Tag: urban

#DidYouAnole – Anolis aeneus


Photo: Mikel2500, iNaturalist

Happy Thursday!

Today’s anole is the Bronze anole, Anolis aeneus! The Bronze anole can be found on most of the Grenadines (the small islands between St. Vincent and Grenada) and Grenada itself, and has been introduced to Trinidad & Tobago and Guyana.

Bronze anoles can be found in forests and some urban environments, and is one of many anole species that also feed on plant matter (Simmons et al., 2005), like nectar and seeds. Males have an SVL of 77mm while females are 55mm.


Photo: Mark Hulme, iNaturalist

Though called the Bronze anole, not all individuals are brown/bronze; some may be greyish brown or olive and their mottled pattern may be light or dark. The dewlap of the Bronze anole is pale white or green and spots of orange or yellow may be near the front edge. They spend a lot of time in a ‘survey posture’ sitting on tree trunks surveying the habitat for prey items that may come along.

Hybridisation between A. aeneus and A. trinitatis (St. Vincent bush anole) has been found to occur, with the possibility of fertile offspring (Losos, 2009).


Photo: Mike G Rutherford, iNaturalist

SICB 2020: Artificial Light at Night Suppresses CORT Rhythmicity

Margaret McGrath at SICB 2020

If you look at a map of the United States at night, the urban areas are aglow with light pollution. Urban light pollution disrupts biological processes from gene expression to ecosystem composition across multiple taxa, including birds, insects, mammals, and fishes. With ever-increasing urbanization, understanding the effects of artificial light at night (ALAN) on organisms is crucial to future conservation efforts.

Margaret McGrath, an undergraduate in Dr. Christopher Howey’s lab at the University of Scranton, is examining the impact of ALAN on glucocorticoids in green anoles (Anoles carolinensis), which are commonly found in urban environments. Margaret specifically examined the impact of ALAN on the daily rhythmicity of corticosterone (CORT) and CORT responsiveness to an environmental stressor. She exposed green anoles to either a natural light-day cycle of 12 hours of light and 12 hours of dark or 24 hours of light. After six weeks of exposure, Margaret performed competitive immunoassays to measure baseline CORT levels at midnight and noon. Additionally, she measured CORT responsiveness after placing the green anoles in a bag for 30 minutes to simulate an environmental stressor.

Anoles not exposed to ALAN displayed an expected CORT daily rhythmicity with higher levels of CORT during the day than at night. Anoles exposed to ALAN lost this CORT rhythmicity and maintained CORT at a level intermediate to the other group. In contrast, ALAN does not appear to impact the anoles’ CORT responsiveness to environmental stressors. Her results suggest that green anoles exposed to ALAN are still able to respond to environmental stressors. However, there could be downstream effects from the loss of CORT rhythmicity because it has been linked to arrhythmic activity in mammalian studies.

In the future, Margaret plans to investigate if the natural CORT rhythmicity can be regained by anoles exposed to ALAN when placed back into a natural light-dark cycle. This future research can aid in determining the longevity of ALAN’s impacts on organisms. You can reach Margaret at margaret.mcgrath@scranton.edu and find more about her research on chowey.net, Dr. Howey’s website.

Living Large in the City: Impacts of Urbanization on Anoles

Brown anoles (A. sagrei) thrive in urban environments.

More and more research is highlighting how living in cities impacts the organisms that exploit urban habitats. Some research in anoles even highlights how organism may be adapting via evolution to these novel urban habitats!

However, we still don’t know much about how urbanization impacts reptiles, and anoles are a great group in which to study these effects. A large team from the Kolbe lab at the University of Rhode Island set out to tackle the question of how living in cities can impact anoles by studying populations of both brown (A. sagrei) and crested anoles (A. cristatellus) in urbanized areas in Miami and remaining natural areas within the urban matrix. The team included two undergraduates at URI, Amanda Merritt and Haley Moniz (currently a MS student in Chris Feldman’s lab at UNR ) who were key contributors to the project.
We caught lizards at 7 different sites in the Miami area and measured their morphology, thermal preferences, and parasite loads. This research was recently published in the Journal of Urban Ecology.

We found that for all groups of anoles studied (male and female brown anoles, and male crested anoles), lizards living in the urbanized habitats were larger (see figure below), but showed no differences in body condition, or how much body mass they had per unit length. Larger body size can be associated with increased fitness in anoles, so the larger size of urban lizards could represent an advantage for anoles living in cities.

Lizards from urban (blue) habitats were larger than those from natural (green) habitats.

Despite cities being known to have higher temperatures (the urban heat island effect), including at our study sites, we found no differences in the temperatures that lizards from urban and natural sites preferred. Our preferred temp values were in line with those found for native range populations of these species, which suggests that we are not seeing adaptation of preferred body temperature to the warmer conditions in very urban parts of Miami. This means that lizards living in cities could end up having higher body temperatures than they would prefer, a potential cost to using urban environments, though see Andrew Battles’ recent paper for a more detailed look at this issue!

Lastly, we examined the presence of parasites in the body cavities of these lizards. Most of the parasites that we found were nematodes in the digestive tract, though we also found some pentastomids, crazy crustacean parasites, in the lungs of crested anoles! We found no difference in the presence of parasites in lizards from urban or natural sites, although brown anoles did consistently have parasites more often than crested anoles. When we looked at parasite infection intensity, or the number of parasites in lizards that had them, we did see that brown anoles in urban habitats had significantly higher parasite loads than those in natural habitats. This result indicates that increased parasitism could be a cost of living in cities for anoles, though it may vary from species to species.

Crested anoles from both urban (blue) and natural (green) habitats have similar levels of infection intensity (number of parasites) to brown anoles in natural habitats, but brown anoles in urban habitats show significantly higher levels of infection intensity.

Overall, our work suggests that there may be advantages (larger body size) and costs (non-optimal body temperatures, higher parasite loads) for anoles living in cities, and that these may vary even between species that are quite similar ecologically. Anoles are an emerging study system in urban ecology, so stay tuned for what should be a fascinating variety of papers on city-loving anoles in the near future!

Christopher J Thawley, Haley A Moniz, Amanda J Merritt, Andrew C Battles, Sozos N Michaelides, Jason J Kolbe; Urbanization affects body size and parasitism but not thermal preferences in Anolis lizards, Journal of Urban Ecology, Volume 5, Issue 1, 1 January 2019, juy031, https://doi.org/10.1093/jue/juy031

JMIH 2016: Escaping in the City

2016-07-10 09.00.19

Kevin Aviles-Rodriguez, from the Revell lab at U. Mass. Boston, gave the second urban anole-themed talk of the meeting. Kevin presented his Master’s thesis work that he conducted with the Kolbe lab at U. Rhode Island in a talk titled, “Structural habitat alterations caused by urbanization influence escape behavior of a common lizard.”

Urban habitats are drastically modified and present novel resources and threats for animals that persist and utilize these spaces. Structurally, urban habitats have different types of surfaces that are smoother, broader in diameter, and often more vertically oriented (90° angle). Urban habitats also present abundant and novel food resources in terms of human food and insects attracted to lights and garbage. But with the abundance of food and novel niche space also comes an abundance of novel predators such as cats and dogs kept as pets.

Kevin wanted to know how Anolis cristatellus from San Juan, Puerto Rico and South Miami behaved in urban habitats compared to forest habitats when perceiving a predation threat. Although there are obvious costs of not escaping a predator successfully, there are also costs of fleeing when not necessary in terms of lost feeding opportunities and disrupted social interactions (mating, territory defense). Kevin wanted to know if the urban environment influenced escape behavior decisions. Specifically, he had two objectives: (1) To quantify escape behavior (squirreling, jumping, or sprinting) and how this relates to different types of perches found in urban areas. (2) To measure flight-initiation distance (FID), or how close one can approach an animal before it flees, to see if there are differences between forest lizards and urban lizards.

2016-07-10 09.07.18Kevin found that as perch diameter increases, the probability that a lizard will squirrel around a perch or sprint up the perch increased and the probability of jumping decreased. Interestingly, when he also looked at perch use, he found that the majority of lizards were using perches of thinner diameter where the probability of jumping was highest. Urban lizards also tended to use more isolated perches, which he defined as the number of nearby potential perches within 1 meter. When nearby perch density was lower, lizards tended to jump less – perhaps not all that surprising since they have fewer places to jump to. Kevin also found that escape strategy differed based on the type of perch used. In urban habitats, on trees and on metal posts lizards squirreled more frequently than they did in forest habitats. Interestingly, on cement walls (e.g. buildings) lizards did not jump at all and mainly sprinted to escape. 2016-07-10 09.10.05Kevin offered a few possible explanations for this trend. For one, building perches tend to be more isolated than trees and so it may simply be that lizards on these substrates have nowhere to jump to. A second possibility is that the lizards have trouble jumping from these perches since they are more vertical than the optimal angle for jumping (39-42°, Toro et al. 2003).

In his final analysis, Kevin found that flight initiation distance (how close you can get to the animal before it flees) was very short for animals perched on urban trees and metal posts. In fact, he commented that on some occasions he was able to get close enough to touch the lizard before it fled! This difference was significantly shorter than for animals perched on trees in the forest and for animals perched on painted concrete walls in the city.

Anole At My Door

I have extensively photographed Anole in an urban environment because they are so readily available here in south Florida literally outside my door and frequently indoors too. Despite the lamentations of displacement of the native Anolis carolinensis, they are frequently observed in my immediate area. I will present a few photos showing confrontations between the variety of West Indian Anole and the native green. Knight anole is also present, mostly juvenile as I do not observe fully grown specimens either because of adult movement to other areas or the wide variety of predators, mostly large birds. More about geckoes, basilisks and iguana will be posted in related forums.

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