Tag Archives: Anolis cristatellus

Tails of the City: Caudal Autotomy of Anolis cristatellus in Urban and Natural Environments

Lead author, Kirsten Tyler, reports on her recent Journal of Herpetology paper with K. Winchell and L. Revell:

Urbanization creates drastic changes to habitats leading to differences in microclimate, perch characteristics and distribution, and ecological communities (competitors, prey, and predators) when compared to natural (forest) habitats. Studies have found increased rates of mortality of many urban species due to generalist urban-tolerant predators such as raccoons, feral cats, and domestic animals (Ditchkoff 2006). Anolis lizards are able to voluntarily drop their tails (“autotomize”) when challenged by a predator, enabling their escape in many instances. The maimed lizards are able to regenerate their lost tails, though the replacement tail is a rod of cartilage and not the original bony vertebrae. The regenerated tail portions are often a different color and texture, and the lack of vertebrae / cartilage rod are clearly visible in X-rays.

We hypothesized that autotomy rates would be more similar between urban areas in different municipalities than to natural areas in the same municipality due to similar predator regimes in urban sites across the island. We compared the frequency and pattern (number of caudal vertebrae remaining) of caudal autotomy of A. cristatellus between urban and natural areas in Puerto Rico.

X-rays of our samples with an intact tail (A) and an autotomized tail (B).

X-rays of our samples with an intact tail (A) and an autotomized tail (B).

We sampled A. cristatellus from paired natural and urban sites in four Puerto Rican municipalities: San Juan, Mayagüez, Ponce, and Arecibo. The natural sites were high quality natural forests and the urban sites were high-density residential areas. Urban sites were dominated by asphalt and other impervious surfaces, had sparse tree cover, and a large fraction of potential perches were manmade surfaces such as walls and fences. We scored 967 X-rays from these eight sites for caudal autotomy and counted the number of remaining tail vertebrae. We tested for an effect of urbanization on caudal autotomy by fitting a logistic regression model with municipality (San Juan, Mayagüez, Ponce, Arecibo) and site type (urban, natural), and their interactions, as model factors, and body size as a covariate.

Our data shows that lizards found in urban sites have a larger probability of having autotomized tails.

Our data shows that lizards found in urban sites have a larger probability of having autotomized tails.

Interestingly, we found higher rates of autotomy in all urban populations compared to nearby natural areas. Differences in autotomy might be explained by differences in predator density and efficiency (Bateman 2011). For example, inefficient predators (those that more often than not fail to capture their prey) tend to leave behind more lizards with broken and regenerated tails (Schoener 1979). In addition, a greater abundance of predators could result in more predation attempts. Unfortunately, we did not collect data on predator abundances or community composition, so we cannot distinguish between these (non-mutually exclusive) explanations. Higher rates of autotomy in urban areas could thus reflect any of a variety of factors, including (but not restricted to) inefficient predators in urban areas, a shortage of refuges offering protection from predators, or an increase in predator density.

For lizards with autotomized tails, we found no significant difference in caudal vertebrae number between urban and natural sites.

For lizards with autotomized tails, we found no significant difference in caudal vertebrae number between urban and natural sites.

Lastly, we did not find that lizards with autotomized tails in urban areas had lost more (or less) of their original tail to caudal autotomy. Since regenerated tails cannot be autotomized past the original break point (i.e. cartilage cannot autotomize), this suggests that lizards in urban areas are no more likely to be subject to multiple unsuccessful predation attempts (resulting in caudal autotomy) than lizards in natural forest. Future investigation quantifying predation attempts or predator community composition in urban and forest habitats could help us better understand the source of this intriguing pattern.

 

Read the paper:

R. Kirsten TylerKristin M. Winchell, and Liam J. Revell (2016) Tails of the City: Caudal Autotomy in the Tropical Lizard, Anolis cristatellus, in Urban and Natural Areas of Puerto Rico. Journal of Herpetology: September 2016, Vol. 50, No. 3, pp. 435-441.

 

References:

BATEMAN, P. W., AND P. A. FLEMING. 2011. Frequency of tail loss reflects variation in predation levels, predator efficiency, and the behaviour of three populations of brown anoles. Biological Journal of the Linnean Society 103:648–656.

DITCHKOFF, S. T. 2006. Animal behavior in urban ecosystems: modifica- tions due to human-induced stress. Urban Ecosystems 9:5–12.

SCHOENER, T. W. 1979. Inferring the properties of predation and other injury-producing agents from injury frequencies. Ecology 60:1110–1115.

JMIH 2016: Escaping in the City

2016-07-10 09.00.19

Kevin Aviles-Rodriguez, from the Revell lab at U. Mass. Boston, gave the second urban anole-themed talk of the meeting. Kevin presented his Master’s thesis work that he conducted with the Kolbe lab at U. Rhode Island in a talk titled, “Structural habitat alterations caused by urbanization influence escape behavior of a common lizard.”

Urban habitats are drastically modified and present novel resources and threats for animals that persist and utilize these spaces. Structurally, urban habitats have different types of surfaces that are smoother, broader in diameter, and often more vertically oriented (90° angle). Urban habitats also present abundant and novel food resources in terms of human food and insects attracted to lights and garbage. But with the abundance of food and novel niche space also comes an abundance of novel predators such as cats and dogs kept as pets.

Kevin wanted to know how Anolis cristatellus from San Juan, Puerto Rico and South Miami behaved in urban habitats compared to forest habitats when perceiving a predation threat. Although there are obvious costs of not escaping a predator successfully, there are also costs of fleeing when not necessary in terms of lost feeding opportunities and disrupted social interactions (mating, territory defense). Kevin wanted to know if the urban environment influenced escape behavior decisions. Specifically, he had two objectives: (1) To quantify escape behavior (squirreling, jumping, or sprinting) and how this relates to different types of perches found in urban areas. (2) To measure flight-initiation distance (FID), or how close one can approach an animal before it flees, to see if there are differences between forest lizards and urban lizards.

2016-07-10 09.07.18Kevin found that as perch diameter increases, the probability that a lizard will squirrel around a perch or sprint up the perch increased and the probability of jumping decreased. Interestingly, when he also looked at perch use, he found that the majority of lizards were using perches of thinner diameter where the probability of jumping was highest. Urban lizards also tended to use more isolated perches, which he defined as the number of nearby potential perches within 1 meter. When nearby perch density was lower, lizards tended to jump less – perhaps not all that surprising since they have fewer places to jump to. Kevin also found that escape strategy differed based on the type of perch used. In urban habitats, on trees and on metal posts lizards squirreled more frequently than they did in forest habitats. Interestingly, on cement walls (e.g. buildings) lizards did not jump at all and mainly sprinted to escape. 2016-07-10 09.10.05Kevin offered a few possible explanations for this trend. For one, building perches tend to be more isolated than trees and so it may simply be that lizards on these substrates have nowhere to jump to. A second possibility is that the lizards have trouble jumping from these perches since they are more vertical than the optimal angle for jumping (39-42°, Toro et al. 2003).

In his final analysis, Kevin found that flight initiation distance (how close you can get to the animal before it flees) was very short for animals perched on urban trees and metal posts. In fact, he commented that on some occasions he was able to get close enough to touch the lizard before it fled! This difference was significantly shorter than for animals perched on trees in the forest and for animals perched on painted concrete walls in the city.

JMIH 2016: Phylogeography and Population structure of Anolis cristatellus

Quynh Quach presenting her Master's thesis work at JMIH.

Quynh Quach presenting her Master’s thesis work at JMIH.

Quynh Quach, a master’s student from the Revell Lab at U. Mass. Boston, presented her thesis research on “Phylogeography and Population Structure of Anolis cristatellus on the island of Vieques.” Before Quynh joined the Revell lab, former  post-doc Graham Reynolds and former Losos lab undergraduate Tanner Strickland looked at the phylogeography of Anolis cristatellus across Puerto Rico and the Virgin Islands using mitochondrial DNA (in review). Tanner’s work revealed that there was a mitochondrial break on the island of Vieques, just off the coast of Puerto Rico. The mitochondrial data suggested that there were two genetically different groups of A. cristatellus, one on the East and one on the West of Vieques. The only problem was, as we know, mtDNA patterns are not always supported by nuclear whole-genome DNA patterns. In addition, Tanner’s dataset only consisted of 9 samples from Vieques.

When Quynh joined the lab, she wanted to know more about this pattern. Would this division be supported by nuclear genome analyses? Were these lineages anthropogenically introduced? If not, what was the origin of these groups – historical allopatry followed by secondary contact or isolation by distance? So she set out to answer these questions by collecting 300 tail tips from across the island of Vieques, extracting and sequencing both mtDNA and nuclear DNA.

The mtDNA variation shows a strong geographic pattern.

The mtDNA variation shows a strong geographic pattern.

Quynh first constructed a mitochondrial phylogeny to verify the pattern observed by Tanner and Graham. The mtDNA analysis confirmed that there are 2 mtDNA clades on Vieques with strong geographic patterns. The island-wide pattern of mtDNA variation was not what we would expect if anthropogenic introduction were the cause since this would be unlikely to show such a clear East-West pattern with the small contact zone in the middle. So then how did this pattern arise?

2016-07-08 13.39.15

Analysis with K=2 shows two clear groups associated with the East and West.

To answer that question, Quynh next looked at nuclear DNA using RADseq. She sequenced 48 individuals: 5 from Virgin Islands, 6 from Puerto Rico, and 37 from Vieques, then de novo assembled the genome and called 16,808 SNP’s. She ran STRUCTURE and DAPC analyses on this data and found that the Virgin Island samples form 1 cluster and Puerto Rico and Vieques form a second cluster with 4.1% divergence between the groups. But she wondered, what if we look at just Vieques and specify K=2? When she did this with DAPC and saw a clear geographic pattern similar to what she found with the mtDNA. Finally, she tested whether this represented isolation by distance. She found that there was significantly reduced gene flow between geographically distant individuals, supporting this hypothesis as the most likely cause of the variation.

Lastly, Quynh emphasized that it is important to consider multiple genetic markers and not just rely on mtDNA results. Had the group stopped at their original mitochondrial analysis, they would have reached a very different conclusion.

City Slickers: Performance and Substrate Properties in Urban Anoles

Anolis cristatellus on a smooth, vertical substrate in Puerto Rico (photo by K. Winchell)

Anolis cristatellus on a smooth, vertical substrate in Puerto Rico (photo by K. Winchell)

In urban areas, the number of natural substrates (e.g. trees) is reduced. In their place are novel manmade substrates (e.g. walls, metal gates). These surfaces undoubtedly have different properties relevant to anole locomotion: they are smoother, harder, and (in the case of walls) much broader and flatter compared to natural surfaces in a forest. In urban areas lizards still use these substrates at high frequency, but do they do so effectively? Kolbe and co-authors began to dive into this complex topic in their recent publication, “City slickers: poor performance does not deter Anolis lizards from using artificial substrates in human-modified habitats” (Kolbe et al. 2015).

The relationship between habitat use, morphology, and performance for anoles has been extensively studied in natural environments (reviewed in Losos 2009). Urban environments add new dimensions to this area of research. Resource distribution and abundances differ drastically compared to natural areas. For example, the distribution of available perches and what they are made of in urban habitats is very different from a forest. Moreover, the properties of these resources differ drastically as well: urban substrates are smoother, broader, and have different thermal properties, to start. Understanding these differences in habitat use and how they influence performance and, ultimately, adaptive responses in anoles is the topic of ongoing collaborative research that I (K. Winchell) and the Kolbe lab  have been conducting.

Continue reading City Slickers: Performance and Substrate Properties in Urban Anoles

On the importance of Dorsal and Tail Crest Illumination in Anolis Signals

With a flurry of recent attention investigating how background light may influence the signalling efficiency of Anolis dewlaps (1,2,3,4), particularly those inhabiting low-light environments where patches of sunlight appear at a premium, it occurred to me that extended dorsal and tail crests may fall under similar selection. Below are some photos of Puerto Rican crested anoles (Anolis cristatellus) – a species in which males exhibit an enlarged tail crest and the ability to voluntarily erect impressive nuchal and dorsal crests during aggressive interactions (the mechanisms of which are detailed in this previous AA post) – that show how crests may contribute to signalling.

IMG_3833

I have no doubt this thought has crossed the minds of many anole scientists before, particularly those current graduate students so successfully studying A. cristatellus and familiar with their ecology and behaviour (namely Alex Gunderson, Kristin Winchell, Matt McElroy, and Luisa Otero). Dewlaps are undoubtedly of primary importance to anole signalling and communication, but what are people’s general thoughts on the relative importance of other morphological features?

IMG_3842

Get a Grip on It! Cling Force and Perch Diameter

An actual perch used by Anolis cristatellus - neither smooth nor flat! (photo by K. Winchell)

An actual perch used by Anolis cristatellus – neither smooth nor flat! (photo by K. Winchell)

In the real world, lizards cling to everything from smooth, flat concrete walls to rough,  rounded tree trunks. So why is it that most studies on cling force in anoles focus on clinging to smooth flat substrates? Does cling force differ if the substrate is rounded or rough? Jason Kolbe sought to answer this question in his recent publication, “Effects of Hind-Limb Length and Perch Diameter on Clinging Performance in Anolis Lizards from the British Virgin Islands” (Kolbe 2015).

We know that morphology impacts performance in anoles and that performance varies with environment. For example, sprint speed is correlated with limb length, but this relationship depends on the diameter of the substrate (e.g. Losos and Sinervo, 1989). We also know a little about clinging performance in anoles. Greater cling force is correlated with larger toepads and more lamellae on smooth flat surfaces (Irschick et al., 1996; Zani 2000; Elstrott and Irschick, 2004), but adhesion on rougher surfaces may be influenced by claw and toe morphology (Zani 2000).

There appears to be an unexplored interaction between substrate properties and clinging ability that involves more than just toepad characteristics. Specifically, Kolbe points out that claws can increase clinging ability by digging into the perch or simply by increasing friction on the surface. Limbs can also increase friction via the application of compression forces to the substrate. In other words, cling force can be increased, particularly on rough surfaces, by using muscular force to grasp rather than relying on van der Waals forces from the toepads, which are more effective on smooth flat surfaces.

Anole species used in this study: Anolis cristatellus (left) and Anolis stratulus (right). Photos by K. Winchell.

Kolbe investigated this further by looking at the interaction between limb length and clinging ability on perches of different diameters with Anolis cristatellus and Anolis stratulus from the British Virgin Islands. Specifically, he hypothesized that cling force should increase as the ability of a lizard to obtain a firm grasp on a substrate improves (i.e. when it can wrap its limbs around the substrate). This ability to form a secure grasp is dependent on both the diameter of the perch and on lizard limb length. Continue reading Get a Grip on It! Cling Force and Perch Diameter

To Eat or Be Eaten: How an Anole Decides When to Forage

Anolis cristatellus in survey posture (photo by K. Winchell)

Anolis cristatellus in survey posture (photo by K. Winchell)

Foraging decisions are the result of a complex decision-making process involving intrinsic factors (physiology, body condition, cognitive ability, sex, ontogeny, etc.) and environmental factors (food availability, structural habitat, presence of predators and competitors). In short, it comes down to the tradeoff between the benefits of energetic gain and the potential costs of predation risk, missed opportunities for reproduction, and expended energy. However, little is known about the specifics of this process – what information are lizards considering when making this decision? By conducting manipulative field experiments on Anolis cristatellus in Puerto Rico, Drakeley et al. (2015) attempt to elucidate what environmental factors influence the decision to forage.

The authors conducted field experiments involving feeding trays in the wild. The Puerto Rican crested anole is a trunk-ground anole and a sit-and-wait forager. When receptive to feeding, it perches head down in “survey posture,” a behavior it reduces when satiated. Aside from movement associated with foraging and social interactions, this species typically remains stationary on a perch. Because of this, the authors were able to easily locate a focal individual and count the number of conspecifics present, using natural variation instead of manipulating the number of animals present.

In the first experiment, they manipulated the food quantity to determine how foraging decisions differ when food is plentiful versus scarce and how this is influenced by the presence of competitors. They found that lizards foraged faster when there were more conspecifics present and food was scarce. When no lizards were near the feeding tray and the feeding tray was full, the focal animal took longer to approach the tray to take the mealworms compared to when there were many conspecifics nearby. Interestingly, this was not related to overall local density, but rather to the number of conspecifics in the immediate vicinity. Therefore the decision to forage likely involves an instantaneous assessment of the local conditions rather than knowledge of the long-term population trends. The authors also considered several other factors and found that although body size was related to foraging latency (larger lizards were quicker to the feeding tray), no other environmental factors were relevant (temperature, humidity, perch height, perch diameter, local density of conspecifics).

Figure 1 from Drakeley et al. (2015). Latency to feed was correlated with the number of conspecifics present and abundance of food.

Figure 1 from Drakeley et al. (2015). Latency to feed was correlated with the number of conspecifics present and abundance of food.

In the second experiment, the authors chose focal animals farther from the feeding trays and considered distance as a proxy for predation risk. The farther the lizard was from the tray, presumably the greater exposure it had to predators as it moved towards the tray. They found that under this scenario, when risk was elevated, there was more latency in the approach of the food tray. This effect was driven mainly by the increased use of intermediate perches rather than a direct approach across open ground. Increased latency to feed was observed regardless of how abundant the food was or how many conspecifics approached the tray, supporting the conclusion that this effect was because of the perception of greater predation risk (i.e. movement over a longer distance). They also found that larger lizards had a lower latency to feed (approached the feeding tray more rapidly) and lizards not in the foraging position had a longer latency to feed.

In summary, it seems that anole foraging decisions are quite complex. Lizards appear to weigh the risk of predation taking cues from conspecific behavior and abundance versus the abundance of food to make instantaneous decisions to approach a novel feeding source.


 

Drakeley M, Lapiedra O, Kolbe JJ (2015) Predation Risk Perception, Food Density and Conspecific Cues Shape Foraging Decisions in a Tropical Lizard. PLoS ONE 10(9): e0138016. doi:10.1371/journal.pone.0138016

Evolution 2015 Recap

Logo for the Evolution 2015 conference.

Evolution 2015 is officially over and we have all sadly left beautiful Guarujá,  Brazil. There were a lot of great talks and posters and a great representation of South American students and researchers. For coverage on the conference as a whole, check out #evol2015 on twitter! The herps were few and far between (I only saw 2 in my 16 days in Brazil!) but the posters and talks on herps were numerous. Unfortunately, anoles were poorly represented at Evolution this year with only three anole talks and a couple of others that briefly highlighted anoles. If you weren’t able to make it to Brazil, I’ve got the recap for you here.

click to read more about Travis Hagey's research

A glimpse at the variation in gecko toepads

Starting off in one of the first sessions was a talk by Travis Hagey titled “Independent Origins, Tempo, and Mode of Adhesive Performance Evolution Across Padded Lizards.” Although his talk was mostly about geckos, he did shine the spotlight on anoles for a few minutes. He focused on the phylogenetic pattern of toepad adhesion in pad-bearing lizards: geckos, skinks, and anoles. Specifically he looked at how clinging ability (measured as angular detachment – check out one of his videos showing this) varied within and among clades. Unsurprisingly, he found that anoles don’t cling nearly as well as geckos. He also demonstrated that gecko toepad diversification best followed a Brownian motion model with weak OU and anole toepad diversification was best fit by a strong Ornstein–Uhlenbeck process. In other words, gecko toepads diversified slowly over a very long period while anoles were quickly drawn towards an optimum over a short time-period. Travis concluded that these patterns explain why there is a large amount of diversity in gecko toepads but not in anole toepads.

Next up was Joel McGlothlin, who also gave a non-anole talk titled “Multiple origins of tetrodotoxin‐resistant sodium channels in squamates.” Continue reading Evolution 2015 Recap

Great Egret Eating a Crested Anole in Miami, FL

Here is a video taken by University of Miami PhD student Joanna Weremijewicz at the Fairchild Tropical Botanical Gardens in Miami, FL last Friday (20th March 2015). There have been lots of posts talking about the predation potential of egrets (and other wading birds) on anoles here on AA similar to this (1,2,3,4), but I think this could be the first one recording predation of A. cristatellus? Cool video!

Fill In The Blank: Obscure Anole Life History Traits

In collaboration with the Conservation Biology course taught by Dr. Karen Beard here at Utah State University, where I am a Ph.D. student, I have been involved in gathering life history data on ~400 species of reptiles that have been introduced outside of their native ranges for an analysis of how life history traits (e.g., diet, fecundity, longevity) interact with other factors to influence the likelihood of successful establishment. Appendix A of Fred Kraus’ 2009 book Alien Reptiles and Amphibians is the source of the species list we are using, and included in this analysis are 26 species of Anolis. This is where you come in.

First, we coded all anoles as (i) sexually-dichromatic, (ii) diurnal, (iii) non-venomous, (iv) oviparous, (v) omnivores that lack (vi) temperature-dependent sex determination and (vii) parthenogenesis. Is anyone aware of any exceptions to these seven generalizations?

Second, we searched for data on clutch size, clutch frequency, incubation time, and longevity. The Anole Classics section of this site and the Biodiversity Heritage Library were particularly useful. After conducting what I feel to be a pretty thorough literature scavenger hunt, I am forced to conclude that some of these data simply do not exist at the species level for all of the species we’re interested in, or are not explicitly stated in a way that is obvious to a non-anole-expert. Of course, there is a lot of literature, including many books that I don’t have access to, and there are also lots of credible observations that don’t get published. I’m hoping that some of the readership here can help fill in at least some of the blanks in the table below. As one member of the team, I did not collect all of the data that are filled in myself, nor have I personally vetted every value, so if you spot an error please do point it out.

Two important points:

  1. Many environmental factors obviously influence the life history parameters of our beloved and wonderfully plastic reptiles, so we appreciate that many of these values would be better represented by ranges and are dependent on latitude, altitude, climate, and many other factors. Where a range is published, we are using its median value.
  2. I should also emphasize that, because of the large size of this study and the diversity of taxa included (ranging in size from giants like Burmese Pythons, Nile Crocodiles, and Aldabra Tortoises to, well, anoles and blindsnakes), it is more important for the data to reflect the relative values of these life history parameters across all anoles (and all reptiles) than it is to specifically and precisely represent all known variation within a given species of anole.

Without further ado (for your enjoyment, and because I know from my own blog that nobody reads posts lacking pictures, I’ve embedded an image of each species):

Species Median clutch size Median clutches per year Incubation time (days) Maximum longevity (months)
A aeneus
A. aeneus
2
A baleatus
A. baleatus
A bimaculatus
A.bimaculatus            
2 43 84
A carolinensis
A. carolinensis
1.15 6  41.5 65
A chlorocyanus
A.chlorocyanus
1 18
A conspersus
A. conspersus
1
A cristatellus
A. cristatellus
2.5 18 83
A cybotes
A. cybotes
1 18 45
A distichus
A. distichus
1 16 45.5
A equestris
A. equestris
1 1 48 149
A extremus
A. extremus
A ferreus
A. ferreus
1 18
A garmani
A. garmani
1.5 18 67
A grahami
A. grahami
1
A leachii
A. leachii
A lineatus
A. lineatus
A lucius
A. lucius
1 3.5 60
A marmoratus
A. marmoratus
2  50
A maynardi
A. maynardi
A porcatus
A. porcatus
1 18 63.5
A pulchellus
A. pulchellus
1
A richardii
A. richardii
1
A sagrei
A. sagrei
2 20  32 22
A stratulus
A. stratulus
A trinitatis
A. trinitatis
2  50
A wattsi
A. wattsi
1

Thanks in advance. I think this is a great blog and I hope to post something more interesting on here soon.

A Second Front in the Sagrei-Cristatellus Wars: Anolis Sagrei Arrives in Costa Rica

Not content with kicking butt in Florida, Anolis sagrei has recently been reported from the Caribbean coast of Costa Rica. Photo by Melissa Losos.

Anole Annals has previously reported on the ongoing interactions between A. cristatellus and A. sagrei in Miami (for example, here and cool video here), as well as the invasion of Costa Rica by A. cristatellus. Now the plot has thickened.

In a 2009 paper in Zootaxa, Savage and Bolaños reported that A. sagrei had been collected in the vicinity of Limon, the same region in which A. cristatellus also has been introduced. Jay Savage has kindly provided further information that A. sagrei is not only common in some parts of central Limon, where A. cristatellus is also known to be common, but it is also reported to be common at a Shell gas station in the nearby town of Moin, a town in which, again, A. cristatellus is common. It will be interesting to see how rapidly A. sagrei spreads in Costa Rica, and how the two species interact. One interesting twist: in Miami, it is A. cristatellus that has invaded in the presence of an already well-established A. sagrei; in Costa Rica, the table is turned. There’s a great research project waiting to be done here!

Thermal Ecology of Anolis cristatellus

The recent literature has been full of doom and gloom regarding the prospects for lizard survival in the face of global climate change (e.g., Sinervo et al. 2010).  A talk by Alex Gunderson from Manuel Leal’s lab at Duke University provided some important new insights on how our favorite lizards are likely to weather this storm.  Gunderson investigated thermal ecology of Anolis cristatellus at nine localities, including four mesic and five xeric locales.  His data included thousands of field collected temperature records from live animals and copper models as well as data on preferred body temperature and sprint speed performance across a range of temperatures.  Temperature data from live animals and co-distributed copper models showed that the xeric, but not the mesic, populations are behavioral thermoregulators that tend to be found in cooler spots than the randomly placed copper models.  Even with the benefit of behavioral thermoregulation, the xeric forest lizards were consistently active at temperatures that exceeded their preferred body temperature.  When Gunderson integrated these findings with data on sprint speed performance and climate change, he found that the xeric forest animals are likely to suffer significant reductions in performance associated with climate change.  Gunderson ended with a teaser by showing that he has accumulated comparable data on performance across a range of temperatures for all the other Puerto Rican anoles.  Next year’s talk should be a blockbuster!

Sagrei – Cristatellus Interactions in Miami

Anolis cristatellus in Miami. Photo by Melissa Losos

In his spare time, photographer and  film-maker extraordinaire Neil Losin doubles as a graduate student studying the ecological interactions between introduced trunk-ground anoles A. sagrei and A. cristatellus in Miami. He’s just begun his third field season, and you can read all about it here.

The Ability of Anoles to Acclimate to Dry Conditions

Lizard in an Evolutionary Tree's reworking of Williams' classic figure. Note that A. gundlachi is a trunk-ground anole, not, as indicated, a trunk-crown anole.

In this famous figure, Ernest Williams sketched out his view of how anole diversification occurred on the Greater Antilles, using Puerto Rico as an example. First, species diverge to use different structural habitat, producing the different ecomorphs. Subsequently, within-ecomorph divergence produces species that use the same structural habitat, but which occupy different climatic micro-climates, ranging from cool and moist rainforest to blazing hot and dry semi-desert. This two-stage pattern of evolution is displayed not only on Puerto Rico, but also on Cuba and Hispaniola (Jamaica, the most species deprived island, has little within ecomorph diversity).

In contrast to the plenitude of research in recent years on the adaptive basis of morphological differences among the ecomorphs, relatively little work has focused on the extent to which closely related species—members of the same ecomorph class—have adapted to occupying different microclimates. Continue reading The Ability of Anoles to Acclimate to Dry Conditions

Introduced Herps of the Caribbean

The knight anole, Anolis equestris, gets around more than you might think. Photo by Neil Losin.

 A new, two-volume set on the conservation of Caribbean herps has just been published. More on that in a minute, but let’s cut to the important stuff. There’s a great summary of the record of anole introductions (discussed previously a number of times on Anole Annals, such as here, here, here and here) in an article by Bob Powell and others. Here’s what they have to say about anoles:

Anoles (family Polychrotidae). Anoles are highly diverse (Losos, 2009), quite adaptable, and often function as human commensals. Many species in the region exploit buildings, ornamental plants, and the night-light niche (e.g., Henderson and Powell, 2001, 2009; Perry et al., 2008; Powell and Henderson, 2008). Some are colorful and available in the pet trade (e.g., Kraus, 2009), but nearly all introductions within our region were inadvertent and attributable to stowaways in cargo such as building materials and ornamental plants.

Anolis cristatellus is native to the Puerto Rico Bank and was the only anole that made the list of most successful colonizing species (Bomford et al., 2009). Continue reading Introduced Herps of the Caribbean

Results of the Costa Rica cristatellus Expedition

Map from http://www.costaricamapproject.com/InfoMaps/topographic.html

I’ve completed the brief survey of the distribution of A. cristatellus in Costa Rica (see previous post for explanation).  The work was hampered by rainy and cool weather.  Nonetheless, several new localities were identified.  In particular, we found cristatellus in Bribri, very close to the Panamanian border.  We actually went to the border town of Sixaolo, and even walked across the bridge, setting foot in Panama for a full 90 seconds (border officials apparently routinely allow tourists across the border to take a photo).  However, by that time, the weather was very overcast and cool, and no lizards were out.  Were I a betting man, I’d wager that cristatellus is already in the land of the canal. Continue reading Results of the Costa Rica cristatellus Expedition

Looking for the Puerto Rican A. cristatellus in Costa Rica

Anolis cristatellus in the front yard of a house in Turrialba.

I’ve just arrived in Limon, a port town on the Caribbean coast of Costa Rica, to track the spread of the introduced species A. cristatellus.  Several realizations occurred to me as we wended our way down the mostly beautiful road from San Jose.  First, I realized that not only have I seen cristatellus in its native range of Puerto Rico and the Virgin Islands, but I’ve also seen introduced populations in Miami and the Dominican Republic, as well as here.  This species gets around!  Continue reading Looking for the Puerto Rican A. cristatellus in Costa Rica