Anole Annals

Which species owns this lovely tail crest?

Some anoles sport fancy dorsal tail crests. It would be interesting to survey the distribution of tail crests–they are only found in some areas, and species of some sizes and not others, and those in particular microhabitats. Quick–can you think of a mainland anole with a tail crest?

But I’m guessing the species above is not one that comes to mind when you think of tail-crest bearing species. Whose is it? The answer’s below the fold.

Read More

A recent study in Oecologica by Terry Ord and myself found striking parallels in habitat use and morphology between the phylogenetically distinct Anolis and Draco genera.  Draco (family: Agamidae), for those who don’t know, is a genus of gliding lizards found throughout southeast Asia that are similar to anoles in that they communicate with conspecifics using bright and diversely coloured dewlaps (see picture).

(L: Draco sumatranus; R: anole)

A defining characteristics of anole ecology is their ecomorphology – a description of the species microhabitat and its morphological adaptions for thriving there. Anole species living sympatrically avoid interspecific competition by partitioning their habitats and resources, and consequently develop morphological adaptations that are suited to their slice of the habitat. As Draco species are also often found in sympatry, we tested whether competition pressures had resulted in similar habitat partitioning and corresponding morphological characters (or ecomorphs). Whilst it’s perhaps a bit early to suggest that Draco have  evolved the full complement of anole ecomorph classes, the Draco taxa studied largely clustered into two groups that shared characteristics with the Greater Antillean anoles. The figure below (panel b) shows a combined Draco/anole phenogram, based on morphology and ecobehaviour (the anoles are labelled only by ecomorph). The Draco species fall out largely in line with groups of ‘trunk-ground’ anoles towards the top of the phenogram, and ‘trunk-crown’ anole towards the bottom.  

One of the better diagnostic features of the Greater Antillean anole ecomorphs are the differences in perch use and subsequent differences in limb length. The plot below shows total hindlimb length (size-free residuals) of adult males of Draco species and Greater Antillean anoles, as a function of perch circumference.  The relationship between limb length and perch size is nearly identical between the groups, with a very similar slope, and only a difference in y-intercept owing to differences in body length (Draco bodies are elongated to accommodate gliding membranes).  The same unit increase in perch size results in the same unit increase in limb length for both genera.

These results are surprising considering that this relationship has not been found in species that are more closely related to the Greater Antillean Anolis (see study for references) and because Draco and Anolis have very different ‘key innovations’ for locomotion in their respective habitats (toe pads for Anolis and gliding membranes for Draco). This implies that Draco species have experienced interspecific competition over resources in similar ways to the anoles, resulting in homologous character displacement. 

It’s an old story: a Cuban émigré arrives in Florida, thrives and then sends out roots, in the process becoming completely Americanized. I refer, of course, to the green anole, Anolis carolinensis, derived from grand-daddy porcatus in Cuba. But the exact story of carolinensis‘s spread–when, by what routes, where–is still unclear. Two years ago, a pair of papers reported interpretations based on sequences of mitochondrial DNA, revealing a somewhat complicated history of green anole diaspora. Now, in a recent paper in Genetica, Tollis and Boissinot revisit this question, bringing to bear the power of a multi-locus, nuclear gene sequencing effort. Their results lead to a simpler, more satisfying story, and suggest that we need to be wary of placing too much faith in phylogeographic/evolutionary scenarios derived from mitochondrial DNA.

Here’s the tail end of their abstract:

“We find that all demographic events occurred during or after the Upper Pliocene and suggest that green anole diversification was driven by population divergence on interglacial island refugia in Florida during the Lower Pleistocene, while the region was often separated from continental North America. When Florida reconnected to the mainland, two separate dispersal events led to the expansion of green anole populations across the Atlantic Seaboard and Gulf Coastal Plain.”

Their inferred evolutionary relationships are portrayed above, and their biogeographic scenario below.

Hard at work studying lizards (from a previous AA post on best practices in lizard videotaping in the field)

The New York Times reported today on a recent paper in Nature Methods that indicated that stress levels of lab rats varied depending on whether the scientist in the room with them was a man or a woman. This effect existed even in response to t-shirts worn by a man or a woman.

This got me thinking: could the same factor effect lizard behavior studies? In many cases, anoles are studied by an observer quietly watching or recording lizards from a distance of a few meters. Many anole species seem unperturbed by the presence of observers and go about their activities in a seemingly natural way. But does the presence of an observer have an effect? Are they warier? Do they display less? And, more to the point, does the identity of the observer have an effect? Men are, on average, bigger than women, so might that matter? Some people are more fidgetty than others. Clothes? Facial hair? I am aware of a few studies on observer effects on lizard behavior (such as this one on the brown anole), but not many.

Something you don’t see every day: a green anole on a pine tree.

Through the years here at AA, we’ve had discussion of the habitat use of the common green anole. In particular, there is a persistent belief that before the brown anole emigrated from Cuba, green anoles used all manner of anole habitat, from the bottom of trees to the very top of the canopy. Once the browns arrived, however, greens seem to have repeated back up the tree, ceding the low perches to the browns.

This is a very nice story, and probably true, but it’s surprising how little documentation we have of the habitat use of green anoles in places where browns don’t occur. In fact, more generally, it is quite surprising just how little we know about the natural history of green anoles throughout their natural range. For such a common species, you’d think its biology would be extremely well-known, but that is far from the case.

A while back, Janson Jones referred to the green anoles in his then-neighborhood (he’s since moved) in Georgia as low-riders, a possible example of green anole habitat use in the absence of browns. With this in mind, I was delighted to get a chance to see what the greens are up to in Alabama, a state that is still mostly–at least for now–mostly brown anole free.

Across the street from Pi Kappa Kappa.

On the campus of the University of Alabam in Tuscaloosa, greens were moderately abundant when the sun was out. The fellow to the right was strutting his stuff on sorority row, but his comrades elsewhere were in similar habitats on trees, moving up to into the canopy when harassed by an old dude with an iPhone.

But then I had the good fortune to get taken to a nearby pine forest by whiptail lizard geneticist turned turtle biologist Peter Scott, a grad student at UA. Peter told me that he often saw (or, rather, heard) green anoles scurrying through the leaf litter when he approached, running to the nearest tree which it then ascended. It seemed unlikely, but sure enough, that’s where the greens we found were, down low, in very un-green anole-like habitat.

Alabama low-ridin’ green anole

Of course, these were just a few observations made over the course of a short hike one afternoon. But clearly there’s a lot to learn about green anoles–what they do in places without competitors, and how that changes when brown anoles arrive. Seems like a great project out there, just waiting for someone to do it.

We’ve had a series of posts on orangey brown anoles in Florida, but this most recent example is a stunner. Thanks to Heather Stewart for providing this photo of a fine male from Boca Raton, FL, photographed this past January. Heather pointed out that other brown anoles in the populations were quite normal looking.

Wrens seem like such harmless, friendly little birds. And with such a dainty little beak, how much damage could they do? Imagine our surprise, then, to learn that they may be voracious predators on our beloved anoles. Thanks to the observations of Roger Birkhead and Mark Benny, reported in the most recent issue of Herpetological Review, we now know the true nature of these little beasts. Here’s what they saw (Herpetological Review 45(1):123-124, 2014):

“On 14 August 2013 around 0730 h MCB was observing the birdfeeders and birdhouses at his residence (Harrison Co., Mississippi, USA; 30.387325°N, 89.021624°W, datum WGS84/NAD83) when he noticed a commotion near the potted plants on his front porch. An adult Carolina Wren (Thryothorus ludovicianus) was observed smacking and shaking something large and elongated. When the wren flew up to the nearby birdhouse it became apparent that it had a juvenile Anolis carolinenis in its beak which it quickly fed to its chicks. This behavior was observed for a second time at approximately 1130 h. A third anole was observed being fed to the chicks at 1619 h (Fig. 1). There were at least two exchanges of food missed while leaving the point of observation to retrieve and set up a camera, but were evidenced by long green tails protruding from the entrance hole of the birdhouse that were longer than the lizard in Fig. 1. Adult wrens were also seen bringing larger unidentifiable pieces of flesh assumed be the remains of a larger dismembered A. carolinensis. Similar behavior has been noted for vireos feeding on A. carolinenis (Sykes et al. 2007. Wilson J. Ornithol. 119:508–510). Additional observations were made on 15 August and 16 August of both whole lizards and parts being brought in by the adult wrens. Lizards are identified in the diet of the Carolina Wren as far back as 1916 (Beal et al. 1916. Common Birds of the Southeastern United States in Relation to Agriculture. Farmers Bulletin 755, 40 pp.), but no species identifications were provided. Generally, predation of vertebrates by passerine birds is considered uncommon (Lopes et al. 2005. Lundiana 6:57–66). This observation is the first documented record of A. carolinensis being consumed by Carolina Wrens and judging by the frequency of captures noted here this wren species may be a significant predator of anoles at least during the bird’s nesting season.”

A few months back, we had a post on the conservation situation in Jamaica with particular emphasis on the Hellshire Hills, last redoubt of the Jamaican iguana. Now in the journal Oryx, Rick Van Veen and Byron Wilson of the University of the West Indies, along with Tandora Grant and Richard Hudson, of the San Diego and Fort Worth Zoos, respectively, express further concern of the situation. Most of the article can be viewed online; add “and the environmental conventions to which it is a signatory.” to the last line and you’ve got the whole article.