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The team at Tropical Herping has done it again! This time, a fabulous, lavish, luscious, information-packed guide to the spectacular herpetofauna of Mindo Parish, Ecuador. Originally available online, the book is now available in print. I had the privilege of writing the foreword, appended below. More information is available on the TH website, as well as an order form.

Foreword:

Small in size, but a global giant in biodiversity, Ecuador is awash in all manner of fauna and flora. Birds, butterflies, trees—the country is a hotspot for just about everything. But no group of organisms is more beautiful, more charismatic, more scientifically captivating than Ecuador’s reptiles and amphibians. The Amazon rainforest dominates the attention of the public, but other parts of the country, especially the mountainous regions, are just as biologically rich. One such area is the small parish of Mindo in Pichincha Province, home to 102 species of creepy crawlies. And what an ensemble! Brilliant colors, toxic skin and venom, sweet serenades, menacing looks, gorgeous displays—this region is an encyclopedia of herpetology in just 268 square kilometers.

Field guides play an essential role in making the fauna and flora of an area widely accessible. They are at the front line of nature education and conservation, the place where the fruits of scientific exploration are distilled, synthesized, packaged, and presented to the public at large. Since the time of Roger Tory Peterson, field guides have played another role, being a venue for beautiful, yet accurate, scientific illustration, allowing readers to not only understand the identifying marks of each species, but also to appreciate them esthetically.

Despite its bountiful herpetofauna, until now no field guides existed for Ecuador’s amphibians and Reptiles. The Tropical Herping team has brilliantly stepped into this void, producing a guide to the herps of Mindo that hopefully will serve both as a model of how guides should be produced and an inspiration to the production of similar efforts elsewhere in Ecuador and beyond. The Amphibians and Reptiles of Mindo is particularly notable in three respects. First is the breadth and depth of information provided for each of Mindo’s species. These authors know their fauna in exquisite detail and have synthesized that knowledge in a clear and lucid manner. The inclusion of frog calls, recorded by the authors themselves, is an added bonus bridging the paper and digital eras. Second, the public often does not understand the connection between scientific research and the information presented in field guides, magazine articles and nature documentaries. Unlike most field guides, The Amphibians and Reptiles of Mindo makes this link crystal clear, providing citations so that readers know where to turn to learn more. Indeed, especially impressive is the fact that the authors did a great deal of field work themselves to round out knowledge of these species, presenting that information for the first time here. Finally, third, the book is simply beautiful. The photographs are simply stunning and the maps and other illustrations lovely as well.

The publication of The Amphibians and Reptiles of Mindo could not come at a better time. The Mindo region is a microcosm for all that ails the natural world. Deforestation, habitat fragmentation, pollution, overharvesting—all are threats. Mindo has one thing going for in its favor—it has become a nature vacation travel destination, providing jobs and economic rationale for preserving natural habitats. But, ecotourism can be a two-edged sword, as people and development are drawn to the area with potentially negative consequences. Mindo has the opportunity to show how responsible stewardship can be mutually beneficial to man and nature, and this lovely book shows what is at stake. Three cheers for the three authors of this magnificent volume. Long live the herpetofauna of Mindo!

We all know that some of our favorite anole species are abundant in urban settings, yet many others are not. Why is this? Do species have to evolve and adapt to city living? Maybe not. In what may be a surprising preliminary analysis, Kristin Winchell over on her blog Adaptability suggests that Caribbean anoles ancestrally had what it takes to live in human settings, and not being able to do so is an evolutionarily derived trait. Sounds crazy at first, right? Until you remember that anoles colonized these islands over water, and so to be successful, had to be flexible and able to cope with whatever life through at them–including, apparently, concrete sidewalks, trashcans, cars, and cats. Check out the details on Kristin’s post.

One of the major experimental advances in recent decades has been the battery of methods capable of functionally validating hypotheses regarding the molecular networks that regulate biological processes. For biologists, these emerging methods allow us to move beyond descriptive and correlational studies to new dimensions where we can experimentally validate our observations. Until recently these technologies were, by and large, reserved for the most well developed laboratory model systems (e.g., mouse, chicken, zebrafish, Drosophila), systems that rarely have direct utility to ecologists and evolutionary biologists. But the topography of biology is changing. These methods are rapidly becoming more easily applied to non-model systems, such as our favorite genus Anolis. In an upcoming paper from the Menke Lab, the tools of functional genomics are applied to anole limb development, taking another step towards making Anolis a truly integrative model system.

In situ hybridization showing expression of of early limb genes in A. sagrei.

Park et al. describe a micromass culture system to explore the molecular regulation of anole limb morphogenesis. In their protocol, Park et al. collect cells from early limb buds of A. sagrei, dissociate the cells from one another, and then add them to a dish as a small (i.e., micro) bolus (i.e., mass) of cells with the appropriate growth media. Even when removed from the embryo, these cells maintain the characteristics of limb cells, developing cartilage after about two weeks and maintaining their molecular signature for at least eight days. This small mass of cells can be grown for up to 30 days and, therefore, provide a useful template for experimental manipulations. More details of this protocol are described in great detail in the paper. Compared to other technologies which require far greater investment, their protocol should be accessible to anyone with access to a tissue-culture laboratory.

Anolis is an emerging model of limb development, but previous studies have focused on describing morphometric patterns of limb growth, not the molecular regulation of limb development. In fact, there have been no studies systematically dissecting the molecular regulation of limb development in any squamate species despite broad interest in this topic in the laboratory mouse and chick systems for 40 years. To study the molecular mechanisms regulating limb morphogenesis, Park et al. forced the expression of the gene Pitx1 – a hindlimb-specific molecule in mouse and chick – in micromass cultures derived from both forelimb and hindlimbs. This experiment verified that one step of the limb regulatory network, the relationship between Pitx1 and Hoxc11, is likely conserved among amniote lineages. While at this time this  may have been a proof of principal experiment, this protocol may have future implications for both developmental and evolutionary research in Anolis. For example, multiple transgenes can be readily cloned and incorporated into the micromass cultures. In addition, micromass cultures derived from species with distinct limb morphologies may also open to door to finding pathways that are regulated in novel ways across Anolis lizards.

Binding domains of Pitx1 in the intergenic region of Hoxc11. Note conservation of binding region throughout mammals (shaded arrows), but lack of conservation among amniotes (white arrows).

A while back, we noted that “apparently no one has posted a picture of an anole sitting on an orchid on the internet.” Recently, alert reader Tsjok De Clercq has discovered that this is no longer true. He has pointed us to an image on The Orchid Source  that shows a festive anole (A. sagrei) on what appears to be a houseplant. Of greater interest is the post on Ricardo’s Blog, Orchids, Parrots, Fish and People describing a Puerto Rican crested anole found in nature on a red orchid, which seemed to be a complete fail in the remaining cryptic department. Thanks for the tip, Tsjok!

The tweet-o-sphere is full of news that there was some sort of anole question on Jeopardy late last week, and that apparently none of the contestants got the answer. But I can’t find any specific online. Does anyone have the inside skinny?

Though we now understand that post-copulatory sexual selection (such as sperm competition and cryptic female choice) can be as important in determining variance in reproductive success as pre-copulatory sexual selection, and though we recognize that the expression of traits subject to pre-copulatory sexual selection is often condition-dependent, it turns out that we know almost nothing about the condition-dependence of traits under post-copulatory sexual selection.

Sperm of Anolis sagrei. Picture by Ariel Kahrl.

In a session devoted to post-copulatory sexual selection, University of Virginia graduate student Ariel Kahrl described her research on the condition-dependence of sperm characteristics in Anolis sagrei. By feeding size-matched male lizards differentially for a period of four months, Kahrl not only generated differences in the body condition of these males, but also ensured that their sperm had developed under her imposed dietary regime. Kahrl predicted that male body condition would affect sperm morphology and sperm count. Pairs of males reared under different dietary conditions were also mated to a single female (making sure to control for mating order by using a reciprocal mating design), thus putting the sperm of two males with different body conditions into direct competition. Kahrl predicted that the fertilization success of males would depend on sperm morphology and count.

Not surprisingly, males with higher body condition had higher fertilization success. It turns out that variation in fertilization success may be influenced by a tradeoff between sperm mid-piece size and sperm number. This situation is interesting, because one can reasonably predict that males on either end of the tradeoff could have high reproductive success—having many sperm per ejaculate could increase the odds of fertilization, akin to purchasing multiple lottery tickets, but having sperm with larger mid-pieces, and thus potentially more mitochondria, perhaps might provide sperm with the burst of energy necessary to win the fertilization race.

In fact, Kahrl found that males with high sperm counts but small midpieces achieve high reproductive success. Intriguingly, she also found that high-condition males had sperm with less variable morphology than low-condition males, and hypothesizes that the dimensions of these uniform sperm match the dimensions of the tubules in females where sperm is stored. Kahrl’s results link pre-copulatory to post-copulatory sexual selection through condition-dependence, and represent a sizeable piece in the puzzle of how sexual selection works in Anolis lizards.

Anolis carolinensis from Miami. Photo by J. Losos.

I’m often a little skeptical of studies that suggest how lab results can have implications for natural systems without actually examining the problem in nature, and studies that address the same question in both lab and field are still rare. That it investigated the same broad question in the lab, in enclosure-style experiments, and in the field is what made Trinity University student Jordan Bush’s poster remarkable.

Bush was interested in the traits associated with dominance, and began by running a tournament of agonistic interactions between a set of male Anolis carolinensis. She used a number of different Markov Chain Monte Carlo algorithms, widely used in predicting winners of sports tournaments, to convert pairwise fight outcomes into individual ranks of “fight-winning ability.” Bush found that rank could be predicted by size-corrected head length, as well as the propensity for aggressive behaviours such as  push-upping and crest-raising.

But do these same traits predict dominance in nature? Not exactly. Bush took the question to the field, and found that none of the traits that predict dominance rank in the lab are correlated with territory size in the wild. In the final piece of the puzzle, Bush constructed experimental enclosures to measure the territory sizes of males with known ranks (by conducting another dominance tournament). As predicted by the first two parts of the study, territory size was not correlated with rank.

By harnessing the power of both lab and field experiments to observations made in nature, Bush’s study will change the way behavioural ecologists think about territory formation. I’ve always assumed that winning agonistic encounters is the means by which anoles increase the sizes of their territory, but like everything in nature, it’s more complicated than that!

Modifying behaviour is often an animal’s first line of defence against a changing environment. We know from Martha Muñoz’s research that high elevation relatives of Anolis cybotes—A. shrevei and A. armouri–modify their perch use to better thermoregulate in colder climates. In a talk entitled “Behavioural divergence along an altitudinal gradient in a clade of tropical lizards,” graduate student Katie Boronow investigated a number of other behavioural traits, asking whether shifting to high altitudes necessitates a suite of behavioural modifications in the cybotoid anoles.

Boronow measured basking, display, escape, and locomotor behaviour in four anole populations–a high-elevation and a low-elevation site in each of two mountain chains in the Dominican Republic. Sites differed substantially in habitat openness–high-elevation sites had a higher proportion of exposed substrate and lower canopy cover than low-elevation sites.

In both mountain chains, individuals basked more and fled more readily at high-elevation sites than at low-elevation sites.  The first result is easily attributed to variation with altitude in thermoregulation–it’s not surprising that lizards bask in direct sunshine more when it’s cold. While the differences in escape behaviour might also be driven by high-altitude lizards being thermally disadvantaged, Boronow found no differences in lizard body temperature between high- and low-elevation sites. Predation risk (as measured by attacks on clay models) also did not differ between sites at high and low elevations, so this variation in escape behaviour remains a mystery.

Given that locomotor behaviour is thought to be tied closely to ecomorph and that both high- and low-elevation cybotoids are still trunk-ground anoles, it is also unsurprising that rates of locomotion (measured by movements per minute, a common metric of foraging behaviour) did not vary by elevation. Patterns of display rates were interesting–while there was no altitudinal effect on display rate, the variation in display rate among populations of cybotoid anoles was comparable to the extent of variation seen across ecomorphs in previous studies. Boronow’s results suggest that differences in macrohabitat can be an important driver of intra-ecomorph behavioural diversification in anoles. 

Readers of the Anole Annals know that the Caribbean radiation of Anolis is a classic example of evolutionary convergence: different ecomorphs have evolved repeatedly on islands in the Greater Antilles and show convergent microhabitat use and morphology. Thus, anoles are a great candidate with which to test a different type of evolutionary convergence: convergence in the physiological mechanisms underlying behavior. If anoles do show convergence in these traits, then there should be a common relationship between physiology and behavior across distantly related species. If not, then different species are using different mechanisms to achieve similar functional outcomes. Michele Johnson of Trinity University addressed this question using a comparative approach in her talk, “The Evolution of Muscle Physiology and Social Behavior in Caribbean Anolis Lizards.”

Species of Anolis that copulate more frequently tend to have a larger RPM muscle.

Johnson’s study focused on two different behaviors: copulation rate and dewlap rate. To quantify these rates, she first collected over 1,000 hours of behavioral observations on adult males across nine different species of anole. To address the mechanistic basis of copulation behavior, she then measured the sizes of the seminiferous tubules, renal sex segments, hemipenes, and retractor penis magnus (RPM, the muscle controlling hemipene retraction). Using phylogenetically independent contrasts, she found a significant positive correlation between the mean species rate of copulation and the mean species size of the RPM, but not with any other trait. Thus, species that copulate more frequently tend to have a larger muscle controlling hemipene retraction. This result supports the hypothesis that the size of a structure is related to how frequently it’s used.

To quantify the mechanistic basis of dewlap extension, she next measured the size and muscle fiber composition of the ceratohyoid muscle (which controls dewlap extension) and androgen receptor expression. There was no correlation between ceratohyoid muscle size or fiber composition and dewlap rate. However, there is preliminary support from four species for an association between androgen receptor expression and dewlap rate. This supports the hypothesis that higher sensitivity to the sex hormone testosterone increases dewlap rate. As the project proceeds, there are plans to add a fourth measure, size of the neuromuscular junction to the study, as well as increase the number of species included.

In conclusion, there appear to be some common physiological mechanisms underlying behavior across the Anolis radiation; however, there are also many physiological traits that may be employed differently among species in the production of behavior.

While we all know that the dewlap of Anolis lizards must provide some information about the signalling lizard to receiver lizards or predators, we remain uncertain about the exact nature of this information. By measuring aspects of dewlap design as well as myriad features of Anolis sagrei locomotor, immune, and behavioural performance, Tess Driessens of the University of Antwerp has begun to unravel the web of information conveyed by the dewlap.

Driessens’ results are complex, to say the least. Different features of the male dewlap relate in un-intuitive ways to various aspects of performance. For example, dewlap brightness was inversely proportional to jumping ability as well as immunocompetence, but directly proportional to haematocrit levels. Most surprisingly, given contrary results from previous work in A. carolinensis, size-corrected bite force in males was not related to any dewlap design variable in A. sagrei. In contrast to the male dewlap, no features of the female dewlap were found to relate to any measure of performance.

Though not unique to anoles, dewlaps are a defining feature of the genus, and I’ve always been amazed at how little we actually know about what dewlaps can say about the individual lizards that bear them. Driessens’ study is an important step towards answering that question.