Anthony Gilbert is a PhD candidate with Donald Miles at Ohio University. He studies evolutionary physiology in desert reptiles as well as the evolution of phenotypic plasticity in response to multiple and simultaneous environmental stressors.
The Society for Integrative and Comparative Biology annual conference is happening next week, January 3-8 2022! With a return to in-person events, we are aiming to highlight the breadth of research talks and posters on anoles given by all the amazing junior researchers at the conference!
This post is a call-to-arms: we can’t cover all the presentations without your help! We are looking for interested folks attending the conference that can help the Annals by contributing blog posts featuring these researchers and their anoles. Folks that elected to do the virtual SICB+ option instead of attending in-person are also encouraged to get involved. If you’re interested, please contact Anthony for any additional details or information.
Below is a list of anole presentations happening at SICB 2022- please reach out if I missed any of any of these peaks both your scientific and blogging interests!
There are so many great anole talks at SICB 2020, I’d be remiss if I didn’t take this opportunity to shed some light on some of our fantastic undergraduate researchers, who turned out in force to Austin this year! As I’m sure Dr. Kristin Winchell will tell you, anole lizards make awesome model organisms for studying the effects of city life and urbanization on wildlife.
Cities can be dangerous though. A lot of different urban environments will present wildlife that have not lived in cities with numerous pressures they might not have faced before, such as different surfaces and substrates on which to run, different temperatures, and even new predators. One of the relatively new pressures that goes along with city life is light at night, and artificial light to boot. If you’ve ever been too disturbed by light during the moonlight hours to sleep and rest, imagine how small lizards feel!
To address the effects of this pressure on green anoles (Anolis carolinensis), Michelle D’Alessandro, an undergraduate student at the University of Scranton working in the lab of Dr. Chris Howey, measured the effects of artificial light at night (I’m just going to call it ALAN) They exposed anoles to ALAN and described the effects of artificial light on metabolism in green anoles. Initially, they did not find any differences between metabolic rates when lizards were exposed to ALAN, however after a sufficient time period, anoles exposed to ALAN increased their metabolic rates during the evening, but not during the day! During this experiment, they also found that ALAN anoles were far hungrier and ate more often than lizards that weren’t exposed to light at night. The term ‘midnight snack’ definitely comes to mind here! Michelle suggests that much like when humans get exposed to changes in sleeping patterns, anoles undergo some energetic changes, causing them to eat more and having to burn more energy. Maybe next time think twice about keeping that porch light on during the waning hours of the evening- give the wildlife some much needed rest.
Another star undergrad alert! If you’ve ever followed the work that comes out of Dr. Michele Johnson’s lab at Trinity University, you’ll know that she produces some incredible science and some even-more incredible undergraduate researchers. Isabela Carson is no exception!
Isabela’s poster was focused on studying intraspecific variation in lizard sperm and testis morphology- she described differences in the size and shape of different testis and sperm features for 6 different species of anole. A lot of this work was founded on Dr. Ariel Kahrl’s dissertation work on describing sperm evolution in anole lizards, and her collaborations with Dr. Johnson’s lab and students always produce some awesome talks and posters wherever they are presented. Isabela wanted to know if longer sperm are produced from lizard species that have larger seminiferous tubules- the part of the testis where sperm are produced, matured, and transported. She found an inconsistent pattern across anole lizards where larger tubules don’t always produce longer sperm.
In talking with Isabela, she noted that there are some big inconsistencies between the external morphology of testes and the sperm they produce, and that there might be some larger ecological or evolutionary patterns at work that go into describing how sperm evolve in different species. I would bet that one day we are going to have data on testis shape and size and sperm length for all anolis species, and there are going to be some awesome patterns and studies that come out of that work. And we definitely have to give heaps of credit to the awesome biologists who are working towards it!
The Howey lab showed up to work at SICB 2020! In keeping with the theme of how urbanization and artificial light at night (ALAN) impacts wildlife populations, Elizabeth Kenny, an undergraduate researcher at the University of Scranton performed a study to describe the influence of artificial light on the immune response in green anoles (Anolis carolinensis).
The researchers used a test for immune response called a phytohemagglutinin test (PHA-L), where they injected the hindlimbs of green anoles with PHA-L and measured how much the foot swelled after both a 24 and a 48h hour period. But rest assured! PHA-L tests are temporary, only induce localized swelling, and have no larger impacts on the health of the organism; it’s sort of like if you’ve ever had a tuberculosis test done at your local physician. Interestingly, Elizabeth found no difference in swelling between green anoles exposed to ALAN and to green anoles that had not been exposed to ALAN. However, Elizabeth suggested that green anoles could respond sufficiently to ALAN by changing how they use the energy within their bodies and where they allocated those limited energetic stores, which provides a lot of support for the work of Michelle D’Allesandro and Meg McGrath. Altogether, the three undergraduate researchers of the Howey lab created a convincing and interesting story about how urban environments influence the energetics and physiology of city-dwelling lizards. Great stuff!
Urbanization was a big theme at SICB 2020 this year, and studies of how city life influences wildlife populations are really important to help us understand the effects of human activity on natural environments and animals. One of the most rapid ways in that city-dwelling animals can adapt to these new environments is by changing the shape and size of various morphological traits.
Anoles in their natural habitat do tend to be tree-dwelling, or arboreal lizards, and they spend a lot of time climbing to find food resources, regulate their body temperature, and do other ecological activities. A lizard that relies so much on climbing performance frequently uses its claws and toe pads in its climbing ventures, so one of the first changes that city anoles might exhibit is changes in toe pad or claw shape to better climb on slick city surfaces (say that 3 times fast!). To get at this question, Bailey Howell from the Mississippi University for Women, along with her co-authors Travis Hagey and Kristin Winchell, compared urban crested anoles (Anolis cristatellus) to forested crested anoles and found that toe pads in urban anoles are longer and wider than toe pads from lizards in natural environments.
Bailey goes on to discuss that these toe pads that have an increased area might be better for urban anoles to climb on slicker and smoother substrates found in city environments. Bailey is going to continue adding to her dataset by incorporating more anoles and testing additional hypotheses such as measuring performance differences between urban and forested anoles. Stay tuned for more urban anole work!
The Panamanian slender anole (Anolis apletophallus).
In keeping with the previous year, Albert Chung (now a Ph.D. student at UCLA with Shane Campbell-Staton), presented in the prestigious Division of Ecology and Evolution Raymond B. Huey best student paper session of SICB2020. Albert’s work encompasses a very old, enduring, and important question in biology: how males and females of the same species exhibit differences in so many traits, despite the fact that males and females share a common genome.
A male brown anole from the island of Great Exuma, in The Bahamas.
This dynamic is called sexual conflict: when what is best for one sex might not be the best for the other sex, and has challenged biologists for decades to study a multitude of incredible organisms to answer this question, including anoles! Albert and his collaborators addressed this question by studying two species of anole, the brown anole (Anolis sagrei) and the Panamanian slender anole (Anolis apletophallus). Brown anoles are one species where males are super large compared to females, whereas in the slender anole, males and females are relatively the same size.
Albert et al. described differences in the genes expressed in both males and females to understand what factors promote the development of male-biased size dimorphism. They found that differences in gene expression between males and females was highest in gonad tissue compared to liver and brain tissue, and that when female lizards are supplemented with additional testosterone (traditionally viewed as a hormone more highly concentrated in males of a given species), their gene expression profiles look like those of male lizards. They also found that liver tissue exhibits the greatest differences in sex-biased gene expression, because the liver is one organ responsible for supplying the body with the energy and molecules needed for growth. They suggest that differences in gene expression between males and females might be one factor promoting the evolution of size differences between the sexes, and that physiological controls on these genes could play prominent roles in having males and females exhibit huge differences in traits despite sharing a similar genetic makeup.
The end of 2019 is nigh, and soon people will be traveling home to spend time with loved ones, eating a superfluous amount of cookies and sweets, and of course, working on that poster or talk for the 2020 Society for Integrative and Comparative Biology (SICB) meeting in Austin, Texas. SICB is one of the largest national conferences for biologists, where an incredible diversity of research is presented each year. And of course, SICB meetings are home to several Anolis presentations, with approximately 45 or more talks and posters this year featuring anoles.
Every year at SICB, Anole Annals tries to cover as many of the anole talks and posters as we can, and this year is no exception! AA relies on conference attendees to blog about all of the awesome anole work being presented, with a strong focus on undergraduate and graduate research. If you’re a student or student researcher attending SICB, blogging for AA is a fantastic way of getting experience in communicating science with a broader audience. In addition, if you are presenting work on anoles at SICB this January and want to help us blog, we’ll return the favor and cover your work for the blog! Anybody can join the AA family- undergraduates, graduate students, postdocs, and faculty. If you’re interested in blogging for AA at SICB this year, please shoot me an email at anthony.gilbert09@gmail.com or leave a comment on this post and we can get you going. We can provide assistance, examples, and answer any questions you may have when it comes to blogging for AA. Thanks all!
Predicting the responses of species to current environmental and climate change is one of the largest duties of current biologists. Ectothermic species (including lizards) are particularly vulnerable because they lack the ability to metabolically generate heat and rely on environmental sources of temperature to maintain their body temperatures. For species that live in the tropics, this task is much harder because tropical environments experience less temperature variation both within and across seasons. Tropical lizards traverse these landscapes to try and maintain optimal and preferred body temperatures, but are all thermal environments equal in the constraints they impose on lizards?
To address this question, Lauren Neel, a student of Mike Angilletta’s at Arizona State University, collected an astounding amount of data from two species of anole: Anolis sagrei from their native range on Great Exuma in the Bahamas, and A. apletophallus in Panama. She collected environmental temperature data using biophysical models, thermal performance data by racing anoles at several different body temperatures and measuring their sprint speed, and preferred body temperatures by placing lizards in a thermal gradient. Despite both lizards living in tropical climates, she found distinct differences between the environments (and anoles!). Anolis sagrei thermoregulated more, was active for longer periods of time than A. apletophallus, and exhibited warmer preferred temperatures. Neel and colleagues also found that A. sagrei is not likely to suffer a drop in performance capacity as environments warm over time, whereas A. apletophallus is likely to experience a significant reduction in their speed performance which might be a physiological precursor to population collapse and a rise in local extinction events. Great stuff coming from Lauren Neel; stay tuned for more!
We tend to think of exercise as a human activity–training our bodies in specific way to accomplish tasks, maintain strength and endurance, and live a healthier lifestyle. Wild animals exercise just as often if not more than humans, but the benefits to animal exercise have been somewhat contentious in biology. The responses to organismal exercise are very conserved with respect to evolutionary change and speciation. Those responses include an increase in performance capacity (such as speed or endurance), but often times trades-off with some other physiological trait, such as immunocompetence. With this trade-off looming, one outstanding question remains: does the exercise response enhance reproductive success and survival? Can we call this response “adaptive”?
To test this idea, Jerry Husak from the University of St. Thomas and his co-author, Simon Lailvaux at the University of New Orleans, measured the exercise response in 90 green anoles (Anolis carolinensis). They had 30 control lizards, 30 lizards trained with speed trials, and 30 lizards trained with endurance trials. They found that overall, exercise enhanced performance for all lizards relative to the controls, but training decreased the ability of a lizard to fight off an infection. They found that lizards that had been trained did not exhibit increases in movement rates, and also found that over time, trained lizards exhibited decreased survival relative to the controls! Is exercise actually bad for lizards?! Green anoles were twice as likely to survive when they were not trained, and differences in lizard body condition might be intimately linked with their probability of survival. Husak and Lailvaux are going to continue to test the idea that the exercise response confers some benefit to lizards outside of performance. Stay tuned!
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.
