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Patterns of Convergence in the Body Shape of Squamate Reptiles

SICB 2015 is off and running and what better way to kick it of than with a lizard talk? Phillip Bergmann of Clark University filled the 8:15 time slot on day one with an intriguing evaluation of broad-scale body shape convergence among squamates. This is a perennial topic on Anole Annals due to the well-studied patterns of convergence among Anolis lizards and, indeed, Dr. Bergmann highlighted anoles early in his talk. He asked whether common functional (ecological) situations lead to body shape convergence at large scales. Rather than search for global patterns of convergence, Dr. Bermann used hypotheses specific to the transformations that occur when lineages transitioned into new habitats. As he pointed out, it is not surprising to find convergence in body shape occurring throughout squamate – after all, convergence is ubiquitous across the tree of life. He concluded his talk highlighting what he feels are some of the most pressing “Big Questions” regarding convergence which included the methods we use to detect convergence, the role of constraints in shaping convergence, and elucidating the mechanisms underlying convergence. Ultimately it was a thought-provoking talk both from the perspective of squamate organismal diversity and the topic of convergence more broadly.

Anolis allisoni displaying. Photo by Pablo Bedrossian

Sister WordPress blog pablobedrossian has a nice post with photos and videos of A. allisoni from Los Cayos Cochinos in Honduras.

Introducing Anolis alocomyos.

Gunther Köhler and colleagues have done it again!This time, they’ve taken Anolis tropidolepis  in Costa Rica and divided it into three species in the December 2014 issue of Mesoamerican Herpetology.

The back-story: the A. pachypus complex (as the authors refer to it, except using the generic name Norops) has in recent years been split in Panama into four species, but complex member A. tropidolepis remained intact in Costa Rica. These lizards are long-limbed, narrow-padded lizards found near the ground at high elevations.

Based on eight years of collecting, Köhler and colleagues now split the group in Costa Rica into three species that are somewhat genetically differentiated at the 16s mitochondrial gene and that differ in hemipenial morphology and to some extent in scalation.  One of the OTUs (operational taxonomic units), comprised of a single individual, has the mtDNA of one species and the hemipenis morphology of another and is interpreted as evidence of hybridization.

The paper includes interesting discussion of bar-coding and how one goes from degree of genetic differentiation to decisions on species delineation.

One highlight of the paper was the icon shown below, which occurred at the bottom of one of the pages at the end of the article without explanation. A quick look at the other two papers in the issue revealed that each has its own logo–nice!

Photo by Christopher E. Smith

Christopher E. Smith recently tweeted this photo of an eyelash viper consuming an anole. The photo was taken in Tortuguero, Costa Rica in 2008 and the incident is recorded on HerpMapper. He provided additional photos which show the anole more fully. It appears to me to be an A. limifrons, though the regenerated tail means that the usual tail banding is not present.

And two more, for good measure:

And Down the Hatch!

Photo by Christopher E. Smith

In going back through the AA archives, I’ve discovered that we previously posted a link to these photos in April, 2011! But here they are again for your renewed viewing pleasure.

Consumption of A. limifrons by eyelash vipers has been previously reported, including a lovely photo by Harry Greene in Lizards in an Evoutionary Tree. A quick Google Image search yields a number of photos, although I suspect most are in captivity.

Here’s an interesting one:

Photo from Many Creatures of Costa Rica

This, in turn, led me to The Many Creatures of Costa Rica blog, which has a whole series of photos of this predation event from La Selva in Costa Rica. The anole seems to be A. humilis. Here’s another from the series:

We’ve reported on bird predation on anoles many times before [e.g., 1, 2, 3, 4], but here’s another. The paper just out in Herpetological Notes has also the gory details of what went down in Veracruz, Mexico.

In an earlier post on anole foraging mode, Jonathan Losos remarked that “much remains to be learned about the specifics of anole foraging and how it differs among species.” One thing we do know, however, about fine-scale variation in foraging mode is that it can depend on microhabitat. Both interspecific and intraspecific variation in movement rates in anoles suggest that low-perching anoles in trunk-ground habitats move less frequently than high-perching anoles in arboreal trunk-crown habitats (Lister and Aguayo 1992; Cooper 2005; Johnson et al. 2008)

One reason that anoles may shift from low to high perches is the presence of a congener. In the spoil islands of Mosquito Lagoon, FL, Anolis carolinensis occurs either on its own or in sympatry with A. sagrei, and recent research by Stuart, Campbell and colleagues showed that the green anoles perch higher on two-species islands than on one-species islands. Back in 2010 as a field assistant on this project, I collected some data on the foraging mode of green anoles on five of these islands, to test the prediction that allopatric A. carolinensis that inhabit lower perches in trunk-ground microhabitats have lower movement rates than sympatric A. carolinensis that occupy higher perches in trunk-crown microhabitats. I used the standard measure of movement per minute (MPM) to quantify foraging mode from a total of 204 lizards (78 females and 126 males, 110 lizards from one-species islands and 94 from two-species islands).

Movement data are messy and MPM varies a lot across individuals, with coefficients of variation within islands ranging from 41% to 74%. Moreover, when one watches lizards go about their lives, one readily realizes that they move for many reasons other than to feed and that MPM is therefore better interpreted as an index of activity than as a measure of foraging per se (Perry 2007).

I found that females show the predicted increase in MPM with increased perch height when sympatric with A. sagrei, while males show the opposite pattern, with higher MPM in the absence of A. sagrei (there was something of an interaction between A. sagrei presence and sex in the ANOVA on island means of MPM for males and females; F_1,1=4.02, p=0.09).

Means of island means of MPM for male and female green anoles in one-species and two-species islands in Mosquito Lagoon, FL.

That males and females differ behaviorally in their response to A. sagrei is perhaps not surprising, as males and females have different motives for movement during the breeding season. Male anoles spend a majority of their time in the breeding season engaged in social interactions and forage only opportunistically. Females, on the other hand, spend most of their time foraging in both the breeding and the non-breeding seasons (Lister and Aguayo 1992; Jenssen et al. 1995; Nunez et al. 1997). The increase in MPM in sympatric females relative to allopatric females therefore suggests that lizards forage more actively at higher perches. In contrast, the decreased movement rates of males on two-species islands might result from male territories being smaller on two-species islands than on one-species islands, with fewer movements required to defend these territories.

Aside from these speculations, the results shown here only allow one to conclude that movement behaviour is complex. Discerning why an individual is moving at any given time, coupled with much larger sample sizes than obtained here, including repeated measurements of the same individuals moving in different contexts, will be crucial to furthering our understanding of fine-scale variation in movement rates and its relationship with microhabitat

Citations

Cooper WE (2005) Ecomorphological variation in foraging behaviour by Puerto Rican Anolis lizards. Journal of Zoology 265: 133-139

Jenssen TA, Greenberg N, Hovde KA (1995) Behavioral profile of free-ranging male lizards, Anolis carolinensis, across breeding and post-breeding seasons. Herpetological Monographs 9: 41 – 62

Johnson MA, Leal M, Schettino LR, Lara AC, Revell LJ, Losos JB (2008) A phylogenetic perspective on foraging mode evolution and habitat use in West Indian Anolis lizards. Animal Behavior 75: 555-563

Lister BC, Aguayo AG (1992) Seasonality, predation, and the behaviour of a tropical mainland anole. Journal of Animal Ecology 61: 717-733

Nunez SC, Jenssen TA, Ersland K (1997) Female activity profile of a polygynous lizard (Anolis carolinensis): evidence of intersexual asymmetry. Behaviour 134: 205-223

Perry G (2007) Movement patterns in lizards: measurement, modality, and behavioral correlates. In: Reilly SM, McBrayer LB, and Miles DB (eds.) Lizard Ecology. Cambridge University Press, Cambridge pp 13-48

In a recent post on the newly described Anolis triumphalis, I stated that the Reptile Database listed 400 anole species. It turns out I was mistaken. Fortunately, Claus Petesen and Peter Uetz have set the record straight in the comments: A. triumphalis makes 396. Four to go! Everyone get out there and find some new ones!

The march of Anolis to 400 species continues with a paper by Kirsten Nicholson and Gunter Köhler describing a new species from Panama.Actually, according to the Reptile Database, there are already exactly 400 species! So this makes 401.

Previously, ten members of the pentaprion group were known, seven from Central America, three from South America.

The new species, A. triumphalis (described under the name Norops triumphalis) has a large orange dewlap, thus distinguishing it from all other members of the group, which have a reddish-purple dewlap.*

Anolis triumphalis is described from a single male that was captured crossing the road between pastures with tall grass and a fence composed of wooden fenceposts and living trees. As the authors note, pentaprion group anoles are very similar to West Indian twig anoles. This story is reminiscent of the rediscovery of another mainland twig anole, A. proboscis, found after forty years by a group of birdwatchers when a male was observed crossing a road in front of a mini-van. Why the twig anole crossed the road is clearly a question that will puzzle philosophers for years to come.

*The authors state that the large, orange dewlap doesn’t distinguish A. triumphalis from A. sulcifrons, but as far as I’m aware, the latter species has a red-purple dewlap like other pentaprion group members.

Here’s the abstract:

We describe the new species Norops triumphalis sp. nov. from Darién, Panama. Norops triumphalis differs from all congeners by having a combination of (1) smooth, bulging, subimbricate ventral scales; (2) a short tail, ratio tail length/SVL 1.54; (3) short hind legs, longest toe of adpressed hind leg reaching to ear opening, ratio shank length/SVL 0.24; (4) a lichenous body pattern; and (5) a very large yellowish orange dewlap in males. In external morphology, N. triumphalis is most similar to the species of the N. pentaprion group. Norops triumphalis differs from the other species in the N. pentaprion group, except N. sulcifrons, by having a very large orange male dewlap (vs. a large red or pink dewlap) and an unpigmented throat lining. Norops triumphalis differs from N. sulcifrons by having the supracaudal scales not forming a serrated crest (vs. a distinct serrated caudal crest present in N. sulcifrons), 4 supracaudal scales per segment (vs. 3 supra-caudal scales per segment in N. sulcifrons), greatly enlarged outer postmental scales, about four times the size of adjacent medial scales (vs. moderately enlarged outer postmental scales, about twice the size of adjacent medial scales, in N. sulcifrons), and no enlarged postcloacal scales in males (vs. a pair of moderately enlarged postcloacal scales present in male N. sulcifrons). We further provide a standardized description and illustrations of the holotype of N. sulcifrons.

Drawing by C.M. Kosemen

Ho, ho, ho. Wouldn’t this be a great Christmas present?