Category: All Posts Page 13 of 146

Anolis occultus sleeping on a branch. Photo by Jhan C. Salazar

I have had the opportunity to search for anoles in three different countries— two in the Caribbean (Puerto Rico and the Dominican Republic; I will write about my experience in the Dominican Republic, too) and one on the mainland (Colombia)— and it always surprises me how diverse this group of lizards is. This year, I finally went on a field trip after the craziness of the pandemic—or should I say, during the craziness of the pandemic? I went for three weeks to Puerto Rico along with the incredible Losos Lab combo (the ones at Washington University): Dr. Kristin Winchell (the leader of the team), Dr. Elizabeth Carlen (the new postdoc of the lab), Ari Miller, Ansley Petherick and me—and three other incredible people: Sarah Swiston (a grad student in the Landis Lab at Washington University), Albert Chung (a grad student in the Campbell-Staton Lab at Princeton University) and Armando Vera (a microbiologist from Universidad de Puerto Rico).

I have been on several field trips in the past working with different kind of organisms, but this field trip had something special; it was the busiest one I have ever participated in. Do not get me wrong here: I really enjoyed my time there. We were doing several experiments (that you will hear about in the future) focused on differences between urban and forest anoles.

Now, let’s talk about why I am writing this post. We arrived in Puerto Rico in August and stayed for most of the month, staying at Mata de Plátano Field Station and Nature Reserve. Since the moment I landed, I felt how warm and nice people from Puerto Rico are—there is nothing better than feeling welcome.  Once we got to the field station, I also realized how much I love to be surrounded by nature and disconnected from the world—I did not have phone reception in the field station.

I am not going to lie: one of the reasons I wanted to go to Puerto Rico was to see some or all the endemic bird species this beautiful island has. I saw a few of them—the Puerto Rican owl or múcaro and the Puerto Rican lizard cuckoo or cuco lagartijero, just to name a couple. Sadly, I did not see species such as the Puerto Rican tody or the Puerto Rican parrot. However, this time we went for a different kind of group: anoles, particularly Anolis cristatellus.

Even though we were looking for Anolis cristatellus, this one was not the only anole that I wanted to see. There were another nie species that I was looking for—sadly, we did not go to Culebras, Vieques, or Mona, so I guess I’ll have to go back to see the ones I’m missing!

On our first day of sampling, we went to the city of Arecibo to look for A. cristatellus, and while we were looking for this species, I saw a weird-looking anole with some black spots in the back. This was when I realized that I had just spotted my second anole species, Anolis stratulus. In the afternoon of that day, we were working in Mata de Plátano when Ari said “Hey Jhan, there’s a crown giant,” and I thought, “there’s no way this is happening so early on our field trip”; but it was true! We saw a beautiful emerald-colored anole, Anolis cuvieri. Later that day, I spotted my fourth species, one small with white lines on each side of the body, Anolis pulchellus. Four anoles in one day! How crazy is that?

Adult male Anolis cooki basking on a tree trunk. Photo by Jhan C. Salazar.

It was not until our second week that I found my fifth species. This time we were in a small forest patch in Mayagüez. We were walking in the forest, and I saw a familiar-looking anole, but I was not sure what it was. I asked Ari which species it was, and he said “that’s Anolis krugi.” On our last days in Puerto Rico, we went to a couple of places where we found the anoles that were missing from my checklist. Our first stop was El Yunque National Park—if you go to Puerto Rico, you should go there. I was impressed by how different the Colombian mountains are from the Puerto Rican ones. Before we even started to hike, someone pointed out an anole on a palm tree (sadly, I do not remember who it was), and it was another green anole! But this time, it was Anolis evermanni, and once again I was amazed by how easy it is to see some species when I used to spend weeks looking for even one individual of one species in the Andes.

When we were about to start hiking, Kristin said, “that’s Anolis gundlachi, look at those blue eyes!”. Once I heard that, I ran to see this anole; when I saw it, I realized that anoles are a crazy group. I did not know they could have blue eyes, or maybe I never noticed it until that moment. The next day, we went to Cabo Rojo, and there we found two species: Anolis cooki and Anolis poncensis. In this place, Sarah, Armando, Kristin, and I were walking on a small forest patch, and we found a grey anole, A. cooki—and again, I was surprised. I never thought anoles could be grey too! What can I say about A. poncensis? Well, I saw it for a brief period—it is a fast species. When we were walking, Armando yelled “Anolis poncensis! I told you it was here!”. Armando pointed the lizard out to me, but I did not see it until it started running; then, it stopped for one second, and in that second, I saw how beautiful that species is—so small, yet so fast.

I had just one species missing, but this story is unique. At the beginning of the field trip, I was talking with Armando about the anoles he saw when he was working with Anna Thonis (a grad student at Akçakaya Lab at Stony Brook University) just a few weeks before, and he said he was missing Anolis occultus—that was the first time I heard about that species. I did not even know how it looked. We made our quest to find that species. While we were in Mata de Plátano, there was another team working on anoles too, and one of them, Alejandro, told us where we could find this anole. That night, Armando and I went to the forest to look for A. occultus; we went at 9:00 pm and returned at 12:30 am empty-handed; we did not see it. A few days later, Armando went on his own to look for A. occultus, and again, he did not find it. Another night, Albert and the other team went looking for A. occultus, and they asked Armando and I if we wanted to join them, but we were tired; the next day, Albert showed us a picture of A. occultus—yes, they found it. I asked Albert to join Armando and I to look for this occult species; that night, we went to look for A. occultus from 10:00 pm to almost 1:00 am, and once again, we were defeated, with no clue where this species was.

On our last night, a Saturday night, Armando, Ansley, Ari, Sarah, and I were determined to find A. occultus. We started looking at 8:00 pm or so. We walked and walked, looking here and there, minutes passed and nothing. I thought we were going to leave Puerto Rico without seeing this species, and at 9:25 pm—yes, I recorded the time—I looked at a branch with something in it, and there it was. I realized that we had found it; after all these attempts, there it was, Anolis occultus. I said “found it, we finally found it”; everyone was excited, especially Armando. Ari then said, “there must be more individuals here,” and sure enough, Ari found another one! We took hundreds of pictures of those two anoles, and that was when I realized that in three weeks, I saw all ten anoles species that Puerto Rico has!

I feel thankful to visit and work in such an amazing place like Puerto Rico, with amazing people, amazing beaches, and food—particularly, mofongo and Church’s Chicken (they never got my order right, but I still like it). Hopefully, I will be back to work a little bit more, but for now: “Con un cariño profundo en ti la mirada fijo”—“With deep affection fixed gaze on you”—poem to Puerto Rico by José Gautier Benítez

Adult male Anolis gundlachi basking on a tree trunk, by Jhan C. Salazar.

Ground-dwelling lizard A. tandai.

From the pages of Natural History magazine.

Ivan Prates

With over 400 species of anoles (Anolis) scattered from Florida to Bolivia, these slen­der lizards, widely sold in pet stores, have long been model subjects in evolutionary biology—keys to ecomorphology, adaptive radiation, and convergent evolution. Yet there is still much to discover about them.

Jonathan Huie, a doctoral candidate at George Washington University, while an intern at the Smithsonian’s National Muse­um of Natural History, set out to determine whether the less-studied anoles of main­land Central and South America have evolved the six ecomorphs—forms adapted to microhabitats, from treetops to trunks to undergrowth—recognized in the much-studied species found on Caribbean islands.

Huie examined 347 anoles preserved in four natural history museums; they represented 205 spe­cies, 99 of them from the mainland clade. He mea­sured thirteen morpho­logical traits associated with habitats and modes of locomotion, including the lengths of tails, bodies, snouts, heads, hands, feet, and limb bones and the width of the toe and finger pads anoles use to cling to vertical surfaces. After averaging these values for each species and correct­ing for body size, he plotted their positions in a multidimensional “morphospace.” He tested their resultant assignments to eco­morphs against available field data.

Mainland anoles were previously consid­ered less ecologically diverse than their Ca­ribbean cousins. But Huie’s findings suggest they occupy all of the same microhabitats; the two groups underwent similar radia­tion—i.e., convergent evolution—over the approximately 30 million years since anoles from the islands recolonized the mainland. He also found evidence of a previously un­recognized ground-dwelling ecomorph in both groups.

Why was this mainland diversity over­looked? Perhaps because it is much easier to study anoles on the islands, which are celebrated evolutionary hotbeds where, with fewer predators, they are more abundant and visible. “Mainland anoles are a lot more secretive and inhabit more complex envi­ronments, such as heavy forest,” Huie noted.

Huie suggests the methods he and his coauthors developed could be applied to study “the relationships between form and function” in other morphological features of organisms, whether plant leaves, frog limbs, or the pharyngeal jaws of fish—especially cichlids, the fast-evolving, highly diverse piscine counterparts of anoles. (Biological Journal of the Linnaean Society)

For more commentary on this paper, see a previous AA post.

Anolis planiceps. Photo by Renoir Auguste.

Hello Anolis network,
I’m interested in networking with fellow native Caribbean-based Anolis researchers (born in the Caribbean, working or worked on anoles). I’m one (from Trinidad), and thought why not reach out to those who follow Anole Annals. If you are a current or recent grad student, or also those who have moved up the ladder to PI, please do reach out if you want to. This is geared towards having general conversations about the work you have, or are doing, and perhaps how we can all help each other and fellow/future Caribbean-based Anolis researchers in some way. Looking forward to virtually networking!
Renoir Auguste, MSc.

In a new study hot off the press at Evolution, Stuart and colleagues experimentally test the dimorphism-richness hypothesis using several mangrove islands in south Florida inhabited by Anolis carolinensis (pictured; credit Wikimedia Commons) and A. sagrei.

New literature alert!

Male and female Anolis carolinensis maintain their dimorphism despite the presence of novel interspecific competition

In Evolution

Stuart, Sherwin, Kamath, and Veen

Abstract:

Natural selection favors sexual dimorphism that reduces resource competition between the sexes of the same species. However, niche partitioning among interspecific competitors should counter such divergence, as partitioning the niche results in smaller total niche widths for each individual species, leaving less room for the sexes to diverge. A straightforward (and long-standing) hypothesis emerges: species in competitor-rich ecological communities should show less sexual dimorphism than species in competitor-poor ecological communities. Here, we test this prediction using a well-documented natural experiment generated by the recent arrival of Anolis sagrei to a set of small islands in Mosquito Lagoon, Florida, containing Anolis carolinensis. Despite known interspecific habitat partitioning and rapid evolution in habitat-use traits by A. carolinensis in this system, sexual dimorphism between male and female A. carolinensis was not reduced as predicted on two-species islands relative to islands with only A. carolinensis. This is consistent with a small but growing body of empirical tests of the dimorphism-richness hypothesis that have been ambiguous in their support at best. A rethinking of the validity of this intuitive hypothesis is needed.

Anolis sagrei (pictured) is the star of a new study by Kahrl et al. (2021) examining selection pressures on sperm. Credit Wikimedia Commons.

New literature alert!

Selection on Sperm Count, but Not on Sperm Morphology or Velocity, in a Wild Population of Anolis Lizards

In Cells

Kahrl, Kustra, Reedy, Bhave, Seears, Warner, and Cox

Abstract:

Sperm competition is a widespread phenomenon that shapes male reproductive success. Ejaculates present many potential targets for postcopulatory selection (e.g., sperm morphology, count, and velocity), which are often highly correlated and potentially subject to complex multivariate selection. Although multivariate selection on ejaculate traits has been observed in laboratory experiments, it is unclear whether selection is similarly complex in wild populations, where individuals mate frequently over longer periods of time. We measured univariate and multivariate selection on sperm morphology, sperm count, and sperm velocity in a wild population of brown anole lizards (Anolis sagrei). We conducted a mark-recapture study with genetic parentage assignment to estimate individual reproductive success. We found significant negative directional selection and negative quadratic selection on sperm count, but we did not detect directional or quadratic selection on any other sperm traits, nor did we detect correlational selection on any trait combinations. Our results may reflect pressure on males to produce many small ejaculates and mate frequently over a six-month reproductive season. This study is the first to measure multivariate selection on sperm traits in a wild population and provides an interesting contrast to experimental studies of external fertilizers, which have found complex multivariate selection on sperm phenotypes.

A Brown Anole (Anolis sagrei)–the species of focus in the study by Cox et al. (2021)–displays a gorgeous bright-orange dewlap. Credit Wikimedia Commons.

New literature alert!

Reproductive tradeoffs and phenotypic selection change with body condition, but not with predation regime, across island lizard populations

In Journal of Evolutionary Biology

Abstract:

In a recent publication in the Journal of Tropical Ecology, we found that the herpetofauna communities of Virgin Islands National Park, on the island of St. John, USVI, were resistant to the large disturbances of hurricanes Irma and Maria, showing no significant change in habitat associations eight months post-hurricane. These findings were born from undergraduate research that grew, due to ample encouragement and funding from the National Geographic Society, into an in-depth examination of community recovery from some of the nastiest storms to hit the Caribbean region.

Anolis stratulus dewlapping. Photo by Sam DiGiulio

I started this work in 2016 as a third-year undergraduate at Northern Michigan University (NMU). My research partner, Sam DiGiulio, and I jumped at the chance to enroll in Dr. Jill Leonard’s class, Field Marine Biology, which took students on a spring-break field excursion to St. John, USVI. During our stay at the Virgin Islands Environmental Resource Station (VIERS), we experienced the biodiversity of Caribbean coral reefs, observed marine sampling techniques, and learned how terrestrial processes affect marine environments. As an additional component to the class, Sam and I designed an independent research project to carry out during our time on St. John. Due our shared passion for herpetofauna, we decided to implement a herpetological inventory of Virgin Islands National Park (VINP), following up on work done by the US Geological Survey (USGS) in 2001 (Rice et al. 2001). The initial goal of our survey was to provide the National Park Service (NPS) with a report that would act as a snapshot of the herp communities 15 years after the USGS survey, but it ended up being a lot more than that.

There is not much better field work than that in VINP. We hiked the trails and conducted visual encounter surveys; documenting the anoles, dwarf geckos (Sphaerodactylus macrolepis), and the occasional green iguana (Iguana iguana). Each transect we walked was classified by one of five landcover types (moist forest, dry forest, scrub, estuarine, and gut – small areas that hold freshwater for extended periods), per the USGS inventory. We also set out to the trails at night to conduct vocalization surveys for the island’s frog species. VINP is home to 19 species of reptile and amphibian, though this number fluctuates as populations of introduced species wink in and out. St. John is the smallest of the US Virgin Islands and does not host some of the rarer endemic species like St. Croix, such as Anolis acutus, or Ameiva polops, or hold the diversity found on Puerto Rico. However, that doesn’t make its residents any less charming, and with over 56% of the island of St. John included within VINP, there are ample places to observe them.

Anolis cristatellus. Photo by Sam DiGiulio

The most common anole on the island is the Puerto Rican crested anole (Anolis cristatellus). We observed all age classes, sizes, and crest shapes of these lizards and in every habitat type on the island. It was a treat to see two huge males duke it out on a tree trunk, head bobbing, dewlapping, and charging at one another, turning almost black, as opposed to their usual brown hues. The fight ended with one tossing the other off the trunk with its mouth.

We were also fortunate to find some of the rarer island residents, flipping just the right logs and rocks to reveal blind snakes (Antillotyphlops richardii) and a Virgin Islands worm lizard (Amphisbaena fenestrata). We conducted our surveys anywhere that we could hitch a ride with the class, or with staff from VIERS as they traveled to and from town for camp supplies. Even without our own vehicle, we were able to cover much of the park on foot in the course of the week and after returning to NMU for the end of the semester, we wrote up the report for the NPS, and presented the data at several scientific conferences.

Come September of 2017, category 5 Hurricanes Irma and Maria struck St. John within the course of two weeks. The forests and infrastructure of the islands sustained serious damage. Countless trees had fallen, and those that were still standing were completely defoliated. I anxiously stayed informed about the damage, but it wasn’t until November of 2017 that we talked about the potential of returning to resurvey the herps of VINP. Jill pointed us in the direction of the program. With encouragement from our advisor, we applied for a National Geographic Society’s Early Careers grant and in March of 2018 we received the funds necessary to return to St. John to re-conduct our herp survey.

Early that summer, Sam and I arrived back on St. John. This time, we were able to secure a vehicle and cover even more of the park, in addition to resurveying the areas that we had visited in 2016. We hit the ground running, first by revisiting our previous survey areas to ensure we repeated the same procedures as 2016. As we had arrived nine months after the storms hit, there were already plenty of signs of recovery. Canopy gaps created by the storms were being filled by early successional growth. Vines covered fallen trees and standing trees were quickly replacing lost leaves. The red mangroves were very slowly sprouting new shoots and leaves from the standing skeletons of prop roots. Clean-up operations and construction projects were coming along in the developed areas of the island. Unfortunately, VINP infrastructure had yet to be repaired, and VIERS had been destroyed. As of writing this post in 2021, the incredible education center is still not functional. However, as we traversed the trails and conducted our visual encounter surveys, the herps of the island appeared to be rather unperturbed.

Anolis pulchellus. Photo by Sam DiGiulio

While the vegetation structure appeared different from our initial surveys in 2016, community composition and the landcover types in which they were found  remained unchanged. Puerto Rican crested anoles remained the most abundant species across the landcover types, taking full advantage of the coarse woody debris as display platforms to show off their dewlaps. The male anoles retained their cantankerous attitude towards conspecifics; this time around, we observed two dueling sharp-mouth anoles (Anolis pulchellus). These anoles are much lighter than the bulky crested anoles, favoring grasses and shrubbery to perch, allowing their background to more easily match their greenish hues. As diligently as we searched, we were unable to find more blind snakes and worm lizards, although this was no surprise due to the rarity of specimens recorded in previous surveys. Sufficient planning allowed the 2018 surveys to unfold even more smoothly than in 2016, and after canvasing the national park, we headed home to work through our results.

As a conclusion to our expedition, we determined that the reptile and amphibian communities of VINP had no observable changes in community composition, or landcover associations after hurricanes Irma and Maria. Interestingly, the communities appear resistant to large disturbances, indicating that they are either able to survive and adapt to the habitat changes, or underwent rapid population growth. Because the hurricanes struck the island over the course of just two weeks, they may have been perceived as a single disturbance event for the island fauna.

While the herpetofauna communities appeared to survive the hurricanes intact, they remain under pressure from many other threats, including invasive species like rats (Rattus rattus) and Indian mongoose (Herpestes auropunctatus), increasing human impact in VINP, and climate change. We recommend a regular monitoring program that would allow managers to observe abundance and population changes of both the herpetofauna species and invasive predators on the island, and give further insight to how these animals deal with disturbances, especially in a time of global biodiversity loss.

The findings from this study were recently published in the Journal of Tropical Ecology (Richter et al. 2021). What started as a class project was able to grow into grant writing, presentation, and publication opportunities that have helped me gain critical skills I’ll be using while pursuing my master’s degree at the University of Georgia’s Warnell School of Forestry and beyond. This work would not have been possible without the encouragement and guidance of our advisors and coauthors, and serves as an example of the advances that can be made by investing in undergraduate research.

Rice KG, Waddle JH, Crockett ME, Carthy RR and Percival HF (2005) Herpetofaunal Inventories of the National Parks of South Florida and the Caribbean. U.S. Geological Survey Professional Paper 1631. Open-File Report 2005-1301: 2, 1-45.

Richter, C. J., S. M. DiGiulio, C. D. Marshall, and J. B. K. Leonard. 2021. Herpetofaunal community response to hurricanes Irma and Maria in Virgin Islands National Park. Journal of Tropical Ecology 37(4): 185-192.

Using a fine-toothed genetic comb, Johnson et al. (2021) investigated the mating system of Anolis cristatellus (pictured above; photo credit Aryeh H. Miller) to better understand both female mate choice and male competition in an explicit spatiotemporal context.

New literature alert!

What Determines Paternity in Wild Lizards? A Spatiotemporal Analysis of Behavior and Morphology

In Integrative and Comparative Biology

Johnson, Kamath, Kirby, Fresquez, Wang, Stehle, Templeton, and Losos

Abstract:

Mating behavior in animals can be understood as a sequence of events that begins with individuals encountering one another and ends with the production of offspring. Behavioral descriptions of animal interactions characterize early elements of this sequence, and genetic descriptions use offspring parentage to characterize the final outcome, with behavioral and physiological assessments of mates and mechanisms of copulation and fertilization comprising intermediate steps. However, behavioral and genetic descriptions of mating systems are often inconsistent with one another, complicating expectations for crucial aspects of mating biology, such as the presence of multiple mating. Here, we use behavioral and genetic data from a wild population of the lizard Anolis cristatellus to characterize female multiple mating and the potential for sexual selection through female mate choice in this species. We find that 48% of sampled females bore offspring sired by multiple males. Moreover, spatiotemporal proximity between males and females was associated with whether a male sired a female’s offspring, and if yes, how many offspring he sired. Additionally, male body size, but not display behavior, was associated with reproductive outcomes for male–female pairs. While much remains to be learned about the mechanisms of mating and targets of sexual selection in A. cristatellus, it is clear that female multiple mating is a substantial component of this species’ mating system in nature.