Author: Jonathan Losos Page 51 of 129

Variation in the back patterns of Anolis sagrei in the Bahamas. From Calsbeek and Cox (2010).

The confusing conundrum of the polymorphic females continues. We’ve written about this phenomenon in previous posts [e.g., 1,2]. Within and between populations, female back patterns vary, including lines, stripes, diamonds, blotches, and nothing at all. What is the significance of this variation? In some cases, but not others, females with different patterns use different microhabitats–higher, wider, etc.

The latest contribution features work on the Bahamian island of Eleuthera, where three patterns co-occur. Writing in Herpetologica, Les et al. add a new twist–back pattern variants differ in hindlimb length. But they don’t differ in sprint speed (which is weakly correlated to body size and relative limb length) or to perch diamter. But they do differ in perch height. Another brick in the wall of female pattern polymorphism, but it doesn’t make the picture any clearer.

Here’s the abstract:

The Brown Anole (Anolis sagrei) is a polymorphic species, with females often exhibiting one of three distinct pattern morphs. Efforts to correlate female-limited pattern polymorphism in anoles to ecological or physiological factors have largely been unsuccessful, with such correlations being either inconsistent among species or among populations of a single species. To test the hypothesis that morph types would differ in their response to putative predators, we observed escape behavior in 84 female A. sagrei from Cape Eleuthera (Eleuthera, Bahamas) and tested 103 females for sprint speed. We found differences between morph types in hindlimb span and perch height. Differences in sprint speed were not significant, nor did morphs differ in escape responses. We suggest further studies to determine whether differences between morphs in hindlimb span are genetic or plastic, and, if plastic, what factor might be responsible. We conclude that perching at different heights could be selectively advantageous for different morph types, and that differences among individuals in sprint speed are largely consequences of hindlimb length. Because morphs in this population did not differ in escape responses, we suggest that different dorsal patterns are not linked to specific behaviors that could reduce detection by a potential predator.

About time! Read all about it in the St. Augustine Record.

The Catalogue of American Amphibians and Reptiles, produced by the Society for the Study of Amphibians and Reptiles, are “Loose-leaf accounts of taxa (measuring 8.5 x 11 inches) prepared by specialists, including synonymy, definition, description, distribution map, and comprehensive list of literature for each taxon. Covers amphibians and Reptiles of the entire Western Hemisphere. Individual accounts are not sold separately, except where indicated.”

CAAR entries are now freely available online; there are 32 anole species accounts. The latest is by Les and Powell and is a very nice CAAR entry for the lovely Anolis smaragdinus.

Admittedly, they were in a piece on space geckos, but you gotta’ take fame where you can get it. Catch the clip here before Youtube takes it down.

And note that this is not the first time anoles have been mistaken for geckos by journalists. Let’s not forget the segment on the Sunday Morning CBS show, a misstep for which AA  led the blogosphere in breaking the news and eventually received a mea culpa from CBS.

Juan Daza asks: Can you identify this lizard?

He continues:

If you have no idea, it’s not because it’s not an Anolis; in fact, this is an imaginary lizard that was reconstructed based on the remains of a 110 my old fossil from the Gobi Desert and a mosaic of features from different living geckos such as Agamura persica, Pachydactylus rangei, Teratoscincus przewalskii, Hemidactylus turcicus, and Coleonyx variegatus (and check the dromeosaurids roosting at twilight).  This digital illustration drawn by Stephanie Abramowicz is the cover of a March Special Issue from the Anatomical Record: New Advances In Morphology and Evolution of Living and Extinct Squamates [freely available at: http://onlinelibrary.wiley.com/doi/10.1002/ar.v297.3/issuetoc].

The idea of a volume like this started with James D. Gardner and Randall L. Nydam. They wanted to put a collection of papers from the Paleo-session of the past World Congress in Vancouver. Instead, they ended up editing another multi-authored volume entitled: Mesozoic and Cenozoic lissamphibian and squamate assemblages of Laurasia (Palaeobiodiversity and Palaeoenvironments, 93(4), Special Issue).

This volume took a different approach, and we (Scott Miller and I) put together herpetologists and paleontologists from around the world in a volume to present new ideas about morphology and evolution of squamates. This volume is a collection of 18 papers about paleontology, functional morphology, and gross anatomy of lizards and snakes, and includes recent findings from researches from 12 countries (USA, Canada, Colombia, Brazil, Argentina, Spain, France, Italy, Germany, Slovakia, South Africa, and New Zealand).

So please feel free to browse this volume that includes original research papers about the fossil record of lizards and snakes, anatomy of the chameleon’s atlantoaxial complex, pedal grasping capabilities, and pectoral girdle anatomy of anoles, fossil record of the Gekkota, cranial joints of squamates, hemipeneal morphology, brille formation, cranial joints, ancestral morphology and niche modeling of rhineurids, Anguimorpha, and the jaw musculature, and gut morphology of snakes. I hope you find this stimulating and pick morphology today, for a change.

Table of Contents:

The Anatomical Record is Alive With Leapin’ Lizards and Slitherin’ Snakes (pages 337–340)
Kurt H. Albertine and Scott C. Miller

What’s So Special About Squamates? (pages 341–343)
Juan D. Daza and Scott C. Miller

Not Enough Skeletons in the Closet: Collections-Based Anatomical Research in an Age of Conservation Conscience (pages 344–348)
Christopher J. Bell and Jim I. Mead

An Overview of the South American Fossil Squamates (pages 349–368)
Adriana María Albino and Santiago Brizuela

The Atlas-Axis Complex in Chamaeleonids (Squamata: Chamaeleonidae), with Description of a New Anatomical Structure of the Skull (pages 369–396)
Andrej Čerňanský, Renaud Boistel, Vincent Fernandez, Paul Tafforeau, Le Noir Nicolas and Anthony Herrel

Anatomy of the Crus and Pes of Neotropical Iguanian Lizards in Relation to Habitat use and Digitally Based Grasping Capabilities (pages 397–409)
Virginia Abdala, María José Tulli, Anthony P. Russell, George L. Powell and Félix B. Cruz

Geometric Morphometric Analysis of the Breast-Shoulder Apparatus of Lizards: A Test Case Using Jamaican Anoles (Squamata: Dactyloidae) (pages 410–432)
Alexander Tinius and Anthony Patrick Russell

On the Fossil Record of the Gekkota (pages 433–462)
Juan D. Daza, Aaron M. Bauer and Eric D. Snively

To Move or Not to Move: Cranial Joints in European Gekkotans and Lacertids, an Osteological and Histological Perspective (pages 463–472)
Marcello Mezzasalma, Nicola Maio and Fabio Maria Guarino

Relict Endemism of Extant Rhineuridae (Amphisbaenia): Testing for Phylogenetic Niche Conservatism in the Fossil Record (pages 473–481)
Christy A. Hipsley and Johannes Müller

Are Hemipenial Spines Related to Limb Reduction? A Spiny Discussion Focused on Gymnophthalmid Lizards (Squamata: Gymnophthalmidae) (pages 482–495)
Pedro M. Sales Nunes, Felipe F. Curcio, Juliana G. Roscito and Miguel T. Rodrigues

Through the Looking Glass: The Spectacle in Gymnophthalmid Lizards (pages 496–504)Ricardo Arturo Guerra-Fuentes, Juliana G. Roscito, Pedro M. Sales Nunes, Priscilla Rachel Oliveira-Bastos, Marta Maria Antoniazzi, Jared Carlos and Miguel Trefaut Rodrigues

A New Miniaturized Lizard From the Late Eocene of France and Spain (pages 505–515)
Arnau Bolet and Marc Augé

Comparative Anatomy of the Lower Jaw and Dentition of Pseudopus apodus and the Interrelationships of Species of Subfamily Anguinae (Anguimorpha, Anguidae) (pages 516–544)
Jozef Klembara, Miroslav Hain and Karolína Dobiašová

Unusual Soft-Tissue Preservation of a Crocodile Lizard (Squamata, Shinisauria) From the Green River Formation (Eocene) and Shinisaur Relationships (pages 545–559)
Jack L. Conrad, Jason J. Head and Matthew T. Carrano

Postnatal Development of the Skull of Dinilysia patagonica (Squamata-Stem Serpentes) (pages 560–573)
Agustín Scanferla and Bhart-Anjan S. Bhullar
Article

Homology of the Jaw Muscles in Lizards and Snakes—A Solution from a Comparative Gnathostome Approach (pages 574–585)
Peter Johnston

A Model of the Anterior Esophagus in Snakes, with Functional and Developmental Implications (pages 586–598)
David Cundall, Cassandra Tuttman and Matthew Close

Short video of a cool, but underappreciated, anole.

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)