Anole Annals

Mystery Anole

Can you identify this species?  It was recently observed in Pinellas County in Florida, where Anolis sagrei is established but not any other Anolis spp.  This photo is your only clue.

Read the sad details on Project Noah. We’ve reported on saurivory in spiders previously, most recent a Nephila eating a brown anole.

Anolis nebulosus

In a recent paper in the Italian Journal of Zoology, Senczuk and colleagues report an interesting finding on the clouded anole, Anolis nebulosus. On the mainland, the species is fairly petite, with males averaging 40 mm SVL. However, on a very small, offshore islet, only half a kilometer from the mainland, males grow to an average of 53 mm, and the average female is larger than the largest male on the mainland.

What is responsible for such great disparity in size? Two prime possibilities are that most of the anoles predators are absent from this small island and that the island has a seabird colony, which may lead to greater quantities of insect prey.

In a fascinating previous study, some of the authors of this paper documented many other interesting differences between the mainland and island populations, such as the fact that lizards in the island population are much more active and display more. Clearly, this is a situation worthy of further study.

Abstract:

The clouded anole Anolis nebulosus (Squamata: Polychrotidae) is widespread on the Pacific coast of Mexico. The species also inhabits Don Panchito, a small islet located near the coast of the Chamela-Cuixmala Biosphere Reserve in the state of Jalisco. We studied the extent of intraspecific differences in morphology (absolute size and body proportions) and in mtDNA sequences (16S and NDH2) between the population living on the islet (N = 18 for morphometry; N = 12 for mtDNA) and the one on the facing mainland (N = 38 for morphometry; N = 16 for mtDNA). The individuals on the islet are larger than those on the mainland with little overlap in size for either males (islet: 52.79 ± 1.82 mm; mainland: 40.96 ± 2.99 mm) or females (islet: 46.18 ± 3.24 mm; mainland 37.14 ± 2.13 mm). The presence of insular gigantism, as here found in A. nebulosus, seems uncommon in the genus and could be explained as a combination of low predation pressure and higher intraspecific competition on the island. Moreover, we found that sexual dimorphism (SD) is higher in the island population than in the mainland one. The molecular analysis shows the absence of shared haplotypes between the island and mainland populations. Ten mtDNA haplotypes belonged to the mainland population and three to the island population. The shape of the minimum spanning network and of the mismatch distribution indicates a single colonization event. These molecular data indicate a certain degree of isolation of the island population notwithstanding its proximity to the coast. The morphological characteristics of the anoles on Don Panchito match with the expectation of the so-called “reversed island syndrome” theory, which predicts an increased body size and sexual dimorphism in lizards living on very small islands characterized by unpredictable environmental conditions.

Anolis ventrimaculatus. Photo by Jonathan Losos.

We (Rosario Castaneda, Anthony Herrel, Luke Mahler and I) have just completed the first leg of our 2.5 week Colombian anole sojourn. First up: La Cumbre in the hills north of Cali. At  2000 meters, it was chilly! Going out our first night, we found plenty of long-legged Anolis ventrimaculatus. Imagine our surprise the next day when they were hard to find when active! This was reminiscent to us of A. gemmosus in Mindo, which also is very abundant at night–we’re talking Caribbean anole night abundance–but not easy to find while active.

The ones we did find were generally low to the ground, often on tree trunks, sometimes on vegetation. They refused to move when we filmed them, but their stomach contents indicated that they had been foraging, even at temperatures in the upper teens. These are tough, wily buggers!

We found two other species in smaller numbers, but only at night. The most exciting was A. calimae, which was not known from the locality at which we were working. We found a male and a female. They look moderately like twig anoles–elongate, slender body habitus–but there limbs are on the long side. We’ll see what the morphometrics say. However, when we released them, they behaved exactly like twig anoles, squirreling to the far side of a branch, creeping forward, carefully placing one foot, then the next, freezing. Unfortunately, despite intensive efforts, none were located during the day, perhaps not surprising, as many twig anoles are very cryptic and hard to find, particularly given that they live in dense vegetation.

Female Anolis calimae. Photo by Jonathan Losos.

Lastly, we found a number of A. mariarum in dense fields of high, stout grass. The photo below shows one such area. These lizards have to be living in the grass; they’re too far from anything else (the occasional tree notwithstanding. Yet search as we might, we couldn’t find them during the day. Our guess is that they are active in the spaces on the ground beneath the grass. In fact, when we let the lizards go, they seemed quiet happy to scamper about, and even display at each other, under the grass canopy.

Anolis mariarum’s field of dreams, where several were found sleeping, but none could be found during the day.

An exciting, if chilly start, but we’ll soon be thinking wistfully of cool days and evenings as we head to our hot and steamy next location.

When I think of colour and pattern in lizards, I tend to think about showy visual displays. An example that springs to mind is this fantastic footage of Draco lizards using multiple appendages as colourful signals.

But despite all the effort an individual lizard puts into signalling to conspecifics, it must constantly remain wary of predators. Mimicry and camouflage are tried and tested means by which to evade predation, but little effort has been made to quantify the colours and patterns that may help lizards escape being eaten. Research presented by Danielle Klomp from the University of New South Wales at the Animal Behaviour Society 2014 meeting addresses this question in Draco cornutus, a South East Asian agamid lizard that uses the patagium, an extendable membrane attached to elongated rib bones, to glide from tree to tree.

Sampling in two populations of D. cornutus, Klomp noticed that though individuals in the two populations had identical dewlaps, they differed substantially in the colour and pattern of the patagium. Remarkably, the colours exhibited in each population seemed to perfectly match the colour of falling leaves of trees in the same habitat.

Patagia and falling leaves from two populations of Draco cornutus. Photos by Danielle Klomp.

By measuring spectral reflectances as well as the proportions of black on lizard patagia, falling leaves, foliage, and dead leaves, and accounting for how these colours might appear to predatory birds, Klomp demonstrated that in both colour and pattern, D. cornutus patagia in each population most closely matched falling leaves in the same population. This suggests that Draco are especially vulnerable to predation while gliding, and have undergone strong natural selection to mimic non-prey items in the particular environment they experience while gliding.

Here’s a link to Klomp’s poster from the International Society for Behavioural Ecology 2014 conference, and here’s a link to a blogpost about some very cool technology that Klomp used to make her poster come alive while presenting it.

From Rachel on Twitter.

Wouldn’t this be great? Maybe there’s one out there, still waiting to be discovered.

httpv://vimeo.com/93621704

We’ve discussed the crisis concerning Jamaica’s Goat Islands previously. This film is the work of Robin Moore. Read more about the film and the efforts to preserve Jamaica’s iguanas on National Geographic‘s Newswatch. More relevant videos can be viewed at the Save Goat Islands website.