There is much talk these days about how human land use (e.g. urbanization) impacts wildlife. Although anoles have often taken center stage in this discussion (Winchell et al. 2016; Tyler et al. 2016; Chejanovski et al. 2017; Lapiedra et al. 2017; Winchell et al. 2018), most of this work has focused on measuring phenotypes of adult males. Very little work has been done to understand how massive habitat alteration impacts early life stages even though we know that these stages are extremely sensitive to environmental disturbance and have the potential to impact population dynamics (Carlo et al 2018). Embryos are particularly sensitive to changes in the environment because they lack the ability to respond to unfavorable conditions by adjusting their behavior (i.e., they can’t run away). Since the 1980’s, we’ve known that egg mortality can have massive effects on population densities and even determine how these densities cycle from year to year (Andrews 1982; Andrews 1988; Chalcraft and Andrews 1999). Still, comparatively little attention is given to embryo development and egg survival when considering how habitat alteration impacts species.
In a newly published paper (Hall & Warner 2018), we sought to understand how extreme ground temperatures in cities and suburbs (i.e., the urban heat island effect) influence patterns of embryo development. Due to a lack of canopy cover (i.e., trees) and an abundance of heat-absorbing surfaces (e.g., concrete), cities and suburbs tend to be much warmer than adjacent forested areas, and this means nest temperatures are higher in urban and suburban areas compared to adjacent forested sites (Tiatragul et al. 2017). Warm temperatures often have positive effects on embryo development; however, extremely warm temperatures can cause mortality and even slow developmental rates (Sanger et al. 2018).
Figure 1. An overview of our experimental design to understand how urban incubation regimes impact embryo development and survival. Eggs from both forest and city populations were factorially distributed into forest and city incubation treatments. At approximately a quarter of the way through development, some eggs were exposed to a spike in temperature measured from the field (either 39 or 43 °C peak). Eggs completed development at their assigned incubation profile (city vs. forest) and hatchling growth and survival were monitored in the lab for three months.
Crested Anole (Anolis cristatellus) under a leaf. Photo by Chris Thawley.
Conservation biologists have long been concerned about the effects of human development on species and environments. Urban habitats can significantly change lighting patterns for animals by increasing nocturnal ambient illumination. Artificial light at night (ALAN) has the potential to disrupt an organism’s physiology, behavior, and ecology. However, light pollution remains poorly studied and is a concern for urban herpetofauna.
Anolis lizards in Miami, Florida are a great system to study the effects of ALAN on behavior, health, reproduction, and survival. Anoles are diurnal and are adapted to a distinct photic habitat appropriate to their sun/shade preferences. However, many anole species have been observed active at night where artificial lights are prevalent. So, what are the effects of ALAN on anole fitness?
Chris Thawley, a postdoctoral researcher in the Kolbe Lab at the University of Rhode Island, is interested in whether ALAN imposes selection on anoles and how they might adapt to these pressures. Chris conducted a field experiment introducing landscape lightning into a previously unlighted habitat within an urban matrix. For over two months, he assessed whether Brown Anoles (Anolis sagrei) and Crested Anoles (A. cristatellus) experienced higher levels of ALAN at their sleeping perches and if these lizards behaviorally avoided exposure to artificial light. Also, lizards were marked and followed to determine if light exposure impacted survival, growth, body condition, and physiology.
Chris found that A. sagrei and A. cristatellus lizards are not behaviorally avoiding ALAN at night. Anoles that were more exposed to artificial light had lower glucose levels compared to those that were less exposed. Also, there were no dramatic changes in reproduction, but ALAN reduced follicle size. Egg mass showed a positive relationship with snout-vent length (SVL) in lizards exposed to ALAN, which suggests that ALAN increases egg mass in larger lizards. Chris continues analyzing growth and survival data and aims to explore if there is a correlation between levels of corticosterone (CORT), melatonin, and glucose.
Trophic ecology deals with questions about the ways in which organisms acquire energy and how that process interacts with the communities and ecosystems surrounding them. Anole-focused research has played a strong role in our understanding of trophic ecology and ideas abut how communities come together and evolve, particularly in papers by Schoener, Roughgarden, and Lister. However, many trophic ecology studies have focused on specific communities or locations and haven’t dealt with how the ecology of one focal species varies across space and as a function of the presence of other close competitors.
Sean Giery, a post-doc at the University of Connecticut, in collaboration with James Stroud, a post-doc at Washington University in St. Louis, worked to address this gap in our knowledge by studying how the trophic ecology of the brown anole, Anolis sagrei, varies across its range. Brown anoles are voracious predators of insects, known to chow down on a diverse range of arthropods, including some of surprising size. Since the brown anole is also a prodigious invader, it occupies habitats with a variety of potential competitors, including locations with few competitors. Sean and James leveraged this situation to their advantage by compiling stomach content data from previously published papers (including a follow-up on Lister’s paper above). They also added their own sampling, including in Southern Florida, the Bahamas, and Hawaii…tough work! Sean and James then used the articles themselves, field guides, and citizen science sources like iNaturalist to determine the presence of other species which might compete with the brown anole, including other anoles and diurnal, insectivorous lizards.
Sean and James assembled an impressive database of the diet of A. sagrei.
They found that as community richness increases, the dietary niche of A. sagrei actually becomes broader, the opposite of the direction predicted by theories of ecological release. Additionally, average niche overlap between individual anoles declines as community richness increases. When only brown anoles are present in a community, individuals are highly similar in the types and proportions of what they eat, another finding which runs counter to models of how niche breadth should vary when a species is released from interspecific competition. Sean concluded his talk by suggesting that interference competition may be more important than generally recognized and soliciting suggestions for ways to continue looking at this impressive dataset. We’ll look forward to reading the paper!
It’s June. It’s orchid flowering season in Grand Cayman. And with nods to #Anole March Madness and #MammalMadness it’s the opening round of the 2018 ANOLE WORLD CUP. #ANOLEGOOAAAAALLLL!!!!
Home Team – Anolis conspersus – against – Away Team – Anolis sagrei
During one recent afternoon’s field work, I heard an unusual noise in the botanical garden I was working in: a sound like someone crunching and crinkling a foil potato chip bag. Tracing the sound from about 20 feet away, I did not find a snacking plant enthusiast, but rather a young Knight Anole (Anolis equestris) in survey posture who had apparently just snagged a large dragonfly out of mid-air. The anole chowed down on its prey while keeping a weather eye on me and conducting a few half-hearted displays to let me know it was aware of my presence. As the anole continued to masticate its rather large afternoon meal, it moved to a higher perch away from the prying eyes of this anolologist.
The dragonfly, a Regal Darner (Coryphaeschna ingens), is a common species in the southeastern United States and an accomplished aerial predator. It was also more than a mouthful for this young knight, which had to chew with its mouth open for over four minutes (and still wasn’t finished when it escaped my view); quite the prey handling time! And yet more evidence that this largest of anole species is willing to take a chance on any prey item that might fit into its maw even if it takes a little work.
History is rich with great rivalries; David versus Goliath, Red Sox versus Yankees, Alien versus Predator, but one of the greatest match ups of our time is anole lizards versus gecko lizards. For readers of this blog that are unfamiliar, for which I assume there are few, geckos and anoles are well matched competitors because of their morphological and ecological similarities. Geckos (infraorder Gekkota) are the earliest branch on the squamate tree (sister to all other lizards and snakes) with over 1500 species around the globe, whereas anoles (genus Anolis) appeared roughly 150 million year after the origin of geckos (nested within the Iguania infraorder). The roughly 400 species of anoles can be found primarily in Central and South America. Geckos and anoles both independently evolved very similar hairy adhesive toe pads that help them adhere to and navigate vertical and inverted surfaces. While anoles can likely trace their toe pads to a single origin (and one loss in A. onca), toe pads likely arose and were lost multiple times within Gekkota, although we are still sorting out the exact details (Gamble et al., 2017). Nearly all anoles are arboreal and diurnal, with only a handful of terrestrial or rock dwelling species. Conversely, geckos can be found thriving in arboreal as well as rocky and terrestrial microhabitats day and night.
While anoles tend to get all of the attention from evolutionary ecologists, with decades of amazing research quantifying their habitat use in the Caribbean, geckos are actually older, with more ecological and morphological diversity. As my prior PhD advisor Luke Harmon can surely confirm, I have been interested in knowing how or if insights from Caribbean anole ecomorphology can be applied to geckos. How similar is the evolution and diversification of geckos and anoles? Do geckos partition their habitat along similar dimensions as Caribbean anoles?
In this post, I’d like to share some of my previous work comparing and contrasting gecko and anole diversification and habitat use and then solicit information and opinions from the anole community for an upcoming field trip in which we will be looking at habitat use of sympatric introduced geckos and anoles.
Fig 1. Our reconstruction of gecko (blue) and anole (green) ancestral toe pad performance based on our best fitting weak OU model of trait evolution. Horizontal bars below the X-axis represent the region in which we constrained the origin of toe pads for each clade. Detachment angle (y-axis) represents our measure toe pad performance (the maximum ratio of adhesion and friction a species can generate). The generation of more adhesion for a given amount of friction results in a higher detachment angle. Shaded bands represent our estimated OU optimum value for each clade. Figure modified from Hagey et al. (2017b).
In 2017, we had two great papers come out investigating the diversification of toe pad adhesive performance in geckos and anoles, and the ecomorphology of Queensland geckos. In our diversification paper (Hagey et al., 2017b), we found that while geckos are an older and larger group than anoles, their toe pad performance does not appear to be evolving towards a single evolutionary optimum. Instead, we found that Brownian motion with a trend (or a very weak Ornstein-Uhlenbeck model) best modeled our data, suggesting geckos have been slowly evolving more and more diverse performance capabilities since their origin approximately 200 million years ago (Fig 1). These results assume a single evolutionary origin of Gekkota toe pads, which was supported by our ancestral state reconstructions, but ancestral state reconstructions are far from a perfect way to infer the history of a trait. And so for now, the true history of the gecko toe pad’s origin(s) remains a ‘sticky’ issue. Conversely, adhesive performance in anoles appears to be pinned to a single optima in which anoles quickly reached after their split from their padless sister group (i.e. a strong Ornstein-Uhlenbeck model, Fig 1).
Given these results and the fact that geckos are such a morphologically diverse group, living on multiple continents in many different microhabitats, our results suggest the adhesive performance of geckos may be tracking multiple optima, and when pad-bearing geckos are considered together as a single large group, could produce the general drifting pattern we observed when we assume their ancestor started without little to very poor adhesive capabilities. On the flip side, we can imagine multiple reasons why anoles appear to be limited in their toe pad performance. Perhaps anoles lack the genetic diversity to produce more variable toe pads or they are mechanically or developmentally constrained to a limited area of performance space. Alternatively, since anoles are nearly all arboreal and diurnal in new world tropical environments, it is possible that they are all succeeding in the same adaptive zone and there isn’t the evolutionary pressure or opportunity to evolve more diverse performance capabilities. Closer studies of the adhesive performance capabilities of the few anoles species that have branched out from arboreal microhabitats, such as the rock dwelling aquatic species would be really interesting!
Fig 2. Our gecko and anole residual limb length calculations suggest geckos (grey triangles) generally have shorter limbs then anoles (black circles). Figure modified from Hagey et al. (2017a).
In our second paper from 2017 (Hagey et al., 2017a), we quantified microhabitat use and limb lengths of geckos across Queensland, Australia and compared these patterns to those known from Caribbean anoles. We found some interesting differences and similarities. Our first result arose as we tried to calculate residual limb lengths and realized that geckos, as a group, have shorter limbs than anoles, which resulted in us calculating residual limb lengths for geckos and anoles separately (Fig 2). We then compared microhabitat use and limb length patterns and found that Strophurus geckos may be similar to grass-bush anoles. Both groups have long limbs for their body lengths and use narrow perches close to the ground. We also found other general similarities such as large bodied canopy dwelling crown-giant anoles and large bodied canopy dwelling Pseudothecadactylus geckos. Unfortunately, we didn’t focus on sympatric Australian geckos and so we couldn’t make direct habitat partitioning comparisons to anoles. We hope to fix that in our next project and would really love to hear from you, the anole community.
Later this spring, I am planning a fieldtrip with John Phillips and Eben Gering, both fellow researchers here at Michigan State University, to Hawai’i (Kaua’i and O’ahu) to investigate habitat partitioning of invasive geckos and anoles, specifically A. carolinensis, A. sagrei, and Phelsuma laticauda. Jonathan Losos one claimed that Phelsuma are honorary anoles! These three species are all diurnal, arboreal, have adhesive toe pads, and are commonly seen in Hawai’i and so we expect them to be competing for perch space. This has been on some of the greatest anole minds since at least 2011 with Jonathan wondering which group would win when the two clades collide in the Pacific. Previous studies of anole ecomorphs across the Greater Antilles and invasive A. sageri in the southeastern US give us a good expectation of how the trunk-crown A. carolinensis and the trunk dwelling A. sagrei should interact and partition their arboreal microhabitat, with A. sagrei pushing A. carolinensis up the trunk. The wild card is P. laticauda. There hasn’t been much microhabitat use work done with Malagasy geckos, and definitely nothing compared to the extensive work with Caribbean anoles. As a result, I don’t know much about exactly what part of the arboreal environment P. laticauda uses in its natural range or how it will fit in with its new pad-bearing brethren in Hawai’i. The best information we have to my knowledge is a study of other arboreal Phelsuma by Luke Harmon in Mauritius (Harmon et al., 2007). He found that while the Phelsuma geckos of Mauritius also partition their arboreal habitat by perch height and somewhat by diameter, they also partition by palm-like or non-palm-like perches. I’m not aware of any anole observations suggesting a palm/non-palm axis of partitioning and so this may be a novel axis that P. laticauda is using in Hawai’i to live in amongst the anoles.
Anoles, geckos, and Hawai’i have come up repeatedly here on Anole Annals
and so we know folks have been thinking about these species and specifically this invasive set of species for a while. We are especially excited to see Amber Wright’s research suggesting P. laticauda was perching above A. carolinensis in her enclosures. We want to know what the anole community has to say. We also don’t want to duplicate or intrude on any projects that are already under way.. If this is something you’ve already started, or started to wonder about… let us know! We would love to collaborate, partitioning interesting questions, if there are already labs working in this arena. We would also be grateful for suggestions, field site recommendations, or relevant publications we may have missed.
A friend of mine sent me the above for identification.
“Anole” I quickly responded, then followed up with, “where are you?” I was shocked by the answer – in New York City! Turns out this little lizard most likely hatched out of a plant purchased about a month ago and quickly made itself at home the New York City apartment of a Fordham graduate student. Look’s like our good friend Anolis sagrei to me, but figured I’d put it to the Anole Annals readers to verify.
The plant in question (pictured below) was purchased at a tropical plant store in Manhattan. Is this the beginning of a northeast anole invasion? Probably not. Winters in NYC are likely too cold for any of its hitchhiking friends to survive. But then again, this isn’t the first time an anole has stowed away to the northeast (check out this salad anole featured previously on AA) and Boston is now home to Italian Wall Lizards (Podarcis siculus)… So who knows!
Anolis garmani, the Jamaican giant anole; Miami-Dade county, Florida (11 June 2016, Nikon D7100).
Every year, I try to get down to south Florida at least a couple of times to stomp around for non-native anoles and other lizards. To date, I’ve only managed to find and photograph three Jamaican giant anoles, Anolis garmani, in south Florida — three individuals over two specific visits to the Miami-Dade area. The first two were in June of 2016, and the third (and largest) was in August 2017. The garmani featured here was the second wee giant from that first visit.
I’d been anxious to photograph garmani for quite some time, and we (James Stroud, Eric-Alain Parker, and myself) were more than a little jazzed to get our hands on both of those garmanis. A. garmani was quite high on my holy-grail list for south Florida non-natives, and, whereas this garmani may have been lacking in the “giant” aspect, it certainly didn’t lack in its color play. The lead image above through the following three profile shots were all taken within the span of two minutes (1:26pm through 1:28pm):
When we first spotted this particular wee giant biding its time in the plenty of existence, it was sporting the familiar bright emerald green:
Minutes later, in hand and not too thrilled about its potential lifespan outlook, the colors shifted quite dark…
…and then, more comfortably, back to a more-emerald green base:
Looking down from above, it had a fairly typical anole head from a central Floridian’s perspective…
But looking up from below? An extremely awesome speckled circus of contrast and patterning:
Yeah, this was one hell of a lizard to get to work with. Actually, all three of them were. I’ll save the bulk of photographs for the other two individuals for a future time, but for quick reference, here’s a single shot of each:
This is the first individual we found on June 2016:
And here’s the much-larger male Eric and I tracked down (and almost caught) in August 2017:
Figure 1. Knight anoles (Anolis equestris) are large, arboreal, and highly frugivorous lizards native to Cuba and introduced to Miami, Florida in the mid-20th century. This adult female was found perched on the trunk of a strangler fig (Ficus aurea) in Miami, Florida, a common sight in south Florida. Strong jaws and a large gape enable knight anoles to consume a range of large food items including snails, locusts, small vertebrates (occasionally), and some moderate-sized fruit. Photo by S. Giery.
I remember the first knight anole (Anolis equestris) I ever caught. Details about how I caught it are gone, but I certainly remember the resulting bloody thumb. I was impressed and intrigued by the force and stamina of its bite – I needed to study this critter (fig. 1). Motivated by the recent publication of a short paper on knight anole diets, below, I break down a few years of research into the trophic ecology of the knight anole into a brief recount of what my collaborators and I have found.
Preliminary observations on knight anole trophic ecology
Following that first encounter I conducted a simple study of anole diet and habitat use around the Florida International University (FIU) campus in North Miami. In general, the findings showed some sensible results: Cuban brown anoles (A. sagrei; trunk-ground) perched low and ate a wide variety of terrestrial insects, Hispaniolan bark anoles (A. distichus; trunk) skittered up and down the trunk and ate – almost exclusively – ants, and Cuban knight anoles (A. equestris; crown-giant) ate larger food items than the other two species and tended to stay in the canopy (Giery et al. 2013). Again, this pattern of diet and habitat use was expected except for one thing – the composition of knight anole diet. Prior to embarking on the study, I had expected, based on their large size, strong bite force, the abundance of smaller anoles, and a few anecdotal accounts, that these powerful lizards would be eating lots of anoles. Surely these were the T-Rex of the trees and their direct interaction with other anoles was a predatory one. Yet in all the knight anoles that I dissected in this first study (n =21), not a single one contained vertebrate remains. Instead, nearly half of the diet (by volume) was fruit, specifically strangler figs (Ficus aurea; look to Supplemental table 1 for summary diet data). Our stable isotope data corroborate these observations – rather than the enriched 15N signature we‘d expect from an anole predator, the isotope data suggested similar trophic levels for brown, bark, and knight anoles. So what gives? Where was the evidence for a swaggering, arboreal meat-a-saurus?
Years later, James Stroud and I assessed the stomach contents of more knight anoles (n = 10) from a different site in Miami (Fairchild Tropical Botanic Gardens. James had directly observed knight anoles eating three different species of anoles there (1,2,3,4) and so we thought another look at their diet would be interesting. Once again, the majority of gut contents consisted of fruit, this time from royal palm trees (Roystonea regia). In fact the only evidence for vertebrate prey in this population was a 1 cm section of green anole tail. These data supported earlier observations (Brach 1976; Dalrymple 1980, Giery et al. 2013) demonstrating that fruit is a major component of knight anole diet, and vertebrates aren’t. It seemed that the canopy superpredator role I’d imagined for knight anoles was increasingly less likely. In fact, in all three previous examinations of knight anole diet, few instances of vertebrate predation by knight anoles are observed (table 1). The evidence spoke, knight anoles were sharp-toothed, veggie-sauruses with a deliberate, powerful bite.
An opportunity presents itself
Understanding the trophic ecology of anoles has been an ongoing project of mine for some time, the paper that we’ve just published in Food Webs (Giery et al. 2017) would not have come without the serendipitous post-capture … deposition … of a few seeds. An adult male passed two royal palm seeds which were planted post-haste in the greenhouse at FIU. It took a few months but the seeds eventually geminated, demonstrating that seeds consumed by knight anoles are viable and suggesting a role as seed dispersers (fig 2).
Figure 2. Adult knight anoles (Anolis equestris) often inhabit the crowns of royal palms (Roystonea regia) in Florida and Cuba. Note the numerous ripe fruits above this displaying male photographed at our study site in Coral Gables, Florida (A). Roystonea regia seedlings resulting from seeds passed naturally by a wild-caught A. equestris. Both seeds were planted at the same time, but germinated nearly 130 days apart (B). Adult royal palms can reach 30m high and are an ecologically and economically important plant throughout their range (C). Photos by J. Stroud (A & B) and S. Zona (C).
We felt that these data filled an important gap in our understanding of how anoles interact with other species. Certainly, the literature (e.g., Herrel et al. 2004; Losos 2009) and our data from Florida (Giery et al. 2013, 2017), Bermuda (Stroud, unpublished), and The Bahamas (Giery, unpublished) show that frugivory is widespread and sometimes quite common in anoles. Yet, the fact that seeds remain viable after passing through the guts of anoles presents a new facet to their interactions with plants. For more about what we know about lizard-plant interactions go ahead and check out the references in our paper (there’s good stuff from Europe, and recently, the Galapagos).
Whether the interaction we illustrate in our paper is ecologically important (i.e., increasing germination rates via ingestion and/or dispersal) requires substantially more study. Yet, the relationship between knight anoles and royal palms has been noted for nearly a century in Cuba suggesting their interaction is more widespread than just Florida. For example, Barbour and Ramsden (1919) remarked on the frequent coexistence of royal palm and knight anoles in Cuba. Interestingly, these early works often focused on the potential consumption of vertebrate prey, despite reports from Cubans that knight anoles often ate fruit – a bias matching my own preconceptions about the nature of this great anole:
“As to the food of the great Anolis [equestris] we know but little; it is surely insectivorous and Gündlach records that he once heard the shrill scream of a tree frog Hyla and found that it had been caught by one of these lizards. The country people all declare that they feed largely upon fruit, especially the mango; it is not improbable that this idea arises from the fact that they are frequently found in mango trees. We have always imagined that this circumstance was due in part at least to the excellent cover offered by the splendid growth of rich green foliage of the Cuban mango trees; it, however, has been seen eating berries (Ramsden). With good luck one may occasionally see two males of this fine species chasing one another about, making short rushes and charges at each other, accompanied by much tossing of heads and display of brilliant dewlaps When this mimic battle takes place about the smooth green top of the trunk of a stately Royal Palm, it is a sight not easily forgotten.” from Barbour and Ramsden 1919.
Anyways, we hope our short paper does two things. First, we hope that our summary of knight anole diet in Florida accurately illustrates their trophic ecology. Second, seed dispersal of native trees (royal palm and strangler fig) by an introduced vertebrate represents an interesting contrast to the negative effects usually attributed to introduced species (e.g., brown anole). We hope our observations highlight the diverse relationships between anoles and plants in the Caribbean region. Finally, we realize that our data are merely suggestive and effective seed dispersal by anoles has yet to be demonstrated. Nevertheless, we’re excited by the potential for new research directions stimulated by our observations.
Photograph was taken in Hahashima, Ogasawara Islands, by Hideaki Mori.
We would like to introduce our recent paper on the invasive green anole (Suzuki-Ohno et al. 2017). In Japan, the green anole Anolis carolinensis invaded the Ogasawara Islands in 1960’s and Okinawa Island in 1980’s. In Ogasawara Islands, A. carolinensis expanded its range and had a significant negative impact on native species and the ecosystem. This becomes a big problem since Ogasawara Islands are designated as a natural heritage.
On Okinawa Island, A. carolinensis was first captured in 1989 and it did not expand its distribution until more than 25 years later, although its density is extremely high in the southern region. In the northern region of Okinawa Island, Yambaru area, native forests are preserved so that it is important to avoid the invasive effects of A. carolinensis. Thus, It is important to determine whetherA. carolinensis has the potential to expand its distribution on Okinawa Island.
Phylogenetic analysis shows that the invader A. carolinensis originated in the western part of the Gulf Coast and inland areas of the United States. Interestingly, all of the invaded A. carolinensis in Ogasawara, Okinawa and Hawaii originated from the Gulf Coast and inland areas of the United States.
ND2 phylogeny using Okinawan, Ogasawaran, and Hawaiian populations in addition to haplotypes used by Campbell- Staton et al. (2012) and Hayashi et al. (2009).The major branches with high posterior probabilities of the Bayesian inference method (>0.99) are indicated in bold. The map was redrawn from Campbell-Staton et al. (2012). Cited from Suzuki-Ohno et al. (2017). Figure 2 of Suzuki-Ohno et al. (2017) lacks bold lines in error.
We used a species distribution model (MaxEnt) based on the distribution of native populations in North America to identify ecologically suitable areas on Okinawa Island. The MaxEnt predictions indicate that most areas in Okinawa Island are suitable for A. carolinensis. Therefore, A. carolinensis may have the potential to expand its distribution in Okinawa Island.
MaxEnt prediction of suitable areas for A. carolinensis in Okinawa Island according to the presence data for North America. Lighter and darker areas indicate high or low suitability, respectively. Points indicate the presence distribution of A. carolinensis. (a) prediction using all parameters, (b) prediction omitting mean diurnal range and precipitation of warmest quarter. Cited from Suzuki-Ohno et al. 2017.
The predictions indicate that habitat suitability is high in areas of high annual mean temperature and urbanized areas. The values of precipitation in summer in the northern region of Okinawa Island were higher compared with those of North America, which reduced the habitat suitability in Okinawa Island. Adaptation to low temperatures, an increase in the mean temperature through global warming, and an increase in open environments through land development will likely expand the distribution of A. carolinensis in Okinawa Island. We think that invasive anoles (A. calrolinensis and A. sageri) prefer open habitats.
Therefore, we suggest that A. carolinensis should be removed by using traps and/or chemicals. In addition, we must continue to be alert to the possibility that city planning that increases open environments may cause their range to expand.
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