Anole Annals

JMIH 2014: Effect of Moisture and Substrate on Egg Water Uptake and Phenotypes of Hatchling Lizards (Anolis sagrei)

On August 4, 2014

Following up on yesterday’s post, more research results from the Warner Lab on egg incubation were presented at JMIH. Corey Cates, a masters student from the Warner Lab, presented his data on developmental plasticity in Anolis sagrei. He used an experimental approach to test whether lizards incubated under dry conditions would survive better in a dry habitat than lizards incubated under moist conditions and vice versa. The idea for the study came from the observation that habitat and substrate differs among small islands in Florida. Some islands are scarcely vegetated and have dry substrate consisting of broken shells. Other islands are more densely vegetated and have dark soil that contains organic matter.

Corey collected 128 breeding pairs from four islands and incubated the eggs using the two different substrates. He also tested two different moisture conditions (wet and dry). He found that lizards incubated under wet conditions hatch on average 4-5 days later and hatchlings were significantly heavier than those incubated under dry conditions. In addition, lizards hatch significantly later when incubated in the soil substrate, which retains moisture longer than the broken shells. Corey further tested whether lizards raised under dry conditions have higher desiccation tolerance than lizards from wet conditions. He measured body mass before and after keeping the lizards in a desiccation chamber. Lizards that had developed under wet conditions lost 5% more mass than lizards developed under dry conditions.

Hatchlings incubated under wet conditions lost significantly more mass than hatchlings incubated under dry conditions.

This suggests, that plastic responses to different developmental conditions have an effect on physiological traits that might increase survival in a specific habitat. To test this, Corey then released the hatchlings on four experimental islands and measured hatchling survival using a recapture method.

Significantly more hatchlings survived in the open, arid habitat when eggs were incubated under dry conditions.

He found that significantly more hatchlings survived in open, arid habitats when eggs were incubated under dry conditions. No effect of incubation condition on hatchling survival was found in the shaded, moist habitat.

JMIH 2014: Effects of Natural Incubation Temperatures on Development and Phenotypes of the Lizard Anolis sagrei

By Rich Glor

On August 2, 2014

In New Research

Yesterday at JMIH, Phillip Pearson reported results from work conducted with his thesis adviser at the University of Alabama, Birmingham Daniel Warner. Pearson investigated the impact of incubation environment on the brown anole (Anolis sagrei), and the effects of incubation in shaded versus open habitat and early versus late season in particular. Pearson reported several significant differences between the eggs (and resulting hatchlings) incubated under these two conditions. He specifically reported longer incubation intervals under early season and shaded conditions, smaller hatchling size under shaded conditions and better performance of hatchlings at 1 and 3 weeks for the eggs incubated under the late season regime. Performance of hatchlings was quantified as their speed and the number of times they stopped during a performance trial. This work is the latest in a string of interesting studies from the Warner Lab on the impact of incubation conditions on anoles. I was going to provide links to previous posts on Anole Annals about the Warner Lab‘s work, but there are so many that I’ll just suggest that you type “Warner” into the search box at the top of the page and enjoy for yourself.

JMIH 2014: Who’s There? The Importance of Familiarity in Discrimination of Avian Calls by the Brown Anole (Anolis sagrei)

By Rich Glor

On July 31, 2014

In All Posts

I saw two talks on brown anoles in the same session this afternoon at JMIH. The second reported on the response of brown anoles (A. sagrei) to potential avian predators. Lisa Cantwell presented results of her work with Joe Altobelli and Sandy Echternacht on the behavior of brown anoles exposed to the calls of potential avian predators in a controlled laboratory environment. Cantwell has previously reported that anoles respond more strongly to the calls of predator birds than to white noise or non-predator birds (see also prior work on A. cristatellus in response to predator and non-predatory birds). Cantwell played the calls of four bird species to captive brown anoles and monitored their reactions. The four birds in the study included one species that co-occurs with, and preys upon, A. sagrei: the American Kestrel. The other birds were species that do not co-occur with A. sagrei: the White-rumped Falcon (gotta love the ornithologists and their descriptive common names), the Shikra, and the Lesser Kestrel (this name seems kind of demeaning and should probably be changed). Cantwell tested if the anoles responded more to the predator that they or their ancestors have likely encountered in nature than to the calls of predators that they or their ancestors have likely never encountered. The types of reactions that were viewed as indicative of increased vigilance in the lizards included head shifts, eye opening, and movement around the enclosure. Although Cantwell found that the lizards responded to all of the various bird stimuli at a similar level to white noise, she hypothesized that this resulted from hyper-vigilance in a contrived laboratory environment. She also reported that the lizards responded significantly more quickly to the American Kestrel and that they remained vigilant for twice as long in response to this sympatric predator than they did in response to the non-sympatric predators.

JMIH 2014: Using Biological Invasions to Model the Fundamental Niche: A Case Study Using the Cuban Brown Anole (Anolis sagrei)

By Rich Glor

On July 31, 2014

In New Research

I caught my first anole talk at this year’s Joint Meeting of Ichthyologists and Herpetologists in Chattanooga, Tennessee. James Stroud presented the results of work with Ken Feeley on modeling the niche of the brown anole (Anolis sagrei). Using data acquired from GBIF, Stroud showed that the environmental conditions experienced by brown anoles in their introduced range are outside of the environmental conditions experienced by brown anoles on Cuba. Stroud discussed how these data from the invasive range of the brown anole might be used to develop a more accurate model of this species’ fundamental niche. This is a work in progress.

There Is Grandeur in This View of Reptilian Genitalia

By Thomas Sanger

On July 31, 2014

In New Research

There is considerable variation in phallus morphology among the major groups of amniotes (phallus used herein to be inclusive of both the penis and clitoris). Just for starters, while most clades – including mammals, birds, turtles, and crocodilians – have a single midline phallus, squamates have paired hemiphalluses. Although herpetologists have long appreciated morphological variation in the hemipenis for its systematic value, understanding the nuances of anatomical homology, homoplasy, and novelty at this larger scale has not been as widely addressed. Recently, the Cohn lab of the University of Florida (of which I am now a member) undertook this challenge from a developmental perspective, studying development of external genitalia in representatives of each reptilian clade: the ball python (Python regius), the pond slider (Trachemys scripta), three duck species, the American alligator (Alligator mississippiensis), and who else, but the green anole (Anolis carolinensis). A synthetic review of the complete series will have to wait for another post, but reprints of each paper are available on the lab’s website to hold over the most curious. But because of the growing interest in anole nether regions, I will briefly highlight the recent findings regarding hemiphallus development in the green anole.

Fig. 2 of Gredler et al. illustrating the development of paired genital and cloacal swellings.

The Wade lab has previously shown that both male and female green anoles develop similar hemiphalluses during the early stages of genital morphogenesis, which then later differentiate into sex-specific reproductive structures. Building upon this observation, Gredler et al. described the embryology of the green anole hemiphallus from the earliest stages of morphogenesis through sexual differentiation. Hemiphallus development begins around the time of oviposition when three sets of paired swellings appear between the cloaca and the developing hindlimb bud, reminiscent of what is observed in other amniote clades. These swellings expand and meet at the midline to form the external lips of the cloaca or remain lateral to the cloaca and mature into the hemiphalluses. Following morphogenesis, the male hemipenis continues to elongate as it forms its distinctive lobes and sulcus spermaticus while the female hemiclitores gradually regress into the cloaca. Further details of the developmental anatomy of internal reproductive structures and gene expression patterns of several key molecules associated with genital morphogenesis are described in the paper.

Fig. 4 of Gredler et al. illustrating sexual differentiation of the hemiphalluses. Red arrow highlights the formation of the sulcus spermaticus.

Although there is some variation among squamates in the relative timing of the emergence and fusion of the paired swellings associated with hemiphallus development, these results are largely consistent with classical embryological descriptions of squamate genitalia (summarized by Raynaud and Pieu in Biology of the Reptila volume 15). But the revival of this body of literature in a comparative and molecular context brings new research questions to our collective table. As discussed by Gredler et al., the seemingly modular relationship between the genital swellings, cloaca, and limb buds may be particularly interesting in the context of repeated body elongation and limb loss among squamates. Better understanding of the relationship between cloacal and phallus development may also shed new light on the mechanisms of reproductive isolation, the coevolution of male and female reproductive organs, and evolving patterns of sexual conflict. Furthermore, there remain open many mechanistic questions regarding the molecular patterning of the hemiphalluses and which processes are hormone dependent that can now be more thoroughly addressed using the newly available sex-specific molecular markers. Considering the growing literature on hemipenis variation and expanding access to genomic resources in Anolis, these may be particularly fruitful areas for future investigation.

More Research on Female Back Pattern Polymorphisms

By Jonathan Losos

On July 30, 2014

In All Posts

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.

Green Anole Named Critter of the Year

By Jonathan Losos

On July 29, 2014

In All Posts

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

Everything You Ever Wanted to Know about the Beautiful Anolis smaragdinus

By Jonathan Losos

On July 28, 2014

In All Posts

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.

Anoles Make Guest Appearance on John Oliver Show

By Jonathan Losos

On July 27, 2014

In All Posts

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.

A Dearth Of Anoles At ISBE And ABS

By Ambika Kamath

On July 26, 2014

In All Posts

August 2014 is a good month for behavioural biologists in North America: at the start of the month, the International Society for Behavioral Ecology and the Animal Behavior Society are holding conferences in quick succession in New York City and Princeton respectively. However, Anolis lizards are pitifully underrepresented at these meetings: of the hundreds of talks at these two meetings, a total of zero–yes, zero–are about anoles. This is a tad surprising–plenty of people study the behaviour of anoles, and I was expecting some presentations at these meetings. I’ll be at ABS talking about Sitana, and would love to meet other anole behaviour enthusiasts, so please let me know in the comments below if you’ll be there.

That said, lizards aren’t too badly represented at these meetings: there will be talks or posters on Draco, Psammophilus, Phrynocephalus, Sceloporus, Crotaphytus, Podarcis and Tupinambis. I’ll be blogging about the lizard presentations from ABS, so stay tuned for a behavioural bonanza!

The wonderful Phrynocephalus mystaceus. Photo by Antoshin Konstantin from Wikimedia.