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SICB 2019: Sex-Biased Gene expression in Brown Anoles

Members of the same species share a common genome, the same set of genes and regulatory networks that build the proteins responsible for phenotypic diversity. However, that means that both of the sexes share a common genome, and that is an issue when males of a species are sensitive to their own environmental stimuli, and when females are required to invest a lot of their energy towards reproduction and rearing offspring. Species are often sexually dimorphic as well, where either the male or the female will be larger than their inter-sex counterpart, and this has to do with what ecological tasks each sex is responsible for. Do you have to defend a territory? You better be big! Do you want to create a lot of high-quality offspring? You better not invest that much energy into your own growth! It’s an interesting question in biology today: what happens genetically when a sexually-dimorphic species develops to adulthood?

To answer this question Albert Chung, a graduate student at Georgia Southern University, and his colleagues Robert Cox and Christian Cox designed an experiment to quantify changes in gene regulation in brown anoles throughout ontogeny and quantify how changes in gene regulation produce sexual dimorphism. They quantified gene expression at four different time points until adulthood across three different tissue types (brain, liver, and muscle) using RNA sequencing (RNAseq). Chung and colleagues found that sex-biased gene expression exhibits age specificity, with different age classes exhibiting different patterns of sexual dimorphism in gene expression. They also found that the number of sex-biased genes increases throughout development, important for a species to be able to develop both a larger sex and a smaller sex. In addition, sex-biased gene expression also varies among the different tissue types, with the liver exhibiting an increase in sex-biased genes throughout development, potentially to increase growth in male brown anoles compared to females! Chung spoke in the Raymond Huey Best Student Paper Award session for the Division of Ecology and Evolution and delivered a fantastic presentation. We look forward to learning more about the development of sexual dimorphism (especially in anoles!) from Albert and his co-authors.

SICB 2019: The Effect of Sinusoidal and Fluctuating Developmental Temperatures on Anole Embryos

Ectotherms such as lizards often take extreme care when it comes to laying their eggs. Eggs are incredibly sensitive! When female lizards don’t retain their eggs and give live births (we call this viviparous), female lizards will seek out the perfect temperature and moisture conditions for her eggs to develop and hatch. Oftentimes, when researchers use anoles in the laboratory for a variety of experiments, they incubate eggs at the temperature that these eggs experience in their natural environment. However, many studies only use a constant, mean temperature, rather than using a more realistic diel cycle of fluctuating temperatures over time. However, does that matter at all? It’s an important question for a variety of anole biologists that raise eggs to hatching: does the thermal regime of your incubator matter when it comes to offspring phenotype?

Josh Hall, a Ph.D. student at Auburn University under Dan Warner, set out to address just that question! He raised brown anole eggs in one of four distinct thermal treatments: a constant temperature, a repeated sinusoidal (sine wave) fluctuating temperature, a fluctuating temperature parameterized by the mean daily fluctuations these lizards experience in the field, and natural environmental conditions. He did this for both a cool developmental temperature (reflecting eggs developing earlier in the reproductive season) and a warmer developmental temperature (reflecting eggs developing later in the reproductive season). Even Josh didn’t recommend doing so many treatments! However, the amount of work that went into these treatments is impressive.

Hall and Warner found that natural temperature treatments increased the developmental rate of brown anole eggs only at cooler temperatures, and actually decreased the developmental rate at warmer temperatures. They didn’t find any other effects of any treatment on egg phenotypes. They also found that natural temperature treatments increased the endurance of hatchlings compared to the constant temperature treatment  at cooler temperatures. I was really struck by this study: it seems really obvious that eggs would do better in the lab when developed at temperatures that they experience in the field, but an experiment like this is so rarely performed because it requires so much intensive care and work! Can’t wait to hear more about how different developmental conditions affect anoles from Hall and Warner!

SICB 2019: Anole Setal Morphological Diversity

An anole toepad imaged with a scanning electron microscope.

In the endless comparison between the adhesive systems of geckos and anoles, today we learned a bit more about anole toe pads. University of Akron grad student Austin Garner, from the Peter Niewiarowski and Ali Dhinojwala labs, presented a poster on setal morphology across the toe of Anolis (Deiroptyx) equestris or the Cuban Knight anole. Like a lot of studies on toe pads, the inspiration for this work can be traced back to a previous study by Tony Russell (Johnson and Russell. 2009. Journal of Anatomy). In their 2009 study, Johnson and Russell found that the more distal lamellae of Rhoptropus geckos were more narrow and that their distal setae were longer, lower in diameter, and more densely packed within and across lamellae. This study came to shape our knowledge of within-toe gecko setal morphology.

Today Garner presented preliminary data evaluating the same patterns in an anole. Although their numbers are very preliminary (N=2), it suggests some interesting deviations from Rhoptropus. The more distal lamellae of equestris are narrower, similar to Rhoptropus. Distal setae are also more densely packed, but setae seem to be the longest and have the widest diameter in the middle of the lamellae, and in the middle of the toe, which is very different than what was observed in Rhoptropus. 

If this pattern holds as Garner et al. increase their sample size, it will have interesting implications for how we think about toe detachment in geckos and anoles and well as how the two groups navigate rough and smooth surfaces. I am really excited to see what patterns emerge from the study and so stay tuned to see how their results shake out!

SICB 2019: Mitochondria Effects on Endurance and Metabolic Rate

 

Animals have to perform a lot of complex tasks within their environment in order to reproduce and survive. To perform these tasks, animals often rely on their ability to move throughout their environment, and animals that do this often are often better fit within their environment. That’s why exercise is so important, ladies and gentlemen! Frequent exercise will increase your ability to run fast or run far, but it often comes at a cost. For one, increased exercise response is met with a reduction in your ability to fight an infection (i.e. immunocompetence) or reproduce.

To further understand the effects of exercise on animals in general, Kara Reardon, a student of Jerry Husak’s at the University of St. Thomas, devised an experiment to understand how increases in cellular mitochondria (the powerhouse of the cell!) influence performance after endurance training. They provided green anoles (Anolis carolinensis) with pyrroloquinoline quinone (PQQ) a training supplement to artificially increase their mitochondria production and found that PQQ (and a higher level of mitochondria) didn’t necessarily influence endurance capacity directly, but found that it lowered metabolic rates in their lizards. They also found that muscle metabolism was not affected by training, but that exercise overall increased the performance capacities of green anoles. Next up, they are going to quantify the genes involved in their observed endurance enhancements in these anoles. Great stuff from Reardon and Husak!

SICB 2019: Impacts of Artificial Light at Night on Brown Anoles

As I’m sure we are all aware, humans are causing a lot of significant changes to their surrounding environments. These changes can include habitat loss or fragmentation or urbanization just to name a few. However, one novel component of anthropogenic change is the introduction of artificial light into ecosystems that were otherwise dark. Artificial light at night (ALAN) is a new pressure that many organisms haven’t necessarily dealt with before humans rose to industrial fame. The impacts of ALAN on species across the globe is something more people are realizing can be severe and harmful to populations of wild animals. ALAN is capable of altering many important ecological factors for species, including their susceptibility to predation, access to food, sleep, hormones, and reproduction.

Chris Thawley, an NSF postdoctoral researcher in the lab of Jason Kolbe at the University of Rhode Island, devised a field experiment to test for the impacts of ALAN on brown anoles (Anolis sagrei) from southern Florida. Previously, Thawley and colleagues found in the lab that ALAN increases growth in female brown anoles and causes them to initiate egg-laying earlier, thereby increasing their reproductive output. But in this study, they aimed to quantify how ALAN affects anoles in the field, to further ground-truth their laboratory results.

Thawley and colleagues traveled to southern Florida, marked over 200 individual brown anoles with individual beads, and monitored their sensitivity and orientation to ALAN. They found that anoles are exposed to a significant amount of ALAN at their sleeping perches, but that anoles didn’t necessarily exhibit behavioral avoidance of ALAN. They also performed physiological analyses and found that ALAN reduced plasma glucose (a good proxy for energy availability) in the bloodstream of these lizards by approximately 10%, a huge energetic cost for these lizards. Thawley and colleagues plan to continue adding individual lizards to their already impressive dataset to provide a holistic story, including ecological, behavioral, physiological costs of ALAN on these brown anoles. Stay tuned!!

Advances in Herpetology and Evolutionary Biology: Essays in Honor of Ernest E. Williams Available Online

I don’t know how long this has been the case, but you can download it, or chapters within it, at the Biodiversity Heritage Library.

Enormous Growths/Endolymphatic Sacs on the Neck of a Green Anole

Can anyone advise our correspondent in North Carolina who writes about the anole above with enormous growths that may be endolympathic sacs out of control:

Maybe you have some ideas about this growth, which I originally thought were calcium storage seen in anoles, but this just looks like it is going to pop any second.  I bred this girl about 2.5 years ago and she usually lives with my boss unless he goes on vacation, which is when I take care of her.  I also still have her Dad and sister (long story and I’ll never do it again!).  I let the other eight (!) babies that I raised and Mom, who was used to the wild, go.  This girl has always been very hyper and green all the time and has laid a bunch of eggs this past spring and started getting these pockets (thought calcium).  But now the one side is sooo big!  She gets almost the same care as my two (Dad and sister), except maybe a little less sunlight (mine are at a window).  I was worried it is an abscess or parasite or something.  I asked someone at the NCSU vet school and he wasn’t sure.  Oh, she hasn’t been eating well, either, the last few days.

Attached is the photo of her and also a fun one for Christmas that was part of our Christmas card.  We rescued Dad out of a spider web when he was maybe a few days old.  He was dragging his hindlegs, but then regained his strength a few weeks later and we couldn’t let him go at that point.  The lady he made the other 10 babies with is a different story.  My husband found her inside our house and I told him to let her go, but instead he put her in with “Gimpy.”  They had sex the same night :).

The Life of Ernest E. Williams

For some reason, this obituary of Ernest Williams is going around the internet again, 9+ years after it was published in the Harvard Gazette.

Ernest Edward Williams

Faculty of Arts and Sciences — Memorial Minute

At a Meeting of the Faculty of Arts and Sciences on May 19, 2009, the following Minute was placed upon the records.

Ernest Williams was a man of many contrasts. Biology at Harvard in the third quarter of the last century was full of outsized personalities—titans in the field with strong opinions and no reservations about expressing them. In such company, Williams appeared a wallflower, seemingly wishing to be anywhere but in the midst of their arguments. Yet, one-on-one, Williams had an incisive wit and a dry sarcasm—discussions with him were always stimulating and provocative as he never missed a chance to challenge one’s thinking, sometimes quite pointedly.

To some, Williams’s work came across as old-fashioned. His subject, systematics — the study of the evolutionary relationships of species—is among the oldest in science, and his papers — florid and opinionated and, above all, long—recalled an approach to scholarship no longer in vogue. Yet much of his work was boldly innovative; some papers are still widely cited, and in several cases his work was well ahead of its time, presaging approaches to the study of evolutionary biology that were not to catch on for several decades.

Ernest Edward Williams was born January 7, 1914, in Easton, Pennsylvania, the only child of middle-aged parents. Like many boys, particularly of that time, he grew up loving nature and spent many hours capturing salamanders and other creatures. After attending Lafayette College, Williams joined the Army, serving in Europe during World War II. Upon his return, Williams entered graduate school at Columbia University, where he was the last graduate student of the great anatomist William King Gregory.

Williams’s doctoral thesis focused on the structure of the neck vertebrae of turtles and how variation among species reflects their evolutionary heritage. The work demonstrated the combination of careful attention to detail with the ability to interpret results in the broader context that was to characterize Williams’s career. More than fifty years later the work is still foundational in understanding the evolution of turtle diversity.

In 1950, after completing his degree, Williams moved to Harvard, where he initially served as a laboratory coordinator for the anatomy course of the legendary paleontologist Alfred Sherwood Romer, then subsequently was appointed as an assistant professor and made coordinator of a General Education course on evolution. The Museum of Comparative Zoology’s Curator of Herpetology, Arthur Loveridge, retired in 1957, and Williams was appointed to take his place.  In 1970 Williams rose to the rank of professor and in 1972 became Alexander Agassiz Professor of Zoology.

Williams initially focused on continuing his work on turtle systematics, leading to a series of publications including a still-important treatise published with Loveridge in 1957. Williams soon realized, however, that the museum’s collections were inadequate for the detailed analysis he conceived, which required large samples from many populations. This recognition that the museum’s herpetological collections were wide in scope, but lacking in depth, led Williams in two directions. First, it compelled him to work greatly to expand the Herpetology Department’s holdings, ultimately leading to a quadrupling of the department’s collections (to more than 300,000 specimens) by the time he retired as curator in 1980, making the Museum of Comparative Zoology (MCZ) one of the greatest herpetological repositories in the world. Second, it led Williams’s attention to focus on lizards in the genus Anolis, a very species-rich group from the Caribbean and Central and South America. A previous curator of herpetology and director of the MCZ, Thomas Barbour, had extensively collected anoles in the Caribbean; Williams, whose focus was much more evolutionarily-oriented than most systematists of the day, recognized that this group could be a model for studying large-scale evolutionary and biogeographical phenomena.

And, indeed, they were, and still are. Williams recognized that anoles have diversified for the most part independently on each of the major islands of the Caribbean (Cuba, Hispaniola, Jamaica, and Puerto Rico); most remarkably, the end-result of these evolutionary radiations has been very similar, with the same set of habitat specialists — which Williams labeled “ecomorphs,” a term now widely employed in evolutionary biology — evolving independently on each island. Such convergence of entire faunas is a rare phenomenon and Anolis has become a textbook example.

Williams’s work on anole evolution synthesized a wide variety of fields, including biogeography, functional morphology, population genetics, behavior, and ecology. Yet, Williams was a systematist by training, with little background in most of these areas. The primary means by which Williams orchestrated this broad-based investigation of anole diversity was his ability to identify the best organismally minded graduate students in Harvard’s biology department, regardless of their specific interests. As a result, the list of Williams’s graduate students reads like a Who’s Who in ecology and evolutionary biology.

At a time when the MCZ’s curators had little say in curricular matters, Williams pioneered a highly popular course on vertebrate biology. This course, which Williams taught for many years, helped keep organismal biology alive at Harvard and was a crucial step in the creation of the Department of Organismic and Evolutionary Biology (OEB).

Williams was not the most gentle-hearted of advisors. Gruff and very critical, he had high standards, expected students and colleagues to meet them, and was not shy about letting them know when they had not. Words of praise were not handed out liberally, but were cherished when received. With undergraduates, however, Williams showed a different side, being supportive and encouraging when needed and available at any time for discussion and advice. A number of Harvard undergraduates who worked with him have gone on to become evolutionary biologists, and several have continued to work on anoles, in many cases following up on ideas he initially conceived.

Williams remained active after his retirement from the Harvard faculty in 1984, continuing his evolutionary and systematic studies. Eventually, he moved back to his native Pennsylvania, where he died in 1998, taking his encyclopedic font of knowledge with him. Nonetheless, his spirit and ideas live on in the form of his many academic descendants, which include many prominent active scientists, several members of the U.S. National Academy of Sciences, a high-ranking U.S. government official, and the current curator of herpetology of the MCZ.

Respectfully submitted,

A. W. Crompton
Karel F. Liem
Jonathan Losos, Chair

Laws of the Lizard Premieres on the Smithsonian Channel Next Week

More information on Laws of the Lizard here.

The documentary, by Days Edge Productions, is all about anoles and the scientists who study them. Accompanying the  film is a 7-part series of short webisodesThe Lizard’s Tale. Here’s the first one:

 

Anolis eewi Rediscovered?

César Barrio (Doc Frog to those of you who know him on Facebook or through his photography) recently posted this:

Here’s more information from César:

“Well, It is not completely sure it is eewi. Anolis eewi was described from Toronó, part of Chimantá tepuy, the neighbor tepuy of Auyan, where this one was found. This individual was at the same altitude (around 2000 m) and conditions as eewi. Norops planiceps is a widespread species in northern South America, and is very variable, but the proportions and the general feeling of my nose as a taxonomist told me this was different. Probably the best way to present it is as cf. eewi, even now eewi is synonym of planiceps.”

The last sentence reminds me to point out that eewi was named after Ernest E. Williams, who was often known by his initials, EEW. Williams then wrote a paper that sunk the species into what was, at that time, A. chrysolepis (if I recall correctly). While searching for the Williams paper, I came across another paper published by Williams in Breviora in 1996 reporting specimens of A. chrysolepis eewi obsercved (collected?) in the Venezuelan tepuis.

 

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