Photo by Dave Welling.

New literature alert!

Heat hardening in a pair of Anolis lizards: constraints, dynamics, and ecological consequences

In Journal of Experimental Biology
Deery, Rej, Haro, and Gunderson

Abstract

Heat tolerance plasticity is predicted to be an important buffer against global warming. Nonetheless, basal heat tolerance often correlates negatively with tolerance plasticity (“Trade-off Hypothesis”), a constraint that could limit plasticity benefits. We tested the trade-off hypothesis at the individual level with respect to heat hardening in two lizard species, Anolis carolinensis and A. sagrei. Heat hardening is a rapid increase in heat tolerance after heat shock that is rarely measured in reptiles but is generally considered a first line of physiological defense against heat. We also employed a biophysical model of operative habitat temperatures to estimate the performance consequences of hardening under ecologically relevant conditions. Anolis carolinensis hardened by two hours post heat shock and maintained hardening for several hours. However, A. sagrei did not harden. Biophysical models showed that hardening in A. carolinensis reduces their overheating risk in the field. Therefore, while not all lizards heat harden, hardening has benefits for species that can. We initially found a negative relationship between basal tolerance and hardening within both species, consistent with the trade-off hypothesis. However, permutation analyses showed that the apparent trade-offs could not be differentiated from statistical artifact. We found the same result when we re-analyzed published data supporting the trade-off hypothesis in another lizard species. Our results show that false positives may be common when testing the trade-off hypothesis. Statistical approaches that account for this are critical to ensure that the hypothesis, which has broad implications for thermal adaptation and responses to warming, is assessed appropriately.

Read the full paper here!

This prototype video from a nature center in Bellaire, Texas has a degree of charm and entertainment, but a few factual errors and some unexpected historical/geopolitical statements. Still, it’s nice to see anoles chosen as the subject of their first video in what could be a series of micro-documentaries. More on the video and anoles at this website.

No, Ze Frank hasn’t created a True Facts about Anoles video–though surely that’s in the works (check out his list of videos). But he does have a very good one on camouflage and mimicry, and anoles make numerous appearances. For the record, my favorite True Facts is the one on chameleons.

It’s invasive eat native time again here in Florida, where this poor but brave male green anole somehow found himself in a battle with a giant invasive gecko, Phelsuma grandis. Check out the video on ladywildbones’ Instagram page.

Phelsuma grandis is native to Madagascar, but has been introduced to South Florida as well, where several breeding populations exist in the Florida Keys.

They eat insects, fruit, nectar, and any animal that will fit into their jaws, including anoles! Like anoles, Phelsuma are aggressive, territorial, and fast-growing. They are the ultimate Florida invader, though rivaled in success by the green iguana.

We can probably expect to see more Day Gecko/Anole confrontations as the geckos increase their population.

From the pages of the Taiwan News. We’ve had posts on the invasion of festive anoles into Taiwan previously.

A brown anole displaying. (Wikipedia, Creative Commons photo)

The brown anole (Anolis sagrei), an invasive lizard species native to Cuba and the Bahamas, has been causing damage to Taiwan’s ecosystems for years, but solutions to controlling its spread have been elusive.

Now a university research team in Chiayi County is trying a different approach — working with plant nurseries in parts of the county to get rid of anole eggs from plant soil — that appears to be promising. Chiayi County was the entry point for the non-native species and has been at the epicenter of its proliferation for nearly two decades.

During that time, the county government has tried to grapple with the problem because of the serious threat posed by the lizard to Chiayi’s biodiversity, said Chen Hsun-wen (陳宣汶), an assistant professor in National Chiayi University’s Biological Resources Department. From 2009 to 2017, local authorities focused their eradication campaign on offering financial incentives to the public for getting rid of the lizards, a system that spurred increased interest in catching brown anoles and controlling their population.

Eventually, however, the county discovered that the more than NT$10 million (US$356,951) in cash rewards handed out through the incentive program did not translate into control of the brown anole population, according to Chen. It may even have been counterproductive, he said, because it caused problems in compiling accurate statistics and resulted in inefficiencies in getting rid of the lizards.

Reptile reputation

That led the Forestry Bureau’s Chiayi Forest District Office to consider a new approach — outsourcing a brown anole prevention and control project to a research team in Chen’s department in 2018. The team adopted a strategy of containing the reptiles instead of slaughtering them and put in place measures to confine them to areas where they already existed to keep them from spreading.

The team’s primary target has been plant nurseries, a common sight in Chiayi, after it found that brown anoles were most likely to spread to different areas through the movement of seedlings and saplings shipped by those nurseries, said Hsu Wei-chieh (徐偉傑), an assistant research fellow in the department.

According to Hsu, the lizards usually lay their eggs in the soil of nursery plants and hide in the branches and leaves of saplings, and the containment plan is aimed at getting nurseries to check for the lizards or their eggs when a batch of seedlings or saplings are shipped out.

Floridians

To assist the nurseries in the effort, the team has dispatched workers to monitor the nurseries and help them check for lizards or their eggs and get rid of them before products are shipped, Chen said.
Because of the difficulty in spotting the lizards or their eggs, the team also sets traps at the nurseries to catch the reptiles.

Chen said gauging the population of the brown anoles is not easy, but it appears that the team’s efforts are having some impact, as the population of lizards in Shuishang Township in Chiayi County, while still high, appears to be growing at a much slower rate than previously. Shuishang Township has several nurseries where many varieties of tree saplings imported from the U.S. grow, and it is where the lizard species was first found in Taiwan.

A genetic analysis found that Taiwan’s brown anoles came from Florida, Chen said, and he believes they came through imports of plants and plant products from Florida that had the eggs of brown anoles in their soil.

The team is now hoping that through their focus on controlling the brown anole population at their source, the species can be contained and be stopped from damaging Taiwan’s ecosystems.

From the pages of Chipojo Lab:

“Manuel recently published a paper in the Journal of Herpetology with Leo Fleishman and Maya Prebish, examining visual acuity and perception of Anolis dewlap patterns. Yesterday, a news feature came out about the article in El Nuevo Día, sharing the findings en español. Keep scrolling below for an English translation!”

Read the entire, extremely interesting post here!