As with the previous issue, the just released September number of IRCF Reptiles & Amphibians: Conservation and Natural History is a bonanza for anoliphiles. The photo above is from the inside back cover, relating to the article on Cuban herps that features several fine anole photos. There’s also an article on herping in the Dominican Republic and another on the reptiles of San Salvador island, Bahamas. As always, the photos are sumptuous.
Author: Jonathan Losos Page 114 of 130
Professor of Biology and Director of the Living Earth Collaborative at Washington University in Saint Louis. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.
- Anolis aeneus. Photo from http://www.kingsnake.com/westindian/anolisaeneus5.JPG.
Surprisingly few studies have examined how anole population density varies geographically, much less trying to explain why. In a recent study, McTaggart and colleagues surveyed herpetological abundance across Union Island (8.4 km2) in the Grenadines (near Grenada). Anolis aeneus was by far the most abundant herp on the island and was found almost everywhere. However, its abundance did vary from 0 to 62 individuals seen in visual encounters performed during the course of a morning and an afternoon. The sites lacking A. aeneus were a mangrove and a transect from a scrubby coastal hillock to a beach; overall, anole abundance was strongly correlated with vegetational complexity (categorized based on the number and variety of trees, height and connectedness of the canopy, and extent of human disturbance), perhaps not surprising for an arboreal lizard often found high in trees.
Genny Wilson, a certified medical illustrator (check out her work here), has tried to imagine what Anolis roosevelti, not seen for 80 years, might have looked like in life. This is her latest version. Have any thoughts or suggestions? Add a comment, or email her directly at hagginwilson@earthlink.net.
Pop on over to Dust Tracks on the Web and help Janson decide if this majestic fellow is a sagrei or a cristatellus…or something else. And read some of his other recent posts on anole adventuring.
Walt Meshaka has just published a fabulous new monograph on the introduced reptiles and amphibians of Florida in Herpetological Conservation and Biology. Check it out here. It includes the latest word on the eight introduced anoles of that fine state.
As the publication of the anole genome approaches, one might ask: “Just how was Anolis carolinensis selected to be the first non-avian reptile to have its genome sequenced?” Turns out that it’s a long and convoluted story, and this is one man’s first-hand account.
To set the stage, we have to go back to the early days of genome sequencing, all the way back to 2005. This was a time when to sequence a genome was a really big, time-consuming, extremely expensive affair (the human genome had cost ca. $2 billion; by 2005, the price had dropped to ca. $20 million per genome). Such a big deal, in fact, that there was an NIH committee that decided which species would be sequenced, and assigned them to one of the three genome sequencing centers (Baylor University, Washington University in Saint Louis and the Broad Institute in Cambridge) that had been created as part of the human genome sequencing initiative. The first few species selected were chosen exclusively with regard to their potential relevance to human health. They were the laboratory model systems, the workhorses of biomedical research, such as the mouse, chimp, Xenopus, chicken, Drosophila and C. elegans.
By 2005, a couple of mammals had been sequenced and representatives of all classes of vertebrates except one: reptiles.
For information on why the anole genome is useful for evolutionary studies, go here.
For information on how the genome is already being used in research, try here, here, here, here and here.
For the history of discovery and study of anoles, go here.
For the evolutionary history of the green anole, check this one out.
For a great story, don’t miss this one.
For great pictures of anoles and their dewlaps, try here, here, and here (among others).
For many other topics in anole ecology, behavior, and diversity, try looking up terms in the blog’s search window.
One of these species has had its genome sequenced, and the other has independently evolved to look very similar and live in the same environment. The anole genome will make anoles an even more powerful group in which to study evolutionary convergence. Photos by Melissa Losos (left) and Pete Humphrey (right).
When the genome of Anolis carolinensis is finally published, most attention will focus on how this genome, the first reptile to be sequenced (not including birds), differs from other vertebrate genomes, and what these differences may tell us about genome evolution. No doubt this will be interesting, but the real value of this genome–in my unbiased opinion–resides in the questions we finally will be able to address about the evolutionary process, particularly in one model system of evolutionary study, Anolis lizards. Chris Schneider published a perceptive article, “Exploiting genomic resources in studies of speciation and adaptive radiation of lizards in the genus Anolis,” on this topic three years ago, and I will briefly expand on his points here.
An anole genome will be useful for evolutionary studies in two ways. First, a long-standing question in evolutionary biology concerns the genetic basis of convergent evolution (i.e., when two or more evolutionary lineages independently evolve similar features). Do convergent phenotypes arise by convergent evolution of the same genetic changes, or do different lineages utilize different mutations to produce the same phenotype? In other words, does convergence at the phenotypic level result from convergent change at the genetic level, or can different genetic changes produce the same phenotypic response? In the last few years, molecular evolutionary biologists have produced a wealth of studies investigating whether convergent changes in coat color in rodents, eye and spine loss in fish, bristle loss in fruit flies and many other changes are the result of changes in the same gene, even some times by the very same genetic mutation. Underlying these questions are more fundamental questions about constraints and the predictability of evolution (these topics have been reviewed a number of times in the last couple of years, most recently in a paper by me, in a paper which refers to other recent reviews).
The anole ecomorphs, habitat specialists behaviorally and morphologically adapted to use different parts of the environment. The same set of ecomorphs (with several exceptions) have evolved independently on each island in the Greater Antilles. Figure from "Lizards in an Evolutionary Tree," based on earlier figures in Ernest Williams' work.
Anolis lizards are, of course, the poster child for evolutionary studies of convergent evolution. Indeed, convergence has run rampant in this clade. AA has prattled on endlessly about the famous anole ecomorphs, a set of habitat specialist types that have evolved repeatedly on each island in the Greater Antilles to occupy different habitat niches. This convergence is usually studied in terms of limb length, tail length, and toepad dimensions: arboreal species have big toepads, twig species short legs, grass species long tails, and so on, with these traits independently evolving many times. But the ecomorphs are convergent in many other traits that have received less attention: head and pelvis dimensions, sexual dimorphism in both size and shape, territorial and foraging behavior, to name a few, and the more closely we look, the more convergent traits we find. And, further, anole convergence is not entirely an ecomorph phenomenon; some traits vary within an ecomorph class, but are convergent among species in different ecomorph classes, for example, thermal physiology and dewlap color.
In other words, there’s more convergence in Anolis than you can shake a stick at, and the availability of the anole genome sequence will provide the tools to investigate its underlying genetic basis.
ok, the little screen.
Anolis allisoni (photo from http://www.kingsnake.com/westindian/anolisallisoni2.JPG)
Everyone’s worried about global warming. For a long time, frogs hogged the herpetological spotlight, with concern that the global amphibian crisis might be driven by climate change. However, in recent years, there has been a growing realization that lizards may be in trouble, too, and again the finger has been pointed at climate change.
One hypothesis put forward by Ray Huey and colleagues is that as temperatures warm, open-adapted species will be able to invade forests, which previously had been too cool for them, and the cool-adapted forest lizards, living in a now warmer home and faced with competition from the invaders, would have nowhere to go and would be in big trouble. Preliminary data from Puerto Rico support this model, and Huey and colleagues have returned to the enchanted island to further test the hypothesis.
Michael Logan, a graduate student at Dartmouth, has set out to test this idea elsewhere, working in the Bay Islands off the coast of Honduras. These islands are particularly interesting because they are one of the few places where Caribbean and mainland anole faunas meet, with members of the sagrei and carolinensis species groups of Cuba coexisting with several mainland species. This juxtaposition is interesting in its own right, but it turns out that the Caribbean species are warm-adapted, open-living species, whereas the mainland species are cool-adapted, forest types. Logan’s goal is to test the hypothesis that as warming occurs, the warm-adapted species will be able to enter the forest, with potentially adverse effects on the species therein. In a recent issue of Biodiversity Science, a newsletter put out by Operation Wallacea, Logan reports preliminary results from last year’s field season, and they’re not what you might expect.