Springer recently published a new and dramatically expanded version of Pardis’s book Analysis of Phylogenetics and Evolution with R. This book is a great way to teach yourself some of the amazing techniques available for phylogeneticists and comparative biologists via the R statistical computing environment. With 386 pages, the new edition is nearly twice as large as the previous version (211 pages). Countless new methods are covered, and many problems with the previous edition are remedied. In spite of the expansion and improvements, the sticker price is actually lower on the new edition ($65) than it was on the old edition ($75). You can pick up a copy for around $50 at places like Amazon.com. This book should be considered required reading for anyone doing modern phylogenetic and comparative analyses. If you need anoles to inspire an interest in learning R, I’ll be posting shortly on some R tutorials that use anoles as case studies.
Category: New Research Page 54 of 66
Most studies that describe anole locomotion are based on the analysis of kinematic and dynamic data. One of the challenges in biomechanics is to deduce from these data the interarticular forces and moments produced during locomotion. Indeed, evaluation of these dynamic data can inform us about the force production and absorption mechanisms that are crucial in movements for which the musculoskeletal system is in high demand, e.g. running, jumping or landing. These movements are essential in the fitness of individuals in arboreal environment during predator avoidance or prey attack and need to develop very high force levels by the musculoskeletal system, and especially by the hindlimbs during takeoff and forelimbs during landing.
To evaluate these dynamic constraints, the most usual procedure is to use a mathematical method called “inverse dynamics.” It consists in deducing the interarticular forces and moments for the knowledge of the ground reaction force, the linear and angular accelerations of the different segments, and their morphometric characteristics. However, there was no morphometric database to date in anoles.
That’s why we conducted a study to characterize the centers of gravity, moments of inertia, masses and lengths of major segments in Anolis carolinensis and Anolis sagrei (Legreneur et al., 2012). To do this,
Anolis carolinensis mating. Photo by Michele Johnson from Wade (2012). Insets: Upper, vertebral column of green anole around pelvis and tail; lower, hemipenis musculature.
Juli Wade has just published a review paper in which she sings the praises of anoles as a group to study the integration of behavior, anatomy, endocrinology and molecular mechanisms in vertebrate reproduction. She notes that a number of model systems exhibit, but synthesis is hindered because courtship and copulatory systems have been studied in different groups and, among studies of courtship biology, very disparate structures have been examined (e.g., bird syrinxes, frog larynxes, fish swim bladders) making comparative analysis difficult.
Anoles to the rescue! Wade notes: “Anoles offer some advantages over these other model systems. A long history of research into the hormones, brain and behavior exists for one species, the green anole (Anolis carolinensis), and a substantial amount of data is also available for the brown anole (A. sagrei). These studies indicate that the hormonal regulation of behavior appears quite similar in these two species of anoles. The genome of the green anole has recently been sequenced, which greatly facilitates investigations at the molecular level. Two features, however, provide unique power for the investigation of mechanisms regulating structure and function.
First, three sexually dimorphic systems exist within the same individuals – portions of the limbic forebrain, which control higher level or more motivational aspects of sexual behavior, and both courtship and copulatory neuromuscular systems, all of which lend themselves to investigations in the field and laboratory. Second, more than 350 species of anole lizards span the Southeastern US, Caribbean islands and Central and South America. Information on the behavioral ecology and phylogenetic history of many of these is accessible. And, while limited data on the neural and muscular structures regulating courtship and copulation are currently available, it is clear that species across the genus exhibit beautiful variation in the degree of sexual dimorphism in morphology on a gross level. Anole lizards therefore represent a terrific opportunity for more detailed investigations from an evolutionary perspective.”
I come to you, anologists of the world, with a request for your photos of anole dewlaps. I’m planning a study of dewlap size evolution across the Anolis phylogeny, but there’s not much data available for many of the less common species. I know many anole-hunters take pictures of their quarry with dewlaps extended after catching them, so I thought I’d try to extract data (e.g. dewlap length and area) from a collection of photos. If you have photos you might be able to share, please read on, and feel free to contact me if you have questions.
Requirements:
-The photo should show a live, adult male caught in the wild. Its dewlap should be fully extended – ideally either of its own volition or with tweezers, but fingers are ok as long as at least 90% of the dewlap area is visible.
-The anole’s entire head should be in the photo (so I can scale dewlap size relative to head size). If there’s a ruler or object of known length in the photo that’s even better.
-The photo should be close to a side-view profile (give or take no more than about 10 degrees angle in any direction).
-At a minimum, identify the species and the approximate location (country or island). Please do include any extra information you can share (e.g. date, latitude/longitude/altitude, snout-vent length of anole, weather…), but I know this may not be available for all the photos.
Clearly I’m new to this – any photo better than this one should be useable.
Check out the comments section of this post for some better examples.
If you have one or more suitable photos you can contribute, please send them to me as an attachment to an e-mail. If you have large files or many photos (more than ~5MB) that may not make it through e-mail servers, drop me a line and I’ll send you a link to a Dropbox folder instead. If you are willing to give permission to use the photo (with full credit, of course) in potential blog posts, web pages (e.g. Encyclopedia of Life entries), or publications, please say so in the e-mail; otherwise I will only use the photos to extract basic measurements.
The good folks at Science magazine are giving away copies of the recent paper for free! Get yours today. Just click here.
Cover of Science, 2 March 2012
Anoles have gotten the cover again! This time it’s on tomorrow’s issue of Science for this work by Jason Kolbe and colleagues, covered here on Anole Annals. The photograph of A. sagrei is by Neil Losin, whose photo- and videographic works have been profiled on Anole Annals several times before.
Green anoles can change from green to brown. Occasionally, they do it only part way. Photo from http://www.floridagardener.com/img/critters/Greenanole.jpg
Widely, if inaccurately, known as the American chameleon, Anolis carolinensis is renowned for its ability to change color from a sparkling emerald to a deep brown. Surprisingly, we don’t really know what factors determine whether a particular lizard chooses to be green or brown at a particular time.
Here’s what I had to say about it in Lizards in an Evolutionary Tree (pp. 279-281; I’ve omitted most references here):
“In theory, we might expect green anoles to match their background, turning green when in vegetation and brown when against a woody surface. Although widely believed, this idea is not strongly supported (reviewed in Jenssen et al., Herp. Monographs, 1995).
Anoles are well-known for a lot of reasons, but conservation is not one of them. Possibly because of the abundance, hardiness, and visibility of the more common anole species, the group as a whole is often regarded as one that’s doing just fine. To date, very few specific efforts have been made to assess the conservation status of anole species.*
Anole species vary, of course, in how they’re doing. Although species such as Anolis cristatellus, cybotes, and limifrons seem to occur on every perch across broad distributions, species like A. fowleri and A. megalopithecus have only been located a handful of times in the wild despite some considerable efforts. Dozens more species are known from just a single locality, where they may or may not be locally abundant. While a lot of rare or little-known anoles may simply be secretive or geographically restricted, some are very clearly endangered.
They thought it was only a three hour tour.
In my career, I have found that the most exciting research is when the results are exactly the opposite of what I had expected. Certainly, it’s nice to show that what you thought was correct, but you really learn something when the opposite occurs–it makes you look at questions in a new way and often leads to new insights. This has happened to me several times, most recently in our experimental study of founder effects in Bahamian anoles (paper downloadable here).
One of the tiny islands on which the founder effect experiment was conducted. Note the scraggly vegetation. Photo by Jason Kolbe.
Here’s the story: we have been conducting studies on anoles in the Bahamas for quite some time, using tiny islands as experimental test tubes. We had seen island populations wiped out by hurricanes, and we had documented anoles colonizing these islands, so we knew that populations often must be founded by overwater dispersal, probably by one or very few individuals. Given the long-running controversy over the evolutionary significance of founder effects, we had long discussed whether we could create an experimental founder effect, in replicate, to see what would happen. But we never started such an experiment, for a simple reason: suitable islands for our various ecological and evolutionary experiments were in short supply, and this experiment wasn’t a high priority.
Enter Hurricanes Frances and Jeanne in short succession in the late summer of 2004.
On Sunday, the Washington Post published a nice news article covering the recent study on island colonization and adaptation in anoles (pdf now available here). Very quickly, back-and-forth exchanges appeared in the paper’s online comments section, but most of them were debates about evolution vs. creationism/intelligent design, as well as invectives, insults, and ad hominem attacks. The same thing happened when I posted a story on the anole genome and its utility for the study of evolution on a National Geographic news website. Who knew that anole research was so pivotal to the evolution/creationism controversy? Or that it could bring out the worst in so many?
Appended below are the 77 comments that had appeared in the Washington Post by mid-afternoon on Monday.
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Castaway lizards put evolution to the test
By Brian Vastag, Published: February 4
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