Author: Anthony J Geneva Page 1 of 6

I am an Assistant Professor at Rutgers University-Camden. I use a variety of evolutionary genetic approaches to ask questions about gene flow, adaptation and speciation.

John David Curlis

Where do you work and what do you do?

 I am currently a graduate student at the University of Michigan, but I conduct most of my research in the tropics of Central and South America. I am broadly interested in trying to answer the question of how to explain patterns of phenotypic diversity found in nature, especially in the context of color and signaling. In other words, why do organisms look the way they do – why do they have certain colors over others, and what sort of information are they conveying by showing off those colors? When not focusing on my research, I spend virtually all of my free time photographing as many animals as I can find, as well as spending countless hours sorting said photos into their respective taxonomic groups. What can I say, I’m a biodiversity nerd!

What aspects of anole biology do you study, and what have you learned? 

I study the evolution of color in anole dewlaps. Even with over 400 species, all anoles possess this extendable throat fan, and it’s often brightly colored. Although we have some understanding of how the dewlap functions as a signal (e.g., species recognition, competitive interactions, courtship, predator avoidance/deterrence), it remains unclear why there are so many different colors of dewlaps. To try to tackle this question, I am looking at how the evolution of these colors may be influenced by the light environment. Since the reproduction and/or survival of an anole can depend on whether its dewlap is serving as an efficient signal, it’s easy to see how the light environment might determine which colors are favored by selection. For instance, a bright orange dewlap would likely show up much better than a dull green one under the dense canopy of the rainforest, just as a pitch-black dewlap would probably be an excellent signal in a bright, open field. I am testing this idea using an experimental island study in the Panama Canal. My study species is the Panamanian slender anole, males of which can have a mostly orange dewlap or a mostly white dewlap. By introducing these lizards onto a multitude of very tiny, highly variable islands in the canal, I can test which color will “win out” over time in different light environments. 

How and why did you start studying anoles? 

 I have loved reptiles since I was a child, so it was by no coincidence that the very first lab I worked in as an undergraduate had a breeding colony of anoles. While there, I studied physiology and metabolic rates. While I can say that metabolism work is not for me (shout out to the scientists who love it!), I very much enjoyed taking care of and working with the anoles, so I decided to stick with them throughout my undergraduate and graduate career.

What do you love most about studying anoles? 

 As someone interested in color, I think that dewlaps are anoles’ coolest feature. I love studying anoles and their dewlaps because I am constantly amazed by the astounding amount of diversity in this little flap of skin. In addition, as a researcher, it’s hard to complain about the incredibly high abundance and ease of capture for many of these species.

What is your favorite anole species? 

My favorite anole species would have to be the Meyer’s anole, Anolis johnmeyeri (named after the scientist, not the singer). This species, found in Honduras, has an absolutely gorgeous dewlap in both males and females. While large, colorful dewlaps are possessed exclusively by males in many anole species, female Meyer’s anoles have a dewlap that’s almost as large and equally as beautiful. Female dewlaps are bright yellow with a brilliant blue spot, and male dewlaps are bright red with the same blue spot. 

Where can people learn more about you and follow you online? 

Website: www.colorinnature.org

Instagram: @johndavidcurlis

Joe Macedonia

Where do you work and what do you do?  

 I’m a retired Associate Professor at Florida Southern College in Lakeland, FL. While at FSC from 2007 through 2016, I conducted research and taught courses in animal behavior, zoology, evolution, and ecology, as well as a capstone course in undergraduate research. I also took students to Jamaica and Bermuda to conduct field research on anoles.

What aspects of anole biology do you study, and what have you learned? 

 I’ve worked mainly on the production and perception of color and motion displays. Most of this research has been conducted collaboratively with my colleague Dave Clark and has been experimental in nature, e.g., video playbacks and anole robots. Leo Fleishman’s work on Anolis sensory ecology has been a major influence on my thinking about how lizards perceive their color displays. I’ve learned that working on anole behavior can be challenging and that, in fact, most experiments fail! But I’ve also learned that it is well worth the effort in the end.

How and why did you start studying anoles? 

 When I was a kid growing up in the 1950’s and 1960’s in central Pennsylvania, individual Anolis carolinensis used to be sold at the circus in little “animal cracker” boxes. I still remember bringing one home. My father built a small cage for it and tirelessly caught insects for it. Much later, as a postdoc at U.C. Davis in 1992, I was reintroduced to magic of anoles by none other than Jonathan Losos. At that time, Jonathan was a postdoc with Tom Schoener and heard about the video playback work that we were doing in Peter Marler’s Lab. Jonathan was interested in figuring out two things: First, would anoles respond to video recordings of other anoles displaying? And second, if they did respond to video, could anoles discriminate conspecific from heterospecific displays? With our Marler Lab colleague Chris Evans, we showed that A. marcanoi males spent more time displaying in synchrony with video clips of conspecific male displays than heterospecific male (A. cybotes) displays. Soon after that, Judy Stamps and I conducted an even more successful video playback experiment on species recognition, in which we used Anolis grahami from Jamaica as subjects.

What do you love most about studying anoles? 

 What’s not to love? I recall Chris Evans calling them “magnificent beasts”, as well as Duncan Irschick referring to them as “mini gods”. Anoles are endlessly fascinating, and you could never run out of species to research.

What is your favorite anole species? 

 Regarding species that I’ve worked with personally, Anolis grahami is probably my favorite. They are reliable performers in behavioral experiments and are always up to the challenge of responding to another anole (or a video of one, or an anole robot!). There are two runners up, however. Anolis conspersus with its blue dewlap (actually a UV-reflecting dewlap whose wavelengths extend into the blue range) is quite photogenic, as a number of contributors to Anole Annals have noted. The other runner up would be Anolis extremus. Their complex color pattern is exceptional, and although they are frustratingly squirrelly to approach in the field, male tail lifting contests can be spectacular. Anolis extremus really are extreme!

Where can people learn more about you and follow you online? 

Website: www.macedonialab.com

Lindsey Swierk

Where do you work and what do you do?  

I am an Assistant Research Professor in the Department of Biological Sciences at Binghamton University, State University of New York. I am also the Associate Director of Research of the Amazon Conservatory for Tropical Studies, outside Iquitos, Peru. My research group studies ecology at the organismal level, with a focus on behavior and herpetology. I primarily conduct fieldwork in Costa Rica and Peru. At the university, I teach courses in animal behavior and ecology, and I am involved with initiatives to promote underrepresented students in biology. I was a postdoctoral fellow at Yale University and received my PhD in Ecology from Penn State in 2013.

What aspects of anole biology do you study, and what have you learned? 

 My background in behavioral ecology first nudged my interest in anoles towards communication and reproductive behavior. I have a particular interest in understanding how sexual signals function and evolve. My group studies anole dewlaps and their costs and benefits. The use of color and patterns, both on the dewlap and the entire body, is also a focus in my group. We use both observational and experimental techniques to better understand how anoles use sexual coloration and behavioral displays to maximize fitness. We’ve found that there are some significant risks posed by bearing conspicuous sexual signals, and that there is a variety of ways in which body color can be used plastically to benefit anoles.

Our work is based on natural history observations, and so we tend to follow where the anoles lead. Lately, that has led us down the path of examining their antipredator adaptations. We are investigating the fascinating underwater diving and rebreathing behaviors of the semi-aquatic anoles, from ecological and physiological perspectives. We documented that some semi-aquatic anole species spend considerable time underwater when pursued. Our interest in antipredator strategies includes a focus on the mechanics of escaping predators, whether that is by swimming, diving, running, or leaping. Semi-aquatic anoles are also remarkably cold tolerant and have very low body temperatures, and so we also investigate their thermal ecology and possible effects of climate change. 

How and why did you start studying anoles? 

 Allergies, initially! I kept anoles as pets almost my entire childhood because a cat or dog was out of the question. Back then, I spent an embarrassing number of hours just watching what anoles did in their tanks. This cemented anoles in my head as the coolest possible lizards Years later, after spending all of my research life studying other cool herps, I stumbled upon anoles again on a teaching trip to Costa Rica. From the moment I saw Anolis aquaticus in the streams, they completely captured my attention. Their habitat and behaviors were so unique from what I had learned about anoles, I knew I had to make them a priority.

What do you love most about studying anoles? 

Two things. Their remarkable adaptations – how evolution has so astoundingly shaped them to particular environments. I love how much is known, but also how much is still unknown about their morphological, physiological, and behavioral traits – I love the element of surprise! Second, I’m still fascinated by simply watching their interactions with one another, which I could do for hours. 

What is your favorite anole species? 

 I absolutely have a favorite – Anolis aquaticus. They’re such quirky representatives of the mere handful of semi-aquatic anoles out there.

Where can people learn more about you and follow you online? 

Website: www.lindseyswierk.com

Twitter: @LindseySwierk

Instagram: lindseyswierk

Aaron Alcala

Where do you work and what do you do?  

 I am a PhD candidate in the Department of Genetics at the University of Georgia. I am doing my thesis research in the lab of Dr. Doug Menke. My research is focused on studying how genes are regulated to build parts of the body during embryonic development, and how changes during embryogenesis can lead to the evolution of novel forms and structures.

What aspects of anole biology do you study, and what have you learned? 

 I am studying the genetic and developmental processes underlying the morphology of limbs in anoles. Although the ecology and evolution of these lizards has been extensively studied, we know relatively little about the underlying mechanisms that have contributed to the evolution of different structures within this genus. One of the most apparent differences among anole species is limb size, which is adapted for the particular microhabitat that each species resides within. Differences observed in adult limb lengths between several species of anoles seem to be due to changes that occur early in embryonic development. I’ve learned that since the genes and signaling pathways underlying limb development are highly conserved, changes in gene regulation may underlie many of the differences in limb morphology observed between species. My current work is focused on comparing DNA sequences in the genomes of different species to find regions involved in regulating genes important for the development and evolution of limb morphology.

How and why did you start studying anoles? 

When I first joined the Menke lab at UGA, our efforts were transitioning into more studies in anoles. I instantly fell in love with the brown anole as a model organism for studies of evolutionary developmental (evo-dev) biology.

What do you love most about studying anoles? 

 For the past few decades, studies of gene function in reptiles have lagged behind other major vertebrate groups. I enjoy being able to contribute to establishing the brown anole as an emerging model organism to investigate the genetic and molecular mechanisms of evolution in reptiles. I am also happy to get out of the lab every once in a while to catch anoles and bring them back for us to study!

What is your favorite anole species? 

 Tough to choose of course, but Anolis grahami is one of my favorites because of its striking colors of greens and blues. 

Where can people learn more about you and follow you online? 

Website: aaronevodevo.wixsite.com/aaronevodevo

Twitter: @aaronevodevo

Instagram: @aaronevodevo

Michele Johnson

Where do you work and what do you do?

 I work at Trinity University in San Antonio, Texas. I teach courses on evolution and vertebrate biology, and I lead a lab of undergraduate scientists studying lizard behavior and physiology. We combine approaches from ecology, evolution, and neuroscience to understand how and why lizards behave the way they do.

What aspects of anole biology do you study, and what have you learned? 

 One of the main areas of my research is the evolution of behavioral mechanisms, and we generally focus on how muscles allow different species to behave in different ways.  A surprising result from this work has been that anole species that use a muscle frequently don’t usually have larger muscles than species that use the muscle rarely. Instead, we found that muscles that move bigger structures are bigger than muscles that move smaller structures, no matter how often the muscle is used. This highlights how different lizard muscles seem to be from muscles in mammals and birds.

Another aspect of our work focuses on how a lizard’s social and physical environment affects how it behaves. We’ve studied why green anoles change their body color, how anoles communicate to form a social hierarchy, how anoles respond to artificial light at night, and many other questions. 

How and why did you start studying anoles? 

 In college, I became fascinated with studying evolution on islands, because I thought islands were where the most exciting evolutionary stories were being discovered. I had never studied anoles before graduate school, but since I joined Jonathan Losos’ lab as a PhD student, they’ve been the focus of almost all my research.

What do you love most about studying anoles? 

 As a behavioral ecologist, my favorite part of studying anoles is watching what they do in the field. I’ve found that observing a single lizard for an hour can often lead to surprising findings, and by combining lots of those observations, we can get a rich understanding of how lizards interact with each other.

What is your favorite anole species? 

 My favorite anole is Anolis bahorucoensis, a lizard that lives in montane forests in the Dominican Republic. They have tiny dewlaps, but their bodies are so vibrantly colored – green and blue and black and yellow and orange.

Where can people learn more about you and follow you online? 

Lab Website: www.johnsonlizardlab.org

Outreach Website: www.lizardsandfriends.org

Twitter: @LizardMichele

“Meet the Scientists” Update: Featuring You!

It’s been a long time since we’ve updated our Meet the Anole Scientists section of Anole Annals, so we’re going to do that now! The last time we did this was back in 2020, so we figured it was about time to put some new faces up on our website. You can see the Meet the Scientists section of our webpage here.

If you are interested in being featured, please fill out the attached Google form here. Thank you for your participation, and we look forward to getting your profile up on the website shortly!

 

Anole Genomes Webinar

Tomorrow (30 June 2020) I will be presenting a webinar on our ongoing work assembling Anolis genomes. The webinar is hosted by Dovetail Genomics who provided the core technology we used to generate high quality genome sequences. The talk is at 11AM EST. If you want to watch live and have the chance to ask questions, you can register here. If you can’t make it but still want to hear what we are up to, Dovetail will post the video on their website alongside other speakers in the series.

A Dewlapped Fish!

Image from Twitter user @OomaTsuna (https://twitter.com/OomaTsuna)

Its clear that possessing a dewlap isn’t a trait unique to anole species. These often colorful, extendable flaps of skin beneath the throats of some female and most male anoles can also be found in other reptiles, and similar structures appear in some mammals and birds. I had always thought that dewlaps were a decidedly tetrapod (and terrestrial) trait. A series of tweets by John Friel, Ichthyologist and Director of the University of Alabama Natural History Museum has shown me just how wrong I was! Behold Triodon macropterus a pufferfish with a most striking dewlap. The thread starts with a retweet of a Japanese language account @OomaTsuna thats post stunning fish photos. Dr. Friel then provides some interesting biological details. This species extends their dewlap as part of their defense display (along with inflating their bodies like other pufferfish species). The flap is extended by a bony protrusion, but instead of deriving from their hyoid as in anoles and other lizards, it’s their pelvic bone that extends the leading edge of skin. See the full twitter thread for all the fishy dewlap detail.

 

 

 

Speciation: How One Species Becomes Two

Speciation is the process by which one species evolves to form two or more new species. Often members of different species are unable to interbreed due to the evolution of reproductive isolating barriers. Exactly how to define a species is a matter of active debate among biologists, but most agree that a species is an interconnected population of organisms that have an evolutionary trajectory independent from other species. This independence is critical to the evolution and maintenance of biological diversity. Populations evolve new traits by way of natural selection, where traits that are adaptive (beneficial to the survival or reproductive output of individuals bearing them) are favored and become more common in a population. However, whether a trait is beneficial or not depends on the species it arises in. For example, while conspicuous coloration in a poisonous frog is beneficial, the same trait would be disastrous for harmless species. If all frogs were a single species this trait would be quickly purged from the population. Reproductive boundaries, formed by the process of speciation, provide a mechanism for species to evolve independently from one and another, and accumulate distinctively adaptive traits.

“Sister species” are pairs of species more closely related to one another than to any other species. Anolis krugi (left) and Anolis pulchellus (right) are sister species of grass-bush anole native to Puerto Rico. Photos by Day’s Edge Productions.

The study of speciation boils down to asking the question “where do species come from?” While speciation is a fundamental part of evolution, our knowledge of exactly how the process of speciation works is surprisingly incomplete. For many years the prevailing theory of speciation focused on isolation. In this model, populations of a single species are physically separated from one and other. This could be due to the formation of some impenetrable barrier, like a mountain or glacier, or due to dispersal, like arriving on a remote island. Once isolated, these populations evolve independent from one another, and given enough time, they will randomly accumulate enough differences to be considered distinct species. The spectacularly blue-dewlapped Anolis conspersus from Grand Cayman island is one likely example of speciation by isolation. This species’ closest relative is Anolis grahami from Jamaica. The ancestors of present-day A. conspersus arrived on Grand Cayman from Jamaica thousands or millions of generations ago and formed a new population. Over, time the Jamaican and Caymanian populations accumulated differences in isolation such that they now considered distinct species. 

The beautiful Anolis conspersus from Grand Cayman is most closely related to Anolis grahami of Jamaica. Photo by Anthony Geneva

Scientists often observe that a species and its closest relative differ in their ecology. These sister species may occupy different habitats or different structural parts of their environment. This pattern is not predicted by the isolation theory and this observation gave rise to an alternative theory of speciation where adaptation plays a central role. The theory of ecological speciation posits that speciation occurs as a side-effort of populations of a single species adapting to different habitats or environments. Adaptive evolution can proceed very rapidly, especially compared to the random accumulation of differences in the isolation theory. While there is evidence for both speciation by isolation and ecological speciation we don’t know which (or if either) are responsible for most of the species diversity on earth.  

Anoles are a great group to study speciation for a number of reasons. First, there are over 400 species of anole, so they are clearly adept at speciating. Second, many anole species appear to be in the process of speciation, for example Anolis distichus populations in Hispaniola are partially reproductively isolated from one and other. Finally third, anoles are particularly well suited to investigate which theory of speciation best fits what we see in nature. Thanks to many decades of evolutionary and functional ecology research, we have a strong grasp on what anole traits are ecologically adaptive. With this knowledge, we can use anoles to test the relative importance of isolation time and adaptive evolution in driving the process of speciation. 

Ecological differences may accelerate the speciation process. Anolis cooki and Anolis cristatellus are two Puerto Rican species that are closely related but occupy very different habitats.[/caption]

A. distichus

Bark Anole

Appearance: Anolis distichus, the bark anole, is a medium sized anole with a body color that varies from gray, to brown, to green – depending on the population. Body coloration is similar in both sexes but females can be distinguished from males by their lack of a dewlap, smaller adult size, and a relatively flatter head than males. Male dewlap color in this species is widely variable with populations ranging from pale white or yellow, to populations with variably sized red or orange spot in the center, to populations with entirely red or orange dewlaps. Bark anoles co-occur with a variety of species, most of which can be easily distinguished as different ecomorphs with larger heads or bodies such as Crown Giant and Trunk Ground anoles, or more slender frames such as of Trunk Crown, Grass Bush and Twig anoles. In Haiti and the Dominican Republic, the range of bark anoles overlaps with those of other closely-related trunk anole species – Anolis brevirostrisAnolis caudalisAnolis marron, and Anolis websteri. These species all have a black spot on their neck, which is lacking in Anolis distichus.

Ecology and Habitat: Anolis distichus are trunk anoles, an ecomorph with a compact body plan – short snout and tail, with a relatively wide midsection. Trunk anoles like Anolis distichus primarily occupy the vertical surfaces of trees, usually below the canopy. They are found in a wide variety of natural habitats including xeric scrub to mesic humid forests as well as human-created habitats like buildings, parks, fruit tree groves, and residential areas. Unlike other ecomorphs that flee up trees or run to the ground when approached, bark anoles often shimmy to the opposite side of the trunk, a behavior commonly referred to as “squirrelling”. Bark anoles will eat nearly any prey that can fit in their mouth but their primary diet includes small arthropods like crickets, beetles, and even bees! Bark anoles are especially fond of ants.   

Geographic Range and Biogeography: Bark anoles are native to Hispaniola (Haiti and the Dominican Republic) and the central Bahamas. Although they were once considered native to Florida, genetic data suggests these populations are the result of multiple introductions from Hispaniola and the Bahamas some of which occurred at least 50 years ago. They are thought to be introduced to Abaco Island in the northern Bahamas, but fossil evidence of this species on Abaco puts the status of this population into question. Phylogenetic evidence finds that bark anoles arose on the northern paleo-island of Hispaniola, dispersed over-water to colonize the the Bahamas, and spread to areas of to the southern Hispaniolan paleo-island after the two paleo-islands fused to form present day Hispaniola. 

The immense variation in body and dewlap color in bark anoles has led to the description of 18 subspecies of Anolis distichus. Research currently underway seeks to understand if these subspecies are in the process of speciation or have perhaps already achieved species status. 

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Research Highlights:  

Bark anoles have long been the intensive research effort with particular interest in using bark anoles to understand 1) the evolution of signals and 2) the process of speciation.  

Most anole species possess and make extensive use of their colorful dewlaps for signaling to each other as well as other species. A series of studies led by Julienne Ng has shown that dewlap color is a heritable genetic trait and is associated with signaling environment that animal occupies. Exciting research, currently underway by Winter Beckles, seeks to understand if bark anole populations shift their dewlap color in response to changes in their light environment caused by hurricanes. 

Julienne Ng has also found that some subspecies with different dewlaps interbreed freely over a wide geographic area. In contrast, other subspecies pairs are confined to a narrow hybrid zone suggesting that, for these subspecies pairs, hybridization may have negative fitness consequences and those populations may be in the process of speciation. Research I performed as part of my dissertation also found that transitions in dewlap color are associated with diversification events suggesting dewlap divergence may play in role in driving or maintaining speciation events.  We also found evidence found that there are more distinct lineages that previously recognized within the Anolis distichus group and one subspecies in particular – Anolis distichus dominicensis is actually three separate lineages. Work I performed with undergraduate researcher (now Yale PhD student) Daniel MacGuigan used multispecies coalescent methods to assess if Anolis distichus represents a single species or multiple species. We found support for at least seven distinct species in the group, but at present we have not updated the taxonomy because the boundaries between these species remain unclear, particularly for the separate lineages of A. distichus dominicensis.  

Species account author: Anthony J. Geneva 

For more information:  

Encyclopedia of Life 

Reptile Database 

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