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A majority of biomechanical studies focus on eliciting maximal performance from animals in laboratory conditions, an approach that can make it difficult to apply results from the lab towards understanding performance in nature. Jerry Husak addressed this issue in his talk entitled “Maximal locomotor performance and sprint sensitivity in green anole lizards (Anolis carolinensis).”

By measuring sprint performance on a variety of perches (two different dowel widths, as well as a broad perch with pegs functioning as obstacles) and comparing these performances to sprint performance on a broad, flat surface, Husak showed that green anoles are substantially worse at running on narrow perches and through obstacles than at running on broad, flat surfaces. This confirms that animals moving through their natural habitats are almost certainly sprinting sub-maximally–in nature, green anoles are found most often on perches even narrower than those tested.

Crucially, the morphological correlates of performance varied by perch, suggesting that fine-scale studies of selection on limb and muscle morphology in the wild will require knowledge of how often and in what circumstances lizards navigate different microhabitats and move on different substrates. Coupled with behavioural observations in the wild, this study can pave the way for a more nuanced understanding of body shape evolution in our favourite lizards.

A figure from Quinn’s poster, showing alternative possible energy budgets in green anoles (click for a better view).

Animals allocate energy that they acquire to a variety of bodily functions and activities. Some of the more important allocations are those toward metabolism and growth, though the relative allocations to these is unclear. McKenzie Quinn, an undergraduate student working with Michele Johnson at Trinity University, presented her work in the third poster session on the dynamic energy budget of green anole lizards. She quantified food intake, excretion, growth, and resting metabolic rate (RMR, the energy required for basic maintenance) of individual lizards over 40 days to create a predictive model to describe how they allocate energy. If metabolism receives a large allocation, then RMR and/or body mass are expected to be significant predictors of energy use. On the other hand, if growth is more important, then aspects of body length (snout-vent length, SVL) are expected to be better predictors.

Interestingly, she found that RMR and body mass were not included in the best model of energy use. Instead, their model building (with AIC criteria, if you’re interested) showed that a decreasing nonlinear function of SVL was the best model. This suggests that metabolic functions are a small, non-significant part of these lizards’ dynamic energy budget. This work was conducted on adult males, so it will of course be interesting to see how this approach might apply to younger individuals or females. However, this is useful information to know for those who wonder how anoles allocate energy in their daily lives.

Arginine vasotocin, the reptilian homolog to vasopressin is a potent modulator of social behavior. (photos from Wikipedia)

For many of us, hearing about arginine vasotocin (AVT), or its mammalian homolog vasopressin, conjures up memories from a physiology class about water balance and the antidiuretic effects of the vasopressin system. However, AVT is also a potent neuromodulator and neurotransmitter in the brain that has strong effects on social behavior, such as parental care and pair bonding. Although most of this behavioral research has been done in mammals and birds, it appears that AVT might have similar behavioral functions in anoles! Leslie Dunham, a graduate student at Georgia State University, experimentally assessed the effects of AVT on male and female green anole behavior. By comparing lizards injected with either AVT or a control solution, Dunham was able to examine the effects of AVT on aggression and courtship in males. The behavior of individuals in the two experimental groups was then assessed in the following contexts: aggression toward a mirror, aggression toward another male, and courtship toward a female. She found:

1. Decreased aggression toward a mirror.
2. No difference in aggression toward a size-matched male.
3. No difference in courtship behavior directed at a female.

AVT decreases aggression in other vertebrates, but the lack of an effect on courtship in anoles suggests that AVT may modulate behavior differently in male anoles compared to fish and birds.

But wait, there’s more! Not to be outdone by other types of vertebrates, females in the courtship trials showed some very interesting behavior. Although Dunham focused on the effects of AVT on male behavior, she also measured female behavior during the trials. She found that females displayed more toward males treated with AVT compared to control males. This was despite any detectable behavioral difference between the male treatment groups. Why is this? Although the answer is still unknown, Dunham proposed some plausible and testable hypotheses for what might be happening. First, there may be subtle changes in behavior brought about by AVT that weren’t detected. Second, there may be a role for chemical communication between the sexes during courtship that wasn’t measured. Anoles, and iguanian lizards in general, aren’t known for their reliance on chemical communication, so this possibility is sure to spark some interesting future research.

Continuing with my theme of posting about non-anoles that anolologists find interesting, here’s a summary of a fascinating poster about tail-curling in two species of Leiocephalus: L. carinatus (the famous consumer of A. sagrei in the Bahamas) and L. barahonensis. Tail-curling is known to function as a predator-deterrent signal in L. carinatus, but its potential as a social signal has remained unexplored. Bonnie Kircher, a student in Michele Johnson’s lab at Trinity University, set about rectifying this gap.

Having never seen a curly-tail myself, I was surprised to learn that these lizards exhibit a variety of tail-curling behaviours.

A figure from Bonnie Kircher’s poster describing how tail-curling was scored in this study.

By scoring the intensity of tail-curling during social encounters as well as during non-social periods, Kircher showed that tail-curling was not used as a social signal in either Leiocephalus species. In an elegant control, she demonstrated that head-bobbing was more frequent in social than in non-social contexts, thus verifying that social contexts were indeed accurately identified.

Kircher also simulated predation by approaching the lizards and observed their use of tail-curling while fleeing. A comparison of the frequency of tail-curling between disturbed and undisturbed lizards confirmed that L. carinatus uses tail-curling as a signal during encounters with potential predators. The same pattern was not observed in L. barahonensis–we therefore don’t yet know why this species curls its tail. Kircher speculates that the behaviour might have been directed at other, undetected, predators, or perhaps plays a role in lending stability to the lizard during locomotion.

This variation in the utilization of the same signal between two closely-related species points to the lability of signal use, and with almost 30 species in the genus, this system is a prime candidate for future work on signal evolution.

Though SICB 2014 is positively teeming with cool anole talks and posters, there are plenty of other lizards that are getting a lot of attention. Yesterday, I happened upon a fascinating talk by Travis Hagey,  a grad student at the University of Idaho, titled “How geckos stick in nature: ecology and biomechanics of gecko feet.”

Strophurus taenicauda, a grass-bush-like gecko. Photo by Dave Fleming.

Addressing an overflowing room, Hagey used the dramatic diversity of gecko toepads to motivate his central question–can this diversity in toepad morphology be explained by the habitat preferences and perch-use behaviour of these geckos in nature? But going down the path of ecomorphology led to a comparison with anoles: if gecko toepads correlate with their habitat, then what about gecko limb-lengths? Using relationships between limb morphology and perch-type from arboreal anoles as well as rock-dwelling skinks, Hagey left for Queensland, Australia, with three predictions:

1. Geckos with shorter limbs would perch on narrower surfaces

2. Geckos with longer limbs would perch on rocks

3. Geckos with higher clinging ability would perch on steeper perches.

Utilizing a simple measure of lizard clinging ability (the “toe detachment angle,” which is the angle of the clinging surface away from vertical at which a lizard can no longer cling), as well as measuring perch characteristics and limb morphology for 13 species of geckos, Hagey began to look at patterns of ecomorphology. He found that different species occupied dramatically different habitats, with specialization even within the arboreal niche. Here’s what he found for each prediction:

1. Contrary to expectations, lizards perching on narrower surfaces had relatively longer limbs than average.

2. Having longer upper legs, however, correlated with rock use.

3. A higher clinging ability was correlated with having longer toes and shorter limbs. There was a qualitative or clade-specific relationship between the use of vertical perches and higher clinging ability.

Pseudothecadactylus australis, a crown-giant-like gecko. Photo from www.gondwanareptileproductions.com

Hagey speculated about the relationship between perch width and limb length in geckos, where he found the opposite pattern from anoles. One distinct possibility is that geckos have, on average, shorter limbs than anoles, meaning that a relatively long-limbed gecko and a relatively short-limbed anole may actually have the same body shape. Hagey is planning a taxonomically broad comparison of body shape and perch use, and hopes to include both geckos and anoles in this dataset–an exciting prospect that could shed light on some remarkable trans-continental convergences in lizard ecomorphology.

Forget to get yourself a calendar over the holidays? Or embarrassed when someone gave you a present and you didn’t have one to reciprocate? Fear not, there’s still time to get an Anole Annals 2014 calendar, at bargain basement prices. Act now!!! Offer expires midnight tomorrow (Jan. 4). Go here, use code

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This is not Anolis roosevelti. No pictures of that species in life exist. But it probably looked pretty similar to this brown-phase Anolis cuvieri. Photo by Alejandro Sanchez.

Anolis roosevelti, the giant anole of Culebra and Vieques, is famous in anole circles. The only Caribbean species thought to possibly be extinct, the species has not been seen since 1932.

Recently I learned of a report of an expedition to Culebra to track down the wily saurian, written by noted author and mycologist Lawrence Millman. As you’ll see, the expedition was a success, but perhaps not in the way you expect.

A Hunt for the T. rex of Anole Lizards: A Trip to Puerto Rico in Search of a Giant Shrinking Reptile.

Christian Science Monitor, July 12, 2007

“Not too long ago I picked up an old travel book about Puerto Rico and read of a rare giant lizard, Anolis roosevelti, on the island of Culebra.
“Fame will visit anyone who finds this elusive creature,” the author of the book proclaimed. Since Fame had thus far given me a rather wide berth, I hopped a plane to San Juan and then a smaller plane to Culebra.
By the time I arrived on the island, the lizard had shrunk. The book had described it as four feet long, but the local Fish and Wildlife person told me that it was no more than a foot long from snout to vent – hardly competition for a T. rex. Still, A. roosevelti is a T. rex compared with other anoles, which are among the smallest of all lizards.
I also learned that this giant among anoles had not been sighted since 1932. Not officially sighted, that is. But there were anecdotal reports of it being seen in the forested areas on Monte Resaca, Culebra’s highest summit (height: 650 feet), as recently as a few years ago.
So I drove to the base of Monte Resaca and started bushwhacking.
Trusting in serendipity, I expected to see the anole in question basking on every boulder as well as ascending every gumbo-limbo tree. I was so intent on my search that I lost all sense of direction and ended up in someone’s backyard.
A Culebran tending his garden looked up at me in surprise. My usual ploy when I trespass like this is to advance confidently toward the person, shake his hand, and announce in a punctilious English accent: “Dr. Basil Withers of the British Antarctic Survey. Jolly good to meet you, old chap.”
Since this ploy would not work in the subtropics, I said, “Hello, Señor. Seen any big lagartos around here lately?”
“Sí,” the man replied. “All the time.”
“What’s their habitat?” I asked excitedly.
“In my bathroom,” he answered. He invited me in, where I saw the lagartos skittering around on the wall. They were geckos, not anoles, and they weren’t even all that big.
Serendipity had gotten me nowhere, so I got in touch with Beverly Macintyre, who knew the island’s backcountry intimately. She mentioned a particular boulder canyon on Monte Resaca, just the sort of place, she said, where a giant anole might hang out. Then she referred to recent development on Culebra; if it continued at its current breakneck pace, she said, a lot more creatures than A. roosevelti would be either endangered or extinct.
In our search for the lizard, Beverly and I entered not so much the forest primeval as the forest prickly. Ground-hugging cacti jabbed us, mesquite bushes stabbed us, saw-toothed bromeliads slashed at us, and a plant known locally as Fire Man (Tragia volubilis) delivered stings that make the stings of a stinging nettle seem positively genteel.
And to add to it, at one point I was gazing up at what turned out to be a green tree iguana and walked into a barbed wire fence.
We did not see a giant anole. We did not even see one of the small anoles that reputedly were common on the island. But near the end of our trek, we did witness this unusual sight: a man on a horse with reins in one hand and a cellphone in the other.
The next morning, as I took a respite from my search, I began noticing other curious sights. A sign in a shop window in Dewey, the island’s only town, said: “Open Some Days, Closed Others.” A road sign indicated Termina Carretera (End of Road) when, in fact, the road did not end at all.
And in the afternoon, I was sitting on Flamenco Beach when a person in an old-fashioned diving bell emerged from the sea. At the north end of the beach, there was a tank left over from the days when the US Navy used Culebra for war games; in this setting, it had a very surreal quality.
I began to think that I had fetched up on some sort of Caribbean fantasy island – an ideal habitat for, among other things, an incredible shrinking lizard.
Several days later, I still hadn’t found the anole in question. My trip was coming to an end, so I asked Teresa Tallevast, the manager of the Culebra National Wildlife Refuge, if there was any area I might have overlooked. She suggested that I check out the trail that wound down from Monte Resaca to Playa Resaca.
Soon I was hiking on this steep trail. Every once in a while I would stop and peer into the surrounding bush. At one point I thought I saw a finned reptilian tail disappear into a tangle of mesquite, but that could have been my imagination … or another iguana.
At the bottom, the trail meandered through a labyrinth of white mangroves. I looked up at the trees’ gnarled branches and then down at their arching prop roots.
Still no anole.
At last I came out on Playa Resaca, a long, yellow swath of sand where I was the only person in sight. The sun was blisteringly hot, but I didn’t go for a swim. Resaca means undertow in Spanish, and if I had gone swimming, I might have washed ashore on the west coast of Africa or, at the very least, in the Virgin Islands.
Suddenly I saw what appeared to be the tread marks of an 18-wheeler in the sand. I was outraged. But then I realized that the tread marks were actually the flipper imprints of a female leatherback turtle who’d plodded ashore the night before to lay her eggs. Weighing a thousand pounds or more, such creatures are the reptilian equivalent of giant rigs; unlike those rigs, however, leatherbacks are an endangered species. I counted myself extremely fortunate to see even the tracks of one.
And so it was that my quest for a rare reptile on Culebra ended in success.”

Anolis grahami in the Hellshire Hills

Today, the genus Anolis represents the most common of Jamaica’s reptiles. Indeed, most Jamaican anoles are quite ubiquitous throughout the island, but the abundance of these and other small lizards  is misleading. Many of Jamaica’s reptiles, several of which are endemic to the island, are in immediate danger of extinction. Indeed the Jamaican herpetofauna is one of the most threatened in the entire Caribbean and several species have already been lost; Many more are now under threat under threat due to  development in Jamaica’s  protected habitats.

Map showing the major protected areas and  reserves of Jamaica
source: http://inweh.unu.edu/jamaica-mpa/

Over the years  numerous protected areas have been established across Jamaica  with the intent of preserving its endemic biodiversity, particularly birds, mammals and reptiles. Two of these areas, the Black River Morass and Portland Bight Protected Area,  are significant refuges for a large number of Jamaica’s threatened endemic reptiles.

Juvenile American crocodile.Crocodylus acutus. A large population of this threatened species currently inhabits the Black River Morass
Crocodylus acutus. Photo by author

By far the most important nature reserve in Jamaica is the Portland Bight Protected Area (PBPA) created by the Jamaican government in 1999. It is the largest protected area in Jamaica and spans approximately 1,880 square kilometers of wetlands, coastal mangroves and coastal dry forests, all three of which are important threatened ecosystems. Although the first priority in forming the protected area was to protect the coral reefs found within, it also serves to protect vulnerable and endemic species. The PBPA encompasses the Hellshire Hills and Portland ridge in the parishes of St. Catherine  and Clarendon respectively; these are the two largest areas of dry forests remaining on Jamaica and form one of the largest areas of relatively intact tropical limestone forests in entire Caribbean.

The coastal dry forests of the Hellshire Hills, part of the Portland Bight Protected Area.
Source: Joe Burgess’s Flickr page

The PBPA  is a reserve for several threatened species of plants and animals and serves as the last refuge for several of Jamaica’s rarest reptiles including the Jamaican iguana, Cyclura collei, which with a global population of 150 lizards is one of the rarest reptiles in the world. The area is also home to the Jamaican skink,  Mabuya fulgida, and the small recently rediscovered blue-tailed galliwasp, Celestus duquesneyi,  both of which have extremely limited distributions outside of the Hellshire Hills, as well as the endangered Jamaican  boa, Chilabothrus subflavus,  which is patchily distributed throughout the Island. The PBPA also encompasses several offshore cays including Little Goat island and Great Goat Island; The  Jamaican government had plans to eradicate the mongoose as well as the feral goats from the Goat islands after which suitable organisms from the mainland dry forests would be transplanted onto the islands in an effort to preserve the endemic dry forest biodiversity. This plan however seems to have hit a a monumental roadblock.

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Ameiva ameiva Photo from Fagner Delfim’s Flickr page

Here at Anole Annals we like to obsess over our  favorite lizards, anoles of course, but there are a vast array of other reptilian marvels out there,  formidable  Cyclurid iguanas, regally patterned Chilabothrus boas and of course the ever wary ground lizards of the Antilles (and elsewhere), the ameivas. Given the ample opportunity for exploration of these seemingly under appreciated animals  I have taken my best shot at writing a post concerning ameivas,  their morphology, ecology an various other bits and pieces of info I’ve picked up over the years; Enjoy!

The large neotropical genus Ameiva contains roughly thirty-two species largely distributed throughout eastern South America and the Caribbean with a few species  extending into southern Central America. Within this genus are some of the  most ubiquitous lizards of the neotropics, though due to their incredible swiftness and skittish demeanor it is rare that one ever sees one of these charismatic lizards out in the open for any extended period of time and even rarer that the casual observer  may encounter enough of them within a single area to appreciate just how numerous they can be. This rather ambitious  post focuses mainly on the  biogeography of  Ameiva, which in many ways mirrors that of Anolis. Most of the information presented herein comes from a 2012 paper  which , among other things, revises the genus Ameiva, recognizing several monophyletic clades and excluding certain species once thought to belong to the genus. More info on ameivas, as well as some amazing pictures, can be found at Father Alejandro Sanchez’s website.

Four geographically coherent clades or species groups have been identified within Ameiva,  two of which, the ameiva and bifrontata groups, occur in South and Central America as well as in Trinidad and Grenada, while the remaining two, the dorsalis and erythrocephala groups,  are distributed parapatrically throughout the Caribbean. Two additional species, A. parecis and A. concolor remain unassigned to any of these four groups.

The bifrontata group is the smallest of the four clades, consisting of one polytypic  species, A. bifrontata, as well as the closely related A. provitaae.

A. bifrontata
source:http://gallery.surget-groba.ch   

 This group is almost entirely South American in distribution, occurring in Colombia and Venezuela as well as on the island of Aruba. The clade is thought to share common ancestry with the West Indian  Ameiva species and both groups share several defining morphological characteristics the most obvious of which is the presence of mild to intense red coloration on the tip of the snout of most species, a feature shared by no other teiids.

The Caribbean  Ameiva form a monophyletic clade thought to be of South American origin
with the South American  A. bifrontata  species group thought to be sister  this one.

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