Author: mjohnson216 Page 1 of 5

Brown Anoles in Montgomery County, Texas

On October 5, 2019

I recently received an email from Chris McMartin, the director of the Southwestern Center for Herpetological Research, about a population of brown anoles near his home in Montgomery County, Texas, just north of Houston. Chris has done a lot of preliminary research to understand how the Montgomery population is spreading, and would like to know how these lizards are related to the larger population in Harris County.

Interested? Keep reading!

With Chris’ permission, I’ve copied part of his email below:

“I’ve been casually (in my free time, mostly in the summer) researching Brown Anoles (Anolis sagrei) and their spread in southern Montgomery County where I live. As I amass observational data, I’ve noticed the lizards are abundant in some yards/neighborhoods, but nonexistent in adjacent yards/neighborhoods. I’m slowly trying to piece together additional factors (presence of outdoor cats, prevalence of certain landscaping features including decorative rocks and tropical plants, age of house/neighborhood, use of pesticides, etc.) which may explain not only the disparity in abundance but provide clues as to how to control their expansion.

One big question I have is whether the lizards are naturally expanding from a single introduction long ago (e.g. rapidly moving northward from Harris County, where they occur in densities many times higher than the highest I’ve observed in Montgomery County), or are an amalgamation of numerous discrete introductions (e.g. when a home installs new tropical plants from a nursery/home improvement store). Brown Anoles first showed up in my yard a little over a year ago, marking an expansion northward of about ¾ of a mile from my previous northernmost observations the year prior.

I have corresponded with Dr. Benson Morrill, who owns Rare Genetics Inc. offering DNA analysis for (at this time) colubrid snakes (primarily for sex determination) and inquired as to the possibility of sending him samples from various neighborhoods in my area in an effort to determine whether they represent a contiguous related population or are the result of discrete introductions. He says the process to conduct this analysis would be cost-prohibitive for a private individual such as myself, but perhaps a university student would like to take on the project.

As it is, I currently spend what surprisingly-little free time I have in the summer exploring neighborhoods in my neck of the woods and documenting my obervations—around 60 hours this past summer between field work and analysis—and I’m approaching my limit of resources in time (and definitely money, if considering DNA analysis as part of the project). This is where I think perhaps a graduate student might be interested in taking on a study of Brown Anoles as a thesis project…lots of possible threads to pull (competition with natives, rate of range expansion, effect of occasional hard freezes on population, etc.).

I’ve published articles in local magazines/newspapers about the lizards and have a public-opinion survey from a year ago (still awaiting analysis) trying to find any links between various conditions (age of neighborhood, presence of outdoor cats, etc.) and occurrence/prevalence of browns, especially with respect to A. carolinensis. Some interesting things seem to be occurring. Anecdotally, browns are eating greens (hatchlings), Broad-headed Skinks are eating browns, and greens are eating the skinks (with photographic evidence)! Sort of a three-way lacertilian arms race.”

If this sounds like just the opportunity you’ve been looking for, contact Chris at yall [at] mcmartinville.com.

Green Anoles in Pennsylvania?!

By mjohnson216

On January 21, 2018

In Natural History Observations

A few days ago, I received an intriguing comment on my lizardsandfriends.org blog:

Hello Michele;

My name is Steve and I found a family of Green Anoles living in my shed this past summer. The interesting thing about this is that I live in Pennsylvania. As far as I understand, they should not be this far north.

At first I only saw the one and would see him every now and again on hot days. Then I saw two at once and then later I saw three at once. So I assume I have a family taking shelter in my shed.

My daughter had a couple of anoles as pets back in 2002. One escaped and the other eventually died. I can’t help but wonder if the one that escaped was pregnant and happened to find my shed and the smorgasbord of insects that also take up residence there and started a family.

Thing is that there have been many winters between then and now and it is often in the single digits here during the winter. We just went through over a week where the temps didn’t get out of the single digits much. Do you think these little guys will be OK? I mean I assume they have been dealing with these conditions for many years but I don’t really know. The three I saw together were of different sizes which makes me think they’ve been there long enough to raise a family.

I am reluctant to change anything regarding how I keep the shed as I assume it has been agreeable enough in previous winters but can’t help wondering how they are doing…

I was, of course, skeptical that there could really be green anoles living outdoors in Pennsylvania – it’s just too cold in the winter. I wrote back:

Hi Steve,

This is indeed unexpected! I assume you know exactly what green anoles look like, having had them as pets. The scenario you suggest is possible, that the escaped lizard was gravid and managed to reproduce and they survived, but is not “supposed” to happen with the kind of weather you experience in PA. Also, anoles don’t usually hang out together, as they defend territories from one another (and have no parental care), so it’s also a little curious that you saw them in a group. In any case, I wouldn’t suggest changing anything about the shed, but I agree it seems unlikely that these guys (if they are anoles) would make it through the winter. Feel free to send me a photo to confirm what they are, if you’d like.

And Steve replied, with photos that make it clear that yes, there are indeed green anoles living in his shed!

I am pretty sure these are green anoles. They at least look exactly like the ones my daughter kept. Also when I saw the first one, he was initially green and then turned brown as I moved closer to check him out. Below is an image of that guy when I first saw him.

I never saw the anoles hanging out together in a group. They were just out in the shed at the same time. They do all seem to have their favorite areas. One hung out above a window with a southern exposure where there was a large spider in a web below (the spider and the web eventually disappeared). I would often see this one basking in that window. The smaller one hung out around the side door of the shed and would often be poking out from around the side door jam. The third one I saw on the chicken wire. I did see one on the vent screen once but I’m not sure which one that was. They all seemed to like the chicken wire though. I also grow Mission Figs here and I use the chicken wire and plastic sheeting, tar paper and burlap to wrap the figs for winter. All this stuff is piled up on the side of the shed where I always saw the anoles.

I have been affectionately calling them Shed Lizards since they can’t be your standard variety anole this far north and I have never seen them outside the shed …

One at the roof vent:

SICB 2018: Evo-Devo of Anole Digits

By mjohnson216

On January 16, 2018

In All Posts

One more update from the SICB conference in San Francisco last week!

Across vertebrates, the ratio of lengths of the second and fourth digits of the hand are influenced by testosterone and estrogen. This could be of particular importance in species such as anoles, in which the fourth digits of the hindlimbs are extremely long and critically important in locomotion, but previous studies of the 2D:4D ratio in anoles have produced varying results. In the final poster session at SICB, undergraduate Griffin McNamara, working with Bonnie Kircher in Marty Cohn’s lab at the University of Florida, presented preliminary results from a study of cleared and stained brown anole (Anolis sagrei) hind feet. Griffin has big plans for continuing this work, so watch for future publications with these findings!

SICB 2018: Anoles and Undergrads: A New Kind of Science Lab

By mjohnson216

On January 11, 2018

In Education and Anoles

This post was written by Brittney Ivanov, research technician in the Johnson Lab.

PhD candidate, Abby Beatty, from Auburn University presented a poster entitled Integrating research into the classroom: causal effects of IGF1 and IGF2 on growth in the brown anole. The poster focused on an enhanced method of teaching science, particularly labs. The program, called C.U.R.E (Course-based Undergraduate Research Experience), allows students to experience teaching labs in a way that is more authentic and typical of the research experiences of graduate students. In most science labs, students are provided with different protocols and methods as well as a predetermined set of goals and results that explains how the experiment should turn out. The teaching method Abby proposed gives students the opportunity to learn from their failed attempts, before receiving the correct answers. Here we can draw a parallel with the approach used by the chemistry tutor.

The course lasted for 2 semesters, consisted of undergraduate and graduate students, and began with a pre-survey that assessed student’s current knowledge as well as their ability in certain cognitive skills: analyzing, applying, creativity, evaluating, understanding, and memory. The students then chose a topic (related to Abby’s dissertation work) to be the focus of the labs. From this, they were able to develop methods and design their labs.

Specifically, the first semester class cloned and expressed IGF1 and IGF2 (insulin-like growth factors) using a bacterial vector. Similarly, the second semester class cloned IGFBP2. Abby then used these proteins to optimize methods for studying the growth rate of eggs and hatchling brown anoles. Hatchlings were monitored for 10 weeks following an injection with either IGF1, IGF2, or vehicle (NaCl + 15% Gelatin). Two trials were performed on the hatchlings and one on the eggs. In the first hatchling trial, IGF1 and IGF2 treatments had significantly higher death rates than control groups, but there was no association with body size. In the second trial, which used refined and updated methods, there was no significant effect on survival or body size, when compared to control groups. Finally, egg treatment did not correlate with survival or body size.

As the class completed each step in this process, they reviewed their work and if their methods were unsuccessful, discussed a better approach. Following completion of the course, the students received a post-survey assessing the same skills and knowledge as the pre-survey.

Abby found the class gained significantly in these skills, particularly receiving higher survey scores in the areas of creativity and understanding. She also found that the average score on the knowledge assessment was higher in the classes post-assessment survey than in the pre-assessment, indicating that the students may be gaining from this method of teaching. Control surveys from a class taught using a typical lab curriculum are not available, but there are plans to include this over the course of coming school semester.

These data, while still preliminary, highlight the benefit of implementing this kind of teaching strategy. When students are able to explore the process of asking and answering questions they generally become more engaged in their work and better prepared for more authentic research experiences.

SICB 2018: How Many Neurons Are in An Anole Brain?

By mjohnson216

On January 7, 2018

In All Posts

Across species, bigger brains usually mean better cognition. But, this relationship rarely holds when considering individual differences within a species. Within species, the number of neurons in the brain may be a better proxy for cognitive ability than brain size. Further, the number of neurons may be independent of brain size. But how to measure neuron number?

Levi Storks, a graduate student in Manuel Leal’s lab at the University of Missouri, set out to do just that. He adapted a protocol that has previously been used in mammals, birds, and crocodiles, but never before in lizards. In brief, he dissected the telencephalon, cerebellum, and other regions of the brain of an Anolis cristatellus and used the isotropic fractionator method to determine neuron number in each of the three. After homogenizing each tissue, he used a double-labeling technique with DAPI to stain each nucleus and neuronal nuclei antibody to stain each neuron, and used a hemocytometer to count the cells under magnification. Now that this protocol is working, look out for Levi’s future results on anole brain structure and cognition!

JMIH 2017: Nobody Gets Tired of Looking for Anoles!

By mjohnson216

On July 20, 2017

In New Research

Amy Yackely Adams presents at JMIH 2017.

Amy Yackel Adams presents at JMIH 2017.

All anole field biologists have been there, right? It’s the middle of the night, and you’re walking around the forest searching for sleeping lizards in the trees. You’re probably wearing a headlamp, so the bugs are flying around your face, and your eyes start to strain as you get sleepy and you’re entering hour three or four of the search. This searcher fatigue could lead to the kinds of unintentional bias that can interfere with our research. But there’s good news when it comes to anoles, as Amy Yackel Adams, a statistician with the USGS in Fort Collins, Colorado, reported on the last day of JMIH.

Dr. Yackel Adams works with a Rapid Response Team whose goal is to prevent the spread of the worst invasive species. When a report came in of a sighting of a brown tree snake on the island of Saipan (in the Northern Mariana Islands, western Pacific Ocean), the team of experienced herpers deployed to Saipan and began intensive nightly surveys to assess the possibility of a brown tree snake population there. Luckily, they didn’t find any of these snakes in the surveys, but they did log 20,000+ sightings of other vertebrates! These included emerald tree skinks, several species of geckos, a variety of small mammals, and the green anole (Anolis carolinensis). Dr. Yackel Adams saw an opportunity to use this rich dataset to statistically test for two types of bias that could occur in such surveys – searcher fatigue (both across the 4-hour nightly searches, and across the up-to-31 day deployment), and searcher bias in taxon detection.

The team of 29 searchers covered a total of 387 km of transects during the 31 days, and found a total of 5,800 sleeping green anoles during this time. (Wow!!) In terms of short-term searcher fatigue, there was a slight decrease in tree skink and mammal sightings as the night progresses, and gecko sightings were generally stable over the night, but far MORE green anoles were sighted in the later hours of the night. And over the long term, skinks and anoles were MORE likely to be detected the more nights a searcher worked, and there was no evidence of long-term searcher fatigue. So, that’s why my take-home message was “nobody gets tired of looking for anoles!”

There was, however, significant taxonomic bias among the searchers – for example, the skink-to-anole sighting ratios ranged from 0.86 to 9.5. Dr. Yackel Adams concluded that this type of bias could be a real problem for certain kinds of studies, and we should be aware that differences among sightings by our survey team members could be potentially problematic in statistical analyses.

JMIH 2017: Brown Anoles Thrive under Artificial Night Light

By mjohnson216

On July 17, 2017

In New Research

Chris Thawley presents at JMIH 2017.

For most of the history of life on earth, the only sources of light at night were the moon and stars. Yet with the invention and rapid spread of electric light, species around the world now face a novel evolutionary pressure: artificial light at night, or ALAN. Artificial light likely has an especially strong effect on animals in city habitats, such as the urban-adapted brown anole lizard, Anolis sagrei. Chris Thawley and Jason Kolbe at the University of Rhode Island set out to determine whether brown anoles were negatively impacted by ALAN.

In addition to their abundance in urban environments, brown anoles are a particularly good species for this study. Previous studies of brown anoles have shown that photoperiod influences the onset of reproduction at the beginning of the breeding season, and that several behavioral traits change under artificial light. In addition, work by Moore and Menaker has shown that pineal production of melatonin in this species is significantly altered by photoperiod. So, would ALAN influence brown anole growth and reproduction?

Chris and Jason collected lizards from south Florida and set up a lab experiment where some lizards experienced a normal photoperiod, and others were exposed to ALAN that mimicked landscape lighting. Their results were quite unexpected! ALAN actually increased female growth, resulted in eggs laid earlier in the season, and increased the reproductive output of small females – but did not affect the number or mass of eggs or hatchlings. And, ALAN females did not exhibit more stress (measured via circulating corticosterone) than control females.

So are brown anoles just superlizards? Do they have no trade-offs that result from ALAN? Chris suggested that it’s possible that such trade-offs may appear in studies over a longer time period, or in traits not measured here. Or, perhaps ad libitum food and the absence of predators in the lab remove the costs of ALAN. Or, maybe these really are indefatigable lizards!

JMIH 2017: Costa Rican Anole Ecology

By mjohnson216

On July 14, 2017

In New Research

Greetings from Austin, Texas, and the Joint Meeting of Ichthylogists and Herpetologists! Chris Thawley and I have appointed ourselves to be your AA reporting team from JMIH, and we’re aiming to post updates from each of the 8 anole talks and posters at this meeting.

Brian Folt

On the first day of the conference, there were two exciting talks on the ecology of Costa Rican anoles. The first was by Brian Folt, a graduate student in Craig Guyer’s lab at Auburn, who developed a model of predator-prey co-occurrence where one of the prey were anoles (Anolis (Norops) humilis) and the predators were…spiders?! Yes, wandering spiders, or ctenids, can prey upon the small anoles on the forest floor. (The other putative prey were poison dart frogs, who have a relatively similar life history to anoles.) Brian performed an extensive field study in 14 plots at La Selva Biological Station, conducting visual encounter surveys for anoles, frogs, and spiders, and recording arthropods in leaf litter samples. He used two-species occupancy models to determine how prey were affected by the presence of the predator and by resource abundance in the leaf litter. The result? Anole occupancy was lower where spiders were absent, and the detection probability of anoles was higher when spiders were present and detected. This suggests that anoles are responding behaviorally, such that they may increase their vigilance when predators are around.

Michelle Thompson

I then ran across the conference center to catch the next anole talk – a terrific presentation by Michelle Thompson, a graduate student in Maureen Donnelly’s lab at Florida International University. Michelle studied whether thermal quality differed across the stages of forest succession, and how that affected Anolis (Norops) humilis and A. (N.) limifrons distributions. She worked across transects of pasture, secondary forest, and old growth forest in both upland and riparian sites. Michelle measured the thermal quality of each habitat, the thermal preferences of the lizards, and the location and abundance of the lizards. She found that thermal quality was lowest in the pasture sites, as temperatures were frequently higher than the lizards prefer. Yet, in these pasture sites, riparian habitat with remnant trees provided a thermal refuge for the lizards. This kind of work can help us understand why and how species may respond differently to human-caused alterations in habitat structure and temperature in our changing world.

Stay tuned for updates from JMIH, and follow the #JMIH17 hashtag on twitter for more herp-related news!

Where Are All the Green Anoles?

By mjohnson216

On July 6, 2017

In All Posts

For the past eight years, my lab has conducted intensive research on green anoles (Anolis carolinensis) in Palmetto State Park in Luling, Texas, about an hour east of San Antonio. This park is beautiful – it’s centered around a swampy area dominated by dwarf palmettos (Sabal minor), and the San Marcos River flows through it. We’ve marked lizards and mapped their home ranges, watched their behavior, measured their morphology and parasite loads, and so much more. In past years, we’ve calculated that the density of green anoles in the park is approximately 0.04 lizards/m², or about four adult lizards in every 10m x 10m area. We could regularly get sample sizes of around 150 lizards for behavioral studies in the park, but we very rarely collected animals from the park – we left them where we found them!

But this year is different. On three field trips to the park this summer, we have found very few green anoles. On our first visit this year in May, we spent 16 person-hours searching for lizards and found four green anoles. On our second visit in early June, we spent 14 person-hours searching and found eight. Last week, we spent another 12 person-hours and found only two. We see green anoles all over the city of San Antonio, and the students in my team are all skilled lizard spotters and catchers, so this isn’t due to inexperience. Also, we see other species of lizards all over the park – most commonly, Texas spiny lizards, little brown skinks, and house geckos– as well as garter snakes, copperheads, and cottonmouths. We also see tons of frogs.

Garter snake eating a tree frog, at Palmetto State Park. Other herps are thriving there!

So what happened to the anoles? We’ve considered a number of possibilities. The first thing we thought of was the possibility of feral cats – but we haven’t seen any cats in the park, and we think cats should have the same effect on the other herp species. What if the insect population had crashed? But again, that would affect the other lizards, snakes, and frogs too. This isn’t a year of particular drought or excess rain (and in previous wet and dry years, we’ve still seen lots of anoles), and the vegetation throughout the park largely looks the same as it has in the past. Perhaps an anole-specific disease has spread through this population?

In any case, the paucity of anoles in the park this year suggests that there won’t be many next year either, as there’s almost no one around laying eggs. It’s a bummer, because we’ve had such success here in the past.

Any ideas to explain this, AA readers?

Work we’ve published from our previous research in Palmetto State Park:

Dill, A.K., T.J. Sanger, A.C. Battles and M.A. Johnson. 2013. Sexual dimorphisms in habitat-specific morphology and behavior in the green anole lizard. Journal of Zoology 290: 135-142.
Battles, A.C., T.K. Whittle, C.M. Stehle, and M.A. Johnson. 2013. Effects of human land use on prey availability and body condition in the green anole lizard, Anolis carolinensis. Herpetological Conservation and Biology 8: 16-26.
Bush, J.M., M.M. Quinn, E.C. Balreira, and M.A. Johnson. 2016. How do lizards determine dominance? Applying ranking algorithms to animal social behavior. Animal Behaviour 118: 65-74.
Stehle, C.M., A.C. Battles, M.N. Sparks, and M.A. Johnson. In revision. Prey availability affects territory size, but not territorial display behavior, in green anole lizards. Acta Oecologica.

Metabolism Rate Data on Anoles?

By mjohnson216

On July 4, 2017

In New Research

I’m hoping that some of you out there have been collecting Basal Metabolic Rate or Resting Metabolic Rate data on Caribbean anoles!

I’m working with a group of scientists on a large-scale comparative database on circulating hormones in free-living vertebrates – we call our collaboration HormoneBase – and we’re hoping to look at relationships between hormone levels and metabolism. (We’ll be presenting some of this work at the Society of Integrative and Comparative Biology meeting in January 2018 – check out our symposium announcement here!) We have a good list of anole species in the database, thanks to the work of Jerry Husak and Matt Lovern (2014), but it seems that very little metabolism rate data are available for these species. Do you know of such data, or do you have them – published or unpublished? If so, please contact me (mjohnso9@trinity.edu)!

Reference:

Husak JF and MB Lovern. 2014. Variation in steroid hormone levels among Caribbean Anolis lizards: endocrine system convergence? Hormones and Behavior 65:408-415.