Insights from Three Years of Measuring Anolis sagrei Reproductive Success

Female Festive Anole (photo: Ambika Kamath)

Female Festive Anole (photo: Ambika Kamath)

Sexual dimorphism–differences between the sexes in what they look like–is rampant across animals. But how do these differences arise? Why and how might natural selection or sexual selection act differently on males and females? In a new paper from Duryea et al. (2016) published last month, we begin to see what answers to these questions look like in our very favourite organism, the festive anole, Anolis sagrei.

The data presented in this paper is unprecedented in anoles–by catching every lizard on Kidd Cay for four successive years, the authors assigned parentage to three generations of offspring, and thus assigned reproductive success to three generations of adults. Using these measures of reproductive success for males and females, they ask a straightforward question: is reproductive success correlated with body size, and do these relationships differ between males and females?

The results, however, are not straightforward: patterns of selection differ quite a bit across the three years of sampling, especially in females. But overall, we see directional selection on body size in males (bigger males father more offspring who survive to adulthood than smaller males), possibly explaining why male festive anoles are 30% larger than females.

We don’t yet understand the origins of sexual size dimorphism in anoles–why in particular, does the shape of selection on female body size vary so much? Do large males sire more offspring who survive to adulthood because they mate more often, or because their offspring are somehow better at surviving? Duryea et al. have propelled forward the state of our knowledge with a formidable dataset that raises exciting new questions.

The Evolution of Variation in Back Patterns in Anolis

Many species of anoles exhibit distinctive dorsal patterns, including spots (e.g. A. sabanus), stripes (A. krugi) or chevrons (A. sagrei) (Figure 1). Dorsal patterns are highly variable in anoles, presenting not only variation across species, but also within species (sexual dimorphism) and within sexes (polymorphism). So why is there such a large variation in dorsal pattern?

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Figure 1. Examples of dorsal pattern in Anolis lizards. A, A. sagrei, B, A. krugi, C, A. sabanus (photograph by B. Falk). D, A. pulchellus. Photographs A, B and D by D. L. Mahler.

Previous posts (1,2) explain the extent of the variation in dorsal pattern within females, a phenomenon known as female-pattern polymorphism (FPP), where females are more likely to present variation in dorsal patterns than males. Other studies have tried to explain within-population variation in dorsal pattern in several Anolis species with montane and xeric distributions. These studies suggest that habitat and crypsis could be an important factor explaining variation in dorsal pattern in Anolis.

Anoles are famous for having evolved convergent ecomorphs in different islands in the Caribbean. Each ecomorph is associated with a suit of adaptive traits that has evolved in response to their ecology. Some years ago, I went to the Losos Lab to explore, using several species of Anolis and hundreds of museum species, whether ecomorphs could explain variation in dorsal pattern. Namely, we wanted to know whether differences between ecomorphs could explain the degree of sexual dimorphism in dorsal pattern and female polymorphism, using 36 species of Anolis from the Greater Antilles.

In our paper, published on early view in the Biological Journal of the Linnean Society, we built a matrix with 11 different characters that described dorsal pattern. We used this matrix to construct a principal coordinate space, and in this space we calculated distances between male and female dorsal pattern for each species  (amount of dorsal pattern sexual dimorphism) and the variation in dorsal pattern within each sex (amount of polymorphism within sex).

We found that species perching closer to the ground have higher degrees of sexual dimorphism, and males and females from these species usually present different patterns (Figure 2). For example, in A. bahorucoensis, a grass-bush species, females present a dorsal stripe, while males have chevrons. We also found that size dimorphism is correlated to dorsal pattern dimorphism, and species perching closer to the ground have larger differences in size and dorsal pattern between sexes, suggesting that both types of dimorphism are evolving together. We suspect that larger differences in habitat use between males and females in low-perching species may explain why some species are more dimorphic in dorsal pattern that others.

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Figure 2. Association between sexual dimorphism in dorsal pattern and ecomorph in 36 species of Anolis. A, Phylogenetic tree with coloured branches representing values of dimorphism in dorsal pattern (Euclidean distance). Circles at tips represent ecomorph and the colour legend is the same as in (B). B, Values of dorsal pattern dimorphism according to ecomorph class.

On the other hand, ecomorph could not explain why some in some species there is higher variation in dorsal pattern in females (FPP). In our study, 44% of the species presented significantly higher female polymorphism than male polymorphism, reflecting how widespread is this phenomenon, but this was not related to ecomorph type. However, species with higher female polymorphism also had males that were more variable, suggesting that they might be under similar selective pressures. More precise information on habitat preferences within sexes, especially in  females, will be required in order to fully understand the mystery of female-biased polymorphism.

Reference

Medina, I., Losos, J.B. & Mahler, D.L. 2016. Evolution of dorsal pattern variation in greater Antillean Anolis lizards. Early view, Biological Journal of the Linnean Society.

Rodolfo Ruibal, R.I.P.

AA is sorry to learn of the passing of Rodolfo Ruibal, an eminent Cuban herpetologist based at UC-Riverside for many years. Rodolfo did important early work on thermal biology andsocial behavior of Caribbean anoles. For example, 1961 paper showed thermoconformity in some lizards (when everyone though that lizards always thermoregulate carefully), it showed that physiology can evolve faster than morphology, and it proposed that only thermoregulators (not thermoconformers) could invade the temp zone.

You can find transcripts from a 1998 interview with Rodolfo as part of a UC-Riverside history project. Here’s the obituary that recently appeared in UCR Today:

Professor Emeritus Rodolfo “Rudy” Ruibal, a founding member of UC Riverside’s Biology department whose passions included lizards, frogs and making beautiful jewelry, died Aug. 30 at the age of 88, just six months after the death of his wife of 68 years, Irene Shamu Ruibal.

“He was instrumental in forging the department in the directions and expertise that form its center now,” said Professor Michael Allen, chair of UCR’s biology department.

Ruibal was a native of Cuba who conducted research in several parts of South America with fellowships from the National Science Foundation and the John Simon Guggenheim Memorial Foundation. He was an early student of temperature regulation in reptiles and amphibians, said friend and colleague Professor Mark Chappell, and was also known for his work with water loss in amphibians and their ability to waterproof their skin by using waxy glandular secretions the animals wipe over themselves.

“He taught the Biology 161 course, on functional vertebrate morphology, or ‘Vert’ to generations of premeds and other life science students, and was renowned for both the clarity of his lectures and for his skill in drawing structures on the blackboard,” said Chappell.

During Ruibal’s 42 years at UCR, he helped establish the Philip Boyd Desert Research Center and spent a year as the acting director of UC MEXUS, created to stimulate teaching and research between California and Mexico. Ruibal also spent a year advising a man he much admired—UC President Clark Kerr—about faculty requests and concerns.

“He always had one faculty member in his office,” Ruibal said during an oral history interview in 1998. “It was his way of simply making sure his faculty were being treated by an academic who knew what the score was, rather than somebody who was just a bureaucrat.”

Ruibal’s life read like a novel. He was born in Cuba on Oct. 27, 1927, an only child who attended the same Jesuit school as Fidel Castro. The budding scientist had an early fascination for animals, said his son, Claude Ruibal of Zurich, Switzerland. Rudy Ruibal’s earliest memories were of watching fish swimming in the waters of Cuba, and chasing lizards in his yard, something his aunt remembered years later, when he returned to Cuba for research on an NSF grant project.

Reptiles and research always fascinated Ruibal, and he excelled at an early age. He enrolled in Harvard when he was just 16 years old, after completing high school at the prestigious McBurney School in Manhattan.

Ruibal took a break from Harvard when he was 18, to serve in the military at the tail end of World War II. But he returned to school a year later and married his wife, Irene, a secretary in the Department of Herpetology in the American Museum of Natural History.

By the time he was 21, Ruibal had finished his BA at Harvard and enrolled at Columbia University for graduate studies in biology. At 26, Ruibal completed his PhD and accepted a position at a new liberal arts college called UC Riverside, where Howard Spieth, one of his former professors at Columbia, had become the chair of the life science’s department, and would later become the university’s first chancellor.

Ruibal began teaching in the fall of 1954, the second semester for a school so new that it had no landscaping or trees. Their son was born the following year, in 1955. Claude Ruibal said his parents were loving but not overbearing. His father, he said, “was a thoughtful guy, a moral guy—very rational and not very emotional. I don’t think I ever heard my parents argue.”

His mother loved to cook and throw dinner parties, and they cultivated a diverse group of close friends—artists, business people, even the publisher of the newspaper. His father loved tennis, playing into his 80s, and did a lot of reading about history and politics.

Ruibal also was a noted local artist. Shortly after he arrived in Riverside, he successfully lobbied the Riverside Art Museum to have real nude models available for sketching (instead of women in bathing suits). He later branched into candle making, ceramics —complete with his own kiln—and finally, making brass and silver jewelry, which were top sellers at the Riverside Art Museum, Mission Inn Museum and other locations.

Anole Fashion: Dorsal Crests and Curlicue Tails

Daffodil’s Photo Blog has some nice photos of stylish anoles. Some anoles–the festive anole (A. sagrei) being a prime example, seem to have a penchant for sitting with their tails hanging in a lovely. Why do they do it? Got me.

We do know why they raise their dorsal crests–to look fearsome, as this mini-dinosaur does. How they do it, though, is another matter, when discussed previously in these pages (1,2).

Age Structure of Invasive Green Anole Populations near Japan

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Figure from a new paper by Yasumiba et al. illustrating how LAGs in the cross sections of bones can be used to infer lizard age.

Anolis carolinensis is a disruptive invasive species in the Osagawara Islands near Japan, a UNESCO World Natural Heritage site.  It was first recorded on the island of Chichi-jima in the 1960’s and has since spread to surrounding islands. A recent post on Anole Annals describes efforts to improve the effectiveness of adhesive lizard traps on the islands by using cricket bait.

A new paper by Yasumiba et al. improves our understanding of these invasive A. carolinensis by quantifying their longevity and growth rates using skeletochronology. Continue reading Age Structure of Invasive Green Anole Populations near Japan

Field Notes from Long Island, Bahamas

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Anolis smaragdinus (left) and Anolis sagrei (right) from Long Island, Bahamas. The individual on the right is marked as part of selection study.

This past August, two field assistants and I went to Long Island, Bahamas to collect data on sympatric populations of Anolis sagrei and Anolis smaragdinus as part of a natural selection study. Our primary study area is a small island (approximately 1000 ft x 200 ft) in the middle of a lake with relatively high densities of both species. While in the field we observed some interesting behaviors that I want to share with the AA community in hopes that you will find them interesting as well!

1) Frugivory by anoles was common at our study site, which had an abundant supply of small berries from black torch (Ertihalis fruticosa) and small-leaved blolly (Guapira discolor).  Anolis smaragdinus was usually the culprit, although we did we did see one adult male A. sagrei eating fruit.

2) We captured (and released) over 150 unique A. smaragdinus and later re-spotted several of those individuals. During a typical eight-hour day, we encountered 15-20 individuals, a surprisingly large portion of which were a male and a female in the same tree. These instances made a particularly strong impression on me when they were separated by long periods of not seeing any A. smaragdinus. I can think of multiple occasions in which we found a couple together, saw no individuals for another three hours, and then suddenly came across another couple. In several instances, there were three individuals in the same tree. I’m not aware of green anoles mate guarding, and unfortunately the data I have don’t have the resolution to provide much insight here, but the pattern was definitely striking.

smaragdinus-cannibalism

3) We observed an act of cannibalism in A.smaragdinus, a species for which cannibalism has not previously been reported (although it has reported for the closely related A. carolinensis). We captured an adult female, saw that she was eating something, and proceeded to lose our marbles after pulling a hatchling (pictured) out of her mouth. Acts of cannibalism by female anoles appear to be rather uncommon (see page 30 of this Anolis newsletter), making this observation perhaps the most intriguing of our adventure!

JMIH 2016: Rock ‘n’ Bowl Anole

At the JMIH in New Orleans this past July, the 100th anniversary celebration of the ASIH was held at the Rock ‘n’ Bowl, where music, food, drink, dancing, and bowling were enjoyed by all. But for those who were alert on their way in, there was an added bonus: anoles! Or, at least, one anole, spotted by Quynh Quach and corralled by Kristin Winchell.

Quynh and Kristin spot their quarry.

As other attendees file in, Quynh and Kristin spot their quarry in the bushes.

Taking a picture of the crowd filing in, I serendipitously caught our two intrepid anoleers  about to make the catch in the bushes to the right of the entrance. Kristin made the grab, and displayed her catch.

Kristin displays the catch.

Kristin displays the catch.

It was, of course, Anolis sagrei, the invasive Cuban species which has been spreading through the southeastern US for more than 80 years now. He was a nice-sized adult male, typical of the nominate form that occurs through most of the species’ US range.  The edificarian habitat– in bushes at the edge of a parking lot next to a building– is also typical of where invasive sagrei can be found.

Adult male Anolis sagrei, New Orleans, Louisiana, 10 July 2016.

An appreciative crowd gathered.

Eager anolologists immortalize the NOLA anole in pixels.

Eager anolologists immortalize the NOLA anole in pixels.

I was glad to see it, because prior to this I had only seen Anolis carolinensis in New Orleans (more on this in a later post).

Quyhn and Kristin show off their catch.

Quynh and Kristin show off their catch.

 

Does Evolution or Ecology of Anolis Lizards Shape the Bacterial Communities Living in their Guts?

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Figure 2 from Ren et al. 2016: “Diversity of Anolis gut microbiota as a function of host phylogeny. Each thin horizontal bar represents an individual lizard, with bacterial diversity (proportion of reads) coded at phylum, family, and genus.”

In recent years, the study of microbiomes – the communities of microorganisms living in certain environments or in association with hosts – has boomed. It’s long been understood that microorganisms (especially bacteria) can play a big role in host health, but recent work has also shown that microbes can have a huge impact on many other important facets of a host’s life, from growth and development to behavior. Despite the importance of these microbiomes, the ecological and evolutionary processes that shape them are still not very well understood.

In a recent study, Ren et al. (2016) decided to use our favorite model system to better understand the relationship between host and microbiome. As a classic example of an adaptive radiation, Anolis lizards provide an opportunity to test both ecological and evolutionary factors that might be influencing their microbiomes. In this study, the authors asked whether the evolutionary and ecological diversification of a host lineage (anoles) has structured the biodiversity of the gut microbiome community.

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A. evermanii and A. gundlachi sharing a perch

The authors used several approaches to address this question. First, they sampled gut microbiomes (using fecal samples) from six Puerto Rican anole species representing three ecomorphs: two trunk-crown sister species (A. evermanii and A. stratulus), two grass-bush sister species (A. pulchellus and A. krugi), and two trunk-ground species (A. cristatellus and A. gundlachi). They predicted that microbiomes of species of the same ecomorph would be more similar to one another than to species of different ecomorphs, reflecting an influence of either ecological similarity or phylogenetic relatedness on gut microbiome composition. Second, they sampled invasive populations of two trunk-ground species in Florida (A. cristatellus and A. sagrei) in sympatry and in allopatry to explore a) whether species that are phylogenetically distinct but ecologically similar have similar gut microbiomes and b) whether gut microbiome is influenced by the local environment. Lastly, they documented individual variation in gut microbiome composition over time by recapturing and resampling marked individuals.

The most striking result of the study was the huge amount of variability in gut microbiome composition between individuals (Fig 2, Ren et al. 2016). For example, on average, any two gut microbiomes only shared 7% of their bacterial OTUs (“Operational Taxonomic Units,” you can think of them as bacterial species). Such high variability from one individual to another is notable, compared to studies of other organisms.

In their analysis of the Puerto Rican anoles, the researchers found that gut microbiomes were more similar between conspecifics than between individuals of different species, but only weakly so. Perhaps more surprisingly, there was no difference in gut microbiome composition based on ecomorph. The authors suggest that this lack of distinction between ecomorphs may stem from the fact that most anoles are dietary generalists; although different ecomorphs do partition habitats, they still overlap in the types of arthropods that they consume, which could impact their gut microbiomes. The authors find further support for this conclusion in their separate analysis of temporal variation in A. sagrei. The composition of an individual’s gut microbial community fluctuated greatly over time, suggesting that transient factors (such as variability in diet) have a significant impact on the gut microbiome.

Interestingly, the two invasive trunk-ground species in Florida showed a much stronger pattern: despite being of the same ecomorph, the gut microbiomes of the two species were significantly different from one another. The authors suggest that the strong signal in these not-so-closely-related invasive anoles along with the weak signal in the closely-related Puerto Rican anoles might indicate that Anolis evolution could have impacted the diversification of the gut microbiome over long evolutionary timescales, but the Puerto Rican radiation just is too young for such microbiome divergence to have occurred. But it’s also possible that the difference in the microbiomes of the two invasive anoles is just a holdover from the source environments (Puerto Rico and Cuba) that has been maintained in their invasive ranges. To throw another wrench into the works, the authors also found that allopatric populations of one of the invasive species (A. cristatellus) were different from one another, while those of the other invasive species (A. sagrei) were not.

So does host ecology impact gut microbiome? Does host phylogeny? Or host environment? Ren et al.’s study suggests possibly yes to all, but with limited (and somewhat conflicting) evidence, it’s hard to draw any certain conclusions. Perhaps more poop from more branches of the Anolis tree will hold the answers.

 

Find the full paper here:
Ren, T. et al., 2016. Does adaptive radiation of a host lineage promote ecological diversity of its bacterial communities? A test using gut microbiota of Anolis lizards. Molecular Ecology.

Ecology of the San Salvador Bark Anole (Anolis distichus ocior)

 An adult male San Salvador Bark Anole (Anolis distichus ocior) displaying. Photograph by Guillermo G. Zuniga.

An adult male San Salvador Bark Anole (Anolis distichus ocior) displaying.
Photograph by Guillermo G. Zuniga.

Dayton Antley and colleagues from Avila University, the home of AA stalwart Bob Powell, recently published a detailed study of the ecology of the San Salvador bark anole (Anolis distichus ocior) in IRCF Reptiles & Amphibians (an open-access herpetological journal, with this article available here). Anolis d. ocior is one of 17 recognized subspecies of the diverse distichus group, and is found on only San Salvador and Rum Cay (Henderson and Powell 2009).

Antley et al. assessed microhabitat use, activity patterns, and approach distances of A. d. ocior in an approximately 0.3ha study area on the grounds of the Gerace Research Centre, dominated by Tropical Almonds (Terminalia catappa), Papaya (Carica papaya), and Ficus trees.

A Google Map view of the Gerace Research Centre. The study site (24°07'05.2"N 74°27'50.9"W) is outlined in white.

A Google Map view of the Gerace Research Centre. The study site
(24°07’05.2″N 74°27’50.9″W) is outlined in white.

In assessing patterns of microhabitat use throughout the day, Antley et al. conducted surveys every two hours for two days from 0700h (about 40 min after sunrise) to 1900h (about 40 min before sunset). Size class, perch height and diameter, body orientation relative to the ground, and thermal microsite (sun/shade/mixed) were recorded for every observed lizard. In the following two days, approach distances were assessed. This was achieved by a surveyor, wearing neutrally-coloured clothing, approaching an undisturbed anole at a steady pace and recording the distance at which the lizard reacted. Over two additional days, 10-minute focal animal observations were conducted of individual adult lizards (including both males and females) at a distance of 5m. The number of movements (changes in location or orientation), head turns, and head bobs were recorded for all lizards, with dewlap displays and pushups being additional recorded for males.

Lizards were active throughout the day, with activity peaking in the early morning and before midday. This was compared to ambient air temperatures recorded 1m from the ground in a shaded and sheltered location. This result surprised the authors, as a second activity peak in late afternoon/early evening was expected, as has observed in other similar studies of bark anoles (e.g. Hillbrand et al. 2011).

Mean number of lizards active (bars) and mean ambient temperatures (dots) per time period. Temperature data were collected on two consecutive days.

Mean number of lizards active (bars) and mean ambient temperatures
(dots) per time period. Temperature data were collected on
two consecutive days.

Adult males experienced highest levels of arboreality during the middle of the day, while subadult males and adult females (grouped together as they can be hard to distinguish from distance) were highly variable (see figure below). Most lizards of all classes were found in the shade, which the authors attributed as evidence for thermal conformity, and facing downward towards the ground, a common trait in many anoles that is most commonly perceived to increase an individual’s ability to monitor potential predators, competitors, or mates. 43% of lizards, however, were observed facing upwards. The author’s note that this behavior is often interpreted as an individual prepared for escape; however as all lizards were observed from distance and undisturbed, they (admirably) explain that this result is difficult to interpret.

A: Mean perch heights (cm) of adult males (L) and subadult males and females (S); B: mean perch heights of adult males at different times of day; C: mean perch heights of subadult males and females at different times of day.

A: Mean perch heights (cm) of adult males (L) and subadult males and females (S); B: mean perch heights of adult males at different times of day;
C: mean perch heights of subadult males and females at different times of day.

Adult male lizards were bolder than smaller subadult males and females, and retreated at a much closer distance when approached by a surveyor (0.99m +/- 0.07m vs. 1.54m +/- 0.18m). Focal observations revealed no significant differences between adult males vs. subadult males/females in shared behaviors, although there was a high variation in the amount of displaying behavior between adult males. The average time spent conducting dewlap displays was 3%, although one male was recorded investing 47% of his time in a combination of dewlap extensions and pushup displays.

Using all survey data combined, Antley et al. estimate that A. d. ocior in this study plot had a population density of 593 individuals/ha, with lizards observed on all but four of the smallest trees surveyed. Antley et al. note that their density estimate is extremely conservative, and much lower than previously published estimates (e.g. 1.070-5,460 individuals/ha, Schoener and Schoener 1978). The authors suggest that the small size of the study plot may have contributed to the relatively low density.

In all, this is a charming (although admittedly short) study of the natural history of the San Salvador bark anole (A. d. ocior) – a great example of an undergraduate research project that follows through to publication!

References
– Antley, D.L. et al. 2016. Microhabitat, Activity, and Approach Distances of the San Salvador Bark Anole (Anolis distichus ocior). IRCF Reptiles & Amphibians 23(2): 75-81
– Henderson, R.W. and R. Powell. 2009. Natural History of West Indian Reptiles and Amphibians. University of Florida Press, Gainesville, Florida.
– Hillbrand, P.A., A.T. Sloan, and W.K. Hayes. 2011. The terrestrial reptiles of San Salvador Island, Bahamas. Reptiles & Amphibians 18: 154–166.
– Schoener, T.W. and A. Schoener. 1978. Estimating and interpreting body-size growth in some Anolis lizards. Copeia 1978: 390–405.

Some Anoles from Cuba – Help for ID

During July-August 2016, I went for a three-weeks holiday trip to Cuba. Being a Ph.D. student at the Lizard Lab, I had to come back with pictures of… lizards of course. This post is dedicated only to the anole species I observed in Cuba. Any help to ID will be greatly appreciated! More of my pictures of the Cuban herpetofauna (anole and non anole) can be found on my website website.

1- Anolis sp (?) from Cienfuegos.

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2- Anolis sagrei – Brown Anole

a) DSC_0307-3

b) DSC_0388-3

c) DSC_0391-3

 

3- Anolis allissoni – Allison’s Anole

a) DSC_0418-2

b) DSC_0483-3

c) DSC_0897-3

 

3- Anolis homolechis – Cuban White-fanned Anole

a) DSC_0515-3

b) DSC_0842-3

4- Anolis porcatus – Cuban Green Anole

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5- Anolis vescus – Purial Bush Anole (??) from Baracoa

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6- Anolis sp (?) from Viñales

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Honduran Anole Identification

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I have been working my way through McCranie and Kohler’s guide to Honduran anoles and thought I would pull out some old photos from when I did some romping about Honduras a decade ago. At the time I had little interest in anoles and barely noticed them on my trips to Honduras (O foolishness of youth!). These photos below, however, represent a species I remember seeing frequently. I believe it is Norops lemurinus but without a specimen in hand it is difficult to use a dichotomous key. I was hoping someone more familiar with this part of the world could offer confirmation or correction. I was on the northern coast a few miles east of Balfate, less than 50 m above sea level.

I took my first trip to Honduras in 2004 at the age of 19 and made six more trips over the next eight years. Unfortunately, what I remember most was how the landscape changed so drastically from one year to the next as more and more people, mostly ‘norteamericanos,’ moved in to extract any and all resources from the land. At 19, I could hardly take one step through the long grasses on my way to the beach without scattering a half dozen lizards. I remember that so vividly! By the time I hit my late 20’s the grasses were replaced with a coconut grove and a size-able complex of condominiums (built by and, I assume, advertised to Canadians).

Of course, there are still plenty of herps around and about: when last I left, the cane toads and hemidactylids were doing just fine.

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A Tale about Two Tails: No Effect of Having a Regrown Tail on Body Condition

A dorsal view of the brown anole male that I collected on the 19th of July 2002.

A dorsal view of the brown anole male that I collected on the 19th of July 2002.

On the 19th of July, 2002, I collected a brown anole (Anolis sagrei) male from the edge of a rice paddy next to a tarred road in Santzepu, Sheishan District, Chiayi County, Taiwan, as part of a diet and reproductive cycle study. As I removed it from the fine-meshed fishing scoop net, which I used for capturing it, I found that it had two tails. I later found that even though the lizard had no abdominal fat bodies the animal was still in a reproductive state, indicating that it was not only able to regenerate a tail twice, but it could also still meet the energetic demands for reproduction.

This finding prompted our study to attempt to address the question of whether there are differences in the abdominal fat body weights and liver weights of A. sagrei specimens that had suffered tail autonomy and conspecifics that had not.

We were surprised when we found no statistically significant variations in the monthly mean abdominal fat-body weight indices or monthly mean liver weight indexes of lizards that had not experienced caudal autotomy and those that had. We hypothesize that A. sagrei specimens that experienced tail autotomy most likely met the energetic demands for regenerating the lost portion of their tail by foraging more.

Editor’s Note: for more on two-tailed anoles, such as the photo below, type “tail” or “tailed” into the search bar on the right.

 

ESA 2016: Top-Down Effects of Brown Anoles on Islands Following Hurricanes

Following up with summaries of anole talks at ESA 2016, Dave Spiller presented a broad summary of his and his colleague’s (Tom Schoener and Jonah Piovia-Scott) research investigating the effects of hurricanes on long term food web dynamics of small Bahamian islands, which has just recently been published in Ecology (see Spiller et al. 2016).

Picture1

Spiller opened by explaining some of the patterns of food web dynamics that have been learned from this research. Most notably, that the elimination of brown anoles – which act as top predators in these simple ecosystems – leads to increased levels of herbivory as arthropods experience a relaxation of predation pressure (Spiller and Schoener 1990).Specifically, the presence of a common moth (Achyra rantalis) on islands without brown anoles can lead to extreme levels of herbivory upon a common island plant, Sesuvium portulacastrum (below).

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Spiller and his colleagues began to notice that following hurricanes, one of the most extreme natural disturbance events in this region, islands with lizards experienced a much more rapid recovery of Sesuvium .

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In an attempt to understand how ecosystems may be stable despite experiencing extreme disturbance regimes, Spiller and colleagues measured the percent ground cover of Sesuvium and abundance of Achyra moths on 11 islands with lizards present and 21 islands without lizards annually for 10 years.

Overall abundance of Achyra was 4.6 times higher on no-lizard islands than on lizard islands. The percent cover of Sesuvium exhibited lower temporal variability on lizard islands when the study site was undisturbed by hurricanes, and higher recovery rate on lizard islands following hurricanes.

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Spiller concluded by suggesting that these stabilizing phenomena are linked to a trophic cascade in which predators (brown anoles) control herbivores (Achyra moths), and therefore enhance plant recovery following hurricanes.

Anoles on Exhibit at the Milwaukee Public Museum

 

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AA stalwart Tony Gamble has provided these two photos from exhibits at the Milwaukee Public Museum. The one above is a knight anole, whereas below, an Archaeopteryx appears to be dining on a green anole, significantly increasing our understanding of the age of the anole radiation.

AA’s other Wisconsin stalward, Greg Mayer, provides the low-down: “The equestris  is from the Rain Forest exhibit. This is a fabulous exhibit based mostly on the Costa Rican rain forest, but including some other tropical/rain forest elements. I take my vert. zool. class there every year, and have used it as part of the pre-trip preparation for Costa Rican field classes. It was funded in part by the NSF, and involved lots of field work–they did latex casts of trees to get the bark right for life size models of them! The Milwaukee Public Museum was much involved in making Costa Rica the center of tropical studies for US-based scientists. The MPM was slightly independent of OTS. They had their own field station, La Tirimbina, which is very nice–I’ve taken students there 2 or 3 times.

Allen Young, the MPM lepidopterist, was the driving force for Milwaukee’s tropical studies. He wrote about his work at Tirimbina in Sarapiqui Chronicle (Smithsonian Institution Press, Wash. DC, 1991). Young first went to Costa Rica in 1968 with OTS, then focused his work at Tirimbina. (Bob Hunter, who owned Tirimbina at the time, also owned part of La Selva, and was involved in getting both places established as field stations.) MPM’s stake in Tirimbina was sold off by then Milwaukee county executive (now governor) Scott Walker, who couldn’t imagine why a natural history museum in Wisconsin could be interested in Costa Rica. Fortunately, another conservation organization bought MPM’s share.

Others were involved in the exhibit creation as well, and though I’ve never asked him, I’ve always thought the Anolis equestris behavior display in the rain forest exhibit may have been a contribution of Bob Henderson. There are several males and females (not sure if they’re freeze-dried, or some kind of model), showing various levels of agonistic display– fans, nuchal crests, open mouth, raised posture– set out on vines/branches. A question I ask vert. zool. students about this display case is how could they tell the lizards are arboreal, even if they were not posed on branches.”

And with regard to the photo below: “The other picture is from the Third Planet exhibit (I’m always tempted to write Third Rock!), from a section of that very good exhibit on the Hell Creek Formation and the end Cretaceous vertebrate extinctions. The MPM has two Archaeopteryx models made up with feathers, and the one in the pic has a dried or model Anolis carolinensis in its mouth, painted a fairly bright green. The other Archaeopteryx model is better done, and that one goes out on loan periodically to other museums (I think I’ve seen it at the Field Museum).

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Owls Eat a Lot of Anoles: Data from Dominica

An owl with a green anole.

A recent paper in the Caribbean Journal of Science on the diet of the Lesser Antillean barn owl on Dominica revealed that anoles, specifically the native species A. oculatus, are a very frequent prey item, constituting 193 of the 517 prey items. The authors note that owls are nocturnal and anoles are diurnal and proffer three explanations: 1. the predation occurs at dawn and dusk, when both species are normally active; 2. the anoles are active around lights at night; 3. the owls are catching the anoles while they sleep. We’ve discussed this topic before: owls are known to eat anoles in Cuba and many other places in the neotropics, and there’s the great photo re-posted below (original post here). As far as I’m aware, that’s the only direct observation of an anole being preyed upon by an owl (although a quick search on Google Images will yield many photos like the one at right). We’ve also discussed the parallel  issue of bat predation on anoles in these pages. Clearly, more data are needed!