New paper in Nature examines the interaction between green anoles and brown anoles, and how the presence of the predatory curly-tailed lizard changes the balance. See also the commentary by Os Schmitz.
Green anoles were trained, marked, released, and tracked in New Orleans. Photo by Jerry Husak.
In the US, we spend a lot of money trying to stay fit. This isn’t necessarily a bad thing, since there is a major problem with obesity and type II diabetes in the country. In humans, investment in increased performance abilities via the exercise response is also associated with numerous health benefits, such as decreased incidences of metabolic syndrome, cardiovascular disease, obesity, and diabetes, and aerobic capacity is considered to be an important predictor of longevity. However, it is these “side effects” that make exercise so interesting to an evolutionary biologist, because those wide-ranging, multi-system responses can tell us something about the evolution of animal life histories.
Superior locomotor performance has been shown to be advantageous to a variety of organisms in terms of male combat success, survival, and fitness. In addition, one of the most striking aspects of exercise physiology is how similar the response to exercise is across vertebrate animals, suggesting that the response to exercise is both ancient (yes, even fish respond to exercise!) and adaptive. However, until now, no studies have tested whether non-human animals that invest in increased athletic performance through exercise realize a fitness advantage in nature.
Jerry Husak and Simon Lailvaux set out to test whether superior performance after exercise training would increase survival probability in green anole lizards. Previous work with green anoles showed that they respond to different forms of exercise training, and that enhanced performance results in tradeoffs in other systems, such as reproduction and immnuocompetence. Why? Because performance abilities are energetically expensive to build, maintain, and use.
Urban islands in New Orleans where the study was conducted. Photo by Jerry Husak.
Jerry and Simon conducted their study in a New Orleans urban park that they cleared of existing lizards. They trained 30 lizards (15 male, 15 female) for endurance on a treadmill, 30 lizards for sprinting with weights on a racetrack, and had 30 untrained controls. All were released into isolated, urban islands in New Orleans, LA, USA and monitored for survival over an active season, over winter, and through the next active season. They predicted that training would enhance survival during the active season, but that the associated maintenance costs of training would decrease survival overwinter compared to controls.
This male made it a year in the wilds of New Orleans, but it looks like it was a rough year. Photo by Jerry Husak.
Contrary to expectations, they found that sedentary controls realized a significant survivorship advantage over all time periods compared to trained lizards. Trained lizards had reduced immune systems and lower fat stores, suggesting that in an environment with limited resources, it does not pay to exercise too much. These results suggest that locomotor capacity is currently optimized to maximize survival in green anoles, and that forcing additional investment in performance moves them into a suboptimal phenotypic space relative to their current environmental demands. We as humans can get away with it because we are not food limited. On the other hand, this is why doctors suggest consultation before going on a diet and doing intensive exercise training.
Source: Husak, J.F., and S.P. Lailvaux. 2019. Experimentally enhanced performance decreases survival in nature. Biology Letters 15:20190160. doi: doi.org/10.1098/rsbl.2019.0160.
Lizard in a grocery store salad
Embed from Getty Images“I got an idea and I can’t get rid of it. I go to sleep and it comes right back at me. Never had anything give me so much trouble. It’s kind of a big idea. Maybe it’s full of holes.” – Adam Trask in East of Eden.
John Steinbeck (1962): The year he won the Nobel Prize in Literature.
So, what was Adam Trask’s big idea in John Steinbeck’s magnum opus “East of Eden”? And, more importantly, how does it relate to anoles? The kernel of an idea that would eventually revolutionize the salad industry—and link anoles to a literary legend—can be found in the fictional dialogue written by Steinbeck in 1952.
“… they’ve dug up a mastodon in Siberia. Been in the ice thousands of years. And the meat’s still good.” said Adam Trask.
“Mastodon?” inquired Will Hamilton.
“Yes, a kind of elephant that hasn’t lived on the earth for a long time.”
“Meat was still fresh?” asked Will.
“Sweet as a porkchop” proclaimed Adam.
Steinbeck was born in the Salinas Valley of Central California, known as “America’s Salad Bowl” for its prodigious production of leafy greens. He spent many summers, while away from college at Stanford, working in the vegetable fields near Salinas. Steinbeck’s fondness for his birthplace and working knowledge of the agriculture industry is a cornerstone to many of his novels, especially “East of Eden.”
“… in the cold parts of the country, don’t you think people get to wanting perishable things in the winter—like peas and lettuce and cauliflower? In a big parts of the country they don’t have those things for months and months. And right here in the Salinas Valley we can raise them all the year around.” declared Adam.
“Right here isn’t right there,” said Will. “What’s your idea?”
“… if you chop ice fine and lay a head of lettuce in it and wrap it in waxed paper, in will keep three weeks and come out fresh and good.” said Adam.
“Go on,” said Will cautiously.
“Well, you know the railroads … they’re pretty good. Do you know we could ship lettuce right to the east coast in the middle of winter?”
The perennial availability of perishable vegetables in the United States is now commonplace, but in the early 1900s, it made literary characters like Will Hamilton exclaim to Adam Trask to “let your damned idea die.” In fact, America’s most popular lettuce variety (iceberg) was originally called crisphead, until Salinas Valley growers began packing it with crushed ice and shipping it nationwide. The genesis of Adam Trask’s business plan was obviously fictional, but the idea of shipping lettuce with ice was successful and revolutionary in the early 1900’s; however, the method never quite kept vegetables fresh for long enough.
“What arrived in New York was six carloads of horrible slop with a sizable charge just to get rid of it.” – East of Eden by John Steinbeck.
In the pursuit of profitable ways to ensure lettuce does not turn into “horrible slop,” the next advance in production came from the humble bag. Lettuce can last for days on ice, but a bagged salad can last for a couple of weeks. It’s always difficult to establish the original (or best) anything in the food industry (vis-à-vis famous rivalries such as Pat’s versus Geno’s for cheesesteaks or Pepe’s versus Sally’s for pizza), but the late 1980s in the Salinas Valley is believed to be when and where the first bagged salads were packaged, distributed from, and then sold nationwide. The bagged salad turned a commodity crop whose predictability was in the capricious hands of nature into a consumer good as constant on the shelves of stores as shampoo or Twinkies.
Over the next decades, prepackaged leafy green vegetables boomed. To keep up with demand, growers invented creative ways to automate aspects of the production process, such as mechanically harvesting leafy greens. They also ramped-up the speed across the entire supply chain, such that lettuce could be bagged in the field within minutes of harvest and then sent overnight to supermarkets nationwide. These overlapping vignettes of industrial prepackaged salads provide the backdrop for a distinctly modern human-wildlife interaction: Small wild animals found by customers in prepackaged produce.
In our recent paper, we attempted to shed light on this poorly understood phenomenon by surveying online news articles for reported incidents. In doing so, we found that this is a much more common occurrence than one might think and that incidents encompassed representatives of several vertebrate groups. Most incidents involved amphibians (treefrogs and toads), and then reptiles (lizards and snakes), mammals (rodents), and birds. Anoles were the most common lizard that we could identify from the pictures and descriptions provided in the reports. The anole incidents included Green Fruit Loop, the aptly named Green Anole that became a class pet at Riverside Elementary in New Jersey. We suggested that the likely source of Green Anoles among the incidents was Florida because not only is the species is common there, but by 2012 the state was the third largest producer of leafy green vegetables in the United States, behind only California and Arizona.
Figure 1 from Hughes et al. (2019): Taxonomic and temporal breakdown for 40 incidents of extemporaneous wild animals found by customers in prepackaged produce items purchased in the United States. A) Vertebrate diversity among incidents; B) Annual distribution of incidents; and C) Monthly distribution of incidents.
An interesting social element emerged from my deep-dive into the trenches of the internet. I found that these incidents were shrouded in uncertainty and thus reporters often relied on anecdotes to discuss and describe them. One common urban myth was that these incidents almost never happen and the second was that if they happen, then it was because the produce was organic. In contrast to these popular views, we found that at least 40 incidents were reported since 2003—so, not exactly rare—and that less than 30% of incidents involved organic produce—most actually came from conventionally grown crops. For greater context and more details, see the Discussion of our paper where we address: 1) why these unfounded views may have persisted; 2) spatial, taxonomic, and seasonal patterns to our findings; 3) our results in the context of competing demands imposed upon the produce industry; and 4) the biosecurity concerns relating to the unintentional translocation of wild amphibians.
Modern agriculture has taken significant steps towards industrialization since the time that John Steinbeck penned Adam Task’s revolutionary idea (see Epilogue). Industrialization of food production will help to address the problems associated with feeding 9 billion people, a figure that is projected for the human population by 2050. Wild vertebrates in prepackaged produce, however, may be one symptom of an overburdened and overstretched produce production system. Any solution to this problem will not likely come from greater controls for wildlife, such as the currently employed “scorched earth” approach, but rather from the decentralization of agriculture. We suggest that the best approach would be to first invest in research aimed at studying a wide segment of biodiversity near agricultural lands, which will help growers assess potential intrusion risks of more species, and second to adopt quality control methods that account for a greater diversity of wildlife to improve screening at more stages in the produce supply chain.
Epilogue:
The birth of Adam Trask’s plan was fictional, but the growth of that idea, as depicted in the novel, is a great example of John Steinbeck’s (often overlooked) scientific mind. While many people my age read “Of Mice and Men” in high school and got to know Steinbeck the literary genius, they may not know Steinbeck the scientist. Ed Ricketts was a marine biologist that became a lifelong friend to Steinbeck when he moved to Monterey in the 1930s. The relationship between the writer and the scientist was one of mutual respect and admiration. At one point, they even undertook a six-week specimen-collecting expedition to the Gulf of California, which resulted in two published books. Not only was Ricketts the basis for Steinbeck’s character “Doc” in several novels (e.g., “Cannery Row”), but the influence he had on Steinbeck is unmistakable in many of his other works, including “East of Eden.” Adam Trask, for example, spawned his idea for preserving lettuce with ice from a scientific expedition that found a frozen mastodon in Siberia, and he read about this finding, refrigeration science, and bacterial growth in articles from “Atlantic Monthly,” “National Geographic,” and “Scientific American.” The mentioning of these specific journal titles in “East of Eden” was by no coincidence as they would have been the same ones that Steinbeck saw, and likely read, in Rickett’s lab, a place that he visited frequently. At the time of Ricketts death in 1948 (which sent Steinbeck into a depression), the two were planning another collecting expedition to British Columbia and another book.
Another great anole book for kids! Author Adi Schneider summarizes it:
This colorful story in rhyme, for both children and adults, will put a smile on your face. You will observe the flamboyant Anatoly flaunting his magnificent dewlap to his female fan club and learn lots of solid facts about these fascinating and abundant little Floridian lizards.
When showing off, with his push-ups and head nodding, there is a crisis when he hits his dewlap on a rock. That red and yellow dewlap of his is now black and blue and he is more than depressed about it. His chance encounter with a Monarch butterfly sets him on the right path toward improving his character and not relying on looks for his popularity.
Yale Undergraduate Fiona Reed has designed a website in which you can answer a few question and determine which anole ecomorph you are. Give it a try! And then tell us what you are?
This is the best picture I took of a suspected A. pulchellus at Punta Borincua. The coloration and size seems consistent with A. pulchellus. Anyone think it might be something else?
This is the best pic I could get of what I believe is an A. stratulus at Punta Borincua. Note the single yellowish stripe down the back with black bars above the base of the tail. Does anyone know the identifying characteristics of A. stratulus?
from the Cayman Compass
Cayman’s island-hopping lizards offer evolutionary insight
Most visitors to Cayman Brac will likely not have noticed one of the island’s now established transplants: the Maynard’s anole.
This non-native lizard spends much of its time just out of eyesight, perched in the tree branches where its bright green colour blends with the foliage. The elusive anole, originally from Little Cayman, has captured the interest of researchers, intrigued by the insight the species can offer about evolution in island ecosystems.
And the Maynard’s anole is not the only island-hopping lizard on the minds of Cayman Islands researchers these days. While far from the invasive status of the prolific green iguana, the brown anole is also creating questions about the potential impact on Grand Cayman’s native blue anole.
Through separate studies – one carried out by Caymanian researcher Vaughn Bodden and another by National Geographic Society grantee Inbar Maayan – biologists are getting a better idea of how invasive species adapt and populate new territories.
Maynard’s anole in Cayman Brac
While the Maynard’s anoles in Cayman Brac are not far from their native home, Little Cayman, the lizard sheds light on how invasive species colonise new habitat.
Fortunately for Cayman Brac, the Maynard’s anole does not appear to pose a threat to the native Cayman Brac anole and has not shown potential for hybridisation.
“Based on similar invasions on other Caribbean islands, we expect the potential for a negative impact to be low. The native anole in Cayman Brac is found low on tree trunks and on the forest floor, while the introduced anole is predominantly found on upper tree trunks and in the canopy so direct interaction between the two species should be limited,” said Bodden, who studied the species while completing his bachelor’s in conservation biology at the University of Plymouth. He is now completing his master’s in biodiveristy and conservation at the University of Glasgow.
“Any impacts on the native anole are more likely to be indirect, such as a shift in habitat use to further avoid interacting with the introduced anole,” he added.
The Maynard’s anole, first spotted in the Brac in 1987, does show signs of adaptation, however, when compared to its counterpart in Little Cayman.
Through fieldwork capturing and analysing the anoles in both Sister Islands, Bodden’s team, assisted by University of Plymouth lecturer Robert Puschendorf, found some interesting differences in their morphology and ecology. While the team hypothesised that the introduced anole might have developed longer hind legs – a trait that can aid dispersal and movement – their findings did not support this. In fact, they found much the opposite. The anole had instead developed longer forelimbs.
“Potential explanations for the rapid divergence could be that the founding individuals of the introduced population had a unique phenotype and these characteristics became exaggerated over time through the process of genetic drift, or that some habitat use characteristics that we did not measure on Cayman Brac are driving the morphological adaptation,” Bodden said.
Another interesting discovery about the introduced anole population was the presence of a parasite not previously recorded in the Sister Islands.
The source of this parasite remains unclear.
“The ectoparasites we found infecting A. maynardi [Maynard’s anole] have not been recorded in the Sister Islands, so this study provides the first evidence of its presence there. It is unclear whether the parasite species is native to both islands, invasive to both islands, or co-introduced from Little Cayman to Cayman Brac with its host,” Bodden said.
“We found that the introduced population [in Cayman Brac] had a reduced ectoparasite prevalence compared to the native population [in Little Cayman].”
The further researchers ventured from long-settled habitats, the lower the prevalence they found of the parasite.
This is something that may have benefited the introduced population and encouraged colonisation.
While the origin of the anole’s introduction to Cayman Brac is unclear, its presence there sends a reminder about the importance of safeguarding borders.
Due to the islands’ prevailing easterly trade winds, Bodden suspects the lizard had human rather than natural assistance in its introduction, possibly as a stowaway in a flight or boat.
“This is a unique situation where we have a species endemic to one of the Cayman Islands being introduced to another one of our islands. Fortunately, this introduction is not a major threat to the ecosystem in Cayman Brac, but it highlights the need for more vigilant bio-security control at our ports,” Bodden said.
“Unchecked cargo transportation provides a route for other invasive species, such as the green iguana, to be transported into or between the three islands.”
Brown anole in Grand Cayman
Theories about how the brown anole, found endemically in Cuba and the Bahamas, arrived in Grand Cayman reinforce the call for careful biosecurity measures at ports. While researchers do not know exactly how the anole arrived here in the 1980s, its prevalence in the western end of Grand Cayman hints that it may have arrived through shipping.
Although Maayan, currently a Ph.D. candidate at Harvard University, did not find brown anoles in the numbers she had expected, she warned of complacency when it comes to invasive species.
“I was expecting them to be more of a problem than I saw, but it speaks to the importance of monitoring introduced and invasive populations,” she said.
Maayan said the brown anole should not be considered invasive in the same sense as the green iguana. But she cautioned that at a time, even the green iguana’s population numbers were much lower than they are now.
Much of the findings of her Grand Cayman research is not ready to share with the public, but she shared a few takeaways from her time on island.
Maayan described Cayman’s native blue anole as an incredibly charismatic and stunningly beautiful animal.
“They are a good ambassador for the Cayman Islands,” she said.
Maayan was interested in whether the presence of the brown anole had led to changes in the native anole’s habitat or physical characteristics. Physical changes in leg and head size, for example, could communicate competition between the species for habitat and resources.
“The reason why these [island] species introductions are particularly useful is they mimic what we would see in evolutionary time,” she said.
“It gives a glimpse in a natural setting of when species come into contact and compete.”
With the help of local researchers, including Vaughn Bodden, Morgan Ebanks and Jane Haakonsson, she scouted out sites where just the Grand Cayman anole lived and sites where both species lived, for comparison.
Finding the brown anole was not as easy as she expected, however. While the lizard is found abundantly in Belize, where it is also an invasive species, this was not what Maayan observed in Grand Cayman.
Researchers sampled two sites heavily, taking data from more than 200 lizards. The team took data on habitat use of both species, and took measurements of the blue anole’s physical characteristics.
Maayan’s next step will be performing DNA analysis on the lizards to determine the level of migration and morphology.
Fortunately for the Grand Cayman anole, Maayan’s initial findings show little impact on how the lizard interacts with its native habitat.
While the brown anoles seemed to prefer perching in lower, sunnier areas, the Grand Cayman anole stuck to shadier natural areas. It would appear the lizards have adapted to separate habitats.
The full findings of Maayan’s research are expected to be released this summer, after the study has been reviewed and published by the National Geographic Society.
Anole Annals‘ woman in Florida, Karen Cusick, has photo-documented more interesting anole behavior (Karen has observed and photographed much interesting green and brown anoles behavior. Search this site for her name or “Daffodil’s Photo Blog” and you’ll find all kinds of interesting observations). oday I saw something I don’t think I’ve seen before, and I’m sending you a few photos. A big male brown anole was sitting in the sun on the upper rail of the fence when a big male green anole approached. He stopped about 6 inches away from the brown anole, and started bobbing his head and displaying his dewlap. The brown anole watched but didn’t react. The green anole moved closer and displayed again while the brown anole watched. Just as I was wondering if there would be a fight, the green anole suddenly ran past the brown anole along the rail and then down off the fence.
Believed to be an A. evermanni, spotted on a tree truck in El Yunque. Does anyone know what the identifying characteristics of evermanni are?