Anole Annals

Anole Annals has undergone some big changes in the past year. We rolled out a new look and are working on adding new functionality to the site, including a meet the scientists page. As the anole community grows, we’re finding it harder and harder to keep up! 

Anole Annals started out in 2011, or so the founders’ imperfect memories recalled. Jonathan Losos and Rich Glor combined their talents to launch the site with the goal of being a repository for everything Anolis. With Jonathan’s vision and Rich’s tech savvy, the blog we all now know and love came into being in 2011. Or was it earlier? The earliest post I was able to track down was a charming poem by Yoel Stuart in 2009, at the time a graduate student at Harvard. A strange first post for the blog, and it was followed by a huge 6-month time gap. This led me to suspect that perhaps some early posts of Anole Annals were lost at some point. Yet it seems, however strange of a start, that this was in fact the first Anole Annals post published on November 21, 2009, as this blog post marking Anole Annals’ 2nd Birthday notes. And if you dig into the comments of that early post, you’ll also find the explanation for that odd early gap. From Rich: “Its worth pointing out that the first two posts to Anole Annals – one published in November 2009 and the second in May of 2010 – are outliers because the blog didn’t really get rolling with daily or near daily posts until late in October of 2010. All the more impressive that we’ve already racked up 369 posts!” Now, 9 years later, I asked Jonathan and Rich if they could shed some more light on these early days of Anole Annals.

The epic story of Gordon the almost eaten anole.

Jonathan told me that his vision for the blog all those years ago was to be a “clearinghouse of information” for anoles — a place where researchers and the public alike could read about new papers, ideas, and observations of anoles. Initially, Jonathan started out with the lofty goal of publishing a post a day, which he carried on for quite awhile (writing many of the posts himself, a huge amount of work!). As the blog grew, Jonathan and Rich recruited graduate students and other anole researchers to write posts. At one point in these early days, the Losos Lab and the Glor lab agreed to have a friendly post-writing competition to see which lab could produce the most content for the blog over the course of a semester. The Glor Lab won, although rumors of “dubious ethical content” abound. In the years since, we’ve seen some amazing breakthroughs shared on the blog. Jonathan’s favorite?  A Cuban tree frog that ate and then regurgitated a green anole that went on to live for several years (affectionately named “Gordon”).

Rich remembers things slightly differently. He noted that he handled the technical aspects of the blog and built the first site while Jonathan was the visionary behind it. The rest of his comments are a little more contentious, so I’ll let him speak for himself. He approved posting his comments verbatim, noting that “Fact-checking probably isn’t necessary.” Here’s Rich’s accounting of the early days of Anole Annals: “My lab and I were also responsible for most of the early posts, and all of the really good posts. Jonathan’s lab was busy trying to have some kind of competition, but we were just doing our thing and making tons of posts. This was also during the period when Jonathan’s Lab was exploring his longstanding belief that creatures like bigfoot, the Loch Ness monster, and unicorns were real, so they weren’t really doing any anole work at the time. They got so desperate that some of their posts were just sarcastic responses to our informative posts. Those were some dark days for the Losos Lab, but I’m glad they made it through the struggles.”

I suspect the truth may be some middle ground between these two stories. Perhaps the early contributors of the blog can fill in some of the details.

Since 2011, or 2009 (or whenever), the blog has grown to 2,605 published posts, 334 contributing authors, and 5,553 subscribers! Our all time view count is 1,840,029, which is probably underestimated because of several hosting switches over the years (some counters we have accessed on older versions of the site suggest the true number is closer to 2.5 million!). On our best day we reached 3,209 views, and the most popular post with 2,690 views on that day? None other than the viral-news anole from last year, Anolis aquaticus, the lizard that breathes underwater. Another top performer? Our series digging into the proposal to split Anolis into 8 genera, which inspired quite the debate here (check out: time to discuss, should it stay or should it go?, the case for splitting, the use of Anolis by the numbers, and a historical perspective). Of course, we’ve covered the new research presented at annual conferences like Evolution, SICB, and JMIH since the start. But we’ve also had some fun. In 2011 we had a poetry contest with some pretty amazing contributions. In 2011 we also launched our first photo contest, which turned into the annual calendar contest starting in 2012 (have you seen the amazing 2020 calendar?!). And then there was that time in 2016 when Martha Muñoz and Pavitra Muralidhar humored me by co-hosting the first (and only to date) Anole March Madness (I personally think we should bring this back). What’s your favorite memory from Anole Annals? Do you remember the early days? Tell us about it in the comments!

Anolis sagrei eggs in the field. Photo by Jenna Pruett.

I would like to start by apologizing for the title of this post. I couldn’t help myself. Let’s move on.

How can organisms respond to climate change? There are basically three mechanisms: move, evolve, or acclimate via phenotypic plasticity. Plasticity is potentially very powerful because it drives changes in traits without the generational time lag and population cost of natural selection. Individuals simply adjust on the fly to prevailing conditions. To find out if plasticity can help in a changing world, the following questions have to be addressed: 1) Are relevant traits plastic? and 2) if so, how plastic are they (i.e., how much can they change)?

The thermal tolerance of most organisms is plastic to some degree, and this includes anoles. For example, if you move adult A. carolinensis housed at low temperatures to warmer conditions, their heat tolerance will increase (Corn 1971). Most of the work on thermal tolerance plasticity comes from studies of “reversible” plasticity, in which the plastic trait shift can be erased. In the A. carolinensis example, moving the individuals from the warm conditions back to the original cooler conditions would be associated with a decrease in heat tolerance. Reversible plasticity in thermal tolerance is fairly weak in lizards: on average across taxa, a 1°C increase is body temperature is associated with only about a 0.1°C increase in heat tolerance (Gunderson and Stillman 2015).

Plastic shifts can also be irreversible if they are induced at the right time in the organism’s life cycle, termed “developmental plasticity.” For example, Drosophila usually have greater heat tolerance as adults when they develop under warm versus cool temperatures (MacLean et al. 2019). Overall however, relatively little is known about the presence and strength of developmental plasticity in thermal tolerance. This is especially the case in lizards. Few studies exist and, importantly for this audience, none have focused on anoles (reviewed in Refsnider et al. 2019).

Heat tolerance of adult A. sagrei that developed as embryos under different temperature regimes.

In a new paper with Dan Warner and Amelie Fargevieille, we tested for developmental plasticity in the heat tolerance of the Cuban brown anole, Anolis sagrei (Gunderson, Fargevieille & Warner, 2020). Eggs laid by females maintained in the lab were incubated under one of three different fluctuating thermal regimes (cool, warm, and hot) that mimicked temperature dynamics measured in nests in the field. Minimum temperatures of each treatment were similar, but they differed in the maximum temperatures experienced during the day. After hatching, all lizards were raised under common garden conditions until sexual maturity, at which point we measured heat tolerance. With this design, we isolated the effect of embryonic conditions on the thermal physiology of reproductive adults. As far as we know, this is the first study to use this design in a reptile system.

We found no evidence for developmental plasticity: embryonic temperature did not influence adult heat tolerance. One conclusion that might be drawn from our work is that developmental plasticity will be of little to help to anoles as the climate warms, meaning behavioral and evolutionary processes could be particularly important in dealing with changing temperatures. Additionally, developmental plasticity may play a minor role in driving observed differences in the thermal physiology of anoles from different thermal environments, making evolutionary divergence a more likely explanation.

But these inferences must be taken with a huge grain of salt. Plasticity itself evolves, and therefore what we find in one or even a few species may not be broadly representative. We will have to wait for more data to emerge to get a clearer picture of the ecological and evolutionary implications of developmental plasticity in reptile thermal traits.

Cellular processes, including metabolism and longevity, are regulated by the insulin and insulin-like signaling network. This cascade of internal systems is regulated by two similar but unique hormones, IGF1 and IGF2. Expression of these hormones not only differs among species, but also varies throughout the lifespan of individuals. For example, in humans IGF1 and IGF2 expression remains on into adulthood. However, in rodents IGF2 expression is switched off shortly after birth; thus, IGF2 post-natal effects have largely been ignored because of the lack of expression in mice. 

Ph.D. Candidate, Abby Beatty, of Dr. Tonia Schwartz’s lab at Auburn University, sought to address this imbalance by using the Cuban brown anole (Anolis sagrei) which, like humans, expresses IGF2 into adulthood. To do this, Abby first quantified gene expression of IGF1 and IGF2 hormones by using quantitative PCR on embryonic, juvenile, and adult A. sagrei liver cDNA. She compared this expression across a variety of taxa including, but not limited to, mice, zebra finches, and eastern fence lizards. Secondly, Abby mined adult liver transcriptomes for all amniotes in NCBI and quantified the expression of IGF1 and IGF2. 

She found that, in contrast to the mice used for many biomedical models, IGF2 is expressed in adult birds and reptiles and in many mammals. Abby speculates that our understanding of IGF expression is biased, with laboratory mice serving as a default for many human-mediated models, and warrants the use of other species to study the function of IGF2. 

Measuring Anolis thermal tolerances has been a hallmark of many studies since the heydays of thermal physiological studies in the mid-to-late 1900’s. However, studies examining the factors affecting thermal tolerances of embryos are still relatively sparse. In the symposium “Beyond CTmax and CTmin: Advances in Studying the Thermal Limits of Reptiles and Amphibians” at the ninth World Congress of Herpetology, Joshua Hall – PhD candidate in the Warner lab at Auburn University – explored critical thermal maximum temperatures in Anolis sagrei during development. He sought to determine (1) How we should measure embryonic CTmax? (2) What is the ecological relevance of embryonic CTmax? And (3) Are there differences between acute and chronic CTmax?

Previous work from Pruett and Warner, determined that constant incubation temperatures resulted in a chronic CTmax of 35°C for A. sagrei. Meanwhile, Joshua tested three methodologies of creating an acute CTmax during incubation including: heat shock, thermal ramp, and thermal fluctuations. All three methodologies showed an acute CTmax of ~45/46°C; there was consistency across methodologies as well as an extremely large difference found between chronic and acute CTmax. Additionally, Josh examined what data were available via the Reptile Developmental Data Base to examine chronic CTmax in nine other squamate species (ranging from 28-36°C). Of those nine species from previously collected data, four had measures of acute CTmax, and in all four cases the acute CTmax was higher than the chronic CTmax. Lastly, Josh recommends that researchers use the terminology acute and chronic when describing CTmax and that more work should be done to better determine the relationships between chronic and acute CTmax in an ecological context. Super cool work, looking into the future of thermal physiological work!

Ectotherms are well known for having an inordinate fraction of their biology linked to thermal conditions. Many of their demographic vital rates and life-history traits are influenced by temperature-dependent physiological processes. This connection between temperature and physiology is particularly apparent during embryonic development, especially in oviparous species lacking parental care after eggs are laid. Jenna Pruett, a PhD candidate in the Warner lab at the University of Auburn, investigated the effect of constant egg incubation temperatures across life stages in the brown anole. Many studies of this nature lack enough temperature treatments to fully characterize the thermal reaction norm and frequently do not follow the offspring past hatching. Jenna sought to fill these knowledge gaps by answering the questions:  1) How does constant incubation temperature affect embryonic development? 2) Do these effects vary across a small geographic scale? and 3) Do effects carry over into later life stages?

To do this Jenna incubated ~350 brown anole (Anolis sagrei) eggs from different locations across eight different constant incubation temperatures. When examining hatching success, temperature seemed to be the only driver of success. Meanwhile, hatchling mass had a significant interaction between temperature and location potentially indicating that lizards at specific locations respond differently to different thermal regimes during development. Overall, she found that geographic variation doesn’t impact hatching success but changes how phenotypes respond to temperature.

The second part of the experiment involved a large release and recapture experiment on experimental spoil islands off the coast of Florida. Hatchlings were released early and late in the summer and then were recaptured the following fall and spring to determine survival to recapture. Jenna found that survival to recapture was influenced by incubation temperature, release date, and an interaction between the two, showing that timing is everything and that in this case the optimal temperature for the greatest survival varied across life stages.

Green anole in Cape Cod in January

Veronica Worthington writes from Cape Cod: “This September I found an anole  in my unheated, open greenhouse. I snapped a picture of him and he scurried off. Cold weather sets in, below freezing off and on, and I figure the anole  must not have made it but to my surprise a few days ago, January 14th,  I see him again and he’s perfectly fine. I have no idea how he could’ve gotten here, I have not brought any plants in to the greenhouse in a few years and I have no neighbors that could’ve had a pet lizard. Have you heard anything about anoles migrating north?”

First sighting, September 2019

Veronica then added in a subsequent email: “I find it so curious that this little guy ended up in my backyard. And that he has been able to survive all this time. No matter who I tell they say he must have arrived as a hitchhiker on a plant But I have not brought any plants into the greenhouse in a few years and it is always unheated in winter and the doors and sides are open all summer. I don’t know how far they travel naturally catchy but I can’t imagine that this little guy would’ve traveled very far on his own. I don’t have any neighbors close to me  that keep reptiles. The first picture is of him two days ago and the second picture is of him five months ago. Both times that I have seen him he is exactly where I saw him the last time, on a bag of wool. I raise sheep and that’s where the wool came from.”