In August, we published a paper in the Caribbean Journal of Science entitled, “Sleeping Behavior of the Secretive Puerto Rican Twig Anole, Anolis occultus.” Check out our new post on the Chipojo Lab blog about the paper!
Levi Storks, Manuel Leal. 2020. Sleeping Behavior of the Secretive Puerto Rican Twig Anole, Anolis occultus. Caribbean Journal of Science 50(1):178–87.
Margaret McGrath at SICB 2020
If you look at a map of the United States at night, the urban areas are aglow with light pollution. Urban light pollution disrupts biological processes from gene expression to ecosystem composition across multiple taxa, including birds, insects, mammals, and fishes. With ever-increasing urbanization, understanding the effects of artificial light at night (ALAN) on organisms is crucial to future conservation efforts.
Margaret McGrath, an undergraduate in Dr. Christopher Howey’s lab at the University of Scranton, is examining the impact of ALAN on glucocorticoids in green anoles (Anoles carolinensis), which are commonly found in urban environments. Margaret specifically examined the impact of ALAN on the daily rhythmicity of corticosterone (CORT) and CORT responsiveness to an environmental stressor. She exposed green anoles to either a natural light-day cycle of 12 hours of light and 12 hours of dark or 24 hours of light. After six weeks of exposure, Margaret performed competitive immunoassays to measure baseline CORT levels at midnight and noon. Additionally, she measured CORT responsiveness after placing the green anoles in a bag for 30 minutes to simulate an environmental stressor.
Anoles not exposed to ALAN displayed an expected CORT daily rhythmicity with higher levels of CORT during the day than at night. Anoles exposed to ALAN lost this CORT rhythmicity and maintained CORT at a level intermediate to the other group. In contrast, ALAN does not appear to impact the anoles’ CORT responsiveness to environmental stressors. Her results suggest that green anoles exposed to ALAN are still able to respond to environmental stressors. However, there could be downstream effects from the loss of CORT rhythmicity because it has been linked to arrhythmic activity in mammalian studies.
In the future, Margaret plans to investigate if the natural CORT rhythmicity can be regained by anoles exposed to ALAN when placed back into a natural light-dark cycle. This future research can aid in determining the longevity of ALAN’s impacts on organisms. You can reach Margaret at margaret.mcgrath@scranton.edu and find more about her research on chowey.net, Dr. Howey’s website.
Chris Thawley presenting his work at SICB 2020
Citizen science is a collaboration between scientists and the general public to advance scientific research. A major citizen science project is iNaturalist. In iNaturalist, anyone can submit an observation of an organism, which includes the date and location. It provides a database over a large area and a long time that would be extremely costly for scientists alone to collect. However, the data’s suitability for ecological analysis is uncertain.
To shine some light on the robustness of citizen science data, Chris Thawley, a visiting assistant professor at Davidson College, worked in collaboration with Amy Kostka, an undergraduate at the University of Rhode Island. When the project was developed, Chris was a postdoc in Jason Kolbe’s lab at the University of Rhode Island. As Amy was unable to go into the field, iNaturalist provided the perfect opportunity for her to experience the research process. They decided to compare established hypotheses of native green anoles (Anolis carolinensis) and invasive brown anoles (Anolis sagrei) against the iNaturalist data. They first coded the anoles’ sex, habitat use, behavior, and morphology, and then compared their coded data against existing hypotheses.
Overall, they found that the iNaturalist data corresponded with existing hypotheses of green and brown anoles. Male brown anoles displayed more frequently than male green anoles, in accordance with results in this paper. Males had broken tails more frequently than females regardless of species, likely due to the more risky behaviors conducted by male anoles than females anoles. Green anoles perched more frequently on natural substrates and perched more frequently in a vertical orientation than brown anoles, in accordance with findings by Stuart et al. (2014). Additionally, the brown and green anoles’ reproductive time period (as measured by when hatchlings emerged) matched with the literature.
iNaturalist is a fantastic tool for individuals who are unable to conduct fieldwork, but still want the research experience. However, Chris pointed out that iNaturalist has spatial biases towards urban areas and temporal biases towards the present day. Additionally, it is necessary to sort and clean the data and to train individuals to standardize coding. This study demonstrates that iNaturalist is still a powerful tool and can be used to estimate phenological patterns, differences between sexes, and corroborate existing hypotheses. Chris hopes that, in the future, iNaturalist could be used to generate new hypotheses.
Resolving how extinct species are related to extant ones is often a challenge, as we may not possess the right information, especially genetic data, needed to understand how these species evolved from others. Recently, scientists have increasingly employed archival DNA, or DNA taken from preserved specimens such as those in natural history collections, to understand the evolution of extinct species, including the quagga and thylacine among others.
Thylacines (Thylacinus cynocephalus) in the National Zoo, Washington D.C. (Smithsonian Institute).
Fortunately, to our best knowledge, only one species of anole is suspected to have become extinct in historical times, Anolis roosevelti, the presumed crown giant anole of the eastern Puerto Rico Bank, where it was found on Vieques, Culebra, St. John, and Tortola. Something of a holy grail for anolologists, many researchers have done their best Indiana Jones and taken a crack at finding living A. roosevelti, including some truly heroic fieldwork.
Puerto Rico and the Virgin Islands, with the known distribution of Anolis
roosevelti (stars). From west to east: Vieques, Culebra, St. John, and Tortola. From Mayer and Gamble 2019.
Despite these efforts, no live individuals have been found. Only six specimens of A. roosevelti are known to exist and thus are precious records of this presumably lost species. Previous work has used quantitative characters to attempt to resolve the placement of A. roosevelti in the anole phylogeny, but genetic data is the gold standard for describing evolutionary relationships. Could archival DNA from these specimens, preserved at museums across the world, resolve how A. roosevelti is related to extant species?
MCZ 36138, the holotype of Anolis roosevelti. Laszlo Meszoly, del. From Mayer and Gamble 2019.
Greg Mayer at University of Wisconsin-Parkside and Tony Gamble at Marquette University have embarked on their own quest to answer this question. First, Greg tracked down all six known specimens of A. roosevelti. He determined that they have all been preserved in ethanol, rather than formalin, indicating a reasonable chance of obtaining DNA from these individuals. Because the roosevelti specimens are so precious, Greg and Tony worked to generate a proof of concept for the use of archival DNA sequencing on them. They extracted DNA from specimens of the common crested anole (Anolis cristatellus) preserved using the same methods by the same collectors and at the same times and general locations.
One of the six extant specimens of A. roosevelti (ZMUK 37642, Vieques, A.H. Riise; photo by Mogens Andersen).
They were able to successfully extract and sequence at least partial mitogenomes from 5 of 8 historical samples, including some preserved as far back as 1861! The sequences from these archival specimens clustered with those collected contemporaneously from similar localities. These results indicate that the sequencing of archival DNA provides quality data and that similar procedures are likely to be effective in A. roosevelti specimens.
Greg and Tony’s next step is to obtain tissue from these important specimens, sequence their mitogenomes, and add to our knowledge of this presumably extinct species. Stay tuned for their findings!
For more info, check out the article in Anolis Newsletter VII:
Mayer, G. C. and T. Gamble. 2019. Using archival DNA to elucidate anole phylogeny. Anolis Newsletter VII, p. 158-168. Eds. Stroud, J.T., Geneva, A.J., Losos, J.B. Washington University, St. Louis MO.
Climate change on earth is accelerating. These changes will have important impacts on all species, but some types of organisms are predicted to be affected more strongly than others. One such group is ectotherms which use the temperatures available in surrounding habitats to regulate their body temperatures. Another such group is mountaintop endemics. These species are restricted to one or several mountain peaks by climate and/or competition with other organisms. As such, they cannot easily disperse to other areas if climate makes their current habitat unsuitable!
Mountaintop endemic species may be particularly vulnerable to climate change (Chand Alli, CC BY SA).
Predicting how climate change will impact ectotherms and montane endemics has become a proverbial “hot topic” in recent ecological work, with studies focusing on lizards, salamanders, plants, and insects among other taxa.
Hispaniola contains several high elevation areas home to mountaintop endemic species, including anoles (NASA).
Many studies use correlative modeling approaches (often termed ecological niche models [ENMs] or species distribution models [SDMs]) to assess a species’ current distribution and predict its future distribution by projecting it into simulated future climate scenarios. This approach has some advantages including ease of implementation across many species. However, it has at least two potential drawbacks: the environmental data used in building such models are often measured at a fairly coarse scale that does not represent how many organisms use their environments, and the models do not explicitly include biological processes such as physiology and behavior.
Anolis armouri in a montane rock meadow (Reptile Database).
Vincent Farallo, a post doc at Virginia Tech, and his advisor, Martha Muñoz (both moving to Yale in a few weeks!), investigated whether incorporating physiology and behavior into modelling might affect predictions of climate change impacts on two mountaintop endemic anoles of Hispaniola, Anolis armouri and Anolis shrevei. Correlative SDMs (via BioMod2) predicted both species would lose much or all of their suitable habitat under climate change, perhaps leading to extinction. However, when Vincent constructed mechanistic niche models (via NicheMapR) that included knowledge about the thermal physiology and habitat use behavior of these species to predict activity time, they showed that habitat would increase in suitability under climate change, the opposite result! Interestingly, these models also predicted increased suitability for a widespread anole, A. cybotes. This result suggests that while climatic changes may not be a direct threat to these mountaintop anoles, increased competition with another anole, an indirect impact of climate change, may be.
Activity time of Anolis shrevei is predicted to increase across its range in Hispaniola with climate change (Farallo and Munoz).
As a whole, Vincent and Martha’s work shows that incorporating more mechanistic knowledge into models, including physiology and behavior, may be critical to predicting the impacts of climate change on organisms and making sound conservation decisions.
Anolis apletophallus from Panama, a well-studied species from the Panama mainland.
Over the past 15 to 20 years, the study of evolution has undergone something of a paradigm shift. Whereas scientists used to believe that evolution in most animals was a slow process, only observable over longer timescales, we now know that evolution is fast. Meaningful change can occur in many types of traits, including morphology and physiology, in just a handful of generations of a given organism. With this shift in our understanding, many biologists have begun conducting experiments which attempt to observe evolutionary processes in action, and shed light on how evolutionary mechanisms play out in the real world.
Dan Nicholson, a student in Rob Knell’s lab at Queen Mary University of London, worked with Mike Logan and a team of researchers to do just this in a tropical anole, Anolis apletophallus. Dan and his colleagues caught over 400 individual anoles from the mainland and introduced them to a novel environment: four small, anole-free islands formed when the Panama Canal was created. Two of these islands were similar to mainland habitats, while two had wider types of vegetation. Prior to placement on these islands, Dan measured a suite of characters of these individuals, including perch height, size, leg length, head, and toe morphology, enabling him to observe any changes in the distribution of these traits over time.
After leaving the anoles on their new tropical island homes for a year, Dan returned to recapture the survivors and measure both them and their offspring. By comparing the traits of the surviving lizards and their young with those of the population founders, Dan could observe changes in traits as well as measure natural selection on them. At SICB 2019, Dan reported that he found that anoles on islands with wider vegetation did indeed use these broader perches and that anoles also perched closer to the ground. Correspondingly, he found that toe pad size decreased and that hindlimb lengths were longer on some islands, potentially allowing lizards to better exploit lower, broader perches.
Anoles on all islands also showed a reduction in head depth. The reason is unclear, but Dan is looking into whether differences in competition or the prey community are potentially driving this pattern. Finally, measuring selection was very difficult and analyses proved problematic, though in some cases selection estimates do seem to match with observed changes in morphological characters. Dan and his team are hoping that adding data from another generation of anoles will clarify these effects, so stay tuned!
Keep track of the latest from Dan on Twitter: @DanJNicholson
Natural Selection on Morphology in a Tropical Lizard After a Rapid Shift in Habitat Structure NICHOLSON, DJ*; LOGAN, ML; COX, C; CHUNG, A; DEGON, Z; DUBOIS, M; NEEL, L; CURLIS, JD; MCMILLAN, WO; GARNER, T; KNELL, RJ; Queen Mary University London
Brown anoles are invasive throughout the southeastern United States and are often transported via the nursery trade.
As invasive species expand across landscapes, they may engage in new interactions including with native competitors and prey as well as encountering novel environmental conditions such as different temperatures or patterns of rainfall. It is often difficult to observe the process of how invasive species which are dispersing across landscapes are affected by these novel conditions, because it may be difficult to find edge populations of invaders, and those extralimital populations which do not survive may have disappeared before scientists can observe them.
In southern Florida, many anole species have been introduced and are expanding their ranges, perhaps none more prolifically so than the brown anole (Anolis sagrei). In the past 75 years or so, brown anoles have occupied all of peninsular Florida, the eastern seaboard of Georgia, and Gulf Coast habitats through Louisiana. Many of these expansions are thought to occur via hitchhikers on cars or via the nursery trade, in which potted plants with adults or eggs are transported to new areas. These introductions may fail for many reasons (e.g., inhospitable environments, low numbers of colonizers, intentional extirpation by humans), but these processes of dispersal, establishment, and extirpation are difficult to study. Dan Warner, a professor at Auburn University, took advantage of a known extralimital population of brown anoles in a greenhouse in central Alabama to study the survival of a population created through this type of dispersal.
This population of anoles existed well north of its continuous invasive range in the United States and was exposed to much colder winter conditions than other studied populations. It was present at the greenhouse from at least 2006, and so survived for at least 10 generations, long enough for adaptation to these novel thermal conditions to potentially occur. Working with a team of undergraduates, graduate students, and post-docs, Dan assessed the thermal conditions in the greenhouse environment, conducted mark-recapture studies of the population, and measured thermal tolerances of lizards.
Dr. Amélie Fargevieille and Jenna Pruett representing the Warner Lab at SICB 2019.
At SICB 2019, Dr. Amélie Fargevieille and Jenna Pruett presented results from the study, showing that the greenhouse population included all life stages of lizards and reached a total size of >1000 individuals. While one might expect that these northern lizards would have altered critical thermal limits, the Warner lab showed that both the upper and lower thermal limits of these lizards (the temperatures at which their movements became uncoordinated), were the same as those found in lizards from warmer, southern populations. These results indicate that existence in a colder northern climate for >10 years did not lead to adaptive changes in thermal limits, perhaps due to the population occupying a thermally-buffered habitat, i.e., the greenhouse.
While hurricanes have facilitated several fascinating studies of anole adaptation (e.g., Schoener et al., 2017, Donihue et al., 2018), they may also take these opportunities away. In the case of this population, Hurricane Irma blew off the greenhouse roof in 2017 (which remained unrepaired), exposing this population to the rigors of a central Alabama winter. Multiple surveys in 2018 confirmed that there were no survivors of this previously robust population. Dataloggers confirmed that, even in the most sheltered microhabitats that remained, temperatures dropped below the critical thermal minima of brown anoles, presumably extirpating the entire population.
Recent Extinction of a Viable Tropical Lizard Population from a Temperate Area WARNER, DA*; HALL, JM; HULBERT, A; TIATRAGUL, S; PRUETT, J; MITCHELL, TS; Auburn University.
Daisy Horr, an undergraduate researcher at Trinity University, discusses how bark anole behavior varies across several different social contexts.
Animals often use diverse behavioral repertoires to adjust to new, unexpected, or changing conditions very quickly. While it may seem like individuals could always use the best behavior for any given situation, we know that instead behaviors are often related within an individual. In other words, an individual’s behaviors are not always independent and may represent an underlying “behavioral syndrome” or correlated set of behavioral responses to related environmental conditions. These behavioral syndromes are also sometimes called “personalities” (though application of this word to animals can be a bit controversial!). So, for instance, an individual that has a “bold” behavioral syndrome might take little time to explore a new habitat or consume a novel food item more quickly, but also be more likely to stay active in the presence of a predator rather than hiding (the safer option!).
While anoles have been the focus of much behavioral research, we still lack an understanding of the diverse behavioral phenotypes, including behavioral syndromes, which are displayed by a variety of anole species. The bark anole, Anolis distichus, is native to Hispaniola but also found in southern Florida where it has been introduced. While small, bark anoles can be quite feisty, and are known for their dramatic display behavior in the presence of male and female conspecifics.
Male bark anoles demonstrate pushup displays prior to engaging in combat.
Taking advantage of the bark anole’s willingness to put on a show, Daisy Horr, an undergraduate student and McNair Scholar in Michele Johnson’s lab at Trinity University, led a group of fellow researchers in assessing whether these anoles show behavioral syndromes. To do this, Daisy and her collaborators measured the degree to which male bark anole behaviors were repeatable across three different contexts: trials with another male present, trials with a female present, and solo trials in which no other anoles were present. They measured variables quantifying movement as well as display behaviors such as pushups and dewlap extensions during these trials. The team also wanted to see whether the measured behavioral traits were linked to morphological and physiological variables.
Daisy and colleagues found no support for the idea that behavior was linked to morphology, including size of the body, head, and dewlap, and mass of the whole body, the liver, and fat pads (structures holding fat as energy reserves), or the hematocrit of the lizards, a metric quantifying how many red cells are present in the blood. Bark anoles did show some level of behavioral consistency, however. Movement behaviors were quite repeatable even between trials with and without conspecifics. Display behaviors, however, including pushups and displays, were repeatable within, but not across contexts. This work suggests that bark anoles have consistent behavioral syndromes in some contexts. Looking forward, research into behavioral syndromes in anoles could offer insights into how behavior may vary with habitat use, ability to invade novel environments, or selection on behavior itself!
I found these two specimens in my farm located in the municipality of Santa Sofia, department of Boyacá, Colombia. The living specimen was found near a stream in a wet area, while the dead specimen was found in the house of the farm. The farm is located in an Andean forest at about 2300 meters above sea level where plants such as oaks and eucalyptus trees predominate, among others.
The nursery trade is a known vector for many invasive species including anoles. Anoles have quite the affinity for laying eggs in the moist soil of potted plants, which may then be transported to various locations. Indeed, the nursery trade is the suspected vector for introductions to Hawaii and California of A. carolinensis and A. sagrei and likely accelerated their spread within those states. In fact, citizen scientists on iNaturalist document a reasonable number of brown anoles well outside their normal range. These observations have a distribution that suspiciously coincides with locations of Home Depots and Lowes. However, while the nursery trade is a suspected vector for other species of anoles, verified instances of long-distance transport via the trade are fewer and farther between.
An (as yet) unidentified anole hatchling transported from Puerto Rico to Virginia. From user kimjy3 on iNaturalist.org
One recent observation on iNaturalist documented a hatchling anole that popped out of a potted plant shipped from Puerto Rico as the user unwrapped it…in Alexandria, Virginia. Can anyone on Anole Annals having experience with Puerto Rican anoles and their hatchlings help ID this little one? The user reports that the anole does not have blue eyes; instead they are brown or black.
Feel free to add IDs/comments on the iNaturalist observation as well!
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