Anole Annals

Thank you to everyone who submitted photos for the Anole Annals 2016 calendar contest, we received so many great submissions! We’ve narrowed it down to the top 30, and now it’s time to vote! Choose your 5 favorites in the poll below. You can click on the thumbnail to view full-size images. You have 5 days to vote – poll closes on Monday at midnight (11/21).

Anolis carolinensis basking mid-winter in the Great Smoky Mountains National Park. Note the icicle in the left foreground. Photo by Sandy Echternacht from The Reptiles of Tennessee (UT Press 2013), and used with permission of the photographer and publisher.

Having recently moved to North Carolina, I am naturally inclined to get out and look for anoles. The state encompasses portions of the northern extent of the green anole (Anolis carolinensis) along the eastern seaboard, and a number of researchers are interested in both the evolutionary history of green anoles (Tollis et al. 2012, Campbell-Staton et al. 2012, Tollis and Boissinot 2014; Manthey et al. 2016) as well as, in particular, their ability to adapt to highly season regions (Jaffe et al. 2016). For a subtropical lizard to survive in areas that regularly see snow and ice is potentially an important study in regional adaptation. Indeed, this dramatic photograph below illustrates that anoles and icicles can coexist in both space and time.

This comes from work done by Sandy Echternacht and David Bishop at the University of Tennessee Knoxville. These researchers have shown that the green anoles in the Great Smoky Mountains National Park (yes, they occur there!) exist mostly on south-facing rocky slopes, and that they do not hibernate during the colder months. Instead, they will often bask on the rock faces when the sun shines directly on the rock (even when ambient temperatures are near freezing). During warmer months, the lizards move from overwintering sites into the forest, often along rivers (Bishop and Echternacht 2003, 2004). South of the Park, this species can be found in abundance along the banks of larger rivers.

North Carolina GAP Analysis Project

In North Carolina, green anoles range up the Atlantic coast to Virginia, but have a more jagged latitudinal distribution moving west across the state. Known records (Palmer and Braswell 1995) decline in latitude as one approaches the city of Charlotte from the east, tapering to just barely north of the South Carolina border. Then, some curious incursions and apparently disjunct populations are recorded from west of the I-77 corridor (what generally constitutes Western North Carolina).

Anolis carolinensis from Chimney Rock, NC.

With one season under the belt, so to speak, my Herpetology class at the University of North Carolina Asheville and I have found what we think might be the closest population of green anoles to Asheville, North Carolina. This population occurs in a steep valley near Chimney Rock, North Carolina. Interestingly, they have access to steep south-facing rocky slopes above the valley. I thought I would poll the group and see if anyone has any hot tips on anole populations in the east Tennessee/Western North Carolina region. We are considering making this a Herpetology class project in the future- to map out the anole populations in this part of the state to see if they are in fact disjunct and whether any additional populations can be found. We will keep AA posted.

Recently, the book Invasion Genetics: the Baker & Stebbins legacy was published online, covering various aspects of the evolutionary biology of invasive plant, animal, fungus and microbe species. One chapter, coauthored by myself, will particularly appeal to Anole Annals readers, as it provides an extensive review of the genetic, evolutionary and ecological differences between exotic and native anole species. Anoles are highly appropriate for a book on invasion genetics, because of the large body of research on both the genotype and phenotype of anoles, the many species that have exhibited the ability to establish populations outside of their native range, and the exponentially increasing number of exotic anole populations since the onset and intensification of travel and trade in the Caribbean and across the world.

The chapter contrasts what is known about the natural dispersal and colonization processes of Caribbean native anoles to the human‐mediated translocation of exotic anoles in the Anthropocene. Previously, natural colonization events rarely occurred, whereas the rate of new (exotic) anole colonizations has increased drastically. The main argument of the chapter is that the many exotic introductions have eroded the previously strong biogeographic structure of anole assemblages.

An exotic crested anole male (Anolis cristatellus) on the island of St. Martin. (photographer: Wendy Jesse)

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Trunk-crown: A. allisoni.

Crown-giant: A. equestris. 

It’s that twice in the year opportunity to get AA anole watches at bargain basement prices in honor of today’s clock changes. Get ’em before they run out of stock (or, more importantly, before midnight). Use Code:

DAYLTSAVINGS

Trunk-Crown: Anolis allisoni

Crown-giant: Anolis equestris

Twig: Anolis occultus

Trunk-ground: Anolis marcanoi

Grass-bush: Anolis pulchellus

Aslam Ibrahim Castellón Maure posted this photo on his Facebook page. Taken in the Zapata Peninsula, it’s a Cuban trogon eating an unidentified anole. The Cuban trogon, or tocoroco, is the national bird of Cuba. But what species of anole? Hispaniolan trogons have also been observed eating anoles. More surprisingly, their lovely relative the quetzal has also been reported to do so, notable because quetzals are thought to be primarily frugivorous.

Figure 1. Anolis cristatellus wileyae; Photograph credit (De Gao)

In his classic work on biogeography, Darlington (Zoogeography: The geographic distribution of animals, John Wiley, New York, 1957) used a small sample of Caribbean island herpetofaunas to show that larger islands have more species. Recently, Gao and Perry reevaluated the regional biogeographical patterns of West Indian native and nonnative herpetofauna by assessing multiple species–area relationship (SAR) models, C– and Z-values (typically interpreted to represent insularity or dispersal ability), and the contribution of area effects towards explaining among-island heterogeneity.

But this time, their sample included over 1600 islands.

Figure 2. Map of the West Indies, showing the distribution of 1668 studied islands

They found that SARs were best modeled using the Cumulative Weibull and Lomolino relationships, both of which can display both convex and sigmoid curves. However, the Cumulative Weibull regressions were more likely to display sigmoid curves within the broad range of island sizes studied – from tiny rocks to major islands like Hispaniola and Cuba. These findings imply that the flexibility of Cumulative Weibull and Lomolino distributions may have been under-appreciated in the literature. Z-values for all herpetofauna in the current study were lower than those reported by Darlington, perhaps because the earlier study oversampled larger islands.

Figure 4. Comparison of Z-values with previous studies

Broadly consistent with previous studies, Z-values reported by Gao and Perry were ranked: (1) native > nonnative; (2) reptiles > amphibians; (3) snake > lizard > frog > turtle > crocodilian. Area had a weaker effect on among-island heterogeneity for nonnative species than for native species, as might be expected given the different processes of species accumulation in the two groups. Lower extinction rates could contribute to low between-island heterogeneity for native species. In contrast, the arrival of non-native species is more closely related to economic activity than to island size. For most small islands less affected by human activities, extinction and dispersal limitation are the primary processes producing low species richness. High levels of among-island heterogeneity underlie the high value of this region as a biodiversity hotspot.

So what does this tell us about anoles? To the extent that the lizard patterns reflect the large number of Anolis species in this region, the findings imply that within-island speciation, rather immigration related to island area, is the main source of new native species in this region. Not surprisingly, perhaps, human activities accelerate the rate of over-water dispersal of both native and non-native species and weaken the area effect within the region. This leads to increases in among-island heterogeneity under human-mediated conditions. Anoles may be more likely to be affected by the increase in extinction rates that is typically seen on the smallest islands.

Figure 3A. Linear Regression_ lizard

Figure 3B. Linear Regression_ lizard native

Figure 3C. Linear Regression_ lizard nonnative

Figure 5A. SAR and additive diversity partitioning_ lizard

Figure 5B. SAR and additive diversity partitioning_ lizard native

Figure 5C. SAR and additive diversity partitioning_ lizard nonnative

One of last year’s winners, Anolis sheplani by Carlos de Soto

Thank you to everyone who has sent in photos for our calendar contest, we’ve been getting some excellent submissions! There are FIVE DAYS left before the deadline (this Friday, November 4) so if you plan to submit, be sure to do so soon!

As a reminder, here are the contest rules:
Submit your photos (as many as you’d like) as email attachments to anoleannalsphotos@gmail.com (note the change in email address from last year). To make sure that your submissions arrive, please send an accompanying email without any attachments to confirm that we’ve received them. Photos must be at least 150 dpi and print to a size of 11 x 17 inches. If you are unsure how to resize your images, the simplest thing to do is to submit the raw image files produced by your digital camera (or if you must, a high quality scan of a printed image).  If you elect to alter your own images, don’t forget that it’s always better to resize than to resample. Images with watermarks or other digital alterations that extend beyond color correction, sharpening and other basic editing will not be accepted. We are not going to deal with formal copyright law and ask only your permission to use your image for the calendar and related content on Anole Annals (more specifically, by submitting your photos, you are agreeing to allow us to use them in the calendar). We, in turn, agree that your images will never be used without attribution and that we will not profit financially from their use (nobody is going to make any money from the sale of these calendars because they’ll be available directly from the vendor). For good quality printing of your images check pricing and options online from the convenience of your home.

Please provide a short description of the photo that includes: (1) the species name, (2) the location where the photo was taken, and (3) any other relevant information. Be sure to include your full name in your email as well. Deadline for submission is November 4, 2016.

Good luck!

Studying Caribbean lizards when you are based in Northern Europe is maybe not the most obvious thing to do. But I couldn’t resist the charm of Anolis and embarked on a postdoc project with the aim of unlocking some of their mysteries. Since I have a background in comparative genomics, I was particularly excited about one odd feature of the green anole genome: unlike other vertebrates, it is remarkably cluttered with transposable elements.

Transposable elements (or TEs for short) are popularly referred to as jumping genes because they can copy and paste themselves within a genome. Traditionally TEs have been considered to be a ‘junk’ part of the genome, selfishly proliferating in an arms race with the host genome that is trying to keep TEs in check. As a defense, the host genome is usually restricting TEs from entering functionally important regions. But in the green anole even the Hox gene clusters, developmental control regions of the genome that are usually kept neat and tidy, got invaded by these TEs.

Even junk can become valuable in a different context. Indeed, there is circumstantial evidence that TEs can contribute to diversification and adaptation. For example, genomic incompatibilities arising from TE insertions have therefore been suggested to promote reproductive isolation. In other words, proliferation of TEs should be positively associated with speciation. Furthermore, some evolutionary innovations, like the mammalian placenta, appear to involve co-option of TEs for gene regulation.

Does the odd feature of the green anole genome indicate that something interesting is going on with TEs also in the evolutionary history of Anolis lizards? My study published in the Proceedings of the Royal Society of London B is a first attempt to take a closer look.

To this end, I compared the DNA sequences of Hox gene clusters of 30 lizard and snake species, including 20 Anolis species. I reconstructed the history of TE invasions of Anolis lizards and linked this to patterns of diversification across the phylogeny. The results revealed that there was a burst of TE activity in the lineage leading to extant Anolis. It did not stop there – TEs have continued to accumulate during speciation events, such that extant Anolis whose evolutionary history is characterized by many speciation events also have accumulated more TEs than lineages with relatively fewer speciation events. This finding supports the hypothesis that proliferation of TEs contributes to reproductive isolation, but what is cause and what is consequence remains to be seen.

Could TE activity also have contributed to the morphological differences that characterize Anolis ecomorphs? Well, I did not find evidence for this as yet, but this hypothesis is much more difficult to test since we need to learn more about developmental genetics to know where in the genome we should look. Nevertheless, I think this study shows that we can begin to unravel the genomics of adaptive radiation of these wonderful lizards!

Nathalie Feiner. 2016. Accumulation of transposable elements in Hox gene clusters during adaptive radiation of Anolis lizards. Proc. R. Soc. B. DOI: 10.1098/rspb.2016.1555.