Many Ways to Achieve an Anole-Like Extendable Dewlap

HagmanOrd_56650Fig1

Different phenotypic forms often serve the same functional outcome. A classical textbook example is the evolution of the wing in dinosaurs, birds and bats. This implies that organisms can respond in a variety of comparable ways to selection and that the same selection pressure thus can produce phenotypic diversity. Terry Ord and I have an early view paper in the American Naturalist that shows that an anole-like dewlap has evolved repeatedly in iguanids (Anolis) and agamids (Draco, Sitana, and Otocryptis), but in each case through different modifications to the underlying hyoid, which is the structure that powers the extension of the dewlap. The main point of difference among hyoid morpho-types, and also the component critical for the evolution of an extendible dewlap, is the angle between a short perpendicular structure called the hypohyal (see the figure) and a longer structure called the second ceratobranchial, which runs along the edge of the extended dewlap. There is also significant variation in the relative lengths of the same structures.

 

Other lizard species have converged around other hyoid morpho-types (our analysis identified a total of eight separate hyoid morpho-types). Interestingly we found evidence for convergence in hyoid morphology among species from distantly related genera, such as Polychrus, Gonocephalus and Trapelus. Species from these genera lack the large dewlap type found in Anolis and Draco, although the hyoid morpho-type of the two groups show some gross similarities. We suggest that the hyoid morpho-type of Polychrus, Gonocephalus and Trapelus might represent what an intermediate step looks like in the evolution of an extendable dewlap. More generally, our study shows that multiple adaptive solutions have been possible in apparent response to a common selection pressure, and that the phenotypic outcome that subsequently evolved in different genera seems to have been contingent on the history of the group in question.

Cayman Islands Anolis Research

Amy in the field working on her first noose capture.

Amy in the field working on her first noose capture.

The following was written by Amy Castle, an undergraduate and Summer Research Fellow in the Reynolds Lab at the University of North Carolina Asheville.

This past May, I had the opportunity to join Dr. Geneva and his team in the Cayman Islands to assist with his research on Anolis sagrei. Along with my mentor, Dr. Graham Reynolds, we were able to spend several days on both Little Cayman and Grand Cayman catching anoles, collecting data, and experiencing the tropics. This experience (my first in the tropics) provided me with an immersive education in both Caribbean herpetology and the ins and outs of working in the field. My adventure began when Dr. Reynolds and I flew to Grand Cayman and then took a small plane to Little Cayman, which is approximately 100 km northeast from Grand Cayman. Flying over these islands gave a good perspective of the topography and available habitat for the lizards. Most of the former island, which is only 16km long and 3 km wide, is lightly inhabited and dominated by tropical coastal coppice forest developed over a limestone base. On the ground, I quickly discovered that the anoles are everywhere!

Dr. Geneva’s research focuses on Anolis sagrei, in particular, the extent of variation in the species across its wide range. We were on Little Cayman to get data from this island as a component of a larger study, described in lots of previous AA posts (Eleuthera, Cayman Islands, Rum CayConcepcion IslandRagged IslandBiminiMangrove habitat, and Great Isaac Cay).

Little Cayman Anolis sagrei.

Little Cayman Anolis sagrei.

These beautiful brown anoles were abundant day and night on the island and could be frequently found at eye level on the trunks and branches of mangrove and seagrape trees. They have brightly colored red-orange dewlaps, short snouts, and a smaller body size, especially when compared to their sympatric congener Anolis maynardi. Anolis maynardi,  large green anoles native to Little Cayman, are often found higher in the trees and have green dewlaps with a yellowish tint.

 

Little Cayman Anolis maynardi.

Little Cayman Anolis maynardi.

During the few days we were on Little Cayman, the weather was really hot and humid. During the heat of the day, A. sagrei ventured deeper into the brush of the forest making it difficult to trudge through the trees without scaring them off. We were, however, able to capture them from several feet away by using an extendable fishing rod with a tied noose at the end. This was my first experience noosing lizards, but after a few tries, I was consistently able to catch individuals. At night, the anoles were much easier to capture. Using our lights and headlamps, we could simply pluck them off the leaves and branches where they were sleeping.

Grand Cayman Anolis conspersus.

Grand Cayman Anolis conspersus.

After finishing data collection on Little Cayman, we headed to Grand Cayman to obtain export permits. I had the opportunity to see much of the island, including the endemic Anolis conspersus. These beautiful anoles have a large degree of color variation across Grand Cayman, and we were able to see at least two of the major color morphs. I was also able to meet some great people (Jessica and Jane) at the Department of Environment, who mentioned that they were finding non-native anoles on Grand Cayman. This developed quickly into a project idea- one of my research projects so far this summer is examining the DNA of these unknown anoles to try to determine what species they actually are and where they came from. A little bit of forensic genetics!

Graham Reynolds and Amy on Little Cayman.

Graham Reynolds and Amy on Little Cayman.

This experience gave me an exclusive look into the world of Caribbean field herpetologists, and was really valuable as I am currently an undergraduate studying Ecology and Evolutionary Biology. I am particularly interested in the Cuban green anole clade, and my research with Dr. Reynolds focuses on Anolis fairchildi, an endemic species found on Cay Sal Island in the Bahamas. I am currently generating genetic data from this species and other members of the clade in order to examine the phylogenetic affinities of A. fairchildi relative to other Cuban green anoles. This trip gave me the opportunity to not only observe wild  A. maynardi, a relative of A. fairchildi, but also to understand the complex relationships between sympatric anole species. It is one thing to study anoles “at the bench” in Asheville, but being able to join Dr. Geneva and his team in the field has really sparked my understanding of, and interest in, these fascinating animals.

 

Introduced Anolis species in Tenerife (Canary Islands, Spain)

Anolis carolinensis (left) and A. porcatus (right), introduced to Tenerife, Canary Islands. [Left photo by G. Frías García; Right photo extracted from Neotropico Foundation].

Female green anole (Anolis carolinensis) photographed in June 2016 in Golf Las Americas (28°03 ̍43.5 ̎N, 16°43 ̍06.3 ̎N), in Tenerife island (Canary Islands, Spain) [left picture; uploaded to Facebook by: G. Frías García].; Right photo extracted from Neotropico Foundation].

In August 2013, a Cuban green anole (A. porcatus) was collected and given to insular authorities in the same locality [right picture; extracted from Fundación Neotropico]. According to this foundation, a small reproductive population of the Cuban green anole was established there at that time for some years. No precise data exist on the individual abundance or distribution of any of these species even though they could become invasive at some point and impact the natural ecosystems of these highly biodiverse islands. There is a lack of information on how these species have arrived to Tenerife, although they might be related to the commerce of plants to the islands, which are mainly imported to create tropical-looking gardens in touristic areas. According to the Invasive Species Database of the Canary Islands, other species of anoles such as A. sagrei, A. allogus and A. equestris have been reported at least once in the Canary Islands, all of them in Tenerife. 

Risque Anole Bachelorette Party Cake

cakeWe’ve seen anole wedding cakes and thesis defense cakes, but here’s a new one. Anole research veteran Natalie Jacewicz reports:

For my bachelorette party, my bridesmaids went to an erotic bakery (quite the business niche) in Boston and brought the shop pictures of Anolis lizards. The bakery evidently usually deals in, er, human encounters, so only had skin-toned frosting, and the store clerks weren’t sure if they could do anything lizard themed. But the shop owner evidently got really into the project, did a lot of independent anole research, and produced the cake below. Yes, that is a bridal veil on the yellow one.

Some Thoughts on Display Evolution in Fan-Throated Lizards

Some weeks ago, a paper I wrote on the display behaviour and morphology of fan-throated lizards was published early online at the Journal of Herpetology. Some unfortunate timing meant that my paper did not incorporate these lizards’ new taxonomy, recently published by V. Deepak and colleagues. In this post, I’m going to summarize my results, and explore them in the context of what we now know about Sitana (Agamidae) systematics.

Male fan-throated lizards (surprise, surprise) have fans under their throats that are displayed in a manner analogous to the Anolis dewlap. The appearance of the throat-fan varies dramatically across this group, from small and mostly white to large and blue, black, and orange. I wanted to answer two broad questions

  1. Does display behaviour vary with throat-fan morphology? In other words, if you have different tools with which to communicate, do you communicate differently?
  2. Can we examine morphological and environmental variation to deduce anything about how this variation in throat-fan morphology has evolved?
Figure 1 from my paper, showing sampled sites and throat-fan variants.

Figure 1 from my paper, showing sampled sites and throat-fan variants.

To address these two questions, I measured the display behaviour, morphology, and environment of eight populations of lizards, from three “throat-fan variants.” I found the following:

  1. The main axis of variation in display behaviour differed between the coloured-fan variant and everybody else. Displays were fewer and longer in the coloured-fan variant, and included more head twists. The same axis of display behaviour did not differ between the white-fan and the intermediate-fan variants, though there was variation in the frequency of head-bobs across populations with different-sized throat-fans. These differences in display behaviour make sense in light of morphology. Head twisting was more frequent in the variant with a large blue section on the throat-fan that appears iridescent. Head-bobs, which often co-occur with a fully extended throat-fan, were more frequent in the variant(s) with smaller throat-fans (see Figure 6 in my paper for more).
  2. Throat-fan elaboration (both size and colour) was paired with increased male-biased sexual size dimorphism, suggesting sexual selection as a likely selective force driving throat-fan variation.
  3. Habitat structure did not co-vary with throat-fan morphology, suggesting that the visual environment is unlikely to play much of a role in the maintenance of this variation in throat-fan morphology. But because these lizards all persist in human-modified landscapes, it is difficult to discern how important the visual environment was for the origin of dewlap diversification in this group.
Figure 2 from Deepak et al. 2016.

Figure 2 from Deepak et al. 2016.

Based on geography, I can tell that all three of the coloured-fan variant populations I sampled belong to the newly described Sarada darwinii. The white-fan populations are Sitana laticeps and Sitana spinaecephalus (+ one population I’m not sure about), and the northern and southern intermediate-fan populations are Sitana ponticeriana and Sitana visiri respectively. Recast in terms of these species delimitations, I found that:

  1. Display behaviour differs between the genera Sitana and Sarada. It doesn’t vary consistently with species within Sitana, though variation in head-bobbing should be explored further.
  2. There are two broad possibilities for throat-fan evolution in the group. One possibility is that throat-fan elaboration and a shift towards male-biased SSD has evolved independently twice, once in Sarada (Clade 1) and once in the South India/Sri Lanka clade (Clade 3 in the phylogeny) in Sitana. The other possibility is the reduction of dewlap size and colour in the west Indian Sitana clade (Clade 2). This question won’t be definitively answerable until we have a phylogeny that includes the remaining north-eastern species of Sitana as well as more species of the sister genus Otocryptis, which also vary in the presence and morphology of the throat-fan.

Before knowing about the phylogeny, I predicted that throat-fan elaboration had evolved twice in fan-throated lizards, based on a suite of differences between the coloured-fan variant (now Sarada) and the intermediate-fan variant (now Sitana Clade 3). The main ones are:

  1. Different display behaviour.
  2. Different allometric relationships between body size and throat-fan size, suggesting different ways in which throat-fans have gotten big.
  3. Different spectral reflectances from the blue and orange patches, plus the presence/absence of black on the throat-fan.
  4. The ability of Sitana, but not Sarada, to turn “on” and “off” the blue colour on their throat-fans (more about this in a future post!).

These differences now lead me to favour the first of the two possibilities outlined above: repeated, somewhat parallel evolution of throat-fan elaboration, as opposed to the loss of an elaborate throat-fan. Given that the sister genus Otocryptis has also either evolved or lost a throat-fan (throat-fans are present in O. nigristima and O. wiegmanni but not O. beddomi), this group is positively rife with lability in display evolution, offering all sorts of exciting possibilities for future research!

Musings on the Lizards, Snakes and Other Herps of Florida

Photo by Janson Jones

Janson Jones is at it again. Actually, he’s been at it for a year, but somehow that slipped below our radar. The former purveyor of Dust Tracks on the Web has a new venue, phosTracks.com: florida wildlife, ecology and more.

Like it’s predecessor, phosTracks is full of keen natural history, engagingly presented and complemented by gorgeous photography. And better yet, anoles are one of Jones’ two favorite animals, neck-and-neck (hard as it may be to believe) with watersnakes.

Check out some of Jones’ recent musings on:

curly-tailed lizards:

Photo by Janson Jones

red-headed agamas:

Photo by Janson Jones

Anolis cristatellus:

Photo by Janson Jones

and more! Stay on these pages for some of his giant anole goodness coming up soon!

JMIH 2016: Genetic Evidence of Hybridization between the Native Green Anole (Anolis carolinensis) and the Invasive Cuban Green Anole (A. porcatus)

Photo by James Stroud

Photo by James Stroud

At JMIH 2016, I chatted with Johanna Wegener, a graduate student at the University of Rhode Island in Jason Kolbe’s lab, about her poster detailing her work identifying hybridization between Anolis carolinensis and A. porcatus in southern Florida.

Interspecific hybridization in anoles is thought to be fairly rare, with the best-known example being hybridization between Anolis carolinensis (native to the southeastern U.S.) and A. porcatus (native to Cuba) in southern Florida. I was surprised to learn how little we know about this rumored hybrid zone.

A. porcatus was likely introduced into Florida within the last few decades, but the striking morphological similarities between A. carolinesis and A. porcatus make anecdotal reports of hybridization hard to confirm. Wegener conducted the first genetic analyses of hybridization between A. carolinesis and A. porcatus. She genotyped 18 nuclear microsatellites from green anoles in Florida (Palm Beach and South Miami) and western Cuba and conducted a STRUCTURE analysis and found support for three genetic clusters consisting of Cuban A. porcatus, and two Floridian groups (one from Palm Beach and one from South Miami). With the addition of the mitochondrial ND2 marker, she found that the South Miami population had both A. carolinensis and A. porcatus haplotypes. Interestingly, there appeared to be very few recent hybrids; instead, the hybrid group appeared distinct from either parent group, suggesting that hybridization has been occurring for several generations.

In addition, Wegener looked at the variation in A. porcatus and A. carolinensis markers in each hybrid individual and found examples of some parent markers being retained at high proportions in the hybrids, possibly suggesting the retention of beneficial parent alleles in the hybrids.

Given that this study was only conducted at two sites in Florida, the exciting next step of this study is to better quantify the genetic makeup of hybrids across southern Florida and map out the hybrid zone.

Detecting the Small Island Effect and Nestedness of Anoles of the West Indies

Figure1. Saddled anole on a fallen tree trunk, Guana Island of the British Virgin Islands.

Figure1. Saddled anole on a fallen tree trunk, Guana Island of the British Virgin Islands.

De Gao and Gad Perry have recently detected the small island effect (SIE) and nestedness patterns of Anolis Lizards of the West Indies. We applied regression-based analyses, including linear regression and piecewise regressions with two (two-slope function and left-horizontal with one threshold function) and three (three-slope function and left-horizontal with two thresholds function) segments, to detect the SIE and then used the Akaike’s information criterion (AIC) as a criterion to select the best model. We used the NODF (a nestedness metric based on overlap and decreasing fill) to quantify nestedness and employed two null models to determine significance. Moreover, a random sampling effort was made to infer about the degree of nestedness at portions of the entire community.

Figure 2. SAR

Figure 2. SAR

Figure 3. Nestedness

We found piecewise regression with three segments performed best, suggesting the species–area relationships (SARs) possess three different patterns that resulted from two area thresholds: a first one, delimiting the SIE, and a second one, delimiting evolutionary processes. Moreover, the traditional two-segment piecewise regression method may cause poor estimations for both slope and threshold value of the SIE. Thereby, we suggest previous SIE detection works that conducted by two-segment piecewise regression method, ignoring the possibility of three segments, need to be reanalyzed. Anti-nestedness occurred in the entire system, whereas high degree of nestedness could still occur in portions within the region. So, nestedness may still be applicable to conservation planning at portions even if it is anti-nested at the regional scale.

Notes from the Field: Predation on Anolis sagrei on Isolated Cays in Abaco, Bahamas

Curly tail with brown anole tail visible from its mouth

Curly tail with brown anole tail visible from its mouth

Kayaking to the cays

Kayaking to cays

I was recently in Abaco, Bahamas with Losos lab post-doc Oriol LaPiedra and Ph.D. candidate Darío Fernández-Bellon from University College Cork, Ireland, to carry out some behavioral studies of Anolis sagrei on the island and its surrounding small cays. We kayaked (a highly recommended transportation mean for its lesser-impact on the marine ecosystem, not having to rely on the tide schedule, while allowing you to see rays and sharks and sea turtles!) our way out to islands that are known to have A. sagrei naturally existing alone, or with one of their natural predators, Leiocephalus carinatus.

Curly-tailed lizards are known to prey on A. sagrei and can have significant impact on anole behavior and adaptation. Twice I observed Leiocephalus capturing and consuming A. sagrei, one of which was an adult male and the other an adult female. We have also noticed that the A. sagrei on these island tend to perch higher and are seldomly seen on rocks or leveled ground compared to those on islands without curly tails, so this behavior could be an effect of Leiocephalus being present.

A female red-winged blackbird with a brown anole in its beak

A female red-winged blackbird with a A. sagrei in its beak

On a different island where Leiocephalus were absent, A. sagrei are still under predation pressure, this time by red-winged blackbirds nesting on the island. We observed a female blackbird with an A. sagrei in its beak waiting for us to leave the island so that it can feed its chicks. This observation suggests that A. sagrei on islands without Leiocephalus might still be under predation pressure by other species that might not be present on the island at all times. Also, predation pressure exerted by an aerial predator differs from that by a terrestrial predator or if both predators are present, so this might be a factor in morphological or behavioral changes in these lizards on these islands.

Anolis sagrei on one of the small cays

Other interesting observations include A. sagrei density on islands seems to be unintuitive. Some small islands with fewer perches hosted many more adult males and females than large islands did. Sizes of individuals also seem to vary greatly between different islands: small cay A. sagrei seem to be, on average, larger than those on mainland Abaco. Personally, I am unable to note major differences between islands which might have resulted in these observations. I’m excited to see if the data we’ve collected will give more insight into these observations as well as other behavioral results that will come from this study!

JMIH 2016: Variation and Distribution of Anolis roosevelti

One of the few known Anolis roosevelti specimens.

One of the few known Anolis roosevelti specimens.

Anole stalwart Greg Mayer gave a wonderful talk discussing the distribution and morphology of the large and maybe-extinct Anolis roosevelti. A. roosevelti, commonly known as the Culebra Island giant anole, was first described in 1931 by Chapman Grant, a US Army Major and practising herpetologist, from a single adult male specimen collected on Culebra. Although Reinhardt and Lutken, in 1863, had already provided an accurate description of A. roosevelti, but under an alternative name of A. velifer.

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Reinhardt and Lutken’s specimens were collected from Vieques, Tortola, and St. John, although Greg having the opportunity to study them meant tracking them down to natural history collections in both Copenhagen and Stockholm. In total, this entire species is known from eight specimens, only six of which are still in existence (Greg had the opportunity to study all six, meaning he’s now seen more roosevelti than any other anolologist?). Greg explains that roosevelti based on the limited information provided by Dimas Villanueva, who collected the holotype, and his own investigations, roosevelti can be classified as a “crown-giant” ecomorph. This means that the eastern islands of the Puerto Rico bank had a series of four ecomorphs, with roosevelti being what Ernest Williams termed a climatic vicariant of cuvieri, occuring in (and presumably being adapted to) the more xerophytic forests of the eastern bank islands.

The known distribution of Anolis roosevelti.

The known distribution of Anolis roosevelti.

Greg went on to describe the morphological features which distinguish A. roosevelti from a A. cuivieri, an ecologically and morphologically similar species from neighbouring Puerto Rico. Roosevelti is a larger, brownish gray rather than green as is seen in cuvieri (although check out these gray cuvieri preveiously mentioned on AA). Roosevelti generally has larger head scales, and a more elongate and deeply grooved head – these differences are confirmed in the ANCOVA analyses below.

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So, what chances are there of seeing roosevelti in the wild? Low, probably. No specimens have been collected since 1932, and several researchers, including Greg, have recently scoured both Vieques, St. John and Tortola but with no success. By far the most extensive searches have been conducted by Ava Gaa, who exhaustively searched Culebra (totalling 1500 hours of looking!) as well as short visits to Vieques and St. John all with no success. Tantalising reports of potential candidates turned out to be juvenile green iguanas. Greg concludes by recommending that the long-protected and relatively poorly explored eastern half of Vieques may hold the secret to if any populations remain.

JMIH 2016: Variation in Limb Length across Lizard Groups

2016-07-10 10.45.27

Travis Hagey presented some new results from his ongoing research on the evolution of functional traits in lizards. Travis normally works on geckos, but frequently includes Anolis species in his studies. Last year at Evolution, Travis told us about toepad evolution by comparing gecko toepads to those of anoles and skinks. Along the same vein, this year at JMIH Travis talked about patterns of limb-length across different lizard groups.

2016-07-10 10.46.47Travis started with anoles as an example of morphology being correlated with habitat use. As we all know, anole limb length is associated with structural habitat. Lizards like Anolis occultus (a twig anole) use thin perches and have very short legs. Other species that perch on broader substrates tend to have longer legs. Travis is interested in finding out if this pattern holds for other groups of lizards.

He started by comparing anoles to geckos to see if relative limb length differed between the groups. He accumulated an impressive database of hindlimb lengths from many gecko and 2016-07-10 10.50.43anole species and when he looked at the relationship between hindlimb length and body size (SVL), he found that for a given body size anoles tended to have longer limbs than equivalently sized geckos. He then added in data for a number of species from Liolaemus, Tropidurus, and Phrynosomatidae. Interestingly, he found that these other groups all clustered with the anoles. This suggests that there are possibly two relationships between limb-length and body size across lizards.

2016-07-10 10.53.02Travis ended by commenting on how this might relate to habitat use. He analyzed hindlimb length by perch diameter for anoles (red line) and geckos (black line). Geckos, it turns out, have a different relationship between perch use and limb length than anoles: geckos with shorter limbs tend to use broader diameter perches! Travis is still working on this research and is looking for data on limb length for many groups. If you have hindlimb length data from lizards you should email Travis to help out!

JMIH 2016: Anolis vs. Phelsuma in Hawaii

The gold dust day gecko was introduced to Hawaii in the 1980s. It is ecologically similar to the green anole, which was introduced to Hawaii in the 1950s.

The gold dust day gecko was introduced to Hawaii in the 1980s. It is ecologically similar to the green anole, which was introduced to Hawaii in the 1950s.

Hawaii has no native herpetofauna, aside from sea turtles. Human-mediated introductions between the 1950s and 1980s have created an interesting new guild of arboreal and diurnal lizards: the green anole (Anoles carolinensis), the gold dust day gecko (Phelsuma laticauda) and the brown anole (A. sagrei ).

Amber Wright next to her poster on Saturday

Amber Wright next to her poster on Saturday

Phelsuma laticauda belongs to a genus that is endemic to Madagascar with almost 50 species, that are known for their incredible color patterns. Anolis carolinensis and P. laticauda are thought to be ecologically similar and thus potential competitors.

Amber Wright’s research investigates whether and how the three species partition their habitat when they occur in sympatry and how that might affect species abundance. Using field observations and morphological data, she found that the three species overlap in body size and habitat use, which suggests that they are potential competitors for food resources and perch sites.

Enclosure experiment

Enclosure experiment.

Preliminary data show that abundance decreases when ecologically similar species are present.

Preliminary data show that abundance decreases when ecologically similar species are present.

In a pilot study, Amber used seven 10x10m plots to simulate different community scenarios: only one species, two species and all three species. Anolis carolinensis and A. sagrei seem to be interacting similarly to populations outside of Hawaii: coexistence with reduced densities and increased perch heights of A. carolinensis. When all three species were present, P. laticauda perched higher than usual, presumably to avoid competition with A. carolinensis. Future work will focus on long term effects of species composition on resource partitioning and abundance of each species.

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: Exploring Social Networks and Species Coexistence of Anolis lizards

Reptiles are often thought of as solitary and not social animals. However, all of us who study anoles know that Anolis are anything but solitary animals. Spend a few minutes observing an anole and you might see it dewlapping, doing push-ups, tail wagging, and fighting with other males or even other anoles species.  James Stroud, a Ph.D. candidate from the Feeley lab @ Florida International University, presented on Saturday about the exploratory results of a new research method he and Robert Heathcote have started to construct social networks of A. sagrei and A. cristatellus in Miami, Florida. A. sagrei and A. cristatellus are similar in morphology and ecology and they wanted to learn how patterns of social interactions between these two species allow them to coexist outside of their native range.IMG_20160709_152928392

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Individual social behavior manifests itself collectively at the population level and interactions between populations (within and between species) might act as a basis for evolutionary processes. James and Robert tagged both male and female anoles in their study to track and recapture the animals in the future for a long term study. They measured the distance between every two anoles observed and inferred the strength of interaction as stronger if the anoles were closer to each other. Both species show a great web of interactions both within and between species. Some individuals are also much more “bold,” interacting with many males and females of either species, while others show fewer social interactions. These preliminary data are exciting since so little is known about Anolis social behavior. James also mentioned that they will be including additional data such as the types of interactions that will add great complexity and insight to this story.

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JMIH 2016: Anolis conspersus Color variation and Habitat Use

Bright and early this morning, Christopher Peterson kicked off the anole talks of the day on the topic “Intraspecific color and habitat use variation in Anolis conspersus.” Christopher noted that on Grand Cayman there appear to be three color morphs for A. conspersus: brown, blue, and green and asked if color morph was correlated with habitat use. Christopher captured 309 lizards across the island, photographed them for color analysis, and took a large number of habitat measurements plus basic morphology of the lizards (mass, SVL). When analyzing the color data, however, he noticed that the picture was not so clear: many of the lizards had both blue and green coloration. Since these were not discrete groups, instead he analyzed body pattern, which appeared to be more discrete and showed the same geographical variation. In general, lizards on the East of the island were brown and spotted while the lizards on the West of the island were green/blue with vermiculated pattern.

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Using a complex logistic regression, Christopher analyzed the discretized character state with his habitat and morphological measurements. Disappointingly, he found no associations between morphology or habitat use with body patterns. He concluded that the variation in pattern and coloration is probably best explained by geographic location alone and that future genetic analyses may help clear up if this is a geographical cline with isolation by distance.

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JMIH 2016: Malarial Infection Rates Greater in Anolis carolinensis than Anolis sagrei in Central Florida

Cells infected with P. floridense (left and right) vs. healthy cells (middle)

Cells infected with P. floridense (left and right) vs. healthy cells (middle)

Brian Devlin, a graduate student from University of Central Florida, presented a poster on differential rates of malarial infection by Plasmodium floridense between two Anolis species in Central Florida. While both species exist in the area, A. sagrei is the more recent invader. Brian hypothesized that the infection rate would be higher in A. sagrei because A. carolinensis has coexisted with the parasite longer and might have developed some resistance to it.

Brian collected blood samples from both species and examined the cells under the microscopes to look for signs of malarial infection.  He actually found that the infection rates of P. floridense were significantly greater in A. carolinensis. Infection rate also did not correlate with SVL, sex, presence of tail autonomy, date or locality of the lizard. However, there is a higher rate of infection in the warmer months (May-July) possibly due to the in increase rainfall resulting greater mosquito presence. From these results, Brian hypothesized that the lower malarial infection rates in A. sagrei might have helped the species to outcompete A. carolinensis and successfully establish in Florida.

Brian's poster

Brian’s poster

 

JMIH 2016: Herp League Graduate Student Award Winner: Urban Habitat Partitioning by Two Common Species of Puerto Rican Anolis

Kristin Winchell, my fellow lab mate at the Revell lab, presented her work on the habitat use of two urban dwellers in Puerto Rico. Past studies have shown that Anolis cristatellus and Anolis stratulus vary in abundances and use different portions of the natural habitat. As early as 1964, Rand showed that A. stratulus was less abundant and perched higher on trees in forest habitat. Picture1However, we know very little about whether these patterns are maintained in urban areas where species have access to novel manmade structures. To address this, Kristin evaluated the habitat use of these two species across seven urban replicates and contrasted it to the available habitat. She found that urban A. stratulus uses more isolated perches with greater vegetative canopy and perches at higher portions of the habitat. Anolis cristatellus uses perches that are less isolated, shaded mostly by manmade canopy (i.e. buildings and houses) and at lower heights. When examining these patterns in a multidimensional space, she showed that A. cristatellus has expanded its urban niche through the use of manmade structures, while A. stratulus uses a subset of the natural portion of the habitat that A. cristatellus also uses.

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Her research shows that these two urban dwellers interact with the novel portions of the habitat differently. Anolis cristellus has expanded its niche towards manmade structures which has implications for adaptation to enhance stability and locomotion when using these structures as shown in some of her previous work (Winchell, et al, 2016).  Anolis stratulus uses the less available remnants of the natural habitat which may have implication for conservation if they become sparser as urbanization expands.

JMIH 2016: Comparative Phylogeography of Three Widespread Anolis species across the Puerto Rico Bank

Alexandra Herrera presented on using genetic population structure to understand how geographical processes have shaped genetic isolation of three widespread Anolis species on the Puerto Rican Bank. Geographical processes are an important event in shaping current populations and can lead to interesting patterns of diversification. However, these processes may not necessarily affect species similarly. In this study, Alexandra used a combination of nuclear genes and one mitochondrial gene to examine the population structure of these three anoles.

Evidence strongly suggests that populations of Anolis pulchellus were separated into two major clades through the formation of mountains. These two clades are made up of one cluster from south Puerto Rico and a cluster that includes both Northeast Puerto Rico and the Virgin Islands.

20160708_144935The diversification of the other two species corresponds with tectonic and sea level changes. For Anolis stratulus, divergence between populations in PR, Culebra, Vieques and the Virgins Islands occurred at the end of the Pliocene after the formation of the Virgin Passage.  These populations formed five clusters east PR, south PR, Virgin Islands, Vieques-Culebra and Peter-Norman islands.

20160708_145223For Anolis cristatellus the divergence between east PR and south PR with the Virgin Islands was estimated around the late Miocene-Pliocene transition when the Mona and Virgin Island passages formed. These populations formed 4 clusters east PR, south PR,  Virgin Islands and Carrot Rock-Peter-Culebra-Piñeiro.

20160708_145426This research shows that each species had a different diversification pattern and that they all occurred around the middle of late Pleistocene. Furthermore, geographical processes may affect species differently, leading to various patterns of population structures.