Author: Martha Muñoz Page 5 of 8

Martha is a postdoctoral researcher in Sheila Patek's laboratory at Duke University. She received her Ph.D. at Harvard University, where she studyied the evolutionary ecology and thermal physiology of anoles, focusing on the cybotoid anoles from the Dominican Republic. Martha serves as Conference Editor for the Anole Annals.
Website: www.marthamunoz.weebly.com

Figure from Nicholson et al. (2007) showing variation in dewlap color among various species of anoles.

As Nick Crawford, recent Ph.D. of Boston University, points out, the genomics era allows scientists unprecedented access to understanding the genetic basis of adaptation and, by extension, the genetics of speciation. For his doctoral thesis, Nick focused on understanding the genetics of colorful adaptation in Anolis lizards, which is genome-enabled. Adaptive radiations provide lots of variation among closely related organisms, making anoles a great system for studying the genetics of adaptation.

One feature of anoles that really stands out is how colorful they are. Just a casual glance at some of the color variation in dewlaps among species reveals that color is likely an important component of species diversification in anoles. Nick focused on Anolis marmoratus, a colorful anole from the Caribbean island of Guadeloupe. Anolis marmoratus is an excellent choice for studying the genetics underlying color. This species exhibits strong geographic variation in coloration and, as I discussed in my talk a few days ago, lacks a strong signal of genetic structure. In this case, searching for the genes underlying local adaptation can be conducted without the confounding effects of population structure.

One of Nick’s slides showing the ranges of A. m. marmoratus (orange color) and A. m. speciosus (blue) on the islands of Basse Terre (left) and Grande Terre (right) in Guadeloupe.

Nick focused on A. m. marmoratus, which has red marbling on its head, and A. m. speciosus, which has a blue head and, oftentimes, a blue body and tail. These two species are clinally distributed along the eastern side of Basse Terre and A. m. speciosus ranges into the nearby island of Grande Terre (see Figure 1). Rather than use RAD tags, Nick sequenced the genomes for 20 individuals (10 each per subspecies). For every 5 kb along the genome, Nick measured divergence using various metrics of structure and assessed sequence divergence.

Overall, Nick found that about 2% of the genome falls within divergent regions for these two subspecies. Importantly, he found divergence in two genes involved in carotenoid pigmentation and one gene involved in melanosome transport. Divergence in the two carotenoid genes could very well underlie the color divergence in A. m. marmoratus, which has distinct red marbling on its head. These genes fall in regions containing several fixed single nucleotide polymorphisms (SNPs) in a row. Nick suggests that these are likely single haplotypes that are being selected in different environments. Finally, he found no evidence of coding sequence changes, and so he posits that the modifications are probably cis-regulatory in nature. For many years we have been waiting to find out how divergence in coloration occurs in anoles. After seeing Nick’s work, it appears we are closer than ever before to understanding local color adaptation at a genomic level, so stayed tuned to his work for more to come.

Program For Upcoming Evolution Conference Released

By Martha Muñoz

On May 18, 2013

In New Research

Academic conferences are important venues for researchers to learn what is new and exciting in science and to present our more recent work. The annual meetings for the Society of Integrative and Comparative Biology (SICB) is one major conference drawing over 2,000 scientists from around the world. This conference is always held in January and usually features an embarrassment of anoles. The 2012 SICB conference in Charleston, South Carolina featured many interesting talks on anoles, ranging from discussions on new eve-devo resources in this emerging model system to studies of behavioral ecology and thermal physiology (1, 2). SICB 2013 was recently held in San Francisco, and those of us following research in Anolis lizards had plenty to see and learn as there were 18 talks and posters featuring anoles. I attended many of these and summarized the findings as best I could in several AA posts this past January (1, 2, 3, 4).

As it turns out, SICB is not the only conference where anole biologists congregate in large numbers. Another major venue for learning what’s new in Anolis research is the joint meeting of the Society for Systematic Biology (SSB), Society for the Study of Evolution (SSE), and the American Society of Naturalists (ASN). This meeting is generally referred to as the Evolution conference, for short.

This year the Evolution conference will be held in Snowbird, Utah in the last week of June. Two days ago the organizers released the online program for the conference. A quick search using “Anolis” or “anole” as keywords revealed seven talks about these lizards. I’ll be attending this conference (and speaking!), and I’ll be getting updates on each of these studies onto the Anole Annals as much as I can, so stay tuned for more! In the meanwhile, here are titles for all the talks I found about Anolis. If there are more out there that I missed, please let me know!

(1) Title: Natural selection, developmental trajectories, and quantitative genetics underlying intraspecific variation in sexual dimorphism in an island lizard.
Authors: Cox, Robert; Daugherty, Christopher; Price, Jennifer; McGlothlin, Joel.

(2) Title: Extreme sex differences in the development of body size and sexual signals are mediated by hormonal pleiotropy in a dimorphic lizard.
Authors: Cox, Christian L.; Hanninen , Amanda F; Cox, Robert M.

(3) Title: Genomics of local adaptation and colorful pigmentation in Anolis lizards.
Authors: Crawford, Nicholas; McGreevy, Jr., Thomas; Mullen, Sean; Schneider, Christopher.

(4) Title: Identification of sex specific molecular markers from reduced-representation genome sequencing.
Authors: Gamble, Tony; Zarkower, David.

(5) Title: Natural selection on the thermal performance curve of Anolis sagrei.
Authors: Logan, Michael L; Cox, Robert M; Calsbeek, Ryan G.

(6) Title: Testing for simultaneous divergence and gene flow in sister-pairs of physiologically divergent Anolis lizards from Puerto Rico.
Author: McElroy, Matthew.

(7) Title: Divergence in coloration and the evolution of reproductive isolation in the Anolis marmoratus species complex.
Authors: Muñoz, Martha; Crawford, Nicholas; McGreevy, Jr., Thomas; Schneider, Christopher.

Observations Of Female Territoriality In Anolis armouri

By Martha Muñoz

On April 9, 2013

In Natural History Observations

Two Anolis marmoratus males fighting on Basse Terre, Guadeloupe

When it comes to territorial behavior male anoles tend to get all the attention. I suppose it makes sense – nothing catches the eye like a brightly colored male doing a few dewlap extensions or engaging in a dramatic battle. It would be a bit of an understatement to say that we like to talk about male-male territoriality and aggressive encounters on this blog (1, 2, 3, 4, 5, 6, and the list goes on!). In fact, we’ve even had photo contests to document the best fights, which tend to feature large, colorful males.

Perhaps it’s no surprise, but females can be just as aggressive as males. At SICB this past January, I learned about Jessica Edward’s research on aggressive encounters between Anolis carolinensis and A. sagrei. It turns out that the victor of female-female staged encounters was nearly always A. sagrei. There are plenty of interesting papers on the topic, for those that are interested (1, 2, among others).

Figure 1. The author waiting for the sun (and the lizards) to come out.

Regardless, I was completely caught off guard during my field expedition last summer to the Dominican Republic when a female A. armouri engaged in a territorial display against a male intruder. Along with Ellee Cook, an undergraduate at Trinity, I was catching A. armouri near Loma de Toro high in the Sierra de Baoruco, the mountain chain that runs between Haiti and the Dominican Republic in the southwest of the island. It’s frequently rainy and overcast at these high elevations and we spent most of our time languishing in the drizzle and waiting for the lizards emerge, as evidenced in Figure 1 and Figure 2.

Anolis bombiceps And Others In Peru

By Martha Muñoz

On March 1, 2013

In Ask the Experts

Anolis bombiceps – Image from www.amazonialifeperu.com

It started with a google search for Clelia clelia, which is one of my favorite snakes. These large colubrids are commonly known as the mussurana and feed upon vipers. Mussuranas are resistant to viper venom, which also makes them very useful for developing antivenoms. They are impressive hunters that take down venomous snakes with the deftness and tenacity of a honey badger. I have always been impressed by their sheer pluckiness as well as their beauty, and have spent many an hour reading up on them. It comes as no surprise, however, that while I was looking up information on tropical snakes from the New World I inadvertently came across some cool images of anoles!

A very lucky group of arachnologists traveled to the Peruvian Amazon in 2009 and posted some of their pictures on this site. The herping gods were on their side and they found an abundance of beautiful amphibians and reptiles, including many poison frogs and Stenocercus fimbriatus. This species, also known as the Western leaf lizard, is also another personal favorite for its beautiful camouflage and a dorsal pattern that is strangely reminiscent of Anolis barbouri, a leaf-litter anole from Hispaniola.

These adventurers also got to see some fantastic anoles, including A. bombiceps, the blue-lipped anole. Like the western leaf lizards, these anoles do a fantastic job of blending in with the leaf litter and background vegetation, so kudos to the explorers for actually spotting them. They also have photos of some unidentified anoles that could use a trained eye or two. Specifically, they have a photo of a large adult that they have tentatively identified as Anolis chrysolepis, and a juvenile or female that they could not recognize. Anyone out there care to offer an opinion?

Let’s Improve A Wikipedia Article For Anoles

By Martha Muñoz

On February 25, 2013

In Ask the Experts

The Wikipedia page for Polychrotidae

The great thing about Wikipedia is that we can rapidly access information about, well, pretty much anything. The bad thing is that the information available isn’t always accurate or professionally curated. As far as the natural world is concerned, folks are better served visiting more curated sites. For example, if you’re looking for information on anoles, my recommendations would be to visit the Encyclopedia of Life, Caribherp, or even the Anolis genome site if you are specifically interested in the genetics of anoles. But the truth is that people interested in anoles will often go straight to Wikipedia. As members of the Anolis research community, we have the opportunity to evaluate the pages and make suggestions for improvements. Follow this link to the Polychrotidae page. I pose the following challenge to you – Can you find the errors on this page? Can you find where this page could be improved? I will compile the appropriate suggestions and send them to Wikipedia so that they can curate this page. Ready, set, go!!

Cybotoid Blitz On The Encyclopedia Of Life

By Martha Muñoz

On February 20, 2013

In Anoles and Anolologists in the News, Education and Anoles

“Try to learn something about everything and everything about something.” –Thomas Henry Huxley

These are lofty words from one the world’s most impressive autodidacts. Thomas Huxley taught himself German and Greek by candlelight, endured years in crowded quarters with teenage midshipmen aboard the HMS Rattlesnake just to be able to learn about jellyfish, and taught himself comparative anatomy though countless hours behind a microscope. He may be most famously known as one the most important champions of evolution, but to me he is equally memorable for his firm belief in equal access to knowledge.

Image courtesy of David M. Hillis, Derrick Zwickl, and Robin Gutell, University of Texas

Were he alive today, I believe that Thomas Huxley would be a huge supporter of the Encyclopedia of Life (EOL). The EOL takes self-learning to the next level by providing unprecedented access to species information that is readable, comprehensive, and professionally curated. Since 2007, this open-access web portal has been cataloging the world’s biodiversity. Yes, you read correctly. EOL wants nothing less than to create informative pages for all of the world’s species. Last count, that was somewhere around 8.7 million species, but I wouldn’t be surprised if that number were much, much higher. In May 2012, the EOL hit one million species pages, which gives a sense of how successful the mission has been, and also how far they have to go.

Frogs Are Lovers; Anoles Are Fighters – Updates From SICB

By Martha Muñoz

On January 7, 2013

In All Posts

Sometimes anoles are lovers, too. But even when they love, they seem to fight. Photo of Anolis carolinensis taken from Wikipedia.

Greetings again from San Francisco! The anticipation for yesterday’s Animal Communication session was palpable. Usually a big Anolis hit at SICB, the Communication session did not fail to impress. The session was divided into two sections – Lovers and Fighters. Can you guess which one had all the anole talks? Three out of the five talks in the Fighters session were about anoles. Incidentally, most of the talks in the Lovers session were about tree frogs. This was perfectly to my liking – I’ll take the blood, guts, and gore any day. The three Anolis talks presented fascinating new work.

The first was by Jessica Edwards, a graduate student working with Simon Lailvaux at the University of New Orleans on aggressive encounters between Anolis carolinensis and A. sagrei, which has successfully invaded much of A. carolinensis‘ range. In a previous study, Jessica and Simon found that A. carolinensis tends to perch higher in the presence of A. sagrei than when found alone. For her experiment, Jessica placed one male of each species into a large cage with a single perch. At the top of this perch she placed a heat lamp, so that there was one optimal site (warm top) and one sub-optimal site (cool bottom) on the perch. She then scored behaviors and recorded the victor in each trial. She found that relative dewlap size was a good predictor of trial outcome, and that the each species was about equally successful at obtaining the optimal perch, although A. sagrei did have a slight advantage. She repeated this experiment using females of each species, and found something exciting and perhaps unexpected – Anolis sagrei was the clear victor in all but one of several dozen trials! Jessica posits that, in the wild, female A. sagrei push female A. carolinensis higher up in the trees. In polygynous systems such as anoles, where one male defends a group of two or more females, then we would expect the males to go where the females do, and so would expect males to increase their perch heights, as well.

Updates From SICB – How Does Climate Warming Threaten Anoles?

By Martha Muñoz

On January 6, 2013

In New Research

Anolis bicaorum from Utila, Bay Islands, Honduras. Photo by J. Losos.

Will global warming allow the blue-headed anole, A. allisoni, to move into the forest in the Bay Islands? This individual was photographed on Roatan by J. Losos.

Climate warming is a sad reality that environmentally defines our era. Over the next century, conservative estimates suggest that air temperatures will rise about 3° C. One imperative in research is to try to understand how reptiles, whose physiology is tightly linked to thermal environment, are going to be impacted by these increasing temperatures. During a symposium honoring Ray Huey, a leading biologist (and an anologist, to boot!), Michael Logan of Dartmouth College gave a talk on how small-scale estimates of thermal variation, rather than weather stations, yield interesting and perhaps counterintuitive results for how tropical lizards will be impacted by hotter temperatures. Predictions of potential impact to date rely heavily on temperature data gathered from weather stations – those provide a resolution of one square kilometer. For small reptiles, like tropical anoles, he argues that we need a finer resolution. To this end, Logan launched several operative temperature devices (sensors that perceive temperature as a lizard would, rather than just air temperature) on Cayo Mayor and Utila, which are islands in the Bay Island Archipelago in Honduras. We’ve discussed the anoles of the Bay Islands here on our blog before. On Cayo Mayor, Anolis lemurinus is found in the closed-canopy forest, while the blue-headed lizard, A. allisoni is found in more open habitats. A close relative of A. lemurinus, Anolis bicaorum, is found throughout Utila. Because closed-canopy forests are more thermally homogenous (less variation in available temperatures due to less access to sun and shade patches), the expectation is that, under a scenario of climate warming, the open habitat species A. allisoni should be able to invade A. lemurinus‘ habitat. Logan says that A. allisoni will not invade the forest habitat, although the details of the analysis suggest to me that they might. From what I saw, increasing temperatures in the forest should allow A. allisoni to invade the newly available warm habitat. He does find that A. lemurinus should experience a loss in potential daily activity hours because of increasing temperatures, putting this species at risk. The common species (A. bicaorum) will actually experience more hours of activity and likely benefit, at least in the short term, from increased temperatures. Logan concludes that more micro-scale measurements provide the appropriate resolution for studies of thermal performance in lizards, and will be the wave of the future.

Day One Updates From SICB

By Martha Muñoz

On January 5, 2013

In All Posts

Greetings again from San Francisco! Day One of SICB has been full of amazing talks and posters. The poster session yielded interesting new research by Diego Castro and Michele Johnson, of Trinity University, on the relationship between testosterone and dewlapping behavior. Diego, an undergraduate studying neurobiology, asked whether muscles involved in sexual or aggressive behavior would have increased testosterone. To answer this question, Diego focused on five species of Dominican anoles, including Anolis brevirostris, A. coelestinus, A. cybotes, and A. olssoni. Diego observed the natural behavior of these species, and quantified the average number of pushups and dewlaps they performed. They found that A. coelestinus and A. cybotes have fewer dewlap extensions and several pushups in their displays, while A. brevirostris dewlaps as often as it performs pushups. They then quantified the concentration of androgen receptors in the ceratohyoid, which controls dewlap extension to determine whether levels of androgen receptor protein correlate with sexual display behavior. They found that species with greater display rates also had a higher number of cells expressing androgen receptor protein. Their next goal is to measure androgen receptor protein in the bicep and tricep. Great job, Diego!

Winners Are Right-Brained – Visual Lateralization In Aggressive Encounters

By Martha Muñoz

On January 4, 2013

In New Research

Aggressive encounter between anoles. Both opponents are watching each other with their right eyes. Photo: Johnson Lab, Trinity University

Have you ever gotten an angry look from an anole? Has he ever displayed at you, demanding that you get out of his territory? If so, chances are that if an anole was giving you the stink eye, he with using his left side! I’m blogging live from the Society for Integrative and Comparative Biology (SICB) meeting in San Francisco. My first stop has been to view Michael Patton’s poster examining the neuroanatomy of aggressive behavior. Patton is a senior undergraduate student at Trinity University working with Dr. Michele Johnson. Early birds at SICB have the opportunity to put their posters up for early viewing, so I got a sneak peek of his work last night although he’s not slated to present until Saturday.

For his project, Michael addressed the question of brain lateralization in aggressive displays. Some evidence suggests that anoles tend to favor their left side during competitive encounters. Patton and colleagues built on these studies by examining behavioral laterality in the field and neuroanatomy in the lab in the same individuals. Through observations of wild A. carolinensis, Patton found support for this idea – the winning male tended to view his opponent from his left side!