Tag: ALAN

Nighttime Day Geckos! You Never Know Where (or When) Phelsuma Are Going to Show up

New natural history note: “Nocturnal foraging and activity by diurnal lizards: Six species of day gecko (Phelsuma spp.) using the night‐light niche”.

A set of observations, recently published in Austral Ecology, noted six different species of day gecko (Phelsuma spp.) using artificial light at night (ALAN) to engage in nocturnal activity (e.g., foraging, courtship, and agonistic behavior). Lizards of this genus are widely believed to be primarily diurnal, however, their propensity to colonize both urban and highly-modified habitats, as well as establish invasive populations within novel landscapes, suggests they are a taxon that is quite flexible and adaptable.

A blue‐tailed day gecko, Phelsuma cepediana, foraging for insects under a fluorescent light in Mauritius. Photo credit J. L. Riley.

Remind you of any other small- to medium-sized adaptable and diverse group of lizards?

Keen readers of the Anole Annals will recall several posts about the effect ALAN can have on anoles, including its impact on physiological stress, metabolism, invasive potential, and reproductive output. With many accounts noting the costs and benefits of shifting diel cycles and daily activity period, but also the general impact light pollution may have. No doubt, there remains a lot of research potential to examine similar questions for the many Phelsuma species across their native and invasive ranges.

Reunion ornate day geckos, Phelsuma inexpectata, engaging in nocturnal activity under a fluorescent light inside a bathroom in Manapany-Les-Bains, Reunion (A,B), including courtship behavior (C). Photos credits C. Baider and F.B.V. Florens.

It is always worth keeping your eyes peeled in the field.

The observations that led to this note came from nine researchers working in various sites, locations, and projects across a number of archipelagos spanning the Indian Ocean and over several years. As with many natural history observations, most of these accounts began with a researcher – who was no doubt occupied with an entirely different task – seeing something out of the ordinary, snapping a picture and jotting down some quick details, and carrying on with their work. A great reminder to never leave home without your trusty notebook; digital or otherwise. Then later on, sometimes much later, this information regarding “something weird you saw” is shared between colleagues, sometimes met with an “oh ya, I saw that too, different species, different location, but the same thing,” and from there, patterns emerge and collaborations bear fruit.

Over the years, Anoles Annals has featured a number of posts related to day geckos, with some keener anolologists expressing the feeling that these colorful, charismatic, and adaptable geckos could be seen as “honorary anoles.” A compliment, surely, the geckos would appreciate and reciprocate toward anoles, if given the chance. Despite their stunning appearance, long history of public awareness, and ability to sell car insurance, there remains a lot of information we do not know about day gecko behavior, biology, and ecology. We hope this natural history note will prompt further research interest into this enigmatic group of lizards.

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.

SICB 2020: Artificial Light Keeps Green Anoles Hungry!

There are so many great anole talks at SICB 2020, I’d be remiss if I didn’t take this opportunity to shed some light on some of our fantastic undergraduate researchers, who turned out in force to Austin this year! As I’m sure Dr. Kristin Winchell will tell you, anole lizards make awesome model organisms for studying the effects of city life and urbanization on wildlife.

Cities can be dangerous though. A lot of different urban environments will present wildlife that have not lived in cities with numerous pressures they might not have faced before, such as different surfaces and substrates on which to run, different temperatures, and even new predators. One of the relatively new pressures that goes along with city life is light at night, and artificial light to boot. If you’ve ever been too disturbed by light during the moonlight hours to sleep and rest, imagine how small lizards feel!

To address the effects of this pressure on green anoles (Anolis carolinensis), Michelle D’Alessandro, an undergraduate student at the University of Scranton working in the lab of Dr. Chris Howey, measured the effects of artificial light at night (I’m just going to call it ALAN) They exposed anoles to ALAN and described the effects of artificial light on metabolism in green anoles. Initially, they did not find any differences between metabolic rates when lizards were exposed to ALAN, however after a sufficient time period, anoles exposed to ALAN increased their metabolic rates during the evening, but not during the day! During this experiment, they also found that ALAN anoles were far hungrier and ate more often than lizards that weren’t exposed to light at night. The term ‘midnight snack’ definitely comes to mind here! Michelle suggests that much like when humans get exposed to changes in sleeping patterns, anoles undergo some energetic changes, causing them to eat more and having to burn more energy. Maybe next time think twice about keeping that porch light on during the waning hours of the evening- give the wildlife some much needed rest.

JMIH 2018: How Does Artificial Light at Night Affect Anoles?

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.

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