Anole Annals

As I mentioned in a previous post (1), community ecology is a confusing field, confounded by the interchangeable use of many fundamental terms.

A group of graduate students and I discussed this paradigm and thought we would see what people’s own interpretations were, as an update and extension of a previous exercise conducted by Fauth et al. (1996). We created an online poll asking contributors to describe which factors are most important in defining the following key terms in community ecology: ‘community,’ ‘assemblage,’ ‘guild’ and ‘ensemble.’

There was certainly a lot of variation! We decided it was interesting enough to draft the results up into a manuscript, and it has eventually found some light in Ecology and Evolution. Specifically, we discussed the interpretation of each term from the perspective of undergraduate, graduate, non-academic, and professor perspectives, and conducted a thorough review of many ecology and evolution textbooks to investigate similarities in use. The abstract is detailed below, and you can find a link to the original paper here. Many thanks to all of you who contributed to the survey, your input it very much appreciated!

Abstract:

Community ecology is an inherently complicated field, confounded by the conflicting use of fundamental terms. Nearly two decades ago, Fauth et al. (1996) demonstrated that imprecise language led to the virtual synonymy of important terms and so attempted to clearly define four keywords in community ecology; “community,” “assemblage,” “guild,” and “ensemble”. We revisit Fauth et al.’s conclusion and discuss how the use of these terms has changed over time since their review. An updated analysis of term definition from a selection of popular ecological textbooks suggests that definitions have drifted away from those encountered pre-1996, and slightly disagreed with results from a survey of 100 ecology professionals (comprising of academic professors, nonacademic PhDs, graduate and undergraduate biology students). Results suggest that confusion about these terms is still widespread in ecology. We conclude with clear suggestions for definitions of each term to be adopted hereafter to provide greater cohesion among research groups.

Figure 1. Relative interest in community ecology terms from 1977 to 2013, as reﬂected by respective citation histories (trends are overlayed, not stacked). The publication date of Fauth et al. is indicated by a vertical dashed line. Terms were searched for in the“ecology” category of ISI Web of Science (accessed 20 February 14).

Stroud, J.T., Bush, M.R., Ladd, M.C., Nowicki, R.J., Shantz, A.A., and Sweatman, J. (2015) – Is a community still a community? Reviewing definitions of key terms in community ecology. Ecology and Evolution, 5(21): 4757-4765

Although one tragedy did occur – we were a month too late to get into the issue sporting a beautiful green anole as the cover photo! Credit goes to Simon Lailvaux and colleagues for getting yet another anole front page.

Battling Crested Anoles (A. cristatellus) in South Miami, FL

By James T. Stroud

On February 17, 2016

In Anole Photographs, Introduced Anoles, Natural History Observations, Notes from the Field

While out watching lizards last week with my undergraduate research assistant extraordinaire, Oliver Ljustina, and fellow SoFlo anole Ph.D. student Winter Beckles, we happened upon a pair of male crested anoles (Anolis cristatellus) ready to rumble! This is quite early – but not unheard of – in the season for the commencement of territorial disputes, so it was a surprise to see them locking horns so aggressively. This couple were battling fairly high in the tree, at approximately 3m.

Anyway, here are the pictures!

Information Needed on Anolis carolinensis in the St. Vincent Grenadines

By Jonathan Losos

On February 14, 2016

In All Posts

Surely green anoles would love it here

Bob Henderson writes to ask:

“Can anyone tell me the source of the record of Anolis carolinensis/porcatus on Canouan in the St. Vincent Grenadines?

It is listed as a waif in the Lesser Antilles island list by Henderson & Breuil (pp. 148–159 in Powell & Henderson, 2012. Island lists of West Indian amphibians and reptiles. Florida Mus. Nat Hist. Bull. 51: 85–166).”

Help, anyone?

Communication in Context: Signal Plasticity and Novel Environments

By Joshua Hall

On February 11, 2016

In New Research

Anolis gundlachi from The Reptile Database

Plasticity is the ability of one genotype to produce multiple phenotypes under different environmental conditions. Once considered a hindrance to the study of evolution, plasticity is now thought to be one basic way organisms may persist in novel habitats long enough for adaptation to occur. Because of its propensity for rapid change, behavioral plasticity is considered one of the most effective ways that organisms can adjust to new surroundings. In some circumstances, behavioral changes can even be immediate. In example, some populations of birds can alter their vocalizations when singing against the backdrop of city noise pollution (Potvin and Mulder, 2013). This ability to instantaneously respond to external stimuli is known as contextual plasticity, and it may be a powerful tool by which organisms adapt to novel conditions.

A new paper by Ord et. al., explores the potential use of contextual plasticity in social communication using species of Puerto Rican Anoles. Anoles use visual signals (head bobbing, pushups, and dewlapping) to communicate with one another, and previous research has noted that these signals are in competition with background visual noise (i.e. presence/movement of leaves and visual obstructions) and their reception is more challenging under low light conditions (Ord et.al., 2007). Anoles must adjust their signaling behavior in order to compete with distractions in their environment. The point of visual signaling is to be seen, so a positive relationship exists between mean visual noise and signaling speed and a negative relationship between mean display duration and mean light levels. See the decibel chart which is used to measure the intensity of a sound.

Anole Question Stumps Jeopardy Contestants

By Jonathan Losos

On February 10, 2016

In All Posts

From Yesterday’s Jeopardy round. Thanks to Joel McGlothlin for the videography, and Ian McGlothlin for the soundtrack. Note also Alex Trebek’s pronunciation of anole. And further note that Jeopardy has an understandable thing for anoles, having featured another anole question two years ago.

Take That Geico: Anole Eats a Gecko

By Jonathan Losos

On February 9, 2016

In All Posts

Scott Trageser posted this photo on Herpnation of Anolis leachii eating a gecko in Codrington, Barbuda. Here’s a few more details he sent while travelling in Madagascar: “The story was, I was photographing the gecko for a distribution note and the A. leachii came down and grabbed before I could even pull the shot off! The leachi would stay high in the trees so despite being large, we seldom saw them.”

Note: it is proper to spell leachii with two “ii”‘s

Vulnerability to Climate warming of Four Genera of New World Iguanians

By carla Piantoni

On February 7, 2016

In New Research

Liolaemus lemniscatus. Photo from Thomas Kramer’s flickr account.

Based on thermal constraints, as deduced from the effects of global warming on key aspects of thermal biology (e.g. field and laboratory temperatures, and thermoregulation indices; after Hertz et al., 1993), Dr. Piantoni and Dr. Navas from the University of São Paulo, Brazil, and Dr. Ibargüengoytía from the University of Comahue, Argentina, assessed the vulnerability of a sample of populations from the genera Anolis, Liolaemus, Sceloporus, and Tropidurus from a broad range of ecological settings such as the deserts of Yucatan, the Brazilian Cerrado, the lowlands of southern Patagonia steppe, the rainforests of Puerto Rico and the Nothofagus forests in Tierra del Fuego. The combined data on the four iguanian lineages, reported in a just-published paper in Animal Conservation, corroborate the hypotheses of increased susceptibility to warming in species from lower latitude and lowlands, and contributes to debate climate-related risk of extinction in lizards.

Thermoregulatory behavior increases with latitude and altitude and tropical and lowland environments are mainly occupied by thermoconforming lizards. In most of the cold and temperate environments (e.g. inhabited by Liolaemus and Anolis), warming could be neutral or beneficial and vulnerability to climate warming is not only linked to the efficiency of thermoregulation, but also to the high geographic and seasonal variation in the thermal biology of these species. Near the equator, susceptibility to climate change is associated with the tendency to physiological specialization as a result of the thermal stability of the forested environment and of the high proportions of operative temperatures exceeding the critical thermal maximum of most lizards of the open environments. The substrate temperatures at these localities will further increase with warming and eventually achieve overheating values. Whereas thermal shelters may assist lizards in the short-term, the compromise between sheltering and activity time may affect fitness in the long-term.

Overheating become a concrete risk in these environments, both as a direct driver of death or as a limiting factor for activity. Although a recent study on A. sagrei confirmed that some tropical populations might be capable of adapting to warmer and thermally variable environments (Logan et al., 2014), adaptive trends are unlikely to outrun global warming. Besides, habitat fragmentation and transformation may constrain the possibilities to disperse to cooler environments accelerating the extinctions, particularly in montane populations that would also face the upward progress of lowland species.

Adult specimen of Tropidurus torquatus from Tocantins, Brazil

Finally, it should be noted that the studied populations are potentially challenged by additional disturbances. Tropical populations, especially the ones inhabiting open and low elevation sites, are also vulnerable to the increasing fragmentation of the landscapes. For example, in Puerto Rico, species like A. cooki, which used to inhabit the dry forests, have been slowly displaced to areas in sympatry with A. cristatellus (Genet, 2002). The Brazilian savanna is gradually being replaced by soy fields and cattle ranches which may raise the soil temperature well above the predicted values and confine populations, such as Tropidurus torquatus‘ in Tocantins, to gallery forests. Paradoxically, the species with the highest vulnerability seem to inhabit the least protected areas, which emphasizes the urgent need of mitigation measures as the increase in conservation units to protect their underestimated biodiversity.

Get a Grip on It! Cling Force and Perch Diameter

By Kristin Winchell

On February 5, 2016

In New Research

An actual perch used by Anolis cristatellus – neither smooth nor flat! (photo by K. Winchell)

In the real world, lizards cling to everything from smooth, flat concrete walls to rough, rounded tree trunks. So why is it that most studies on cling force in anoles focus on clinging to smooth flat substrates? Does cling force differ if the substrate is rounded or rough? Jason Kolbe sought to answer this question in his recent publication, “Effects of Hind-Limb Length and Perch Diameter on Clinging Performance in Anolis Lizards from the British Virgin Islands” (Kolbe 2015).

We know that morphology impacts performance in anoles and that performance varies with environment. For example, sprint speed is correlated with limb length, but this relationship depends on the diameter of the substrate (e.g. Losos and Sinervo, 1989). We also know a little about clinging performance in anoles. Greater cling force is correlated with larger toepads and more lamellae on smooth flat surfaces (Irschick et al., 1996; Zani 2000; Elstrott and Irschick, 2004), but adhesion on rougher surfaces may be influenced by claw and toe morphology (Zani 2000).

There appears to be an unexplored interaction between substrate properties and clinging ability that involves more than just toepad characteristics. Specifically, Kolbe points out that claws can increase clinging ability by digging into the perch or simply by increasing friction on the surface. Limbs can also increase friction via the application of compression forces to the substrate. In other words, cling force can be increased, particularly on rough surfaces, by using muscular force to grasp rather than relying on van der Waals forces from the toepads, which are more effective on smooth flat surfaces.

Anolis cristatellus (photo by KMW)

Anolis stratus (photo by KMW)

Anole species used in this study: Anolis cristatellus (left) and Anolis stratulus (right). Photos by K. Winchell.

Kolbe investigated this further by looking at the interaction between limb length and clinging ability on perches of different diameters with Anolis cristatellus and Anolis stratulus from the British Virgin Islands. Specifically, he hypothesized that cling force should increase as the ability of a lizard to obtain a firm grasp on a substrate improves (i.e. when it can wrap its limbs around the substrate). This ability to form a secure grasp is dependent on both the diameter of the perch and on lizard limb length.

Urban Hibernacula

By Joshua Hall

On February 2, 2016

In All Posts

Urban environments often create a diversity of novel habitats that differ from natural areas in thermal variance and spatial organization. Sometimes this results in a broader range of usable microhabitats for species able to thrive in human-disturbed areas. A few days ago I discovered such a microhabitat in an unlikely place. Last October, after getting mucked up seining for turtles in a slow moving Alabama stream, I quickly rinsed my muddy boots with a water hose and tossed them absentmindedly into a sunny spot to dry. There they remained until I went out a few days ago (January 30) with my daughter to look for green anoles coming out to enjoy a brief break in winter weather. Temperatures for the day were expected to reach the upper 60’s° F. Even in midwinter, green anoles (Anolis carolinensis) will sometimes emerge from their hibernacula to sun if the weather is right. As we walked outside, I noticed such an individual emerging from one of my steel-toe boots; he was covered in a dry layer of mud that most likely still lined the insole from my turtle trip last fall. He was quite sluggish so my daughter (3 ½) was able to inspect him for a moment before he got spooked and scurried off to a sunny brick wall some distance away. This was the only anole we found for several hours, so we called it quits and went looking for salamanders. Later that evening, once the sun was long down and temperatures had returned to a squamate-chilling 52° F, my skepticism got the best of me, and I returned to the boot for another look. After probing around a bit I found what I was looking for: a little green lizard had returned to bed down for the rest of the mild Alabama winter.

Are Anolis aeneus active at night?

By Renoir Auguste

On February 1, 2016

In All Posts

Photo from The Reptile Database.

Recently here in Trinidad, West Indies, I came across an Anolis aeneus. I observed the individual at 1930 h; sun had set at 1810 h. It was perched vertically on a wall, roughly 1 m off the ground facing down – as if in a foraging position. There was a bright light shining over it. I’m curious as to whether this type of behavior has been noted before; are these anoles also known to be active at night?