Hello all! I’m working on Puerto Rican anole field identification. Here’s a specimen I photographed on the ruins atop El Yunque on March 4, 2019. I think it’s a juvenile A. evermanni, but I’m curious what you guys think!
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Scanning electron microscopy (SEM) is a technique that utilizes electron beams that interact with and reflect the surface of a viewed specimen. These reflections allow the evaluation of surface topology and ultrastructure and give high-resolution detail about external structures and cellular arrangements (Goldstein et al. 2017). To create a reflection on specimen surfaces, a thin layer of gold is mechanically applied through a process known as “sputter-coating.” Recently, graduate students at Auburn University had the opportunity to view their own collected biological samples with SEM through an Applied and Environmental Microbiology course taught by Dr. Mark Liles.
As a student in this class, I had the opportunity to view a chosen sample under this process. While I highly debated bringing in an anole fecal sample (which would have been gold-coated and placed on my desk for a lifetime), I decided to view a recently dried, fertile A. sagrei egg collected from the lab of my advisor, Dr. Daniel Warner. The microbial communities on the surface of this egg were most likely highly impacted by the influence of drying (see image descriptions below); this is due to sample preparation required by conventional SEM, whereby water vaporization will distort images if the sample is not completely dry. Part of my research within the Warner lab involves investigating the microbial communities on the external surface of eggshells; thus, this class has provided an excellent opportunity to explore how varying environmental factors can influence eggshell microbiomes. The photos taken and attached were observed on 03 April 2019.
In Image 1 at 42X magnification, you can see the influence of drying from the large indentions on the egg as well as horizontal cracking within the surface itself. However, under closer inspection fungal and bacterial structures begin to appear. In Image 2 at 397X magnification, you can view a filamentous structure that we predict to be fungi. One of the limitations of SEM is that while structures can be easily viewed, they may not always be as easily identifiable. At 1,500X and 1,5700X, we can see a magnified image of a fungal root (Image 3) and potential bacterial cells above the spiral filamentous structure (Image 4).
Image 2. SEM image of A. sagrei egg at 397X magnification.
Image 3. SEM image of A. sagrei egg at 1,500X magnification.
Image 4. SEM image of A. sagrei egg at 1,5700X magnification.
The images above highlight the interesting use of SEM for reptilian eggs, especially those small enough to be entirely encompassed under a microscope (< 1.5 mm long). SEM observations can also be used to elucidate differences in eggshell structures, thickness, and porosity (Heulin et al. 2002). Additionally, SEM use within the classroom setting has allowed students to gain applicable skills and techniques, as well as their own photographs (Beane 2004).
References:
Beane, Rachel J. 2004. “Using the Scanning Electron Microscope for Discovery Based Learning in Undergraduate Courses.” Journal of Geoscience Education 52 (3): 250–53. https://doi.org/10.5408/1089-9995-52.3.250.
Goldstein, Joseph I., Dale E. Newbury, Joseph R. Michael, Nicholas W. M. Ritchie, John Henry J. Scott, and David C. Joy. 2017. Scanning Electron Microscopy and X-Ray Microanalysis. Springer.
Heulin, Benoit, Samuele Ghielmi, Nusa Vogrin, Yann Surget‐Groba, and Claude Pierre Guillaume. 2002. “Variation in Eggshell Characteristics and in Intrauterine Egg Retention between Two Oviparous Clades of the Lizard Lacerta Vivipara: Insight into the Oviparity–Viviparity Continuum in Squamates.” Journal of Morphology 252 (3): 255–62. https://doi.org/10.1002/jmor.1103.
Read more about Elaine Powers’ books, including her most recent post, “Stop and Meet the Anole Lizards,” on her author’s webpage.
Up until the mid-1980s, there had never been a recorded sighting of the Maynard’s Anole (Anolis maynardi) on Cayman Brac island despite it being less than 10km from its native territory, Little Cayman.
However, since the species was first discovered on Cayman Brac in 1987 – in what is thought to have been a human-assisted colonisation – its population has spread right across the 39km² island.
For this study, recent graduate Vaughn Bodden and Lecturer in Conservation Biology Dr Robert Puschendorf conducted a detailed analysis of the invasive species.
They wanted to assess whether individuals at the forefront of the invasion have developed distinct biological traits that are advantageous for dispersal, and compared their findings to animals in the area of first introduction and the native population on Little Cayman.
They discovered the Cayman Brac population has diverged morphologically from the native population, and within the invasive range there was trend of increasing forelimb length from the core to range edge areas. This ran contrary to the expected findings that longer hindlimbs would be the trait selected as a dispersal-related phenotype.
They also showed that the introduced population had lower levels of parasite prevalence, and that both males and females were of significantly higher body condition than the native population.
Writing in the Journal of Zoology, they say the results are a perfect example of how a species can colonise a new territory, and the biological adaptations it can make in order to do so.
Vaughn, who graduated with a First from the BSc (Hons) Conservation Biologyprogramme in 2018, said:
“There has been a history of lizard studies indicating that longer hindlimbs are an important factor affecting movement ability, so to not find longer hind limbed animals on the range edge was a surprise. For parasites, we found a clear decreasing trend in prevalence within the invasive population from the area of first introduction to the range edge, indicating that the parasites lag behind the host during periods of range expansion.
“We think our findings add to the growing body of literature that demonstrates the complex dynamics of species’ invasions. The results highlight that the animals on the range edge of an invasion are likely to be experiencing different ecological selection pressures that can result in changes in behaviour, morphology, and health for the animals.”
Dr Puschendorf has spent several years researching the consequences of emerging infectious diseases and climate change on biodiversity, with a particular focus on Central America. He added:
“Biological invasions are an important conservation threat across the world. However, every invasion needs to be carefully investigated to identify impacts to native eco-systems and identify potential mitigation strategies.
“In this instance there is likely to be limited overlap with, and therefore a limited threat to, the endemic anole population – the Cayman Brac Anole (Anolis luteosignifer) – because one inhabit the crowns of trees while the other is found closer to the ground. This in some ways highlights the challenges biodiversity managers face when managing species invasions with limited resources, and emphasises the need for greater collaboration among scientific and policy communities.”
Inbar Maayan tells all about her ongoing work in the cover story of this month’s issue of Flicker, the bimonthly bulletin of the Cayman Islands Department of Environment’s Terrestrial Resources Unit. Check it out, and also read about Caymanian fossils and the massive effort to eradicate invasive green iguanas (half a million and counting!).
I recently wrote a post on the history of Anolis species descriptions using the Reptile Database (Uetz & Stylianou 2018). This got me thinking, how does my current institution fit into this? I’m currently a grad student in the herp department at the Museum of Comparative Zoology, former home of many anole greats, including Albert Schwartz, Ernest Williams, Skip Lazell, Jonathan Losos (still affiliated but now based at WashU), and many more. And as Jonathan has pointed out previously, it’s home to the greatest number of Anolis specimens of any museum. So I wondered, with such a rich history of anole research, what do our collections look like? How many specimens do we have now? How many species? How has the collection grown over time? So get ready for Anoles by the Numbers Part II: MCZ.
A brief note on methods – all data comes from a spreadsheet I downloaded of all current Anolis specimens in the MCZ from MCZBase (downloaded 2/8/19). For total numbers of specimens per species/subspecies/locality, I simply count records (each record corresponds to a single specimen). For the main summaries of collectors, I treat every collector listed with a specimen as independent, so if someone is listed as the main collector for one specimen but as a “co-collector” for 9 others, they will be summarized as collecting 10 specimens. Due to some formatting issues, a small number of specimens got filtered out (early ones in particular), but I think it’s a pretty good start. I also did a subset of visualizations for the “Top 10 Collectors” – these were defined as the 10 researchers who collected the most specimens overall.
The MCZ was founded in 1859 by Louis Agassiz (more on the history here). The first Anolis specimen collected for the MCZ was an A. carolinensis from Milledgeville, GA collected in 1854 (before the MCZ was founded), but the collector is unknown. I can’t track down much info about that specimen. More Anolis specimens were deposited in 1858 and 1859, and since then, the MCZ Anolis collection has grown to include a total of 52,293 specimens. 44,889 of these have specific info on when they were collected.
So, when were the peak periods of growth for the Anolis collection? Looks like the majority happened in the 1960’s and 1970’s.
These specimens were collected by 886 researchers. Most collected <100 specimens each, but a few collected tons! (That doesn’t include the prodigious researcher we know and love, “et al.” I took them out of the analysis.) Some of these collectors spread their work over a number of years, while some had very concentrated efforts. The top 10 collectors together collected a whopping 21,564 specimens.
And how many species do these specimens represent? In total, the MCZ has 378 species (out of 427 described), so 88% of species diversity! Not too shabby. About half of the species are represented by <10 specimens, but a fair number of them have tens to hundreds of specimens. Eleven species even have more than 1000 specimens each! From highest to lowest, these are: distichus, cybotes, sagrei, cristatellus, roquet, grahami, marmoratus, gundlachi, lineatopus, brevirostris, and pulchellus (they’re not on the plot below because they cause so much skew).
What about type specimens? While we don’t have the type for the genus Anolis (that honor belongs to the North Carolina Museum of Natural Sciences), we do have 146 species holotypes! Their collection follows a similar pattern to general Anolis collection, with a peak in the 60s-70s, but is more scattered throughout the 1900s.
How were all of these specimens geographically distributed? Unsurprisingly, considering the history of research on Caribbean diversification and ecomorphology at the MCZ, 72% of the specimens in the collection came from Caribbean Islands, with 39% from just the Greater Antilles. Central and North American species make up an additional 22%, while South American species make up only 6%. A few specimens came from introduced populations in Guam, Japan, and Micronesia. Hopefully the collection will continue to grow and expand as the field of anole research does too!
I hope you’ve enjoyed this journey through MCZ Anolis history. I’m still relatively new to the field of Anolis biology myself, so if you have any insights or perspectives (or suggestions of other things you’re curious to see with this data), please leave them in the comments!
As we all know, anoles are super diverse, but how diverse exactly? I often read that there are ~400 species of anoles, but how many precisely? And what about subspecies? And who described them?
Other AA authors (e.g. Greg Mayer, Rich Glor) have written about these questions in the past, but I’d like to add to this thread of anole history by using a great new resource – Peter Uetz’s reptile database. If you’ve ever googled any reptile species, you’ve probably found yourself on the Reptile Database website at some point, which has great info on species taxonomy, distribution, and often natural history. But recently, the database itself was published in Zootaxa with some interesting stats and plots of reptile species descriptions over time. The database is nuts – it contains information on the taxonomy of literally every reptile species! It’s a really incredible resource. And since it’s got every reptile, it has every anole! So I decided to explore the Anolis section of this database.
First, a couple details – the main data contained in the database is the species taxonomy, species description date, and author(s) of the description. For the main summaries here, I treat every author of a species description as “describer” whether they are the lead author or not, so if someone is a lead author on one description, but a coauthor on nine others, they will be summarized as describing 10 species. However, the info on number of coauthors per description and author order is retained. Also important to note that the database only contains current taxonomy; species or subspecies that have been sunk/synonymized/etc. won’t appear.
So let’s jump in! According to the Reptile Database at the time of publication (Jan 2018), there are 427 species of anoles. The number of new species descriptions peaked in the 1860’s, again in the 1930’s, and again in recent years. A number of you reading this are no doubt represented on this plot!
In total, Anolis species have been described by 171 different researchers. 21% of these species descriptions were done by just three people: E. D. Cope, Ernest Williams, and Gunther Koehler (currently active). Wow! Many of the remaining authors (47%) only described one species. The rest fall somewhere in the middle. After the three mentioned above, the researchers who have described the most species are Garrido (26), Boulenger (22), Barbour (18), Schwartz (18), Dumeril (15), Hedges (15), Poe (15), and Smith (15).
We’ve looked at how species have been described by different researchers, but I was curious to know how collaborative this process has been – how many authors normally contribute to a given species description? Well, 274 species descriptions were written by one author, 92 by two authors, and 61 by three or more authors. So most anole species were described by one or two authors.
As one might expect, as science as a whole has become more collaborative, the number of coauthors for species descriptions has increased over time. Almost all descriptions up to the early 1900’s were done by one author, while in the 2000’s that’s almost never been the case.
Now what about subspecies? According to the Reptile Database, there are currently 144 described subspecies from 36 different species. Most of those species have just a few subspecies, but a few of them have higher numbers, with a maximum of 11 in A. distichus and A. equestris. In the case of subspecies, 52% were described by just three people! Albert Schwartz, Orlando Garrido, and Skip Lazell (hi Skip!). Subspecies descriptions really hit a peak in the 1970s.
Most of the species that are split into subspecies are distributed in the Caribbean islands (33 of the total 36). Is this just because more phylogeography and taxonomy work has been done on the islands? Or is this another example of how patterns of diversification are different between mainland and island environments? I think probably the first.
Lastly, what was the first anole described? I thought it was A. carolinensis, but was surprised to learn that it was actually A. bimaculatus! Although that species was originally described as Lacerta bimaculata, later reassigned to Anolis. The first species actually described as Anolis was still not A. carolinensis though – it was A. auratus! Described by F. M. Daudin in 1802. So why is A. carolinensis the type specimen for the genus? Well, in 1963, Hobart Smith, Ernst Williams, and Skip Lazell petitioned* to change the type species to A. carolinensis due to a dubious prior designation of the genus type. The ICZN voted to approve their proposal, and granted the change in 1986**. For those interested in a deep dive, take a look at the 1986 decision**, which describes the back-and-forth between the the original proposers, the nay voters (Dupuis and Holthuis), a yay voter (Thompson), Jay Savage, and A. F. Stimson in the Bulletin of Zoological Nomenclature.
I hope you’ve enjoyed this brief history of Anolis by the numbers. Stay tuned for Part II: a look at the history of the Anolis collection at the Museum of Comparative Zoology!
* The Bulletin of Zoological Nomenclature. 1963. Vol 20: Pt. 1-6, pp 438-439.
** The Bulletin of Zoological Nomenclature. 1986. Vol 42: Pt. 1-4, pp 125-127.
Recently, the guys over at SquaMates Podcast — a podcast about all things herpetological — asked if I would be interested in joining them for a special episode on anoles to discuss the recent Anolis Newsletter VII. The podcast is hosted by Mark D. Sherz, Ethan Kocak, and Gabriel Ugueto, who was responsible for the wonderful drawing which graced the cover of ANVII.
The Anole Special, “Episode 8: The Last Anole”, has just gone live and you can listen to it at the link below. Here’s hoping the title isn’t true and there are many more anole episodes to come in the future!
You can also subscribe to the SquaMates Podcast at any of the podcast streaming services below!
Apple Podcasts | Android | Google Podcasts | Stitcher | TuneIn | RSS | More
In a somewhat autobiographical romp through the history of species delimitation, David Hillis, in a recently published article in the Journal of Herpetology, details the state-of-the-field in terms of phylogenetic and species delimitation, detailing both the many advances that have been made over the last few decades, but also pointing out where things are out of whack and need some recalibration. There’s much more to the article than the figure above, but that’s a good place to start!
Anolis landestoyi. Photo by Miguel Landestoy.
As reported by Science Daily:
Elevation matters when it comes to climate change, deforestation and species survival
- Date:
- February 25, 2019
- Source:
- University of Toronto
- Summary:
- A study examining the impact of deforestation on lizard communities in the Dominican Republic demonstrates differing outcomes at different elevations. In the lowlands, deforestation reduces the number of individuals, but not which species occur in an area. In the highlands, it’s the opposite. When the forest is cut down at higher elevations, the newly created pastures become filled with species found in the warmer lowlands. But locally adapted mountain lizards cannot survive as temperature rises.
University of Toronto student George Sandler was shocked to see the rainforest floor suddenly come to life around him, as if in a scene from an Indiana Jones movie.
“The forest floor started rustling around me,” says Sandler, “as dozens of crabs emerged from holes and crevices. Some were huge, the size of dinner plates. I even spotted a hermit crab climbing up a tree, lugging its heavy shell along with it.”
But Sandler wasn’t in the field to study crabs. He was in the Dominican Republic to take a census of the region’s Anolis lizard species for a study on the effects of deforestation being conducted by researchers Luke Mahler, Luke Frishkoff and collaborators. In the Caribbean nation, deforestation is the main form of natural habitat loss as residents cut down rainforest in order to produce charcoal, as well as create pastures for livestock and farmland for crops.
It is no surprise that deforestation has a profound effect on biodiversity; scientists have been studying this problem around the globe for decades. What is surprising is the difficulty they still face in making detailed predictions about which species survive, especially in relation to other factors such as climate change and natural local conditions.
Now, using the data collected in the census, the research team has discovered details about how Anolis lizards are being affected by the loss of their habitat.
“When it comes to predicting the effects of deforestation,” says Mahler, “elevation matters.”
Mahler is an assistant professor in the Department of Ecology & Evolutionary Biology (EEB) in the Faculty of Arts & Science at the University of Toronto. Frishkoff led the research while he was a postdoctoral fellow in Mahler’s lab at U of T and is lead author of the paper describing their findings, published today in Nature Ecology & Evolution; he is currently an assistant professor at the University of Texas at Arlington. Sandler and researchers from the National Museum of Natural History in Santo Domingo were also co-authors.
Mahler and Frishkoff analyzed populations of lizards in both lowland and highland regions affected by deforestation. Generally, the lowlands are warmer than the highlands due to altitude; also, forest canopy blocks direct sunlight, making forests at any altitude cooler than their immediate surroundings.
“It turns out that deforestation changes lizard communities in fundamentally different ways in the lowlands as compared to the highlands,” says Mahler. “In the lowlands, deforestation reduces the number of individuals, but not which species occur in an area. In the highlands, it’s the opposite.”
“When the forest is cut down at higher elevations,” says Frishkoff, “the newly created high elevation pastures become filled with species we saw down in the warmer lowlands. But, the locally adapted mountain lizards cannot survive.”
The invasion into the highlands by lowland-dwelling lizards was made possible by a combination of human activity and natural factors; i.e. deforestation and elevation respectively. Thanks to the altitude, the temperature of deforested fields in the highlands was comparable to the temperature of forested lowlands.
As it is in many regions around the world, the problem of deforestation in the Dominican Republic is dire. In 2016, Mahler announced the discovery of a previously unknown chameleon-like Anolis lizard on the island of Hispaniola. In the paper describing the discovery, Mahler and his co-authors recommended that the new species, dubbed Anolis landestoyi, be immediately classified as critically endangered because the lizard was threatened by illegal clear-cutting in the region.
Unlike the crabs that crowded around Sandler in the rainforest, the lizards were more elusive and difficult to survey. In order to obtain accurate counts, the students employed a technique known as mark-resight.
“We hiked out to our designated plots,” says Sandler, who was an undergraduate student while conducting the field work and is currently an EEB graduate student at U of T. “Then we walked around looking for lizards. We carried a paint spray gun filled with a non-toxic, water soluble paint — a different colour for each of the six observation periods. If we saw a lizard we would note the species, if it had any paint on it already, and the colour of the paint. Then we would spray the lizard with the paint gun we were carrying, a task that was a little tricky with some of the more skittish species!”
Paint on a lizard indicated that it had already been counted; and the number of unpainted lizards that were observed during each period allowed the researchers to calculate how many lizards were going uncounted.
“It’s not your typical summer job,” says Mahler. “Each survey is essentially a game in which you try to find all the lizards in an area and zap them with paint. It’s a messy affair, but we get great data from it.”
“Our results help us better understand the likely consequences of climate change and how it will interact with human land-use,” says Frishkoff.
For lowland forest Anolis lizards, deforestation just means a decline in abundance or relocating to the highlands. But for highland species, the situation is more critical. Unlike their lowland cousins, they have reached high ground already and in the face of deforestation have nowhere to go — a situation facing more and more species around the world.
“Our data suggest that while many lowland Anolis species might not be seriously affected by deforestation and the gradual warming brought about by climate change,” says Frishkoff, “the opposite is true for the unique mountain lizard species which do not tolerate land-use change well, and which are already on the top of the island.
“Land-use and climate change are a double whammy for these species. If we cut down the mountain forests these lizards have nowhere left to go. Gradual warming might push species up slope, but when you’re already at the top of the mountain, you can’t move any higher.”
Story Source:
Materials provided by University of Toronto. Note: Content may be edited for style and length.
Journal Reference:
- Luke O. Frishkoff, Eveling Gabot, George Sandler, Cristian Marte, D. Luke Mahler. Elevation shapes the reassembly of Anthropocene lizard communities. Nature Ecology & Evolution, 2019; DOI: 10.1038/s41559-019-0819-0