Reaching Safety

When somebody talks about roads crossing along natural forest, we could think about the perturbation this may cause to local fauna, especially in the Tropics. At least in Panama, wildlife crossings are not so popular in terms of design, deployment and monitoring. To my knowledge, the few existing ones are aerial and designed keeping in mind the crossing of monkeys or sloths for example. This issue came to my mind on the 3rd of November when I saw a Dactyloa insignis trying to cross an 8 m road traversing Santa Fe National Park, one of the pristine forest in central Panama.

Captured at Santa Fe National Park, Panama

Captured at Santa Fe National Park, Panama

It made three short attempts and looked clumsy when trying to run on the pavement puting him at risk of death, so we caught him and helped him reach the other side of the road.

Should the Use of Subspecies Be Revived?

The last week has seen a spirited discussion of the pros and cons of splitting recognized genera into multiple, smaller genera. We’ve had 34 comments already. Check it out! And if you’re an advocate of splitting genera, that viewpoint has been getting the short end of the stick and could use more support.

As a tangent, the topic of subspecies has come up, and David Hillis has strongly argued for reviving its use. Here’s what he has to say:

First, I don’t think either species or subspecies are “clades.” Species are lineages (the branches on the tree of life). Sexual recombination among individuals results in tokogenetic relationships within species. Clades, on the other hand, are monophyletic groups of lineages on the tree of life. Rather than being defined by tokogenetic relationships, they are defined by phylogenetic relationships.

Traditionally, subspecies are geographical races of species. In other words, they are geographically distinct populations that nonetheless meet and interbreed at contact zones. Sometimes, these contact zones are very broad, as with broad-banded versus southern copperheads. If the contact zones are very narrow, and there is strong evidence that the contact zone is a genetic sink (there is no gene flow across the zone, because of strong selection against hybrids), then I agree that the two entities can be considered separate lineages, and hence species. But in many recent cases, as with the copperhead example, there is abundant evidence that the contact zone is NOT a sink, and that there is NO selection against hybrids. In this case, I disagree strongly with the authors who proposed to split these subspecies into distinct species. That is inconsistent with any lineage species concept…there is a huge area where these two forms intergrade, with no evidence of any loss of fitness. Thus, the two forms are geographical, intergrading races, or subspecies.

I think we will soon see a backlash against the splitting off of geographic races as species as well. Frank Burbrink (who was an author on the copperhead example I mentioned above) and I plan to write a pro/con article about this together, each arguing our respective points of view. Hopefully, this will re-kindle the conversation about subspecies.

Subspecies are unpopular right now because they were long abused in several ways. Inappropriate uses include (1) to describe non-geographic “varieties”; (2) to arbitrarily break up clines; and (3) to describe distinct, isolated lineages that clearly are species. But used in proper context to designate a geographically distinct race, they are certainly reasonable and often useful. They are rarely used in some groups, for several reasons: Groups like freshwater fishes have discrete ranges, so taxa don’t interbreed over broad areas. And many groups are too poorly studied to understand geographic variation. But in well-studied terrestrial groups (like herps), subspecies are perfectly reasonable and useful taxa to designate intergrading geographic races.

Dragons from the Old World

The Neotropical and Oriental realms both were once a part of Gondwanaland. Interestingly, both of these realms exhibit same ‘type’ of lineages occupying equivalent niches. Boas dominate the Neotropical zone whereas pythons flourish in the Oriental. Similarly, in the Old World (or Oriental or Indo-Malayan realm), there are lizards belonging to family Agamidae which exhibit uncanny parallels to Anolis sp. in their natural history.

CSC_5284One example is from Yelagiri Hills in the Eastern Ghats region of the Indian state of Tamil Nadu. This is Psammophilus dorsalisDuring the breeding season, males of this species turn their drab and dull dorsal region to bright yellow or red to impress conspecific females. The brighter the male, the more chance he has to win over females. Males display such behavior for the entire day; at night these lizards hide under rocks.

When equally bright males encounter each other, competition is settled by ‘ducking’ heads and throwing off the opponent from the rock.

Taxonomic Splitting Revisited: When Should Genera Be Subdivided?

Over the last several years, ever since Nicholson et al. proposed dividing Anolis into eight genera, the topic of taxonomic splitting has periodically been discussed in these pages (for example, this post, its comments, and links to other posts).

The general question of when to split taxa recently has been revisited in several comments in AA. A week ago, David Hillis wrote:

Anolis is a valid name for a monophyletic group on the Tree of Life. It is “special” as a genus only in that the genus name is used as part of a binomial for particular species. It doesn’t make sense to change the scope and application of generic names unless the names are actually misleading about phylogeny (e.g., if Anolis were polyphyletic, then that problem should be fixed). But splitting a valid, monophyletic genus into a bunch of smaller genera, and thereby needlessly changing the names of many species, without fixing any phylogenetic problems with the existing taxon names, is not science. It is just playing around with names. If someone wants to name the groups within genera, then do so…but there is no reason to change the meaning of a existing name (or the names of the all the affected species) in doing so. That is the kind of silliness that gives taxonomists such a deservedly bad reputation among biologists.”

Elswhere, David posted a flowchart on his recommended decision-making process about whether and how to divide recognized genera:

Hillis flow chart

Ivan Prates, in line with comments he made in a recent paper on A. punctatus, then remarked:

“This seems more like a sociological matter.

During the ‘taxonomic revolution’ of the amphibians, about 10 years ago, the (perhaps?) most influential (or faster?) group was the splitter one, and their taxonomic scheme prevailed. Currently, nobody is upset about which species were once named as Bufo, Hyla or Rana. A few do care about Dendrobates – like Anolis, a sexy group with a body of dedicated investigators.

It seems that a single genus makes sense for the community that investigates dactyloid lizards more closely. On the other hand, those who deal with overwhelming levels of herpetological diversity in the tropics (waaaay beyond lizards) see benefit in more partitioned schemes, which correlate more closely to morphology and geography.

So, when we discuss names, it may be healthy not to forget about our diversity as investigators as well. About science, splitting Anolis is not science, but well, not splitting Anolis isn’t science either.”

On the Origin and Diversification of the (Hemi)Penis: Anolis Takes Center Stage

Over the last decade the term “model species” has taken on new meaning. Species that were once the building blocks for distinct disciplines have taken on new importance in comparative evolutionary studies that integrate perspectives across biological disciplines. Nowhere is this better illustrated than with Anolis lizards. For decades anoles were a workhorse of ecologists and evolutionary biologists, but have, more recently, been embraced by developmental biologists, genomicists, physiologists, and neurobiologists among others. This disciplinary expansion is perhaps most evident with the rapid increase of penis/hemipenis research that has been published using anoles within the year.

For many herpetologists, including those focused on anoles, the hemipenis is ripe with taxonomic characters, easily allowing for the identification of new species. Julia Klaczko and colleagues recently demonstrated that features of the hemipenis are some of the most rapidly evolving characters among anoles, a group already well known for its rapid anatomical evolution. Independent from these taxon-specific interests, developmental biologists became interested in the anole hemipenis because of its unique anatomy compared to other amniotes. Marissa Gredler and members of the Cohn Lab used anoles as one of their reptilian models of external genital development in what is arguably the broadest embryological survey of reptilian phallus development to date. In parallel, Patrick Tschopp and colleagues probed the cellular and molecular regulation of early phallus development among anoles, snakes, chickens and mice, demonstrating that the hemiphalluses (hemipenes and hemiclitores) and hindlimbs of squamates utilize similar molecular networks at the earliest embryonic stages of morphogenesis. Now, just within the last month, two more papers have used anoles in studies of phallus evolution and development, one using cutting-edge molecular techniques to better understand the relationship between limbs and external genitalia and the other addressing the fundamental question of external genital homology using museum specimens that are more than 100 years old.

Before getting into the findings of this new research, lets lay out some of the dirty details of penis evolution. First and foremost, the penises of amniotes are extremely diverse. Squamates have paired lateral phalluses while other clades have a single midline phallus. Each of the amniote lineages uses hydrostatic pressure to achieve an erection, yet accomplish this using different bodily fluids (lymph or blood). In mammals sperm is transferred to the female through a closed urethral tube, but other groups utilize an open channel. Most birds (97%) and the tuatara, have absent or highly reduced phalluses and reproduce with the famed “cloacal kiss.” These large differences in anatomy should not overshadow the spines, bulges, corkscrews, and dramatic differences in size that give species their distinctive features. But with such striking variation, we are forced to wonder how many times the penis evolved. Perhaps the amniote ancestor possessed an intromittent phallus capable to transferring sperm to the female that later diversified in each lineage independently. Or, perhaps the last common amniote ancestor used cloacal apposition to foster internal fertilization and unique phallus morphologies evolved independently at the origin of each lineage. Because adult anatomy provides few clues to phallus homology, Thom Sanger (me), Marissa Gredler, and Marty Cohn looked towards the embryo for help.

Table 1 from Sanger et al. 2015 summarizing phallus variation in amniotes

Table 1 from Sanger et al. 2015 summarizing phallus variation in amniotes

The tuatara, a species lacking an adult phallus, has presented a problem in attempts to reconstruct the last common ancestor of amniotes because it raises the distinct possibility that reproduction through cloacal apposition was the ancestral condition.

Anole Photo Contest Is Back!

Lucas Bustamante-Enríquez’s Grand Prize-winning photo of A. chrysolepis from the 2013 contest (© Lucas M. Bustamante-Enríquez/TROPICAL HERPING)

We know you’ve all been waiting, so here it is! Anole Annals is pleased to announce the return of the Anole Photo Contest, 2015 edition! We’re closing in on November, which means it’s time to gather the best anole photographs for our 2016 calendar. As with previous contests, the goal is to identify 12 winning photos. The grand prize winner will have his/her photo featured on the front cover of the 2016 Anole Annals calendar, second place winner will have his/her photo featured on the back cover, and they’ll  both win a free calendar! (Check out the 2013 and 2012 winners). We’re a bit late getting things going this year, so get your photos in as soon as you can!

The rules: submit your photos (as many as you’d like) as email attachments to anoleannals@gmail.com. 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).

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. Twelve winning photos will be selected by readers of Anole Annals from a set of 28 finalists chosen by the editors of Anole Annals.  The grand prize winning and runner-up photos will be chosen by a panel of anole photography experts. Deadline for submission is November 21, 2015.

Good luck, and we look forward to seeing your submissions!

 

A Few Meters Matter–Landscale Thermal Heterogeneity and Reproductive Output in a Puerto Rican Anole

Anolis cristatellus. Photo by Janson Jones.

If you ever come to Puerto Rico, the first thing you’ll probably notice is the warmth. Yet, for an anole, things are not that simple. Different habitats can have different thermal regimes that potentially influence the lizard’s biology and natural history in different ways. What might be a hot and humid urban park for us can be a heterogeneous thermal landscape for a small lizard.

This is the case for Anolis cristatellus, a lizard common in most parts of Puerto Rico. Back in the early70’s, Ray Huey (1974) studied how habitat influenced this anole’s thermal biology. He found that in open and sunny habitats, this lizard actively thermoregulates and has relatively high and stable body temperatures, but that in shaded forests it is a thermoconformer and has relatively low and variable body temperatures.

Also back in the early ’70s, George Gorman and Paul Licht (1974) found that altitudinal and seasonal variation in temperature had major effects on reproductive cycles of Puerto Rican anoles. So, do reproductive cycles differ between lizards living in thermally distinct — but contiguous — habitats? Ray Huey, George Gorman and I teamed up to find out, and you can find the answer in our recent paper just published in The American Naturalist.

We studied seasonal reproductive cycles of this lizard in two localities in lowland Puerto Rico. Both localities have contiguous but thermally distinctive habitats: open parks and forests, separated by only a few meters. We caught female lizards every month for more than two years and palpated their bellies to establish reproductive condition. At both localities, lizards living in open habitats were more often gravid than were those in the forest. This difference was especially marked during winter months (of course… in a tropical sense). During these cooler months, more than 20% of open lizards were gravid, while essentially none of the forests ones were.

Large-scale geographic variation in reproductive cycles has been described in many taxa, but this is one of the few examples on a micro-geographic scale. Very likely these difference will have significant effects on the population ecology of the species, and these will be reported on soon. But in the meantime, we can say that at least for the reproductive output of Anolis cristatellus, a few meters matter!

 

Brown Anole with a Busted Dewlap

Photo by Karen Cusick

From Daffodill’s Photo Blog.

You’re Never Going to Guess Who’s a Big Anole Lover

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Rush Limbaugh, that’s who! To wit: “But I love those little lizards.  They’re anoles, actually.  I love ’em.  They’re our buddies. They eat insects and all that.”

And it turns out that Jeb Bush is just like a cat chasing an anole. Read all about it here (or listen to it here), skipping to paragraph four if you want to get to the important, mostly non-political stuff.

The Incredible Shrinking Dewlap!

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Photo by Bonnie Kircher

Here in north-central Florida, summer is giving way to fabulous fall weather. While this change means an infinitely more comfortable bike commute, it also means that the anoles which were abundant throughout the summer are starting to disappear. Although pedestrians can still find lizards basking in the afternoon sun, Floridians are much less likely to see anoles at every turn. The lizards that are still out and about are also far less likely to be strutting their stuff, keeping their dewlaps tucked away, as they are not needed for mating or competition until the next breeding season. When the dewlap is little used for such an extended period of time during the non-breeding season, could the morphology of this structure be altered?

Indeed, studies have demonstrated that there are marked changes in dewlap size between breeding and non-breeding seasons. Specifically, this already amazing structure seems to change in size, being larger in the summer when it gets the most use, and smaller in the non-breeding season! Simon Lailvaux and colleagues first hypothesized that changes in dewlap size might be correlated with variation in resource availability throughout the year. However, the group found that changes in dewlap size do not correlate with resource availability at all! Recently, following the results of the dietary restriction study, Simon Lailvaux et al. (including yours truly) again asked the question, “Why?” More specifically, are there instead physiological changes that cause dewlap size to expand in the summer and shrink in the non-breeding season?

Lailvaux et al. first asked whether dewlap size was changing because of inherent changes in lizard physiology between seasons or, instead, if changes were due to the extensive use of the dewlap during the breeding season. The authors captured male A. carolinensis lizards before the onset of breeding season and constrained the dewlap in half of the lizards so that the lizards could not extend their throat fan. They found that lizards with unconstrained dewlaps had larger dewlaps in the summer that shrunk again in the fall. The constrained males, on the other hand, had smaller dewlaps in each consecutive season. These data suggest that changes in dewlap size stem from the behavioral use of the dewlap – when a dewlap is extended more often, it gets bigger!

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Apparatus for measuring skin elasticity. Photo from Ecology and Evolution. Volume 5, Issue 19, pages 4400-4409, 19 SEP 2015 DOI: 10.1002/ece3.1690

Next, the authors tested the hypothesis that dewlaps change in size due to seasonal changes in skin elasticity that correlate with the increased seasonal behavioral use. One of the authors, materials engineer Jack Leifer, developed a novel technique for measuring skin elasticity that involved pulling a piece of lizard skin on a machine that measures force until the skin sample sheared (see picture).The authors compared the force it took to break pre-breeding, breeding, and post-breeding dewlap skin, using measurements taken from belly skin as a control. They found that dewlap skin is more elastic than belly skin and that both belly skin and dewlap skin are more elastic in the summer. These results support the idea that dewlap skin is inherently stretchier than other skin!

Thus, it seems that changes in dewlap usage, coupled with changes in skin elasticity across the year, make the dewlap a dynamic signal. This work does not demonstrate any mechanism for these changes and leaves the door open for many exciting follow-up studies. Why is dewlap skin more elastic than belly skin overall? How are changes in skin elasticity regulated between breeding and non-breeding season? What are the ecological implications of a dewlap that changes in size over the course of the breeding season?

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