Anole Annals

Gratuitous plug for a brand of sunscreen featuring a lizard.

Lizards not only sit in the sun to thermoregulate, but also to synthesize Vitamin D. It tends to reason, then, that the amount of basking might depend on the amount of Vitamin D in the diet. And so it does, at least in A. sagrei. But, not in the more shade-loving A. lineatopus. Read all about it in Gary Ferguson’s paper that appeared in the Journal of Herpetology at the end of last year.

Abstract:

In Jamaica, free-living male and female-sized Anolis sagrei are exposed to more natural ultraviolet-B (UVB) from sunlight than male and female-sized Anolis lineatopus. In the laboratory, we tested predictions derived from the hypothesis that Anolis possess a mechanism for behaviorally photo-regulating their exposure to UVB depending on their dietary intake of vitamin D3. Anolis sagrei voluntarily exposed themselves more frequently to visible and UVB light and received higher doses of UVB in an artificial light gradient when fed a low vitamin D3 diet for 6 weeks than when subsequently fed a high dietary vitamin D3 diet for 6 weeks. When we returned the anole’s diet to the low vitamin D3 regimen for a third 6-week period, UVB exposure remained lower than in the first 6-week period. This suggests an initial UV photoregulatory adjustment to high dietary vitamin-D3 but a slow return to greater reliance on UVB-induced endogenous vitamin D3 production. Conversely, while exposing themselves to UVB with similar frequency and doses as A. sagrei over the course of the 18-week experiment, A. lineatopus did not show the same decreased attraction to visible and UVB light in response to increased dietary vitamin D3. The response of A. sagrei in the laboratory to visible light without UVB was similar to their response to visible light with UVB. Therefore, the anoles appeared to be responding primarily to visible light. Anolis lineatopus may be unable to use dietary vitamin D3 to restore low vitamin D status.

We first reported on the blessed event a couple of weeks ago. Now here’s some video of the darling newborn.

The Howard Hughes Medical Institute earlier this year introduced a short film on anoles for use in teaching principles of evolution to high school and science biology classes. Now they’ve come up with a fabulous set of online class exercises to be used in conjunction with the film, the Lizard Evolution Virtual Lab!

I have to say, the exercises are fantastic! The exercises, which include data collection and analysis, include how to study phylogeny, natural selection and adaptation. Here’s how they describe it:

The virtual lab includes four modules that investigate different concepts in evolutionary biology, including adaptation, convergent evolution, phylogenetic analysis, reproductive isolation, and speciation. Each module involves data collection, calculations, analysis and answering questions. The “Educators” tab includes lists of key concepts and learning objectives and detailed suggestions for incorporating the lab in your instruction.

It is appropriate for students in high school biology and environmental science classes, and undergraduate biology, ecology, environmental science courses. The focus on observation, measurement, and experimental methods makes the lab a good fit for addressing “science as a process” or “nature of science” aspects of the curriculum. The emphasis on the collection, analysis, and graphing of data, connects to the mathematical dimension of biology and general goals of STEM integration.

Key Concepts:

• An adaptation is a structure or function that confers greater ability to survive and reproduce in a particular environment. (Modules 1 and 3)
• DNA sequence comparisons among different populations and species allow scientists to determine how distantly related different species are and how long ago they split from a common ancestor. (Module 2)
• Different species can independently evolve similar traits by adapting to similar environments or ecological niches in a phenomenon known as convergent evolution. (Module 2)
• The biological definition of a species is a group of interbreeding individuals that are reproductively, and thus genetically, isolated from other groups. (Module 4)
• When two groups within one species become geographically isolated—separated by a physical barrier, such as a river, canyon, or mountain range—genetic changes in one group will not be shared with members of the other, and vice versa. Over many generations, the two groups diverge as their traits change in different ways. (Modules 3 and 4)
• For two groups to become distinct species, traits must change in ways that will keep members of each group reproductively isolated—meaning that they will not mate or produce fertile offspring with members of the other group—even if they come to be in the same geographic location. (Module 4)
• Graphing data is an important way to objectively document differences and similarities. It can make it easier to spot patterns that would otherwise be difficult to see in tables of measurements or direct observations. (Modules 1, 3, and 4)
• Statistical tools provide a way to quantify variability in biological data and describe the degree of uncertainty in the results obtained using these data. (Modules 3 and 4)

Photo by Luis Diaz.

The ninth most viewed page of Anole Annals of all time is dedicated to this beauty, a member of the Anolis equestris species complex. That post referred to a PDF version of a poster with photos of some reptiles and amphibians of Cuba. Luis Diaz, Curator of Herpetology at Museo Nacional de Historia Natural de Cuba, recently commented on the beautiful photo above that was in that poster and posted on AA:

I’m the author of two of the pictures you posted a long time ago on Anole Annals. At the moment the pdf you mentioned was published, only one subspecies of Blue Giant Anole existed (A. e. potior). Now populations in Cayo Coco (like the individual shown in the picture), are considered Anolis equestris cyaneus, not potior as mentioned in the referred photographic guide. We named Anolis equestris equestris the individual with a large black blotch on the neck (actually from Peralta, Zapata Swamp, a bit far away from Playa Larga), but it has the coloration of A. e. calceus. However, we have new genetic evidences (information obtained during a joined project with Antonio Cadiz, University of Havana, and Masakado Kawata from the University of Tohoku) for the taxonomic re-assessment of Cuban giant anole species and subspecies. We are working in a soon coming review of this group. I’m very interested in the photograph linked as: http://www.pbase.com/image/100014648. This is a really diverse and complicated group of anoles.

Dr. Luis M. Diaz
Curator of Herpetology
Museo Nacional de Historia Natural de Cuba

Green anole chowing down on a smaller brown. Photo from Tim’s Fertile Turtles.

Tim Mitchell from Iowa State University reports a great observation of a green anole eating a brown anole. There’s even a video!

The website actually has a whole bunch of blog posts about Tim’s research project. Check it out!

Note: we’ve actually featured this video before with a description of the project from a different website, but it’s so cool, it’s worth posting again!

We all know that much of the natural world is being destroyed, fragmented, and altered by man’s activities. In many cases, the survival of species will depend on their ability to live in these human-transformed habitats. The field of “countryside ecology” has developed in recent years to investigate just how much diversity can be maintained in such habitats and to identify the factors that are most important in maximizing this diversity.

In a recent paper in Ecology, Mendenhall et al. look at the area surrounding the Organization of Tropical Studies’ Las Cruces Field Station. As in many areas in Costa Rica and elsewhere, much of the landscape has been changed to pastures and coffee plantations. Surprisingly, however, there are lots of little bits of forests meandering through these disturbed areas.

The authors find that a reasonably large amount of the species diversity of herps is maintained in these areas. In addition, the forest fragments turn out to be crucial for much of this diversity. Why these fragments are maintained is not known by the authors and an important area for further inquiry.

And what about the anoles? Anolis polylepis was the single most common herp in the area. As the chart below shows, the extent to which anoles are found in disturbed areas varies by species, not surprising given the differences in ecology of the species.

Not shown on the graph are several other anoles seen in lower numbers, specifically four A. biporcatus (two in pasture, two in coffee plantation) and nine A. woodi (four in the forest reserve, five in the forest fragments).

Here’s the paper’s abstract:

The future of biodiversity and ecosystem services depends largely on the capacity of human-dominated ecosystems to support them, yet this capacity remains largely unknown. Using the framework of countryside biogeography, and working in the Las Cruces system of Coto Brus, Costa Rica, we assessed reptile and amphibian assemblages within four habitats that typify much of the Neotropics: sun coffee plantations (12 sites), pasture (12 sites), remnant forest elements (12 sites), and a larger, contiguous protected forest (3 sites in one forest). Through analysis of 1678 captures of 67 species, we draw four primary conclusions. First, we found that the majority of reptile (60%) and amphibian (70%) species in this study used an array of habitat types, including coffee plantations and actively grazed pastures. Second, we found that coffee plantations and pastures hosted rich, albeit different and less dense, reptile and amphibian biodiversity relative to the 326-ha Las Cruces Forest Reserve and neighboring forest elements. Third, we found that the small ribbons of ‘‘countryside forest elements’’ weaving through farmland collectively increased the effective size of a 326-ha local forest reserve 16-fold for reptiles and 14-fold for amphibians within our 236-km2 study area. Therefore, countryside forest elements, often too small for most remote sensing techniques to identify, are contributing; 95% of the available habitat for forest-dependent reptiles and amphibians in our largely human-dominated study region. Fourth, we found large and pond-reproducing amphibians to prefer human-made habitats, whereas small, stream-reproducing, and directly developing species are more dependent on forest elements. Our investigation demonstrates that tropical farming landscapes can support substantial reptile and amphibian biodiversity. Our approach provides a framework for estimating the conservation value of the complex working landscapes that constitute roughly half of the global land surface, and which are experiencing intensification pressure worldwide.

Brown and green anole on South Padre Island. © Dave Welling

Here’s a marvelous photo of something I’ve never seen before. Nature photographer Dave Welling, who has some fabulous shots of anoles and other wildlife (don’t miss the rattlesnake striking the green jay), describes how he was “just photographing birds one day on South Padre Island and found a green anole. He started displaying on the tree branch when a brown anole approached from another direction. They both decided to see whose dewlap was bigger and they spent about 10 minutes moving around each other and displaying. Quite a sight and I too have never seen it before or since.”

That’s no viper

If there’s one thing we like here at AA, it’s convergent evolution (e.g., 1,2), so we’re always delighted to learn of new examples. Thus, we were delighted to read the recent report on convergence between Australian and North American snake faunas, written by Grundler and Rabosky and now available online at Proceedings of the Royal Society.

Australia is famous for being the only continent on which venomous snakes outnumber non-venomous ones. That is the result of radiation of a single clade of elapid snakes, known as the oxyuranines. It has long been noted that some oxyuranines seem convergent on counterparts elsewhere, such as the death adder, which looks and acts much like a heavy-bodied viper (photo above).

Grundler and Rabosky set out to test this idea of convergence more quantitatively, specifically asking whether the Australian radiation as a whole was more statistically similar to North American snakes than one might expect by chance. That is, does the convergence extend beyond a few pairs of species to encompass the entire radiation–is the radiation-wide degree of convergence greater than one would expect by chance? Alert readers will recall that this is the same question that Mahler et al. recently asked about Greater Antillean anoles, and Grundler and Rabosky used some of the new techniques presented in Mahler et al.

And the results, in a nutshell, are positive. Not only are there many cases of convergence (see figure below), but the overall amount of convergence is statistically significant. This can be seen in two analyses. First, for Australian snakes, the nearest morphological neighbor in North America is more similar than one would expect by chance. Second, Australian elapids have diverged to occupy 10 phenotypic peaks in morphological space, and seven of these are occupied by North American snakes as well.

The paper has three interesting twists:

1. Despite the great convergence in morphology, North American and Australian snakes are not convergent in diet. In particular, the Aussies eat a lot of lizards and snakes, and insect-eating is much more prevalent in North America.

2. There has been speculation in some quarters that replicate adaptive radiation is an island phenomenon, but this study shows that it can occur between mainland faunas as well.

3. Moreover, the convergence spans multiple lineages. Although the oxyuranines are a single radiation in Australia, their counterparts in North America belong to five different colubroid lineages (not that this analysis was restricted to colubroids, which include the great majority of snakes).

I think it’s safe to conclude that snakes aren’t quite as cool as anoles, but they’re getting there.

Battling female Anolis gundlachi. Photo by Ellee Cook.

Territorial behavior in anoles has been extensively studied, but mostly between the males. Yet, females engage in all kinds of aggressive interactions and seem to have territorities. What are the similarities and differences between their behavior and what males do?

Ellee Cook is studying just that in Puerto Rico, focusing on A. gundlachi. She’s in the field right now and has just filed a report on Chipojolab. Among other things, she witnessed a drag-down, knock-down fight, pictured above.

Of course, we’re all waiting to know–is this what females use their dewlaps for?

A blessed arrival. How often do females lay their eggs? Information needed!

We’ve previously reported on a study of seasonal population  reproductive cycles of female A. cristatellus from adjacent shade-dwelling and open-sunny sites being conducted by Luisa Otero, Ray Huey and George Gorman. George writes in to say that they “would appreciate ANY information on egg laying intervals for individual female anoles [of any species] either from captive breeding programs or from field studies. If published,  references are appreciated. If unpublished, access to your data is doubly appreciated. Obviously, if there exist ancillary data on temperature regimes of the egg depositors, that would be even more wonderful.”

Please respond as a comment or write George directly.