On march 19, 2013, Jonathan Losos wrote about Anolis heterodermus in this blog, on a post called “Adventures with Phenacosaurus”: “…I have to comment on the little-studied thermal biology of this species. The weather when we were there was usually overcast with the sun occasionally bursting out. Temperatures were usually in the 16-20̊ range. And the lizards were active! Moreover, we were at only about 2600 meters, but I have heard reports of them being found as high as 4000 meters! Clearly, a study on the thermal biology of this species would be fascinating!” One year later, I began to investigate this topic on A. heterodermus.
All my life I’ve loved reptiles, but only recently as part of my undergraduate studies in biology in the National University of Colombia, have I started in the herpetological world with Drs. Adriana Jerez and Martha Calderón. I was particularly intrigued by the thermal biology of these organisms. Soon I discovered that I’ve always lived in a high-elevation, cold city, Bogotá, in a neotropical country, Colombia, making the reptile species around me, which are ironically unknown, perfect models for questions about thermoregulation in reptiles.
A female Anolis heterodermus
As I tried to decide which of these species would be my model for my undergraduate thesis, I realized that my professors and some of my colleagues had already started to study some of the high-elevation species, like the high-Andean snake Atractus crassicaudatus, the microteiid Anadia bogotensis, and the collared tropidurids Stenocercus trachycephalus and S. lache. I realize now that my choice of the high-Andean lizard Anolis heterodermus for my study was one of the best decisions of my life as a biologist.
Between 2014 and 2015, I carried out my undergraduate thesis research under the direction of Dr. Martha Calderón on thermoregulation of Anolis heterodermus in Tabio, a town at 2650 m asl, close to Bogotá, Colombia. During my research, Martha, my colleagues and I had the opportunity to know Dr. Barry Sinervo and his group, who helped us with equipment and suggestions for our projects. Finally, in 2017, after my thesis was approved and I obtained my biology university degree, Martha and I published my first article.
Measuring an individual of Anolis heterodermus with calipers
Anolis heterodermus lives in a cold, low-quality thermal habitat that gets worse in wet seasons. Surprisingly, during the wet season, Anolis heterodermus copes succesfully with this seasonal variation and adjusts behaviorally to thermoregulate more actively to compensate for the reduction in the thermal quality of the habitat. In this way, these lizards match achieve their preferred temperatures just as in dry season. This match also occurs mostly at midday, particularly in sunny perch sites, confirmed by operative temperature data, which suggests that A. heterodermus is a heliothermic species. Additionally, sexes and ages are not different in their thermal traits, such as body and preference temperatures.
Study site: Tygüa Magüe Ecopark, Tabio, Colombia, at 2650 m asl.
But the most incredible trait of this species is its capacity to take advantage of the few sunny hours and sunny microhabitats to thermoregulate, taking into account that the tropical high-elevation ecosystems like the high-andean shrubs and forest, and subparamo and paramo not always are cold environments, but have large thermal fluctuation during the day too, which is reflected in the wide range of body (16.6-31.9°C) and preferred (19.1-30.2°C) temperatures. Definitely Anolis heterodermus is a very plastic thermoregulating species, as it has to be, because it is the anole species found at the highest altitude known.
We are looking for a field assistant to help us conduct behavioural research on Anolis sagrei on small dredge-spoil islands near Ft. Pierce, FL, from April 22 to May 21. Daily activities include searching for and observing marked lizards as well as collecting habitat data. We will work long hours on most days (beginning 7-8am). Applicants should be prepared for hot and humid work conditions as well as travel on a small boat. Applicants must be comfortable handling lizards and using binoculars and should be adaptable to changing plans. All expenses (airfare, food, lodging) will be covered and a stipend will be provided.
If interested, please contact Ambika Kamath: ambikamath@gmail.com and Nick Herrmann: nicholas.carl.herrmann@gmail.com with a
brief letter describing why you are interested in this position and any relevant research experience along with your CV and the names and contact information of a professional reference whom we may contact by email. We will review applications as they arrive until the position is filled.
Stan Rand’s Super 8 Film from the 1972 Malpelo Expedition
Kevin de Queiroz
Research Zoologist and Curator of Amphibians and Reptiles
National Museum of Natural History, Smithsonian Institution
This film was made by Austin Stanley Rand (1932–2005), a biologist at the Smithsonian Tropical Research Institute (STRI) (1964–1997), during a six-day expedition to Malpelo Island, a small (1.2 km2), remote, oceanic island located some 500 km west of the Colombian mainland, in late February and early March of 1972. The Expedition involved 17 scientists from STRI, the republics of Colombia and Panamá, and several US universities, as well as the assistance of the United States Navy. The scientific findings of the Expedition were published in the series Smithsonian Contributions to Zoology (Number 176) in 1975, in a volume edited by Jeffrey B. Graham (1941–2011), one of the STRI biologists who participated in the Expedition. The volume contains 14 articles, five of which are on the lizards of Malpelo, including three on the endemic Anolisagassizi, two on the endemic Diploglossus millepunctatus (one of which is also on A. agassizi), and one describing a new endemic species of leaf-toed geckos, Phyllodactylus transversalis. As a result of prompting from George Gorman, who participated in the Expedition, and Jonathan Losos, I obtained a digital copy of the film from the Smithsonian Archives with the help of Archivist Ellen Alers. The film is a little under 11 minutes long and there is no audio. The notes about the contents of the film below were prepared mostly from information in the Malpelo Expedition Volume, with some additions based on web searches and input from George Gorman. Literature citations are for articles in the Smithsonian Contributions to Zoology Malpelo Expedition Volume unless otherwise indicated. Thanks to George Gorman and Ross Kiester for comments on an earlier version.
0:10: Adult male Anolis agassizi, Malpelo or Agassiz’s Anole. The species was named by Smithsonian Zoologist Leonard Stejneger in 1900 after Alexander Agassiz, leader of an 1891 Expedition aboard the USS Albatross that visited Malpelo and collected the first specimens.
0:20: Map showing the location of Malpelo Island (ca. 500 km west of mainland Colombia).
0:29: The USS York County (US Navy). This De Soto County-class Tank Landing Ship transported the Expedition participants from Panama to Malpelo and back.
0:32: Ship deck (the ship was decommissioned later that same year, 1972).
0:40: Crew members of the USS York (sweeping the deck).
0:46: A. Ross Kiester (Ph.D. 1975, Harvard University, Advisor: Ernest E. Williams; STRI Predoctoral Fellow, 1970–1971). Kiester authored a paper in the Malpelo Expedition Volume on the natural history of the endemic anguid lizard species Diploglossus millepunctatus.
0:53: George C. Gorman (Ph.D. 1968, Harvard University, Advisor: E. E. Williams; UCLA professor at the time of the Expedition) lying on deck. Gorman co-authored three articles in the Malpelo Expedition Volume, including one on the natural history, behavior and ecology of Anolis agassizi and another on the chromosomes of Anolis agassizi and Diploglossus millepunctatus.
1:00: Several Anolis agassizi licking a cut orange. The anoles are very abundant on the island. In the Malpelo Expedition Volume, Rand et al. (1975) estimated the population density to be 1 anole/5-10 square meters and a total population of at least 100,000 anoles on the small island.
1:11: Malpelo Island from the southeast (?).
1:20: Part of island closer up. The sides are very steep and landing is difficult.
1:27: Close-up of rock (island surface). The island is composed primarily of igneous rock and is of volcanic origin. Very few large (vascular) plants occur there, though several species of mosses and lichens are present.
1:33: Aerial view of island (from the northwest). The Expedition produced a new map of the island (see Kiester and Hoffman, 1975).
1:39: Map showing the topography of the ocean floor. Malpelo is part of Malpelo Ridge and is the only island on that ridge.
1:45: Nazca Booby (Sula granti). This is most abundant breeding bird species on Malpelo (Pitman et al., 1995, The marine birds of Malpelo Island, Colombia. Colonial Waterbirds 18:113–119, wherein it is called Sula dactylatra). The population was estimated by Pitman et al. (1995) to be 24,000 individuals. Referred to in the Malpelo Expedition Volume as Masked or Blue-faced Boobies, Sula dactylatra granti.
1:50: Seabirds flying. Other bird species known from Malpelo include Red-billed Tropicbirds, Red-footed Boobies, Black and Brown Noddies, White Terns, and Great and Magnificent Frigatebirds (Pitman et al., 1995).
2:00: Diploglossus millepunctatus, a Dotted or Malpelo Galliwasp. This is an anguid lizard species endemic to Malpelo.
2:02: Preserved specimens of Phyllodactylus transversalis, Malpelo Leaf-toed Geckos. This was a new species discovered on the Malpelo Expedition and described in the Malpelo Expedition Volume by Raymond B. Huey (Ph.D. 1976; Harvard University, Advisor: Ernest E. Williams).
2:06: This shot seems to show the abundance of anoles in a small area. Anolis agassizi was found not to be territorial, unlike most of its close relatives, and to exhibit relatively little intraspecific aggression.
2:21: Anole on a camera illustrating tameness and/or curiosity. Rand et al. reported that they often approached observers and unusual objects.
2:24: Clipboard with a map of Malpelo showing the routes taken by the exploration party (compare with Figure 4 in Kiester and Hoffman, 1975).
2:26: Anoles in a scuffle (chase and display).
2:32: Anoles on equipment (again showing abundance and curiosity).
2:37: Anoles at orange, licking, numerous individuals. Oranges were put out after the researchers noticed that the anoles seemed attracted to the color orange (Kodak film package, cap of suntan lotion container). The anoles normally eat insects, primarily ants and beetles (Rand et al., 1975).
3:21: Large marked male anole performing a headbob display. Marking was used to estimate home ranges.
3:30: More headbobs (different individual?). This is a typical anole display. The Malpelo anoles performed it infrequently compared to other anole species.
3:37: Large marked male A. agassizi performing more head bobs and dewlap extension. Malpelo anoles have relatively small dewlaps.
3:50: Attacks another male.
3:53: Nuchal crest and dewlap extended. This species has a relatively small dewlap, likely related to its lack of territoriality and reduced aggression.
4:04: Two males displaying and biting. The closer one appears to be tethered.
4:15: Males with jaws locked. Despite these cases, at least some of which appear to involve instigation by the researchers, aggression was found to be low in this species (Rand et al., 1975).
4:21: Male anole. Rosario Castañeda (2010, Ph. D. dissertation, George Washington University) found A. agassizi to be ecomorphologically divergent from other Dactyloa-clade species in having an exceptionally large number of toepad lamellae.
4:31: Anoles (some of which are marked) at orange. Note that the anoles do not attempt to monopolize this resource by displaying at each other or chasing each other away (Rand et al., 1975). The larger ones with the black heads are males.
4:47: Series of preserved Anolis agassizi specimens. No hatchlings were found during the Expedition, suggesting seasonal reproduction (Rand et al., 1975).
4:57: Dissected Anolis specimen showing testes. Probably one of the large males with a black head and nuchal crest.
5:02: Dissected Anolis specimen showing an egg. A little over 50% of the sampled females had oviducal eggs or enlarging follicles (Rand et al., 1975).
5:06: Testes again. Rand et al. (1975) found that some large males lack male secondary sexual characters (black head and erect nuchal crest) and have regressed testes (obviously, this isn’t one of them).
5:11: Back at the orange. The anoles both lick and bite the orange.
5:28: Dissected gut cavity. Possibly showing fat bodies or perhaps this is the male morph with regressed testes or perhaps showing the darkly pigmented peritoneum, a characteristic of lizards that live in areas of high insolation (Rand et al., 1975).
5:35: Back at the orange again.
5:51: Part of island with ocean in background (and birds). The shot pans to a small boat that was presumably used to transport the researchers to the island from the large ship.
6:02: Endemic Malpelo land crab, Johngarthia malpilensis. (Referred to in the Malpelo Expedition Volume as Gecarcinus malpilensis.)
6:08: Crab interaction with Diploglossus. D. millepunctutus is one of the largest anguids and one of the largest Diploglossus species. It is known to feed on dead crabs (Kiester, 1975).
6:24: Anolis agassizi male (marked).
6:30: A researcher tying a hookless fishing fly on fishing line. Ross Kiester thinks that the researcher may be William M. Rand, brother of A. Stanley Rand and co-author of the article on Anolis agassizi in the Malpelo Expedition Volume (Rand et al., 1975).
6:33: Anoles trying to capture the fly. Malpelo anoles are known to eat real flies (Diptera).
6:45: Anoles with green chuckles candy. The “Chuckles Experiment” was undertaken to test for a color preference (Rand et al., 1975). The results indicated a preference for orange and yellow Chuckles candies over red and green ones and even more so over black ones. Rand et al. speculated that this preference could be related to feeding on the yolks of broken seabird eggs.
6:52: Setting out red Chuckles candy.
6:54: Anoles on rock (more Chuckles).
6:59: Anole with red and orange Chuckles candies.
7:15: This sequence shows anoles drinking from a crevice, as reported in the Malpelo Expedition Volume by Rand et al. (1975). There are many small seeps, springs and rock pools on the island (Rand et al., 1975). Other experiments have shown that Malpelo anoles are not particularly tolerant of water loss (Rand et al., 1975).
7:43: More drinking.
7:57: Taking body temperature via the cloaca (a standard herpetological method). Rand et al. (1975) found that A. agassizi exhibits similar body-temperature preferences to other anoles.
8:05: Part of island (from boat?).
8:10: Anole runs and stops in the shade. Anoles were active during most of the day in the shade and didn’t spend much time basking (Rand et al., 1975).
8:24: Back at the half orange.
8:38: Anoles flee and a Diploglossus approaches. The Galliwasp is known to prey on anoles, but anoles are not its primary food source (Rand et al., 1975). On the other hand, Rand et al. reported that 85% of the Malpelo Anoles had regenerated tails.
8:49: Anoles.
8:52: Diploglossus departs. This is probably the individual mentioned by Rand et al. (1975) that repeatedly approached the orange when anoles were present, but did not eat the orange.
8:57: Large male anole moving up rock.
9:05: Diploglossus millepunctatus.
9:09: Anole running.
9:12: Diploglossus running. I assume that the anole is running from the galliwasp rather than the other way around.
9:17: Land crab (Johngarthia malpilensis).
9:20: Land crab and Diploglossus. Malpelo Galliwasps are known to feed on dead crabs (Kiester, 1975).
9:26: Nazca Boobies (Sula granti), adult and chick.
9:28: Diploglossusmillepunctatus. Kiester (1975) reported that when a booby chick squawks upon return of the parent to the nest, nearby galliwasps immediately run to the vicinity of the birds and will snatch and eat any fishes that are dropped.
9:33: Nazca Boobies (adult and chick) again.
9:36: Diploglossus eating a crab claw.
9:40: Two Diploglossus eating a dead crab.
9:46: Anoles back at the half orange (zoom out).
10:20: Close up of anoles at orange again.
10:40: Different shot of anoles at orange (some dart in and out).
In August 2019, while feeding a captive colony of brown anoles (Anolis sagrei) in Dr. Daniel Warner’s lab at Auburn University, I noticed a female anole crouching on the side of her nesting pot. Upon closer inspection, I realized she had dug a hole in the soil and was perched above it- apparently preparing to lay an egg. Gently prying up the lid of the cage, I snapped a few photos of this (somewhat still mysterious) event.
During the subsequent observations of this female in the lab, she laid an egg on the topsoil; however, jumping from the nesting pot, she knocked the freshly oviposited egg into the hole she created. She then returned to the nesting pot and looked to be positioning the egg within the hole (see video attached). This behavior has been previously documented in Anolis species (Propper et al. 1991; Stamps 1976) and suggests that females may provide additional influence on offspring survival and phenotype through egg-positioning.
Nest sites are critically important for embryonic development and resulting offspring phenotype (Tiatragul et al. 2019; Reedy, Zaragoza, and Warner 2013). The sequence of nesting events (i.e., oviposition, “egg-rolling” [Tokarz and Jones 1979]) may also assist females in choosing a nest-site that will maximize the survival of her offspring. While female nesting behavior has long been documented in scientific literature, it was interesting to see such (what I think of as) cryptic anole behavior! Thanks for letting me spy in on you little one!
References
Propper, Catherine R., Richard E. Jones, Matthew S. Rand, and Harriet Austin. 1991. “Nesting behavior of the lizard Anolis carolinensis.” Journal of Herpetology 25 (4): 484. https://doi.org/10.2307/1564774.
Reedy, Aaron M., David Zaragoza, and Daniel A. Warner. 2013. “Maternally chosen nest sites positively affect multiple components of offspring fitness in a lizard.” Behavioral Ecology 24 (1): 39–46. https://doi.org/10.1093/beheco/ars133.
Stamps, Judy A. 1976. “Egg retention, rainfall and egg laying in a tropical lizard Anolis Aeneus.” Copeia 1976 (4): 759–64. https://doi.org/10.2307/1443460.
Tiatragul, Sarin, Joshua M. Hall, Nathaniel G. Pavlik, and Daniel A. Warner. 2019. “Lizard nest environments differ between suburban and forest habitats.” Biological Journal of the Linnean Society 126 (3): 392–403. https://doi.org/10.1093/biolinnean/bly204.
Tokarz, Richard R., and Richard E. Jones. 1979. “A study of egg-related maternal behavior in Anolis Carolinensis (Reptilia, Lacertilia, Iguanidae).” Journal of Herpetology 13 (3): 283–88. https://doi.org/10.2307/1563320.
Just over 3 weeks ago a wild cold front swept through Florida, bring a decade-low temperature to the subtropical region. The National Weather Service released the following warning:
But what about the anoles?! Did any of our Floridian AA readers snap a pic of a cold-stunned anole on 22nd Jan? We would love to see it!
In it’s 10+ years of existence, Anole Annals has united the anole community, becoming your one-stop-shop for information on everything Anolis. It seems to me that the site has lived up to Jonathan’s vision, although he will tell you it can still get better. I for one regularly peruse old posts when I start on a new project. For example, just last month I read up on the anoles of Guadeloupe before visiting the island for the first time and was blown away at the amount of quality information on the blog. It’s function as a repository of information and a go-to source for everything Anolis is something I think is highly valuable to the anole community. And so now, to keep it going, we are looking to you, our readers and contributors.
As time has gone on we’ve added new types of posts and have had a rotating roster of unofficial editors pulling the strings behind the scenes. As we look to the future of Anole Annals, we realize that we need a long-term plan to keep this thing running and up to our high standards. For this reason, we have come up with developing a formal “Board of Editors” for Anole Annals. Many of the positions we envision are jobs some of you are already doing (with little recognition!). We hope you will join on formally so our readers know who to thank for all the hard work you do. For some of the other positions we have thought up, we will need new volunteers! Here’s a brief rundown of the positions. If any sound interesting to you, send us an email or leave a comment!
Social Media Manager(s)1-2 people — The Social Media Manager(s) will be in charge of the Twitter and Facebook accounts to share latest blog posts. (Twitter is currently managed by James Stroud).
Technology Manager1 person — The Technology Editor will help keep the inner workings of this site up to date, implement new functions and pages, and keep the blog running . We run on a custom WordPress platform.
Recent Literature Editor1 person — The Recent Literature Editor is responsible for sharing new anole literature as it comes out. This involves posting the title and abstract of the paper when it comes out (or a list on a weekly or monthly basis) with a link to the paper and reaching out to the authors to ask if they would like to summarize their paper in a blog post.
Conference Editors 3+ people — The Conference Editors will be in charge of planning, recruiting, and scheduling summary posts of conference talks and posters. We mainly cover Evolution, JMIH, and SICB and would welcome a single editor for all three or one for each (and are open to other conferences too!). (Currently conferences are managed by Kristin Winchell, Anthony Gilbert, and Chris Thawley).
Contributing Editor4+ people — Contributing Editors will be responsible for generating content and for recruiting posts from contributors. Depending on the number of editors, we will determine a schedule of post frequency to make sure we have high-quality content posted regularly. Contributing Editors will also proofread / QC posts and schedule them.
Managing Editors 2 people — The Managing Editors will pull the strings behind the scenes. QC and scheduling posts, recruiting new contributors and posts, and generally making sure Anole Annals continues to produce high-quality content on a regular basis. (Currently Jonathan Losos is the Managing Editor, with help from various Losos lab members).
Now’s your chance to get in on shaping the future of Anole Annals! We can’t keep it going in the long-term without your help. Please contact Jonathan or Kristin if you are interested in being a part of our Board of Editors and we will be in touch.
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.
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.
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.
