Author: Jonathan Losos Page 42 of 129

Photo by James Christensen

Anolis auratus is one of the most widespread mainland anoles, with a range stretching from Costa Rica through much of northern top of South America on both sides of the Andes. It’s biology is surprisingly little known, though it is thought to be a grassland species; that and it’s morphological similarity to grass-inhabiting Caribbean anoles has led some to argue that this species is a member of the grass-bush ecomorph category.

Given it’s wide range in Colombia traversing the Andes, the species is ripe for investigation of geographic variation, and that is just what Martha Calderón-Espinosa and Leidy Alejandra Barragán-Contreras did, examining a large number of museum specimens in the collection of the Instituto de Ciencias Naturales, Universidad Nacional de Colombia. Their work was recently published in Acta Biológica Colombiana. The abstract is appended below, but to make a not-so-long story short, sexual dimorphism exists for several characteristics independent of body size (the sexes don’t vary in size), and these same characters vary geographically. What this means about variation in habitat use of the species across its range remains to be studied.

Abstract

Anolis auratus is a widely distributed species, from Costa Rica in Central America, through northern South America, including Colombia, Venezuela, northern Brazil, Surinam and the Guyanas. In Colombia, its widespread distribution across different life zones suggests that these lizards occupy different environments and exhibit different microhabitat use in different geographic areas. On the other hand, some observations suggest that this species prefers open areas, selecting grasslands over brushy areas, and thus, an alternative hypothesis is that microhabitat use is similar among different populations. In Anolis, body variables related to locomotion (body size and shape) define structural microhabitat use, so two distinct patterns could be expected in this species: conservative or highly variable body size and shape throughout the species distribution. To test these predictions, we characterized geographic variation in morphometric traits of this species in Colombia. Females and males were similar in body size, but exhibited differences in some variables related to body shape. These characteristics also varied among males and females from different regions, suggesting heterogeneous use of structural microhabitat, between sexes and among populations. As an alternative, phylogenetic divergence among populations could also account for the observed differences. Absence of ecological and phylogenetic data limits our ability to identify the underlying causes of this pattern. However, we provide a general framework to explore hypotheses about evolution of body size and shape in this species.

We’ve previously had both a photo and a video of egrets downing not-so-festive brown anoles, and here’s another example from Wild about Spain. Word on the street is that egrets can be major anole predators in some places.

We previously mentioned that the Wild Amelia Nature Festival is featuring the green anole for this year’s shindig in mid-May. Now comes the welcome news that our favorite green graces this year’s t-shirt, a picture of which is shown above thanks to the kind offices of Karen Cusick. A bargain at $15!

Despite the intense study of all things anoles for several decades, some aspects of their natural history are not all that well known. For example, the mating behavior of most species has not been described, and egg-laying behavior has been documented for only a few species.

In the most recent issue of IRCF Amphibians & Reptiles, Alfonso et al. take a small step to remedy this situation by describing these behaviors in the Cuban crown-giant anole, A. smallwoodi. The mating observations are from a year’s fieldwork by the senior author, whereas the observations of egg-laying are from the captive husbandry efforts of second author Veronika Holanova.

I was particularly interested in the description of how gravid females come down to the ground and poke around with their snouts until they find just the right spot, at which point they dig a hole with their snout, lay the egg, and then cover it up by pushing soil over it with their snout and forelegs.

The picture above comes from a post on Jacqui Thurlow-Lippisch’s blog, about an epic battle in Sewall, Florida. Jacqui kindly put me in touch with the photographer, Nina Barcik, who provided some more information:

• The two bricks beneath the snake are:  4½”x 6″ and   6″x 9½” to give you some reference for size.
• One hour and 20 minutes after the picture was taken, the lizard was completely consumed and the snake was on it’s back with the head and first 6″ leaning vertically against the side of the planter.

30 minutes later the snake was gone.

By the way, who prefers the name corn snake to red rat snake?

Here’s another shot:

Nearly two years ago, we reported that Dynomighty, a Kickstarter-like operation, was seeking funding to produce an anole themed wallet. And sure enough, they got enough backers (who wouldn’t want to support development of such a needed product?). So get yours today–only fifteen bills.

And once you do, open them up to buy these anole pillowcases.

Anolis transversalis. Photo by Bejat McCracken.

AA reader Shawn McCracken writes:

While conducting ground-level herpetofauna surveys at the Tiputini Biodiversity Station in Ecuador’s Yasuní Biosphere Reserve, I was lured to the canopy by the cacophony of what had to be undiscovered species coming from the bromeliad, orchid and epiphyte microhabitats. This led me to think how many possible new species may be living in this new frontier? While birding at the canopy towers I saw the Tropical Thornytail Iguana (Uracentron flaviceps) and Banded Tree Anole (Dactyloa [Anolis] transversalis) scurrying about in some of the adjacent trees, amongst other anoles I could not quite identify, there was no doubt I was headed up. Of all the available microhabitat in the canopy, the big tank bromeliads caught my attention the most – little swamps, everywhere at 20+ meters off the ground. Surely there had to be herpetofauna using these as a resource and refuge in the harsh canopy environment.

Aechmea zebrina, the bromeliad species examined by McCracken and Forster.

Before the next field season, I decided I needed to get up into the canopy and collect some bromeliads to have a look inside. After a self-taught crash course in tree climbing, I returned to Tiputini, but quickly realized I didn’t have a long enough rope or the skills to get to those big bromeliads. Packing plenty of rope and a greater confidence in my climbing abilities, I returned for another field season the next year. This time was a success. Along with my assistants, we collected 40 bromeliads representing three species that we sealed in 55-gallon trash bags and carried back to camp. Once we began dismantling the bromeliads, we realized we had hit a treasure trove of invertebrates and herpetofauna. Now several years later and a total of 240 bromeliads collected, we have a pretty good idea of the herpetofauna utilizing canopy tank bromeliads in northwestern part of Yasuní. In this latest publication, we summarize the herpetofauna of one high canopy tank bromeliad species, which includes the gecko Thecadactylus solimoensis and two anoles, Anolis ortonii and A. transversalis.

Some other bromeliad denizens

We’ve heard a lot about Gunther Köhler in the last few days. What you might not know is that when he’s not busy snatching sleeping lizards off of leaves in the highlands of Mesoamerica or counting scales in his Frankfurt laboratory, he plays guitar in a flaggstaff, a country band. The band is about to release its latest CD, Stomping Grounds, and one single, Chiriqui Stream, is appropriate for our pages. You can download the MP3 and then sing along:

Chiriqui Stream

1. When the nights grow late and the fires die down

When the fog and mist start boiling around

At camp site down by the Chiriqui stream

Where we search for creatures nobody’s seen

2. The thrill of the night hike blows you away

As we move on, magic’s underway

We poke through the forest with its pines and oaks

With the sound of the woods, the creeks and slopes

Chorus: Living my dream at the Chiriqui stream

Finding my fortune in this unreal scheme

With a family of creatures nobody’s seen

Right down at the Chiriqui stream

3. On the fog shrouded slopes and rugged peaks

A world of its own with its lovely creeks

Its unforeseen bugs and mystical sounds

No doubt we’re here on unknown grounds

Photo by Benny Diaz

AA stalwart Liam Revell was forwarded the photo above on Facebook and decided to look into it. Here’s what he reports:

This impressive photo showing a Puerto Rican crested anole (Anolis cristatellus) being attacked by a Puerto Rican racer (Borikenophis portoricensis) was recently posted to the Facebook group ‘Biodiversidad de Puerto Rico’ by a photographer Benny Diaz. He has kindly allowed us to re-post his photo here and also supplied the following description of the predation event he witnessed transpiring in the Puerto Rican state forest Bosque Estatal Guajataca (translated from Spanish):

“I first saw this anole and tried to take a photo of it after noticing that it was marked with two different colored spots of paint on its back. As I slowly approached it, the animal suddenly reacted with a jump and just at that moment a Puerto Rican racer (Borikenophis portoricensis) appeared out of nowhere and captured the anole in midair!”

Although the predation event is remarkable in itself (and the photo capturing it terrific), perhaps even more notable is the fact that the lizard appears to have been marked by an investigator conducting research on anoles! After some (social media-aided) investigation of the matter, led by Puerto Rican USFW biologist and avid photographer J.P. Zegarra, this scientist revealed herself to be University of Puerto Rico Ph.D. candidate, and friend of Anole Annals, Luisa Otero. Luisa is studying anoles in Puerto Rico as part of a multi-institutional collaborative NSF project to investigate the vulnerability of tropical ectotherms to global climate change. More can be learned about this project, and Luisa’s research, from the project website.

Luisa recounts the following about this particular lizard:

“Yes, we took the Tb (Editor’s note: body temperature) of the poor lizard in the picture a few weeks ago in Guajataca. Prof. Hertz was here and we were taking body temperatures and operative temperatures from models. It was the last trip of the ‘ vulnerability of tropical ectotherms’ project!! I usually use paint to mark the lizards so we don’t re-sample them the same day. This poor guy was sampled two days in a row…. (that’s why it has two colors)… and a few weeks later was eaten by this Alsophis (Ed. recently renamed Borikenophis)… very sad.”

Some years ago, Manuel Leal and Javier Rodríguez-Robles conducted a study in which they investigated what happened when a Puerto Rican racer confronted a crested anole. I summarized the study in Lizards in an Evolutionary Tree:

“In laboratory trials, Leal and Rodríguez-Robles (1995) showed that the snake, (which can attain a length of more than 1m), attacked anoles much less often  when the lizard displayed. Moreover, they demonstrated that when attacked, the lizards fought back, often biting the snake on the snout for as long as 20 minutes and managing to escape in 37% of the encounters (Leal and Rodríguez-Robles, 1995)—remarkable given the size discrepancy of the snake and the lizard.”

Diaz’s observations confirm that this behavior is not a laboratory artifact–crested anoles will chomp down and hang on for all their worth. But, just as in the majority of the lab trials, the valiant defense was for nought. After a few minutes, Diaz reports, the lizard

appeared to be immobilized (probably the result of the rear-fanged snakes venom) and the snake began to work the lizard around, little by little, until it was able to swallow it head first.

After the lizard let go of its grip, the snake slowly moved its grip up the lizard’s body. Photo by Benny Diaz.

The time between the first photo (above) and the last one (below), in which the lizard is well on its way to digestion, was eight minutes.

Photo by Benny Diaz

It’s also worth mentioning the follow-up study Leal conducted. Again from Lizards: “

In field trials, Leal (1999) found that the extent of display behavior toward a snake model correlated with the endurance capacity of the lizard (as determined in subsequent laboratory trials); the greater the endurance capacity of the lizard, the more it displayed to an approaching snake model. Anole displays to predators may be an example of a pursuit deterrent signal (reviewed in Caro, 2005). By signaling their endurance capability, anoles may be indicating their ability to fight back, escape, and potentially even injure a snake (Leal, 1999).”

In the most recent issue of IRCF Reptiles & Amphibians, Powell and Watkins provide an eyewitness account of an adult male Anolis sabanus killing a juvenile, presumably en route to eating it (which occurred off stage). The paper also provides a listing of other documented cases of Caribbean anole cannibalism, of which A. sabanus becomes the 19th species known to eat its own.

Editor’s Note: The IRCF webpage appears to be down. You can access the paper here.