Category: All Posts Page 77 of 146

In an effort to keep anoles hip, I will be curating an anole Snapchat!

Add “bon_anole” (“good anole”) for daily updates on the lizards of north central florida! This is for those of you who don’t get anoles year round (as well as for those of you who love A. sagrei)!

Photo by K. Winchell

In a global change scenario, the persistence of numerous animal populations is challenged by the consequences of human activities. Urbanization, for instance, represents a dramatic habitat transformation that has led to a general pattern of reduced biological diversity in these areas. Paradoxically, some species are doing very well in these new environments. This leads to the question of whether and how these populations are adapting to these new environmental conditions.

Although the number of studies providing evidence for phenotypic differences between urban and natural areas is growing fast, few studies have investigated whether and how animals might be evolutionarily adapting to the intensively modified urban habitats. Kristin Winchell and collaborators address this question in their recent publication in Evolution “Phenotypic shifts in urban areas in the tropical lizard Anolis cristatellus.” The authors studied the habitat use and morphology of forest vs. urban populations of Crested Anoles, Anolis cristatellus, from three municipalities in Puerto Rico. In short, this article provides evidence suggesting that urban anoles are under differential selective pressures as compared with those from forested habitats, and that these differences may have a genetic basis.

As the authors detail in their paper, anoles are a great system to study the morphological consequences of urbanization. This is because much information is available on the relationship between their habitat use, morphology and performance (reviewed in Losos 2009). In urban habitats, natural substrates have largely been replaced by artificial structures such as metal poles and walls. Consequently, it can be predicted that their performance on these surfaces is not optimal, as their morphology may not be suited to use these substrates. Indeed, it has been shown that lizards tend to perch on narrower, less smooth surfaces in natural habitats –a topic that has been dealt with in previous AA posts.

In this paper, the authors use field observations to show that lizards in urban areas use artificial substrates a large proportion of the time and that these urban substrates are broader and smoother than those in natural areas. Then, by X-raying lizards from the different habitats, the authors show that urban lizards have longer limbs (relative to their body size) and higher number of subdigital lamellae -which improve traction for perched lizards- than individuals from forested areas (Fig. 4). This is indeed consistent with ecomorphological predictions that anoles with longer limbs perform better on wider perches. Increased lamellae number should provide lizards with a better grip on smoother surfaces.

Fig. 4 from Winchell et al. (2016). This -really cool- figure shows how urban and natural populations differed in key morphological variables: (a) subdigital lamellae number and (b) limb length

Finally, the authors conducted a common-garden rearing experiment in which they reared individuals from one of the three pairs of populations studied. The aim of this experiment was to rule out the possibility that morphological differences are merely the consequence of phenotypic plasticity. When measured at approximately one year of age, the first generation offspring of urban lizards showed longer forelimbs and more lamellae as compared to offspring of forest-dwelling lizards (Fig. 5). This result suggests that anoles in urban areas are under significantly different natural selection pressures and may be evolutionarily adapting to their human-modified environment.

Fig. 5 from Winchell et al (2016). Offspring reared in captivity showed the same trend as wild-caught populations of more subdigital lamellae and longer forelimbs in urban individuals: (a) relative limb length and (b) subdigital lamellae number

References:

Winchell, Kristin M., Reynolds, R. G., Prado-Irwin, Sofia R., Puente-Rolón, Alberto R., and Revel, Liam J. (2016). Phenotypic shifts in urban areas in the tropical lizard Anolis cristatellus.

Kolbe, J.J., Battles, A.C. & Avilés-Rodríguez. K. (2015) City slickers: poor performance does not deter Anolis lizards from using artificial substrates in human-modified habitats. Functional Ecology.

Losos, J.B. (2009) Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles. University of California Press, Berkeley, CA, USA.

Anole egg from http://www.anoleimaging.com/Anoles/ag_16_egg2.html

A concerned Anole Annals reader writes in:

My dog just violently chomped  a female alone. Along with her entrails protruding from her body we two eggs. One was small, under-developed the other was the size they are laid. I have at the time done my best to put it into a container and emulate the  same conditions outside ( I live in Florida) with  dirt, leaf litter (small) moisture and heat. I removed the placental outer membrane which would have been separated if she had laid. I feel terrible my young and excitable dog did this. Is there any hope?

Can anyone advise?

A noble beast and mighty warrior.

Read all about it in Rodríguez-Cabrera et al.’s new paper in IRCF Reptiles & Amphibians.

Hello AA readers! I’m writing today with a favor to ask. I’m planning to do some research on Anolis lemurinus in Costa Rica this summer, and I’m looking for potential field sites. I’ve been to La Selva Biological Station, which seems to have a healthy population, but if you know of any other localities in Costa Rica where A. lemurinus are abundant, please let me know! I’d greatly appreciate it.

Please contact me at pradoirwin [at] g.harvard.edu

Thanks!

Egret and maybe anole

We’ve come to realize, sadly, that just about everything will eat anoles. Birds are particular culprits and we’ve seen some horrifying examples of egrets downing the little green and brown fellows. Now comes a report that a whooping crane, of all things, will also indulge.

Vladimir Dinets–he of crocodilian behavior fame (check out his awesome book, Dragon Songs )–reported on dietary observations a reintroduced population of cranes in Louisiana. The anolivory represents the first instance of whooping crane predation on a lizard (but not on a squamate, as the photo above attests).

Photo by Pat Shipman

We’ve often commented on the interactions between the green anole, Anolis carolinensis, and the brown anole, Anolis sagrei. We’ve also had periodic posts from Pat Shipman on Little Cayman, who moonlights as an anthropologist and science and history writer when not watching anoles.

Here’s further evidence that greens and browns can coexist: A. maynardi (a relative of A. carolinensis) and A. sagrei side-by-side, ten feet up on a wall.

From New Scientist:

Kristin Winchell

By Carolyn Beans

City living comes with unique challenges. If you’re a lizard, scaling a windowpane without sliding off is one of them. One lizard has already evolved traits to help it do just that.

“Urban areas are just another environment. The animals that live there aren’t somehow immune to natural selection,” says Kristin Winchell of the University of Massachusetts Boston.

Her team compared males of the anole lizard (Anolis cristatellus) in the Puerto Rican cities of Mayagüez, Ponce and San Juan with those in nearby forests.

They found that city lizards regularly clung to objects like walls and windows, proving that they use the full urban environment instead of restricting themselves to wild patches more similar to their forest roots.

Compared with forest-dwellers, city lizards had longer limbs and more lamellae – scale-like structures that help their toes stick to surfaces. These traits probably enable them to stay attached to slippery urban perches. “I chased a lizard that ran straight up a window 30 feet and was out of reach in 15 seconds,” says Winchell. “I couldn’t catch this well-adapted lizard.”

The team also raised urban and forest lizards from the Mayagüez region in the lab and found that differences in limb length and scale number remained, suggesting a genetic basis to the urban lizards’ abilities.

The anole frequently wows scientists with feats of rapid evolution in natural environments. The new finding suggests that this capacity applies to cities as well.

Other urban animals also adapt. We know, for example, that birds alter calls to be heard over city noise and leafcutter ants adapt to elevated temperatures in an urban heat island.

But well-studied examples are rare. “Urban evolution is a really young field,” says Winchell.

Evolutionary biologist Jason Munshi-South of Fordham University in New York agrees. “There aren’t many documented cases of urban evolution yet, but people are going to start looking for them in earnest,” he says.

Munshi-South believes Winchell’s study is an excellent addition to this emerging field. “The next step,” he says, “which I’m excited to see them do, is to identify the genes underlying these adaptive traits.”

Winchell says that, ultimately, understanding urban adaption could help conservation. “Having a grasp on which animals tolerate urbanisation gives us a better idea of which ones we need to focus on when preserving natural habitats,” she says.

Evolution, DOI: 10.1111/evo.12925

I did a bit of herping in Luquillo on the northeast coast of Puerto Rico and the abundance of anoles and frogs  was incredible. I was hoping for help IDing these guys and any insight you might have on these species. I think the first three are the same species?

1. We found this sleeping anole perched up on the back of a sign.

2)    

3)        

4)

5) 

6) This last one was found in the Yunque, not in Luquillo. Not the best photo, but it was a beautiful anole.

Thanks again!