Author: Anthony Gilbert

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!

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!

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!!

Happy Holidays everybody!

My name is Anthony Gilbert, and I’ll be coordinating the upcoming Anole blog posts for the Society of Integrative and Comparative Biology conference this 3-8 January in sunny Tampa, Florida. We have over 30 different talks and posters presented by students, postdocs and faculty at this conference this year and we are looking for some additional volunteers to help us get these posts up!

If you’re going to be in Tampa, and you want to help the Annals out, send me an email at anthony.gilbert09@gmail.com. We welcome folks who both have and have not blogged for the Annals in the past.

If you’d like to help us out, contact me and I’ll forward you a spreadsheet a few days before the conference so you can slot yourself in for whichever presentations you’d like to cover. I can also send you instructions on how to write up a post if you would like!

Check out the Anole Annals twitter account (@AnoleAnnals) with the #SICB2019 hashtag during the conference for updates on talks, posters, and other conference-related events. It is supposed to be sunny in Florida this year, so the anoles themselves might be out in force along with all of the conference attendees!

Urbanization is a global issue that alters the way many natural populations survive and reproduce. The construction of new developments, housing, and other man-made structures alters the environment available to many species of lizard, and anoles perhaps most famously. Urban anoles in Florida and other parts of the southern United States are a common feature in many cities, why, everybody that attended SICB 2015 in West Palm Beach, Florida remarked that there were anoles on almost every tree! Particularly, the addition of artificial and smooth substrates poses a concern to many species of arboreal lizard that need rough and heterogeneous surfaces in order to climb and run effectively. The differences in structural habitat available to these anoles can in turn affect their morphology, leading to evolutionary changes in body shape and form over time to better adapt to urban lifestyles. Andrew Battles, a PhD student with Jason Kolbe at the University of Rhode Island, recognized this problem and designed a clever experiment to understand just how smoother surfaces impact the running ability of anoles.

Andrew sampled crested anoles from two sites: an urban and a natural site, and used a series of running experiments to understand how the addition of smooth, urban substrates affects the ability of anoles to move. Using two different inclinations (37 and 90 degrees), 2 substrates (smooth and rough), and the running power of 13 crested anoles, they found that anoles exhibit a decrease in speed due to increasing incline, and exhibited slower speeds on a smoother track relative to a rougher one. They also found that stride length decreased on smooth and vertical tracks, and that urban and natural anoles responded similarly to these changes in substrate and incline. They also found that anoles will try to change their gait and increase their stride width due to incline, but not so much on different substrates. Their major take-away was that smoother substrates do decrease lizard sprint performance, which is a fundamental trait for a lizard to survive and reproduce. And while there are no differences between habitat types, the build-up of urbanization over time might lead to evolutionary shifts for crested anoles in urban environments so that they might better adapt and live in cities. Keep up the stellar experiments, Andrew!

As many of us I’m sure know, many lizard species have the ability to lose their tail in order to escape predators or competitors. However, the tail doesn’t grow back as originally lost! The bone, muscle, and fat is replaced by a cartilaginous rod. Lizard species that use their tail in social communication might suffer a severe cost associated with losing their tail because they might lose their ability to communicate information to predators or members of the same species. Amy Payne, a student with Michele Johnson at Trinity University, recognized this issue and used a cross-species comparison to determine just what factors influence tail breakage.

Amy set out to test the hypotheses that species that use their tail in a social context will have lower rates of tail loss, species that use their tail in a predatory context will have higher rates of tail loss, and that species that primarily store fat in their tail will have lower rates of tail loss. They used curly-tail lizards, earless lizards, house geckos, and crested and green anoles in their work and found that curly tail lizards exhibit the greatest tail loss despite using their tails constantly. Earless lizards exhibited the lowest rates of tail loss and they used their tails quite frequently, and anoles had intermediate rates of tail loss based on social use. Tail use in a predatory context was rare for anoles, but quite common for curly tails (that exhibited a higher rate of tail loss) and earless lizards (that exhibited a lower rate of tail loss). They also found no relationship between tail autotomy and energetic storage in the tail. Their major takeaways are that species that use their tail very frequently in communication can exhibit either large or low rates of tail loss, and that there are a lot of intermediate rates of tail loss perhaps due to the multi-faceted role tails play in the evolution, ecology, and behavior of lizards. They are going to follow up this work using bomb calorimetry to more precisely measure species differences in the energy stored in the tail, and increasing the species sampling to incorporate more species (especially more anoles!)

One of the most challenging things an organism will do throughout its lifetime is balance its energy budget. Energy is used to grow, develop, reproduce, survive, and how animals allocate that energy will forever be a fascinating question to biologists. If you have more energy, then in theory you should be able to be more active and be a “fitter” individual. For most lizards, excess energy can be represented by fat stores, so if individuals tend to store more energy, then they should be less able to put energy into other reproductive or physiological traits. This was the idea tested by Marzieh Rouzbehani of Trinity University, working in the lab of Michele Johnson.

They studied two anole species: crested and bark anoles (Anolis cristatellus and A. distichus) and found that the two species exhibit different energy-physiology relationships. They found crested anoles with larger eggs had more fat stores, and that crested anoles with larger eggs did not exhibit activity tradeoffs. Bark anoles on the other hand exhibited no relationship between egg mass and fat stores, but found a trend where bark anoles with larger egg masses had lower activity levels. In addition for both species, they found no relationship between hematocrit (the volume percentage of red blood cells in blood) and activity levels, and their work emphasizes the complexity that is species-specific physiological dynamics for female anoles. Different anole species are likely to have different physiological traits influence their behavior and activity in different ways. Fascinating stuff!

Sometimes, males and females of the same species differ in traits linked with their ability to survive and reproduce. These differences, called sexual dimorphisms or polymorphisms are quite common in lizards, including anoles! Female brown anoles have a polymorphic back pattern while males are usually of a single pattern. A lot of work has tried to uncover why this back pattern polymorphism exists in nature and what advantages it offers these lizards. Rachana Bhave, a Ph.D. student with Robert Cox at the University of Virginia were interested in determining just how these male and female-like morphs of brown anoles differ in their morphology, behavior, and which traits influence survival.

Using a captive island population in Florida, Bhave et al. captured all of the lizards on the island and measured differences in morphology between the morphs, finding that female-like morphs tend to have higher survival as juveniles but not as adults. These morphs differed in their growth rates but did not experience different selective pressures, indicating perhaps a very complex control regulating the back pattern maintenance in this population. They also found that while female-like morphs tend to display at a higher rate, there weren’t any differences in the morphs probability to attack. They plan to integrate more physiological data such as growth or performance metrics to try and uncover the governing factors responsible for maintaining this back-pattern polymorphism. Awesome stuff to come!

Male-male competition is one of the most widespread phenomena in lizards. Males compete for access to critical food resources, territory space, and female lizards, making a male’s ability to win competitions against other males critical to survive and reproduce. However, how the behavior of a male can vary depending on what social environment he grew up in, the abundance of certain predators or competitors, or the density of other male and female lizards. Therefore, determining what environmental factors influence the behavior of male lizards as they attempt to procure resources necessary to survival and reproduction is a critical question in biology today.

From Virginia Tech, (now a Ph.D. student with Shawn Kuchta at Ohio University) Emily Watts and her collaborators sought to understand what environmental factors influence the behavior of male brown anoles (Anolis sagrei). They used males reared in a common garden from four different populations in the Bahamas to try and determine if genetic or environmental factors influence the aggression differences among males of different populations. Using male-male competition experiments and mirror experiments (where a single male perceives himself as a rival), they tested the hypothesis that males reared in a common garden will not differ in aggressive behavior. They found that aggression varied significantly among populations when using mirror tests, but they found support for their original hypothesis when using male-male competition experiments. This work highlights that aggressive behavior of males is shaped by a multitude of pressures from the environment, to genetics, and ultimately how and where a lizard develops to adulthood. More is to come as they continue to increase the number of their experimental trials with more Anoles!

The end of 2017 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 2018 Society for Integrative and Comparative Biology (SICB) meeting in San Francisco, California. The 2018 SICB meeting in San Francisco held from 3-7 January is going to be one of, if not, the largest SICB meetings ever with nearly 1950 abstracts being submitted! 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 40 or more talks and posters this year featuring anoles.

Every year at SICB, the 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. Here is an example post from a previous SICB meeting. Thanks all!