ok, the little screen.
Year: 2011 Page 18 of 42
Acrobatic bushmaster says hello!
At the Nashville Zoo we have a large mixed species exhibit that contains two species of dart frog, a bushmaster, Gonatodes, and 2.3 Roquet’s anoles (Savannah anoles). We are working on some new graphics where we hope to incorporate videos, and in that attempt we captured some great footage of our two male A. roquet displaying towards one another. The two males are approximately a foot apart and right in front of the glass of the exhibit. The females were watching anxiously as shortly after the video stops one male chases the other up a tree. I hope you enjoy the clips.
http://www.flickr.com/photos/66876684@N04/6086156957/in/photostream
http://www.flickr.com/photos/66876684@N04/6086649388/in/photostream/
The sequencing of the genome of the green anole (Anolis carolinensis) is a landmark in the age of genomics, and a highpoint in the annals of anole studies. It is the first complete genome sequence of a reptile, and a great step forward in the development of comparative genomics. Results are already coming in: Matthew Fujita, Scott Edwards and Chris Ponting have a paper in press in Genome Biology and Evolution, using an earlier release of the anole genome, showing that the green anole genome lacks the large guanine-cytosine rich regions (called isochores) that are characteristic of birds and mammals. Is this lack unique to the green anole, or a feature of some larger group? We don’t know, of course, because the green anole is the first non-avian/non-mammalian amniote to be sequenced, but it is a hint of new things to come. As Rich Glor put it in his commentary here at Anole Annals,
Fujita et al.’s work is a good example of the insight offered by comparative genome sequencing; as the number of available genomes expands, this work is sure to continue to challenge overly simplistic assumptions about genome architecture and evolution derived from biased sampling of the tree of life.
Green Anole, Anolis carolinensis, New Orleans, LA. Note the expanded subdigital toepads.
So why was an anole chosen to be the first reptile sequenced? The short answer is that, among a small group of candidate species of reptiles announced by the NIH in May of 2005, the response of the biological community favored the green anole over the garter snake. But the longer answer includes why the community preferred the green anole: it has long been the subject of diverse physiological, behavioral, ecological, and other studies (a “model” organism in the functional biology sense), and, more importantly, anoles in general have been favored and favorable materials for a diverse array of physiological, behavioral, ecological, evolutionary, and zoogeographic studies over many decades. The goal of this post is to review a bit of the rich history of anole studies to provide some background on why so many researchers have found anoles to be vastly interesting animals.
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.
According to NOAA, the eye is over Abaco right now, with sustained wind speeds of 115 mph
Doesn’t look good. Staniel and particularly Abaco are right in the path of Irene–Category III for Abaco. Hang in there, lizards and people!
a juvenile Anolis orcesi, in the afternoon of an all-day recording
They wake up, but hit the snooze button before they really get moving. They poop, grab something to eat, and then check out the neighborhood. They take wrong turns, and have to turn around when they reach a dead end. Young boys try to impress each other with their dewlaps. They take naps in the afternoon, and yawn throughout the day. They even sleep in the same bed, most nights.
As Jonathan Losos hinted at in an earlier post, we observed 4 Anolis orcesi individuals from dawn to dusk (12 hours!), and several more individuals for 1 to 6 hours, in the vicinity of Baeza, Ecuador. More to come after several months of video analysis!
AA readers may recall a series of post this past May, in which I discussed research on anole ecology and evolution in the Bahamas. Those posts discussed studies that have been ongoing in Abaco for several years on the effect of predators (curly-tail lizards) on anoles, as well as studies initiated this year to the south in Staniel Cay.
Hurricane Irene, predicted to reach Category IV status, is now bearing down on the Bahamas from the south. And if you examine the hurricane’s track, you’ll see that she is aiming right at our study sites. What will happen? In the past 13 years, we’ve had three experiments terminated by hurricanes. Please cross your fingers, toes, and any other extremities in hopes that fourth time is a charm.
Figures from Fujita et al. illustrating relative homogeneity of GC content across the anole genome (left) and shifts in GC3 along branches in the vertebrate tree, with black branches indicating descreases of GC3 and gray branches indicating increases of GC3 (right).
Genomes are rarely homogeneous aggregations of Gs, As, Ts, and Cs. Indeed, variation in basepair frequency can have important implications for how genomes, and the organisms they generate, evolve. Regions with relatively homogenous GC content that extend for more than 300 kb known as isochores are prominent features of previously sequenced amniote genomes. Isochores are associated with a range of important variables, including gene density, intron length, DNA replication timing, and gene expression. GC-rich isochores also tend to experience high rates of recombination, resulting in elevated effective population sizes and increased efficiency of purifying selection relative to drift.
A fifth grade teacher prepares for a lizard sprint trial. (Notice the two different perches in the cage in the foreground.)
A few days ago, I posted a description of an anole-based project I assign in my college Evolution course, but of course, anoles are fascinating to students of all ages! In this post, I’ll describe materials I developed this summer as part of Trinity University’s Science Teaching Institute, teaching 20 San Antonio fifth-grade science teachers to use green anoles (Anolis carolinensis) in their classrooms. These materials were specifically designed to meet Texas Essential Knowledge and Skills (TEKS) standards, but I expect they would be appropriate for many elementary school science classes.