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Anolis carolinensis from North Carolina. Photo by Graham Reynolds.

In response to a previous post on North Carolina anoles, AA reader John Philips asks:

Anyone notice a significant reduction in the population of anoles in SE NC? I live on Bradley Creek in Wilmington, NC and I have noticed very few this year. Used to see 3-5 per day sitting on various surfaces in the sun while walking my dogs, especially because my shihpoo is always “hunting” them. However, this year I probably only see 1 per week.

I assume this could be due to the cold winter? Any other predators that might have reduced the population? We have seen an increase in brown thrashers in the area and thought since they forage on the ground they might be a predator?

Guadeloupean anole (Anolis marmoratus) feeding on the back of a Lesser Antillean iguana. Photo courtesy Jérôme Guerlotté.

Jérôme Guerlotté of the Muséum National d’Histoire Naturelle in Paris reports:

“As in a new Jean De la Fontaine fable “L’iguane et l’Anolis“, this intrepid anole (Anolis marmoratus marmoratus) on Guadeloupe had just hunted a fly on the back of this Lesser Antillean iguana (Iguana delicatissima) (top) and rids it of small insects on the snout (bottom).”

Who knows what yummy morsels reside on the snout of an iguana? Photo courtesy Jérôme Guerlotté.

Short break from TE annotation to explore the botanic garden’s fabulous greenhouses. Even spotted an anole lizard that is helping with pest control #annotaTE_18 @alexander_suh pic.twitter.com/GkM6p3e94s

— Dr. Jessica Stapley (@jessstapley) April 27, 2018

Reporting from Germany where she was leading a course on Transposable Elements, Jessica Stapley  — of mainland anole fame — posted this picture to Twitter. It appears brown anoles (A. sagrei) have set up a new home in one of the greenhouses at Berlin’s Botanical Gardens!

There are reports of un-established populations of green anoles (A. carolinensis) in southern Spain and the Canary Islands (reviewed here), as well as a report of Cuban knight anoles (A. equestris) also on the Canary Islands.

Does anyone know of other European records of anole populations?

Anolis krugi. Photo by Manuel Leal from the Leal Lab webpage

Anole biologists are fascinated by the variation in dewlap colors and patterns both within and between species. One popular hypothesis is that dewlaps are adapted to be easily detectable against the background in which they are found. A variety of tests have been published, correlating dewlap colors with ambient light, background vegetation and other characteristics. Now Alex Gunderson and colleagues have developed an experimental method of directly testing the hypothesis. Manuel Leal, a coauthor on the paper, reports on the pages of Chipojo Lab, reprinted here:

Brighter is not always better

Those that follow the Chipojoblog are familiar with one of our core tenets: strive as best you can to design experiments under natural conditions. This philosophy reflects my own view that behavior should be studied in the field whenever possible. Our recent paper in Current Zoology, “Visual playback of colorful signals in the field supports sensory drive for signal detectability,” is a prime of example of the power of this approach, in which an intimate understanding of the ecology and behavior of anoles was used to test a major prediction of the sensory drive hypothesis: are signals locally adapted? In other words, are dewlaps locally adapted to effectively grab the attention of an inattentive receiver?

Over the years we have published a series of papers supporting the hypothesis that dewlap diversity can be partially explained by selection to increase the probability of detection. However, until this paper, experimental evidence from the field was missing, in part because manipulating dewlaps of live anoles is not trivial. Furthermore, even if we were able to successfully manipulate dewlaps, there are still many other signals (e.g., body color, motion pattern, size and posture) that would be out of our control. This problem was solved by researchers working with acoustic signals a long time ago by figuring out ways to play the signal of interest in isolation in what have become known as ‘playback experiments.’ We stole a page from their book and constructed a remote-control dewlap apparatus, which provided an opportunity to display only the dewlap under natural conditions (see gizmo below).  Alex’s building and painting skills was key to the success of this gizmo. He was able to construct dewlaps with similar reflective and transmission properties of real dewlaps while taking into account the visual system of the anoles (please see papers for details).

Control-remote dewlap display apparatus. A) Acrylic box within which electrical components were housed. B) Electrical components. C) The apparatus at a mesic site with a fake dewlap displayed.

Besides presenting the dewlaps in the field, we wanted to test the hypothesis that the dewlaps are locally adapted. Under this hypothesis, increased detection in one habitat comes at the cost of decreased detection in another habitat. This functional approach to test for adaptive value of a trait is commonly used as robust evidence to support selection favoring the evolution of the trait in question. In this paper we tested if the observed differences in dewlap brightness between xeric and mesic populations of Anolis cristatellus is adaptive. If so, dewlaps from mesic populations should be more detectable in mesic habitats and dewlaps from xeric habitats should be more detectable in xeric habitats. Furthermore, detection probability should decrease in the ‘wrong’ habitat. Below are the results of the experiments.  In A. cristatellus individuals from xeric habitats have dewlaps which are darker, that is less brighter,  than individuals from mesic populations.

Responses of free-ranging A. cristatellus to fake dewlaps that mimic the brightness properties of real dewlaps.

Our findings support the sensory drive hypothesis and strongly suggest that the brightness  properties of A. cristatellus dewlaps are locally adapted via selection on signal detectability.  Furthermore, we have demonstrated that a brighter signal is not always the most detectable or effective signal. A common misconception, which is partially the result of not including the sensory system and habitat conditions as part of the analysis. Studies addressing potential functions and selective forces promoting the diversity of dewlaps found in anoles have flourished over the last decade,  nevertheless, these results are the best experimental evidence that we have to support the hypothesis that diversity of dewlap colors might be partially explained by local adaptions to habitat light conditions and the best smoking gun to support the idea that diversity of dewlap colors can be the result of local adaptations to habitat light conditions.  Additionally, our study once again underlines the need to measure both reflection and transmission when asking questions regarding the potential function of the dewlap because the two combine to determine dewlap coloration (brightness, coloration, etc.) in the real world.

Ever been tempted to buy a Google Pixel cellphone? Well now you might have extra incentive! 

To highlight how a Google Pixel may lead you on an adventure, Google highlight’s its new photo identification feature — Google Lens — with a picture of a brown anole!

Now…how do we convince Google to give us all brand new cellphones sponsor us…?

HerpHighlights is a Podcast run by Tom Major and Ben Marshall in which they discuss recent advances and interesting news on reptile and amphibian behavior, ecology, and conservation.

Frantically reading before recording @herphighlights at an ungodly hour in the morning (sorry @Ben_M_Marshall). Turns out #anoles are pretty excellent. pic.twitter.com/59QzJfwaJC

— Tom Major (@Thomas_Major) April 25, 2018

Anole annals you are 100% getting a shout out on the show! Very cool to see a genus of reptiles being the focus of an active and engaging blog.

— Tom Major (@Thomas_Major) April 25, 2018

This podcast is now live and you can listen to it by clicking the link below:

https://herphighlights.podbean.com/e/026-assortment-of-anoles/

In this episode, Tom and Ben discuss many interesting research topics – both new and old – involving anoles. Notably touching on Kamath & Losos’ recent commentary on the mating systems of brown anoles (A. sagrei) in Florida, as well as Medina et al.’s review of the evolution of dorsal patterning across Caribbean anoles.

Check it out!

Kamath, A, and JB Losos. 2018. “Estimating Encounter Rates as the First Step of Sexual Selection in the Lizard Anolis Sagrei.” Proceedings of the Royal Society B: Biological Sciences 285 (1873): 20172244.

Medina, I, JB Losos, and DL Mahler. 2016. “Evolution of Dorsal Pattern Variation in Greater Antillean Anolis Lizards.” Biological Journal of the Linnean Society 120 (2): 427–35.

Camera traps have been placed in front of some karst solution holes in the dry-transition forest of the southern slopes of the Sierra de Bahoruco, in the Pedernales province, Dominican Republic.

The holes hold water after rains, making it one of the very few spots where water is available in that forest (no surface rivers or marshes around). These holes are visited by a variety of animals, which include herps like whiptails, curlytails, racers, iguanas, and other rarities like the solenodon, and many birds.

I wanted to share this photo, since in it is the first anole recorded, an Anolis strahmi, which seems to be displaying at a nearby bird (Ovenbird, placed at extreme right of the frame).

This particular lizard did not show much fear towards our plastic snake. Photo credit: Bjorn Briesen

And now for something completely different … lacertid lizards. It almost feels like I am releasing an invasive species within Anole Annals, but dr. Jonathan Losos nevertheless kindly asked me to write something about our recent paper on the effect of insularity and urbanization on the foraging decisions of the Dalmatian Wall lizard (Podarcis melisellensis), stating that “Lacertids are honorary Anoles.”

The Functional Morphology Lab of the University of Antwerp has a long-standing tradition of research on the Croatian islands. Once a year, several members of our team travel to Croatia, accompanied by a bunch of students in the context of a course on Island Biology. In fact, four out of six collaborators on our paper (including me) were still undergraduate students when conducting the fieldwork. We soon came up with the idea to compare risk-taking and reaction to novelty of wall lizards during foraging in both urban and insular environments. Strange choice? Not at all. Both urban and insular habitats are characterized by reduced levels of predation, but also a lack of resources (e.g. lower abundance and diversity of arthropod prey). Such conditions should prompt both insular and urban lizards to behave bolder during foraging, and act less neophobic, since the risk of predation is low, but the value of the food reward is high. Fortunately, the Croatian islands are perfect to test these kind of hypotheses. Sampling both rural and urban areas on the larger island of Vis was a piece of cake, especially since wall lizards can easily be found in the harbour of Vis.

Believe it or not, wall lizards can easily be found in the harbour of vis. Photo credit: Gilles De Meester

Vis itself is surrounded by many small islets, most of them inhabited by dense populations of lizards. Some of these islets, like Biševo and Veli Budikovac, are (semi-)inhabited. Others, like Brusnik, are completely devoid of any human activity. So, small islets? Check. Urban and rural areas? Check. What else was needed? A predator model to test risk-taking, and a novel object to test neophobia. After a few pilot trails in which we compared the response of lizards to a plastic snake model and a stuffed rook (Corvus frugilegus), it was clear that lizards showed more fear of the snake. Our novel object was randomly chosen to be a flashy red drinking bottle.

Lizards from smaller islets did indeed take more risks while foraging compared to lizards from the main island. Islet lizards were more likely to leave a safe refuge in order to get a tasty mealworm, despite the presence of the snake model, and also on average left their refuges faster to do so. In fact, on multiple occasions, lizards did completely ignore the snake model, even running over it to get to the petri dish with food.

Another example of a very bold lizard. Photo credit: Bjorn Briesen.

But even on the main island of Vis, lizards behaved very boldly. In fact, between observations, we were often capable of hand-feeding some wild individuals. On the island of Brusnik, a few lizards showed absolutely no fear at all of humans, even licking and biting our hands when we came close to remove the petri dish at the end of a trail. This is, of course, a very nice illustration of  the phenomenon known as “island tameness.” Due to a lower number of predators on islands and islets, insular species often lack normal antipredator behaviour, something that even Darwin already reported after his famous voyage on the Beagle. Unfortunately, this tameness is the main reason for the historical decline and extinction of many insular species, especially after humans started bringing new predators (rats and cats) to these islands.

Maybe he was just thirsty? Photo credit: Gilles De Meester

Neophobia, whether the lizards were willing to feed in front of a novel object, did not differ between main island and small islets, despite the assumption that islet lizards should behave less neophobically as they will benefit more from exploiting new resources. In fairness, lizards overall seemed to lack a neophobic reaction towards the novel object, as they did not differ in feeding latencies from the control group. Interestingly, however, in Brusnik, lizards behaved very neophilically towards the drinking bottle. Some individuals even completely ignored the offered food in favour of this novel object.

Surprisingly, lizard behaviour did not differ between urban and rural environments. While numerous papers have proven that urban birds and mammals  behave more boldly and less neophobically compared to their rural conspecifics, the few studies on reptiles have yielded mixed results. In fact, it is still unclear whether lizards do indeed experience lower predation risk in urban areas. While natural predators might be rare, they are often replaced by dogs, rats or cats (and we all know that cats are the killing machines of nature). We did indeed observe predation on wall lizards in the harbour of Vis, not by a cat, but  by a hooded crow (Corvus cornix). A strong argument can be made that urban habitats are more open, leaving foraging lizards at greater risk of being seen by predators.

More detailed studies of behaviour of urban lizards, together with estimations of resource availability and predation pressure, could help us understand why lizards seemingly adapt different to urban environments compared to mammals or birds.

More detailed interpretation of our results, complete with nice graphs and interesting p-values, can be found in our published paper.