, along a transect on the western coast of Haiti (Fig. 1, above). Starting in the south, the lizards have a white dewlap. Then, abruptly the dewlaps become intensely orange; moving northwards, the intensity and size of the orange spot diminishes until it has almost disappeared, whereupon again there is an abrupt transition back to intense orange coloration that characterizes the northernmost populations.

Using the tools of the day, Webster and Burns employed starch-gel electrophoresis to examine six geographically varying protein loci. Analysis of these data yielded three important discoveries. First, the populations sorted into three groups: the white-dewlapped forms in the south, the orange-dewlapped forms in the north and a third, intervening form that exhibited clinal variation in the proportion of white vs. orange in the dewlap. Second, at the point of contact between the groups in both the north and the south, adjacent populations did not share alleles at several loci. Third, within the middle, clinally varying group, populationsshowed little genetic differentiation despite the differences in dewlap colour among populations.

Webster and Burns concluded that they were dealing not with a single species, but three—subsequently, the middle populations were described as A. caudalis and the northern ones as A. websteri. More importantly, what had seemingly been an incoherent pattern of geographic variation in dewlap colour variation now had a clear explanation. The apposition of orange vs. white at both ends of A. caudalis’s range is most parsimoniously explained as the result of selection for differences in species recognition signals in sympatry. The fact that A. caudalis maintains the clinal variation in the face of possibly strong ongoing gene flow, as evidenced by the lack of genetic differentiation among populations, was interpreted as powerful evidence for ongoing natural selection favouring dewlap colour differences at the contact zones with the other species.

Given this provocative pattern and the great interest in evolutionary reinforcement, it is surprising that this example has not been subject to further investigation as molecular tools have developed over the past four decades. Undoubtedly, the transect’s occurrence in Haiti, a notoriously difficult place for fieldwork, has been a factor. Finally, however, this case study has come under further scrutiny.

On a trip in Haiti that was no doubt a story in itself, Lambert et al. revisited Webster and Burns’ transect and report in this issue of Molecular Ecology the results of their phylogenetic and phenotypic analyses. Examining variation at mitochondrial and nuclear loci, Lambert et al. have demonstrated that Webster and Burns pretty much got it exactly right. Chalk one up for old school electrophoresis! Not only do the three species each fall out as monophyletic, but, as with the allozymes, A. caudalis exhibits little interpopulation genetic differentiation, in contrast to the deep genetic structure apparent among populations in the other two species. Moreover, phenotypic examination of dewlap coloration reaffirmed the patterns of clinal variation within A. caudalis and the abrupt shifts in coloration between sympatric species at either end of its range (Fig. 2).

figure 2

Lambert et al.’s study not only completely corroborates Webster and Burns’ conclusions, but adds several important new perspectives on this case study. Continue reading Reproductive Character Displacement And Dewlap Color In Haitian Anoles

Global Warming Effects On Tropical Ectotherms

Ray Huey giving the first talk of the symposium, illustrating that present day temperatures are more suitable for A. cristatellus than A. gundlachi at the El Verde Field Station (the red circles show average temperature through the day now; the gray circles are for corresponding temperatures 40 years ago).

Ray Huey giving the first talk of the symposium, illustrating that present day temperatures are more suitable for A. cristatellus than A. gundlachi at the El Verde Field Station (the red circles show average temperature through the day now; the gray circles are for corresponding temperatures 40 years ago).

This is part II of my report on the the symposium “The Biological Impacts of Tropical Climate Warming for Ectothermic Animals,” which was recently (Aug. 1-3) held in San Juan Puerto. Previously I discussed several of the talks that focused on anoles; today I summarize the rest of the symposium (the program is listed here).

Symposium co-organizer Ray Huey kicked off the symposium with opening remarks, including some important background. The symposium was funded as part of a grant headlined by Huey to investigate the effect of global warming on Puerto Rican reptiles. Huey joined forces with Paul Hertz, George Gorman, and Brad Lister, all of whom had studied Puerto Rican anoles in the 1960’s and 70’s. The goal of the proposal was to revisit their study sites to see how things had changed in the intervening time, as the climate had warmed, including as much as 2 degree  C at the El Verde Field Station. A particular species of focal interest was the forest interior montane anole, A. gundlachi. This species is adapted to low temperatures, whereas its close relative, A. cristatellus, thrives at warmer temperatures. Huey and colleagues speculated that as the forest warmed, it would become more suitable for cristatellus and less for gundlachi, resulting in a forest invasion by the former and the disappearance by gundlachi from lower elevation forests.

Imagine their surprise, then, when they found not only that cristatellus had made no inroads into the forest at El Verde, but that gundlachi, previously found only at higher elevations, could now be found at sea-level! Exactly the opposite of what had been predicted–what a conundrum!

Noted forest science Ariel Lugo explained this result clearly in the next talk. It turns out that Puerto Rico has experienced massive reforestation in the last 50 years. Consequently, even if the world is getting warmer, it is also getting more tree-covered, at least in Puerto Rico, and this latter effect has had a greater impact on gundlachi’s distribution, allowing it to occupy newly re-emerged forests at lower temperatures. An important lesson that warming is not the only thing going on in the world today and that we must consider other factors as well.

Barry Sinervo showing the grim news for lizard populations worldwide

Barry Sinervo showing the grim news for lizard populations worldwide

Much of the rest of the day was pretty gloomy, with projections of massive ectotherm disappearance in the tropics as global temperatures rise (turtles, as well as lizards, as Barry Sinervo showed), the reason being that tropical species are often closer to their upper thermal limits, and so relatively small increases in temperature may push them over the edge. Michael Kearney’s talk was particularly notable in taking an extremely detailed mechanistic analysis of how increased temperatures affect all aspects of ectotherm biology through their entire life cycle. Such studies, though very elaborate, promise particularly rich insight into the specifics of how changing temperatures will affect ectotherms. One finding of particular interest is that the amount of shade available in a habitat will be critical: more shade = good; less shade = bad. In many cases, Kearney argued, it is not the warming per se, but the effect on vegetative cover that may be most significant in effecting species like lizards.

All of the talks were fascinating and I can’t discuss them all: a few particular points stick in my head: Mike Kaspari showing that the boundary layer of air around a surface is particularly important for small animals such as ants, that may experience temperatures as much as 10 degrees C higher than the air temperature a few centimers above the surface; symposium co-organizer Patricia Burrowes showing that changes in seasonality are extremely important, particularly with regard to host-pathogen dynamics; Carlos Navas discussing the relative importance of temperature and water availability for amphibians; Ana Carnival examining geographic patterns of genetic variation to understand responses to climate change in the past; and Brad Lister showing that anoles and almost everything else at his study site in the Luquillo Mountains have declined greatly in abundance in the last 40 years.

Have this many anole biologists ever been in the field together previously? And who are they?

Have this many anole biologists ever been in the field together previously? And who are they? This photo was taken at the El Verde Field Station, site of James Stroud’s observations on rock-using canopy anoles.

Global Warming Effects On Tropical Lizards

Martha Munoz starting the all-anole morning with a comparison of the thermal niches of different species of Hispaniolan cybotoid anoles

Martha Munoz starting the all-anole morning with a comparison of the thermal niches of different species of Hispaniolan cybotoid anoles

The symposium “The Biological Impacts of Tropical Climate Warming for Ectothermic Animals,” was recently (Aug. 1-3) held in San Juan Puerto, and it was a great success. In a two-part post, I will provide a brief summary. Today will focus on four talks on the second morning, all of which focused on Anolis. In the next post, I will review the rest of the symposium.

Martha Muñoz began the day by talking about the thermal biology of cybotoid anoles (members of the cybotes species group) in Hispaniola. These species show a remarkable elevational range from sea level to over 3000 meters. Martha pointed out that in this respect, Hispaniola is a much better place to look at questions related to elevation than Puerto Rico, a comment greeted with jeering from much of the crowd. Nonetheless, she scoffed at the discussion of the “high elevation” A. gundlachi at 850 m. Why, A. shrevei, in Hispaniola doesn’t even occur that low! In any case, what Martha showed is that despite the great thermal differences in habitats at different elevations, the cybotoids maintained approximately the same body temperature at all sites and have the same preferred temperatures and critical thermal maxima. Clearly, they are using thermoregulatory behavior to buffer their thermal physiology from selection in different environments and, indeed, field observations show that high elevation species do bask more. However, anoles can’t thermoregulate at night, and there is where adaptive differentiation occurs: high elevation anoles can withstand lower temperatures than lower elevation species. To clinch the deal, Martha measured the temperatures lizards experience at night. Indeed, the species at high elevation experience temperatures that would kill low elevation species.

Luisa Otera showing a slide of her collaborator, George Gorman, in his cowboy salad days

Luisa Otera showing a slide of her collaborator, George Gorman, in his cowboy salad days

Luisa Otera spoke next on the “Effects of recent climate warming on the reproductive phenology of Puerto Rican Anolis lizards.” Luisa revisited sites at which George Gorman had examined A. cristatellus 40 years ago. Gorman had found that at higher elevations, female reproduction tapered off in the winter, whereas at lower elevations, they continue reproducing year-round. Her prediction was that with higher temperatures, reproduction should be extended in the winter at high elevations. For the most part, this prediction was confirmed, though surprisingly not so at the sea-level site.

Most surprising, in a new twist, Luisa found that female reproduction could vary over a very short spatial scale. In particular, if a lizard has a territory in the open with a lot of sun, it can breed year round, whereas it’s neighbor under the shade of trees a few meters away may not be able to do so in the winter. Perhaps this explains the contrary finding at the sealevel sites: greater tree cover may have actually made conditions worse.

Luisa pointed out that warming isn't always bad--for some lizards, it allows them to extend their breeding seasons

Luisa pointed out that warming isn’t always bad–for some lizards, it allows them to extend their breeding seasons

gunderson

Gunderson’s data show that even lizards with body temperatures outside of their preferred range are still quite active

Alex Gunderson spoke next on “Behavioral responses to climate change: natural selection on the thermal physiology of Anolis sagrei.” Perceptive readers will note that these three talks focused sequentially on the trunk-ground anoles of three different islands. Coincidence? You be the judge. In any case, in a very thought-provoking talk, Alex pointed out that much of the literature predicting the response of species to global warming focuses on the effect that higher temperatures will have on the time in which lizards can be active, which affects factors like food acquisition. However, Gunderson note that although activity time is usually treated as a binary variable—a lizard is either active or it isn’t—his extremely detailed behavioral data (299 focal observations), indicate that, in fact, the effect of temperature on activity is continuous rather than binary. Indeed, lizards engage in all major activities—eating, mating, fighting—at temperatures substantially outside (mostly below) their “preferred temperatures.” This finding calls for a re-thinking of how we model the effects of climate change on lizard populations—they may be forced to be active at temperatures they’re not so happy about, but they will do more than stay in their hidey-holes.

Next, Michael Logan reprised his talk on the “Rapid evolution in response to climate change: natural selection on the thermal physiology of Anolis sagrei” which he gave at the Evolution meetings five weeks previously. But here he had twice as much time to speak and correspondingly gave greater details. Since I’ve reported on the talk previously, I’ll just summarize here: in a very cool experiment, he moved brown anoles from a shady habitat to a much hotter one. Before doing so, he measured the performance curves of each lizard (i.e., how their ability to sprint was affected by temperature). His prediction was that individuals that could sprint at higher temperatures would be favored by natural selection in the new habitat. And sure enough, they were! By contrast, another population in a shaded habitat experienced no selection on thermal performance. If thermal sensitivity of sprinting is a heritable trait—a big if, Mike noted—this strong selection could suggest that populations might be able to adapt very rapidly to warming climates.

Anoles on the rocks, so to speak

After a wonderful trip to Puerto Rico for the recent Thermal Ecology meeting mentioned here on Anole Annals and so heavily attended by anolologists, we had the opportunity to visit some of the natural forests that the country had to offer.

Riparian habitat in the forest by the El Verde Field Station, Puerto Rico

Riparian habitat in the forest by the El Verde Field Station, Puerto Rico

Whilst in El Verde National Park, we were regaled with stories of local Anolis advancing to the ground and using riparian habitat despite what their ecomorph classification might suggest. Given the recent AA interest in aquatic anoles (1,2,3), I thought a short note on this may be appreciated. Apologies for the deceivingly melodramatic title; alas it was literal, not figurative.

An adult male A. evermanni perched on a boulder surrounded by fast flowing water

An adult male A. evermanni perched on a boulder surrounded by fast flowing water

Anolis evermanni, a trunk-crown ecomorph, has been known to use boulders along one of the streams for the past two decades or so. With great anticipation, whilst marching through the forest spotting copious numbers of Anolis gundlachi, we were en route to our final destination to find out! Upon reaching the stream, which incidentally offered some beautiful tropical scenery accompanying the break in the canopy, we were not disappointed to find A. evermanni dotted all around the waterway!

I assure you there is an anole there - this wasn't just an excuse for a rest...!

I assure you there is an anole there – this wasn’t just an excuse for a rest…!

An adult male A. evermanni displaying

An adult male A. evermanni displaying

Back in 1990, Jonathon Losos postulated that this shift in microhabitat from trees to boulders forced a change in locomotor strategy. Whilst anoles are able to travel continuously in a forest, by travelling down a tree, along the ground and then up another, the structural heterogeneity presented by these riparian boulders meant that jumping needed to be more commonly adopted. He posited that the difference in thermal strategy of A. evermanni and A. gundlachi, a heliotherm and a thermoconformer respectively, would affect their likelihood of using these boulders along the highly sunny stream. Although A. gundlachi were observed present along the shaded edge, they rarely ventured further out. After some thought on site, this prompted a brief hypothesis by a couple of us; when the sun began to disappear, would the larger A. gundlachi displace the A. evermanni on the boulders?

This may take some imagination, but that blur to the right of the central vine - I assure you that's a boulder-loving A. gundlachi!

This may take some imagination, but that blur to the right of the central vine – I assure you that’s a boulder-loving A. gundlachi!

After a couple of hours of enjoying the forests of El Verde, we returned to the field station. As we were leaving and the sun was beginning to calm, I spotted our first A. gundlachi out on a stream boulder followed shortly after by a handful of A. stratulus. This would seem to offer a cool behavioural research opportunity for someone that enjoys sitting in the sun by a river watching lizards…(can’t be that bad a gig, can it?).

A. stratulus also getting in on the gig

A. stratulus also getting in on the action

A New Confirmation Of Pair Bonding In Anolis Limifrons

Monogamy, or the formation of stable pair bonds between males and females for reproductive purposes, is thought to be relatively rare across animals. While social pair formation is observed (commonly in birds and occasionally in reptiles), genetic assessments of parentage have revealed that mating fidelity is infrequent. Social monogamy is therefore not equivalent to genetic monogamy. However, the reasons for the persistence of social monogamy despite promiscuous mating remain unclear.

Sleepy lizards are the best known example of pair-bonding in lizards

Sleepy lizards are the best known example of pair-bonding in lizards (photo by J. Todd Kemper)

A new paper by Alexis Harrison revisits one of the only examples of social pair-bonding known from anoles–a population of Anolis limifrons in the La Selva Biological Station in Costa Rica. While most anoles are polygynous, with the territory of one male overlapping the territories of several females, Talbot (1979) noticed that 70% of adult A. limifrons in La Selva were found in pairs of a single male and female in close proximity to each other. However, such pair bonding has not been documented in any other population of the species, making La Selva an intriguing outlier.

A pair of Anolis limifrons

A pair of Anolis limifrons (photo by Jason Weigner)

Continue reading A New Confirmation Of Pair Bonding In Anolis Limifrons

Hueyfest: A Symposium Honoring Ray Huey

Ray Huey and friends at last year's World Herpetological Congress in Vancouver

Ray Huey and friends at last year’s World Herpetological Congress in Vancouver

Learn about Ray’s storied past.

Ray Huey has been a pioneer in the field of physiological ecology and evolution. Building on the work of Ruibal, Rand,Williams and others (as he always stresses), Ray was instrumental in making anoles a model for understanding thermal biology, integrating behavior, physiology, evolution and,  most recently, conservation biology. And then there’s Ray’s other side. Who else could get away with using a Rolling Stone‘s album in the title of a paper?

A symposium in Ray’s honor will be held in Seattle on Friday, October 4th and is open to anyone, but attendance is limited, so register today. All the details are available on the fest’s website. Whether you attend or not, check out the Hueyblog and add your own tributes and reminiscences.

Eye Color In Anolis Of The Guadeloupe Archipelago

The geographic variation of the highly variable anole Anolis marmoratus from the Archipel de la Guadeloupe (France) has focused interest on the process of speciation resulting from divergent selective pressures. Nice detailed analyses such as that recently published in Molecular Ecology confirmed that differences in body color seem to correlate with environmental characteristics. Within the large diversity of form and color of anoles of the different islands of the archipelago, one phenotypic feature that appears to be variable is the color of the scales around the eye.Untitled
For two years, the team FORCE (UMR 7205 Museum National d’Histoire Naturelle/CNRS, Paris, France) in collaboration with La Direction des collections of the Museum National d’Histoire Naturelle (Paris, France) has been conducting different studies of the behaviors and forms of the anoles of the different islands of the archipelago. The contrasted orange color of the scales around the eye of males Anolis desiradei is remarkable and could probably play a role within the context of behavioral ecology of these anoles. At La désirade, these anoles are living in the same habitat as the endangered Iguana delicatissima. We also recorded some populations of males of Anolis marmoratus on the Basse-Terre with marked black scales around the eyes. In Marie-Galante, the scales around the eye are blue, green or yellow while the head is more often blue or green. The scales around the eye of females of all of the studied populations are often white or pale yellow.Untitled1

We are now measuring the diversity of this phenotypic trait to test various hypotheses of the role of these colors in the communication between the individuals within the selected populations of Anolis from different islands.

More Remembrances Of Ken Miyata

Ken Miyata's handiwork on display outside David Wake's office

Ken Miyata’s handiwork on display outside David Wake’s office

Recently, a chapter of Ken Miyata’s thesis on the ecology of Ecuadorian anoles was published in the Bulletin of the Museum of Comparative Zoology, along with remembrances of Ken–who died 30 years ago–by Jerry Coyne, Chuck Crumly, Ray Huey, Eric Larson, Greg Mayer, and B Wu.

David Wake knew Ken Miyata, too, and here’s what he had to say: “Ken did an undergraduate honor’s thesis with me in MVZ.  He was far ahead of his time — we had no digital database but he wanted to do detailed mapping of some species so he selected Batrachoseps attenuatus and then laboriously went through the large MVZ collection.  He made a pin for each locality and on the pin recorded the MVZ catalogue number (or first in a series in the case of multiple specimens). Then he researched the exact locality, often going to field notes.  The result is still on the wall outside my office!  From time to time someone suggests taking it down, but it has now gained the status of historical document!  And it is a constant reminder to me of Ken and his enthusiasms and diligence.”

Anoles Link Spatially Distinct Terrestrial Food Webs – Part 1 Of 2

IMG_0613

LIke all the anoles in our study, a considerable fraction of A. equestris’ diet was derived from the flow of allochthonous resources into its habitat.

A. sagrei, probably the most common vertebrate in Florida perch low on trees making occasional forays to the ground to feed.

A. sagrei, probably the most common vertebrate in Florida perch low on trees making occasional forays to the ground to feed.

The ecological importance of small, terrestrial insectivores such as litter frogs and small geckos is a topic that I’ve been curious about for years. While my dissertation research does not include anything about it, I am still quite curious about how these small, diverse and abundant vertebrates fit into ecosystems. Anoles possess all of the attributes that seem to predispose them to strong interactions and soon after arriving in Miami to begin my Ph.D., I decided to launch a small, side-project using tried-and-true food web tools, stable isotopes and gut content analysis to try to illustrate if and how these small, rather inconspicuous predators might affect ecosystem structure and function. The results of this study were just published online in Functional Ecology.

Basically, we found that anoles couple adjacent food webs by consuming insects that move across habitat boundaries. While food web linkages are a potentially important ecological dynamic and our study yielded some unique findings, there are other bits of information for those more generally interested in anole biology. Therefore, I’ve decided to break this post into two parts. Part 1 deals with our primary findings and contextualizes them within current understanding of food web ecology linkages. It’s sort of a geeky treatment of the subject. Part 2 will illustrate some of the other data that we’ve collected that were not dealt with explicitly in the paper that will be of interest to, I suspect, AA readers.

Bidirectional trophic linkages couple canopy and understory food webs

Sean T. Giery,Nathan P. Lemoine, Caroline M. Hammerschlag-Peyer, Robin N. Abbey-Lee, and Craig A. Layman

1.  Cross-system resource flux is a fundamental component of ecological systems. Allochthonous material flows generate trophic linkages between adjacent food webs, thereby affecting community structure and stability in recipient systems.

2.  We investigated cross-habitat trophic linkages between canopy and understory food webs in a terrestrial, wooded, ecosystem in South Florida, USA. The focal community consisted of three species of Anolis lizards and their prey. We described interspecific differences among Anolis species in the strength and routing of these cross-habitat flows using stable isotope analysis, stomach content analysis, and habitat use data.

3.  All three Anolis species in this study consumed different prey, and occupied vertically distinct arboreal habitats. Despite these differences, carbon isotope and stomach content analysis revealed strong integration with understory and canopy food webs for all Anolis species. Modes of resource flux contributing to the observed cross-habitat trophic linkages included prey movement and the gravity-driven transport of detritus.

4.  Our study shows that terrestrial systems are linked by considerable bidirectional cross-system resource flux. Our results also suggest that considering species-specific interactions between predator and prey are necessary to fully understand the diversity of material and energy flows between spatially separated habitats.

MAp

The study system was dominated by St. Augustine grass and isolated Ficus trees.

Some basics – The community was composed of four anole species, Anolis sagrei, A. distichus, A. carolinensis*, and A. equestris. The study site was recently featured in AA. Generally, the purpose of the study was to describe variation among species in resource use using stomach contents, habitat use, and stable isotope analysis. But based on some initial observations and a bit of stable isotope data, we had considered that there might be a role for anoles in ecosystems via linking spatially distinct food webs. That is, anole diets might be sourced, in part, by primary production originating outside their respective microhabitats. Basically, we knew that anoles occupy distinct arboreal habitats, but when we examined the stomach contents of each, we found that some prey were from habitats spatially distinct from the ones used by each anole species (e.g., How do terrestrial grasshoppers get inside a canopy giant anole such as A. equestris?),which spawned a more in-depth investigation. Additionally, some initial stable isotope data strongly supported the same interpretation – that is, anole diets might be at least partially derived from allochthonous resources. Continue reading Anoles Link Spatially Distinct Terrestrial Food Webs — Part 1 Of 2

Ecological And Population Data On Some Little Known Ecuadorian Anoles

Ken Miyata–naturalist, fly-fisherman, and photographer extraordinaire–died tragically young 30 years ago at the age of 32. Among the many items of unfinished business was his gargantuan thesis, Patterns of Diversity in Tropical Herpetofaunas, 787 pages in length and entirely unpublished. The dissertation ranges far and wide over topics herpetological and ecological–check out the Table of Contents at the bottom of the post. Over the years, Ernest Williams tried to talk a number of scientists into guiding some of the chapters into print, but the task was too large and so it has remained shelf-bound.

Anolis peraccae. Photo by Luke Mahler.

Anolis peraccae. Photo by Luke Mahler.

After a recent trip to Ecuador, I happened to be looking at the thesis for other reasons (parts of it were incorporated into the description of A. lyra by Poe et al. in 2009) and came across Chapter 2. This multi-part section includes separate studies on the habitat use of three anole species at the Río Palenque field station (A. chloris, A. festae and A. peraccae) and population biology and dynamics of two other species elsewhere (A. boettiger and A. gemmosus). Miyata argued that little was known of the population biology of South American anoles. Thirty years on, the situation isn’t all that different.

Anolis chloris. Photo by Luke Mahler.

Anolis chloris. Photo by Luke Mahler.

As a result, the data presented by Miyata in 1983 are still very relevant today and deserve wider circulation. And for that reason, we decided to publish a lightly-edited version of parts Chapter 2 in the Bulletin of the Museum of Comparative Zoology, appropriate given that Miyata was a grad student in the Museum (this paper, like all other Bulletins of the MCZ, is available online). In addition, in an online supplementary file, a number of his friends) Jerry Coyne, Chuck Crumly, Ray Huey, Eric Larson, Greg Mayer and B Wu) provide reminiscences of Ken.

The paper ranges widely over matters of anole ecology, behavior, and population biology, providing data on five species for which almost nothing exists in the literature. The paper’s findings are summarized in the abstract:

Anolis festae. Photo by Luke Mahler.

Anolis festae. Photo by Luke Mahler.

Little is known about the ecology and natural history of South American anoles. This study reports the results of a variety of different studies on several relatively common species of Ecuadorian Anolis. In part I, habitat use and population density are compared among three species of Anolis that occur in sympatry at a number of sites in Ecuador. The three species—A. chloris, A. festae, and A. peraccae—are roughly the same body size. These species perch primarily on tree trunks, and A. chloris perches substantially higher than the other two species, which are similar in perch height. Large differences from one year to the next were observed both in mean perch height and in population densities.

Anolis gemmosus. Photo by Jonathan Losos

Anolis gemmosus. Photo by Jonathan Losos

In Part II, natural history, growth rates, and population densities are reported for two little known Anolis species, A. bitectus and A. gemmosus. Although the two species are from nearby regions and are similar in microhabitat use, they show more differences than similarities in most aspects of their biology. The species have similar ranges in active body temperatures, but A. bitectus is thermally passive, whereas A. gemmosus appears to thermoregulate. Populations of A. gemmosus tend to remain constant through time, whereas A. bitectus undergoes moderate population fluctuations. Both species exhibit little sexual size dimorphism, but in A. bitectus females are larger, and in A. gemmosus males are larger. Anolis bitectus has a fairly high characteristic growth rate, whereas that of A. gemmosus is quite low.

Microsoft Word - Table of Contents entire thesis.docxMicrosoft Word - Table of Contents entire thesis.docx

Evidence Suggests That Cloacas Carry Risk: Venereal Disease and Lizard-Parasite Coevolution

Anolis cristatellus wileyae - Does this pair need to worry about Cyrtosomum infections?

Anolis cristatellus wileyae – Does this pair from St. Thomas need to worry about Cyrtosomum infections?  Read on.

I wanted to write a few posts about parasites because hey – anoles have some really neat parasites! First up are the nematodes in the genus Cyrtosomum, which have been reported from several anoles and some other lizard taxa like Sceloporus and Cyclura. You might remember Cyrtosomum because C. penneri was the worm that AA-contributor Gerrut Norval and his colleagues used to infer that the Taiwanese population of A. sagrei originated from Florida and not Hawaii, something that wasn’t clear from sagrei molecular data (cool!).

Aside from pinworms (we’ll get to these another day), Cyrtosomum species are probably the most widespread nematode parasites in anoles. They’re really small (difficult to see without magnification), and occur in really large numbers in the lizards’ large intestines (many hosts have worm burdens of 100-200). Until recently, we knew very little about their life history – we knew that they could multiply within a single host individual via infective larvae, but we didn’t know how they moved between host individuals. Several authors (including Norval et al.) noted that Cyrtosomum species are only found in adult lizards, and suggested the possibility that these are sexually transmitted parasites.

Okay, let’s just take a moment… Worms, from sex. Yep.

Gabe Langford and his students tested this hypothesis in C. penneri, and Continue reading Evidence Suggests That Cloacas Carry Risk: Venereal Disease and Lizard-Parasite Coevolution

A Dearth Of Anole Talks At The Ecological Society Of America Meetings

In contrast to their ubiquity at the evolution meetings [1,2], anoles are barely in attendance at the enormous Ecological Society of America meetings. Last year there were but three (including the famous “Kitty Cam” talk), and this year the dearth is worse, with but a single talk this week in Minneapolis. So, here it is, by Rich Glor and part of the symposium on “Coexistence of Closest Relatives: Synthesis of Ecological and Evolutionary Perspectives”:

Patterns of Anolis lizard coexistence across a complex island landscape

Thursday, August 8, 2013: 3:40 PM

M100EF, Minneapolis Convention Center

Richard E. Glor , Biology, University of Rochester, Rochester, NY

Background/Question/Methods

In species rich adaptive radiations, complex patterns of species coexistence result from speciation and natural selection acting over evolutionary time. In Anolis lizards, similar communities of 4-6 arboreal microhabitat specialists that partition available perches by size and height have evolved independently on each of the four largest Caribbean islands. These well-studied communities of anole ‘ecomorphs,’ however, account for only a fraction of anole species diversity. Most anole diversification has occurred subsequent to microhabitat specialization, resulting in complexes of closely-related species that belong to the same ecomorph but appear to be allopatrically or parapatrically distributed in different macrohabitats. We use integrative analyses that combine thousands of anole species occurrence records from public biodiversity databases, GIS environmental data, molecular phylogenetic and population genetic data, and data on phenotypic variation to test three predictions about anole species co-occurrence across the island of Hispaniola: (1) local communities tend to be comprised of microhabitat specialists that evolve relatively early in anole radiations, (2) closely-related or incipient species tend to be allopatrically or parapatrically distributed in distinct macrohabitats, and (3) habitat filtering in extreme habitats leads to communities in which species that are more closely related to one another than expected by chance.

Results/Conclusions

Our analyses support the prediction that local communities tend to be comprised of phenotypically distinct microhabitat specialists that evolved early in anole radiations and are relatively distantly related. Our analyses also support the prediction that closely-related species tend to be allopatrically or parapatrically distributed in distinct macrohabitats. This result, together with a growing body of molecular population genetic data, suggests that both geographic and ecological processes play an important role in recent anole speciation events, and dictate patterns of co-occurrence in closely related anole species. Finally, we find preliminary support for the importance of habitat filtering by recovering evidence for a latitudinal gradient in the phylogenetic composition of local communities whereby communities at the highest altitudes tend to include more closely-related species than communities at lower altitudes. This pattern is particularly evident in the Cordillera Central, where communities of closely related and ecologically unusual species tend to occur at the highest altitudes.

A $90 Night Light?

Several years ago I reviewed some lighting options for people interested in hunting anoles at night (Who wouldn’t? Throw that noose away!). At the time I recommended several readily available lights ranging from 300 to 700 lumens, $60 to $500 respectively. Needless to say, most anole enthusiasts were likely priced out of the brightest lights. However, I recently found an option affordable to even our dedicated summer field assistants. A relatively new company to the US, Magicshine, advertises an 1100 lumen light for only $90, the MJ-808U.

Maginshine MJ 808U

Maginshine MJ 808U

Now the first thing we should all do is assume that this is too good to be true. In just a few years our discussion has gone from $500 to $90 for a supposedly superior light. Come on! Online reviews of Magicshine’s products are generally favorable, but mixed. Reviews on mountain bike forums comment on the relatively poor construction and historically bad batteries. Several reviewers have also commented on overheating problems for riders not peddling their hardest.The best part of Magicshine is by far their price. But the last I checked we rarely look for anoles on bikes at night so we will need to take all of this in with some hesitation.

So what about herping? Time will ultimately tell how these lights hold up to our uses. I received my light in the mail earlier this week and have used it twice. To keep my hands free I also purchased the accessory head strap for about $8. I also need to purchase the extension cable as the attached cable between the battery and light is too short to reach my backpack from my head. First impressions, the light is retinal burning bright. I have absolutely no complaints there. I will warn you now, however, that the light gets hot, but has yet to overheat for me. I haven’t fully run down the battery yet either, but it has lasted for over 90 minutes of burn time so far. In summary, my first impressions are as the online reviews suggests, there are both pros and cons to this product, but for $90 why not give it a try. I am cautiously optimistic.

Has anyone else discovered this light yet? If so, please share your reviews with the community.

 

Biomechanics Shed Light On Differences In Signal Behaviour

ordWhy do closely related species sometimes differ in signalling behaviour, despite apparent similarities in the selection pressures that act on the signal? That question is addressed in a paper in Functional Ecology now available as an early view.

Comparing Anolis species from Jamaica that extend the dewlap rapidly with more slowly extending relatives from Puerto Rico, Ord, Collar and Sanger have modelled the performance of the dewlap and then simulated changes to the system to predict its effects on the speed of the dewlap extension. The predictions are then compared with data on both morphology from cleared and stained specimens and actual dewlap speeds for lizards recorded in the field.

The analyses show that morphological changes have affected the performance of the dewlap display in Jamaican and Puerto Rican anoles differently. Within islands structural changes have led to differences in dewlap speed among species, whereas differences between islands are the result of an increase in muscle contraction velocity present in Jamaican species, but absent in Puerto Rican species.

The study is an excellent example of how investigations into the biomechanics of motion-based visual displays can increase our understanding of differences in signal behaviour.

Anole Display Behavior: Posters At the Animal Behavior Meetings

The 50th annual conference of the Animal Behavior Society kicks off today in Boulder, Colorado. Anole presentations are few: only two posters, which begs the question, why aren’t more behavioral biologists studying anoles? Certainly, their behavior is easily observed and manipulated. And, indeed, some such work is conducted, but not nearly as much as one might expect given the ubiquity of the animals in the southeastern U.S. and throughout the neotropics. And, moreover, the behavioral work that is done is relatively infrequently published in the behavior literature or, apparently, reported at behavior meetings. Behaviorists, you’re missing the boat!

In any case, the sole anole reporter at ABS is Joe Macedonia, who is presenting two posters. The first is a comparison of the behavior of the odd gray-dewlapped green anoles with more ordinary, red-dewlapped populations, and the second is a study using anole robots to determine the relative importance of dewlap color and behavior in species recognition; this study has recently been published and we should be hearing more about it soon.

A Comparison of Headbob Display Structure in Gray-Dewlapped and Red-Dewlapped Anolis carolinensis

JM Macedonia, LE Cherry, DL Clark

Many species of diurnal lizards engage in motion displays, termed ‘pushups’ or ‘headbobs’. In the diverse genus Anolis, headbob display structure typically exhibits substantial interspecific, and in some cases population-level, variation. The green anole (Anolis carolinensis) exhibits a red-dewlapped (RD) form found throughout the southeastern USA, as well as a gray-dewlapped (GD) form that is restricted to southwest Florida. Prior research has shown that RD A. carolinensis produce headbob displays of three basic types (Type A, B, C) that vary primarily in display unit durations. Based on known genetic and physiological differences between the two dewlap color forms, we hypothesized that GD and RD males also would differ in headbob display temporal structure. We quantified 440 displays from 24 GD and 15 RD males, and found some, though not all, display units to differ significantly in duration between the two populations. Our results therefore indicate that stereotyped display behavior can be added to the list of known traits that differ between the gray-dewlapped and red-dewlapped forms of A. carolinensis.

Color and motion display discrimination in Anolis grahami: evidence from responses to lizard robots

JM Macedonia, DL Clark, DJ Kemp

Anolis lizards exhibit color and motion displays that are thought to mediate species recognition, but direct experimental support is limited. We used lizard robots in two field experiments to test the relative importance of dewlap color (calibrated using a computational visual model) and headbob display structure for species recognition in Anolis grahami on Bermuda. Results from experiment 1 revealed equivalent, significant decrements in responsiveness of 102 adult male subjects to color and motion display manipulations, relative to the conspecific robot control. Findings also suggested that dewlap hue, not brightness, was responsible for reduced subject response to non-control dewlap colors. In experiment 2 we presented 93 different A. grahami males with conspecific or heterospecific (Anolis extremus) robots that performed their own, or the other species’, headbob displays. Results revealed species-specific body/dewlap coloration to be more important than headbob display structure for species recognition. Although more work is needed, our findings support the proposition that interspecific variation in color and motion displays provides important cues for species recogntition in anoles.

Central American Green Anoles Mating

display

Photo: Cesar Barrio-Amorós/ Doc Frog Photography

Cesar Barrio posted this quadtych on his doc frog facebook page. Taken from his balcony in Ojochal, Puntarenas province, Costa Rica, the photo shows Central American green anoles, A. biporcatus, mating in a cecropia tree. Other than the fact that it is a cool set of images, the photos show the dichromatism in dewlap color displayed by this species, which we’ve discussed previously, and also that the male changed color during the course of mating. I wonder why. It also illustrates that this species exhibits relatively little size dimorphism.

As a bonus, Cesar sent me a photo of the inhabitant of the next tree beyond the cecropia, an A. charlesmyersi strutting his stuff.

Photo: Cesar Barrio-Amorós/ Doc Frog Photography

Photo: Cesar Barrio-Amorós/ Doc Frog Photography

The Incomplete Guide To The Wildlife Of Saint Martin

yokoyamaMark Yokoyama’s second edition is now out, and available for download for free. Or, if you want to go old school, hard copies are available for purchase on Amazon.

The 128 page guide covers both the native and introduced fauna of Saint Martin, with more than 500 photographs and considerable treatment of invertebrates as well as vertebrates.

Of course, the most important subject of the book are the anoles, two native and two introduced, each of which gets a page. Mark has published previously on the introduced anolesA. sagrei and A. cristatellus. Both for the moment are restricted in range–to a resort complex and a cruise ship terminal,  respectively. If they expand their ranges–and I’m betting they will–it will be interesting to see how they interact with the native A. gingivinus, as well as each other.

The image below on A. pogus will give you a feel for the book. Certainly a must-have if you’re going to St. Martin, and a nice-to-have even if you aren’t.

pogus