Category: New Research Page 47 of 66

Here on the Anole Annals we like to talk food. Although anoles are predominantly insectivorous creatures, we have documented some of their stranger eating habits on this blog. For example, through recent research we have learned that they are more frugivorous than previously thought. They also include other vertebrates into their diets, such as frogs. Chamaeleolis anoles, we have learned, have specialized molars to aid in crunching mollusks.

Sadly, however, anoles are often also on the receiving side of predation. Anoles are important prey items for many different animals. Sometimes, even plants get their fill on anoles.

In her recently published undergraduate thesis, Dr. Yudisleidy López Ricardo from the University of La Habana, Cuba discusses the diet of the barn owl (Tyto alba furcata) in several localities in Villa Clara and Ciego de Ávila. Dr. López Ricardo examined nearly 300 owl pellets (regurgitated bits that contain food remains) and found 69 different prey types. As expected, small mammals such as the house mouse and black rat were common prey items. A novel finding of this study, however, is that large species of anoles, namely A. equestris, A. porcatus, and even Chamaeleolis sp. lizards were found in the owl pellets. Smaller anoles, including A. jubar, A. sagrei, and A. lucius were also found in the diets of the barn owl. The authors also found that a different herp, the Cuban tree frog, Osteopilus septentrionalis, was not uncommonly found in owl pellets, but this species is nocturnal.

The finding that anoles are a small, but important, component of this species’ diet is quite interesting in light of the fact that Tyto alba, like most owls, is nocturnal. The main question for me is how they are finding and catching anoles. Owls rely heavily on sensitive hearing to locate moving prey at even great distances. But anoles are predominantly diurnal creatures, and are typically asleep and quite still by nightfall. Owls also have great vision and may be spotting anoles during crepuscular hours. Or are they opportunistically feeding on anoles? Perhaps a different predator scares an anole out of its sleeping site and owls are snatching up fleeing anoles.

Any thoughts from the Anolis community on this interesting finding?

Squares are A. gaigei; circles are A. tropidogaster; triangles are locations of members of the species complex for which specimens were not examined and thus determination to species has not yet been accomplished.

Gunther Köhler’s at it again! This time with a merry band of colleagues he’s split Anolis tropidogaster, a little brownjob of an anole widespread in southern Central America and Colombia, into two species, A. tropidogaster in Colombia and eastern Panama and A. gaigei sandwiching it in western panama and the Santa Clara Mountains of Colombia.

Like a number of recently differentiated mainland anoles, the species differ markedly in the shape of their hemipenes. However, in contrast to some other cases, they also differ in dewlap color and a number of scale characters. Further, a limited genetic analysis suggests that the two forms may be substantially differentiated genetically.

The title of the paper says it all: “It is time for a new classification of anoles (Squamata: Dactyloidae).” No doubt, AA contributors will have something to say about this before long, but comments–or posts–are welcome now. The paper–by Nicholson, Crother, Guyer, and Savage–is a 108 page monograph in Zootaxa (text runs to page 69). Anolis is proposed to be split into the following genera: Dactyloa, Deiroptyx, Xiphosurus, Chamaelinorops, Audantia, Anolis, Ctenonotus, and Norops. In addition to presenting a phylogeny and a new classification, the paper also has sections on biogeography, dating, ancestor reconstruction and–most intriguingly–“Evolution of ecomodes in the family Dactyloidae.” Stay tuned!

High school students conducting anole research. Read all about it in the author’s post on the paper.

Everyone knows that anoles, like most reptiles, are not good parents. They just drop off the eggs, and that’s that. If they come across their offspring, they might even eat them! Not a paragon of parenthood. But does that mean the anole moms don’t do anything to help their kids? If nothing else, perhaps they could lay their eggs in places that would lead to maximally healthy offspring.

To test this idea, Aaron Reedy and a cast of dozens conducted an experiment in which they gave female brown anoles a choice of nest substrates varying in moisture content to see if they preferentially put eggs in some places over others. Then, they raised the eggs in the different environments to see if it matters.

The results were clearcut: females prefer to lay eggs in the soil with the highest moisture levels available. And, in turn, it matters: eggs put in such soils (the placement of eggs was randomized after the females laid them) had high hatching success, produced large offspring, and led to an overall increase in offspring survival.

These results are interesting and in agreement with a variety of studies on other reptiles. What is particularly notable about this research is that it was conducted in a low-income neighborhood city high school science classroom. The first author, Aaron Reedy, was a science teacher (he’s now in grad school at the University of Virginia), and the project was conducted by him and a large number of his high school students. Now, that’s remarkable! Reedy provides an interesting account of how the experiment came to be and what the students thought of it in a post at Scientific American’s website.

This paper also brought to our attention another paper published earlier this year that had eluded AA‘s notice.

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Figure from Leal and Powell paper showing that members of the same ecomorph category are not convergent in brain structure.

The Caribbean anole radiation is famous for its convergence. First detected in features related to habitat use and locomotion, such as limb length and toepad size, we now know that the Greater Antillean ecomorphs are convergent in many other attributes such as sexual dimorphism, territory structure and head shape. One might wonder what other features are convergent as well. For example, brains. The anole ecomorphs differ in the complexity of the environments in which they live, which might lead to selection for different brain configurations in different habitats. Brian Powell set out to examine anole brains for his just completed doctoral dissertation at Duke University, and he has now published the results. The short story: the anole ecomorphs are not convergent in brain structure! You can read more details in Chipojolab’s first-hand account of this paper, or check out the paper’s abstract here:

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Dan Rabosky and co-authors have just published an important report on patterns of organismal diversity in PLOS Biology, with one of their main conclusions being that clade age does little to explain species richness.  Luke Harmon has a commentary on this article in the same issue of PLOS Biology, and I’ll refer readers there for a general summary of the work’s implications.  I wanted to give this article a shout-out here at Anole Annals because they used an anole as their icon for squamates in Fig. 3 (see above).

Inspection of their supplemental Table 2 and consultation with the authors, however, reveals that anoles were inadvertently left out of the final analyses due to a book-keeping error involving use of the timetree age for Iguanidae sensu Schulte et al. 2003 but the species richness for Iguanidae sensu Frost & Etheridge 1989. (A quick taxonomic review for the uninitiated: The family diagnosed as Iguanidae by Frost and Etheridge included only a subset of the species previously regarded as members of the much larger family Iguanidae.  Frost and Etheridge assigned Anolis and many of the other genera previously included in Iguanidae to other newly defined families.  They considered this taxonomic revision necessary because they did not recover a monophyletic Iguanidae sensu lato.  Because molecular phylogenetic analyses do tend to recover a monophyletic Iguanidae sensu lato, some subsequent authors, including Schulte et al. 2003, have advocated retention of Iguanidae sensu lato and treatment of Frost & Etheridge’s families as subfamilies [see Daza et al. 2012 for another perspective on this taxonomic debate].)

If we imagine crudely adding a circle to represent Anolis in Rabosky et al.’s figure 3 (assuming an age of ~50 mybp and species richness of ~400 for the genus), its clear that anoles would be among the youngest, yet also most species rich, of all squamate clades, providing further support for Rabosky et al.’s main conclusion that clade age has little role in explaining clade richness.

When alerted of this issue, Rabosky and his co-authors re-ran their analyses including anoles and their relatives (i.e., Polychridae/Polychrotidae of Frost and Etheridge) as well as all of the other Frost and Etheridge families that were overlooked for the same reason (e.g., Tropiduridae, Phyrnosomatidae).  Rabosky sent me a figure that illustrates the position of all these missing clades (in blue), including the clade that includes Anolis (in red) as well as the other squamate clades in the original analysis (in grey).  Because many of these clades stem from series of basal branching events within Iguanidae sensu lato and are relatively similar in age, they rather nicely illustrate the reported absence of a correlation between clade age and species richness.  Not surprisingly, Rabosky et al.’s overall conclusions about clade age and species richness are unchanged by inclusion of these additional datapoints.

At the end of the day, this discussion nicely illustrates how monkeying around with the names of formal Linnean ranks can cause chaos for anyone who is not intimately familiar with a particular name’s complete history.

Rabosky, D. L., G. J. Slater, and M. E. Alfaro (2012). Clade Age and Species Richness Are Decoupled Across the Eukaryotic Tree of Life PLOS Biology DOI: 10.1371/journal.pbio.1001381

Wrapping up our coverage of the World Congress of Herpetology held in Vancouver last week, I have a report on Nick Crawford’s talk on the genetics of colorful pigmentation in Anolis.  Nick began by talking about the basic types of pigments that contribute to anole coloration, which include both pteridines and carotenoids.  Synthesis of pteridines is much better understood, thanks largely to work on zebra fish (reviewed in Braasch et al. 2007).  Nick first showed preliminary evidence from rtPCR analyses suggesting that specific genes along the pteridine synthesis pathway differ in predictable ways among parts of anoles with different coloration (e.g., white venter, green dorsum, pink dewlap).

Crawford went on to note that pteridines may be less important to dewlap coloration than are carotenoids, but that the latter represent a bit of a black box genetically and developmentally.  Crawford then discussed a project in which he uses a bulk segregant approach to ask if regions of the genome associated with color differentiation can be identified by examining genomic sequence data from species with polymorphic coloration.  Crawford was particularly interested in the polymorphic Lesser Antillean Anolis marmoratus.  He obtained sequence data from two phenotypically distinct populations of this species using the Illumina hiSeq platform.  Fortunately this data could be aligned to the A. carolinensis genome, and showed a relatively high degree of synteny with this previously published genome.  Analyses of the new A. marmoratus dataset are still in their early stages, but preliminary analyses recover 1,300 fixed SNPs (only 330 of which appear to be exonic) and suggest the presence of genomic islands of differentiation similar to those reported in many other recently diverged species and incipient species.

Note Added in Press:

One talk we failed to cover at WCH was by Chris Schneider on a similar topic. Here’s the Abstract:

Schneider, Christopher (Boston University); Crawford, Nicholas; McGreevy, TJ; Messana, Nick (Boston University, Canada)

The genetic basis of phenotypic variation and divergence in Anolis marmoratus

In what should be our final belated post about talks at the Evolution meetings in Ottawa last month, I’d like to share some results from Bryan Falk from Susan Perkins’s Lab American Museum of Natural History.  Bryan has been investigating the diversity of anole malaria parasites (Plasmodium).  Like many other species of vertebrates, anoles have their own strains of malaria (not the same as the ones that effect us humans), and these lizard malaria have been the focus of numerous fascinating research projects over the years (see Schall 1996 for a review).

Bryan’s work investigated phylogenetic relationships among West Indian strains of lizard malaria using sequence data from mitochondrial DNA plus six nuclear loci.  He found that Plasmodium samples on most islands form monophyletic groups, although some clades are found in both Florida and Cuba, suggesting travel between these two regions.  Bryan also reported very low overall genetic diversity, the presence of most genetic variation among (rather than within) populations, and no evidence for purifying selection.  Bryan’s previous work used tree-based delimitation to diagnose previously unrecognized or ambiguous taxa of Plasmodium on Hispaniola, and his new work uses a similar approach across a broader geographic scale.  In the new study, species tree analyses tend to recover island-specific clades and identify 11 potentially unrecognized species within Plasmodium floridense (see Perkins 2000 for more on species delimitation in Plasmodium). Bryan’s time calibration work suggests that intra-island divergences are very young and his demographic analyses suggests that recent divergence and serial bottlenecks may be responsible for low diversity with in populations but high divergence among populations.  It seems like more exciting new results with anole malaria on are on the horizon from Bryan and his collaborators.

The New York Times covered the story, too. http://graphics8.nytimes.com/images/2012/08/08/blogs/cat/cat-blog480.jpg

We reported earlier this month on the talk at the Ecological Society of America where a University of Georgia researcher put kitty cams on housecats to see where they went and what they did. And one finding: they caught a lot of anoles! USA Today ran an article on the front page, and included a video online that has some grisly (ok, not that grisly) footage of this, as well as other cool stuff (encounters with other animals, secret lives of housecats). Check it out!

One of the brown anole males in the McMann and Paterson study. Photo by Stephen McMann.

Anole Annals readers know otherwise, but many people consider lizards to be simpletons, with nary a thought in their head. But that’s mistaken–it’s salamanders that are the truly stupid ones (sorry for the tangential ad hominem). Lizards have more going on upstairs than people realize. Sure, they’re not the sharpest knife in the drawer, but they’re no dummies, either.
Case in point: lizards are able to recognize and differentiate among other lizards. This conclusion, which has now been demonstrated a number of times, was reinforced by a recent paper by McMann and Paterson in Herpetological Conservation and Biology. They set out to test whether  brown anoles react differently when confronted with a neighbor than when confronted with a lizard that lives farther away and that, presumably, the lizard has not interacted with in the past. This is a test of the phenomenon termed “dear enemy,” the idea that neighbors get to know each other and come to a mutual coexistence in which, when they encounter each other, they go through perfunctory displays, but don’ t get all riled up, because they’ve already been through all of that before. The dear enemy phenomenon has been demonstrated previously in a variety of other lizards. Indeed, these authors have demonstrated it before with brown anoles, but that work was conducted in experimental arenas. This time, the authors wanted to see what happened when the research was conducted in nature, in animals’ own territories. To do this, they presented territorial males with another lizard enclosed within a small cage.

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