By Michael McGuire

Taxonomy, the study of naming and classifying organisms, how hard could that be right? Turns out, pretty complex when you have a bunch of similar looking chameleons! For the longest time, a group of chameleon species in Madagascar have been put into the same species name “bucket”, if you will, and been collectively called Calumma nasutum. It has been long known that these chameleons were likely not all the same species, but taxonomy is a difficult and time-consuming task especially when chameleons in the genus Calumma look so similar! This is known as a species complex, and recently scientists have untangled these tiny and adorable lizards and given them official names. In this process, involving CT-scans, genetic analysis, and incredibly nitpicky measurements, they discovered three new undescribed species! They also designated official scientific names to three known species, for a total of six! To put it simpler, a species complex is like if you gave out the name “potato” to the potato, but also to an apple. Both are called potatoes, but one clearly is not a potato. This is a big deal for conservation since what was previously assumed to be one species with stable populations has turned into many, with more uncertain prevalence.

          Chameleons in the C. nasutum “complex” are tiny, often no larger than your finger. Surprisingly however, they are not as tiny as Madagascar’s smallest chameleons, Brookesia micra which only grow an inch long! First on the list of newly minted chameleons is Calumma emelinae which has a bony nose protrusion much like most Calumma species, and males can have a gorgeous green coloration with spines along their back.

Next is Calumma ratnasariae which is mainly a drab grey or brown, but when mating season rolls around and males don their display colors is when the magic happens. As you can see below, they are a pretty pastel rainbow of colors, the likes of which you may see on a trendy interior decorators Instagram page.

And finally, the last new species is Calumma tjiasmantoi which turns a rusty shade of orange when at their most vibrant.

Scientists have had a difficult time describing the original species, Calumma nasutum. It wasfirst described almost 200 years ago by some of the first French zoologists to visit Madagascar, Duméril & Bibron in 1836. That chameleon described all those years ago and the cause of this complicated mix-up is on the left.

By contrast, Calumma radamanusis this very similar-looking species.

And the last described species, Calumma fallax is very easily confused with most all the rest of these chameleons, but most of all C. nasutum! The main identifier between them is their location, as C. nasutum are found in eastern and northern Madagascar, whereas C. fallax occurs at high elevation along the east coast.

Herpetologist and taxonomist Dr. Mark Scherz noted that a few of these species are already threatened. This illuminated an interesting quandary between taxonomy and conservation. All these species, being called C. nasutum previously, were listed as Least Concern according to the IUCN. But now what we thought as one species is in fact many, which divides the group and shows that some of these lizards are in fact endangered. Many of these chameleons exist in highly fragmented populations, and conservation policy takes a long time to update.

Scherz shared with me his frustrations with the Madagascan government for the difficulty to get permits to take these lizards for scientific research. Conversely, many permits are given to those taking chameleons to fuel the exotic pet trade. Scientists taking one or two individuals is a drop in the pool compared to the exporters. This disproportionate treatment between scientists and citizens is a problem, and one that makes it difficult to do necessary research for conservation. The Madagascan government feels as though researchers are taking advantage, since they do not see any return for allowing an animal to be taken. On the contrast, exporters are giving back to the government in taxes. This viewpoint is understandable, but Scherz noted that change needs to come from within. Madagascan citizens and researchers are the only ones who can push back against this. But in one of the poorest countries in the world with a university with only minimal resources, that is easier said than done.

Madagascar’s habitats are being lost at an unprecedented rate, largely due to agriculture. Farming techniques are outdated with many citizens doing slash and burn agriculture to produce rice. This strips the soil of its nutrients within years and the process must be repeated. This populice driven deforestation is the biggest threat to Madagascar’s flora and fauna.

There is some hope however, Dr. Scherz mentioned he has worked with many up and coming Madagascan citizen researchers who are discovering new species and trying to protect the countries natural wonders. Perhaps with enough protection and hard work conservation policies will be put into place before these newly discovered small chameleons are lost.

Prötzel, D., Scherz, M.D., Ratsoavina, F.M., Vences, M. & Glaw, F. (2020) Untangling the trees: Revision of the Calumma nasutum complex (Squamata: Chamaeleonidae). Vertebrate Zoology, 70(1):23–59. DOI: 10.26049/VZ70-1-2020-3 [pdf] 

Photos by Dr. Mark Scherz & MadCham.De

By Connor McCarthy

It’s completely dark. The eastern-European cave you find yourself in is silent, save the whirring of a passing aquatic invertebrate. Your undeveloped eyes can’t see it, but the vibrations on your slimy pink skin let you know as it passes, just out of reach. You know more food will come if you are patient, so you cling to your submerged rock and wait. And wait. And wait. And wait some more until seven long years have passed by your mysterious, unblinking eyes.

No, this is not a study-abroad-psychedelic-experience gone haywire or the opening to a B-list horror movie starring a Bosnian cave monster. This is the reality of the Olm salamander (Proteus anguinus), a slender pink cave-dweller from eastern Europe that spends its entire life cycle in the underground rivers that flow from the region’s karst limestone bedrock. The species is 20cm long when full grown, lives its entire life underwater, and keeps its external gills into adulthood. Like most other salamanders, the Olm eats a mix of snails and other aquatic invertebrates. What sets the Olm apart from other salamanders and other animals in general is its ability to remain effectively motionless for years at a time.

This behavior (or lack thereof), was first studied by Gergely Balázs, an accomplished cave diver and researcher at the Department of Systematic Zoology and Ecology at Eötvös Loránd University in Budapest, Hungary. Balázs and a team of other divers conducted a mark-recapture study on Olm in the eastern part of Bosnia and Herzegovina, a small country in southeastern Europe. Mark-recapture studies are one of the herpetology field’s most commonly used tools for estimating population, the idea behind them being if you capture a group of amphibians, mark them, release them into the wild, then come back later and capture roughly the same number as before, the proportion of marked individuals captured in the second survey is equal to the proportion of the total population captured in the first survey, which gives you a rough estimate of total abundance.

Due to their inaccessibly Olm are a fairly large question mark on the map of herpetology. Very few studies have been conducted on their life cycle and natural history, and most of what is known about the species has come from captive populations in zoos and aquariums. As a result, the species is shrouded in mystery. In medieval times, Olm were thought to be the offspring of cave dwelling dragons, as they would occasionally wash out of the caves during flood events. Though they cannot breathe fire, reproduce with donkeys, or do any of the other things dragons from our pop culture do, a wormlike creature with gills understandably must have seemed to be the spawn of something much more sinister.

According to Balázs, the species sedentary lifestyle makes them somewhat easy to catch. Researchers would use a flashlight to locate the Olms from a few meters away, then shut the light off (Olm are blind but can still see light and dark) as they slowly swam up to the salamanders. Once they were close, they would turn the light back on, grab the Olm, mark it with a visible implant elastomer (a liquid polymer injected under the salamanders’ skin that solidifies, allowing for re-identification later on). The Olm would then be set free, returning to the subterranean riverbed in a single burst of writhing speed.

The study itself had several layers and included data from previous expeditions into the caves. Balázs and his team conducted their first study in these caves in 2010, where they tagged 7 Olm, five of which were recaptured in the 2020 study. 19 additional individuals were tagged in 2016, 13 of which were observed in the subsequent 28-month monitoring period.

By comparing the locations of individual Olm during each of fifteen recapture expeditions, Balázs and his team attempted to discern exactly how much moving these salamanders were doing in the darkness. Like people, some Olm seemed to be travels whereas others were not. One salamander moved an impressive 38 meters over the course of 230 days, while another was found in the exact same spot after 2569 days (just over 7 years). It is unclear if this sedentary individual (along with the rest of the Olm in the cave studied) was feeding during this time or exercising its starvation resistance.

Over the entire study, no Olm traveled more than 80 meters from the site it was first captured at and on average they only moved about 5 meters a year. In the 37 total recaptures in the study, only ten animals had moved more than 10m away from their original location.

 Interestingly, all the Olm captured in the study were quite out in the open and very visible to the divers. This is in stark contrast to Olm behavior of captive Olm, which hide in cracks and crevasses of rocks. Furthermore, individuals could be found within a few meters of each other, but displayed no sign of grouping or avoidance behaviors. Essentially, Balázs and his team couldn’t make any conclusions as to why Olm spend so little time moving especially considering they have no natural predators or other competitors.

But are these individuals really not moving, or do they just move back and forth between the same places like retired old men and therefore create the illusion of a sedentary lifestyle? Balázs’ current theory is that the Olm are trying to minimize the amount of energy expended. Female Olm only reproduce about once every twelve years and it is predicted the species can live to be over 100 years old. Furthermore, they are extremely resistant to starvation and some studies have shown individuals can go ten years without eating. They do this by eating large quantities of food at once, then storing excess nutrients, glycogen, and lipids in the liver. When food is scarce, they can reduce their metabolism and in extreme cases reabsorb their own tissue until more food becomes available. They also have a high tolerance for hypoxic water, meaning their oxygen demand is quite low which allows them to survive in cave environments. Essentially, everything about the Olm, from there anatomy to their reproductive cycle, is perfectly designed for to survive in the some of the most abysmal reaches of the earth’s surface. So, will we ever really know what goes on in the caves of eastern Europe while Balázs and his expert team of divers are not there to document it? For the time being, it’s unlikely. Setting up a motion trap for a species that hardly moves is a task in itself especially when these cameras would need to be placed in subterranean rivers. What we do know is these slender, pale, blind salamanders might have the most stoic lives of any vertebrate. While it’s difficult to envy a creature that spends in entire life in darkness, hardly eating, rarely moving, and reproducing once every decade, it’s also hard to argue the evolution and lifecycle of the Olm is anything but fascinating. Hopefully future studies will give us more insight on their mysterious lives as their delicate karst environments may be at risk due to stormwater runoff, pollution, and climate change.

By Mitch Maver

Across the globe, the introduction of exotic species is having catastrophic negative effects on the health of our planet’s natural ecosystems. Reptiles and amphibians are commonly caught and transported far from their native range to be sold as pets for humans. This practice has lead to the accidental, or in some cases intentional, introduction of exotic reptiles and amphibians into areas where they are not naturally found. In many locations, populations of exotic reptiles and amphibians have proliferated and are now reeking havoc on beloved local species. Invasive species disrupt natural ecosystems and can significantly reduce the biodiversity of an area. In other words, say goodbye to your beloved songbirds or deer because that pet snake your neighbor let “free” may become invasive and those charismatic local species could vanish from the landscape in the blink of an eye. Invasive predators can reduce the abundance of native species by eating them or by simply out-competing them for resources. This can then have a domino effect where the introduction of a single invasive species causes one effect which has another effect and so on until the next thing you know the whole ecosystem has collapsed. Unfortunately, this process, which in science terms is called a trophic cascade, is all to common across the globe.

            Today, the invasive Burmese python, Python bivittatus, is a destructive force that is taking over Florida’s Everglades National Park. Populations of this huge invasive serpent have skyrocketed since they were first detected in the 1980s and 1990s. Although it is not known for sure, the invasion of Burmese pythons in south Florida is believed to be the result of humans releasing pet pythons, that they either did not want or could no longer care for, into the wild. Burmese pythons are native to southeast Asia and are one of the largest species of snakes on earth, reaching sizes of 23 feet! Because of their size, these snakes can feed on a wide range of species such as wading birds, small alligators, and mammals. Cases where the introduction of exotic reptiles has lead to significantly reduced biodiversity and localized extinctions of native species has historically only been observed on islands. However, in south Florida, the decline in opossum, raccoon, deer and other mammal populations has been attributed to the introduction of the Burmese python. Recent research in south Florida has provided evidence that Burmese pythons are currently causing a trophic cascade where direct reductions in mammal populations due to python predation is having indirect effects on non-prey species such as turtles. In other words, mammal populations in south Florida have decreased due to python predation to such an extent that there are now less animals, specifically raccoons, around to feed on the eggs of certain turtle species. In addition, it is believed that Burmese pythons are having an indirect impact on the vegetation dynamics of south Florida.

In a 2017 study, Dr. John D. Willson, of the University of Arkansas, and his research team examined how Burmese pythons are indirectly impacting south Florida ecosystems. The study hypothesized that predation rates, specifically on turtle eggs, would be lowest in the southern part of the Everglades National Park, where pythons have been established the longest and where mammals are rare. Dr. Willson constructed artificial turtle nests baited with quail eggs at 13 sites and used camera traps to monitor predator activity. The 13 sites were divided into three categories; “core” sites, areas where pythons have been detected the longest, “peripheral” sites, where pythons have only recently been detected, and “extralimital” sites, where breeding python populations have not been detected yet. The spatial distinction of the study design allowed Dr. Willson to examine what animal species were present and their abundance so that conclusions could be drawn regarding both the direct effects pythons have on mammals and the indirect effect that has on turtle nest predation.

Dr. Willson, and his research team, found that nest predation rates, and the observed number of species, were significantly greater at “extralimital” sites where python breeding is not yet believed to be occurring. Nest predation at “core” sites, where python populations have been established the longest, was low and only a few species of mammals were observed. In addition, the nest predation that did occur at “core” sites were done almost exclusively by crows. Whether or not the greater occurrence of crows at core nest sites compared to “peripheral” and “extralimital” sites can be attributed to decreased competition with the prey species of the Burmese python could not be “conclusively concluded based on the [Study’s] data”, says Dr. Willson. However, data from the camera traps at each site did indicate that the “spatial pattern of mammal abundance is inversely correlated with the spatial expansion of python population”.  In layman’s terms, what Dr. Willson means by this is that mammal abundance was found to be lower in areas where pythons were abundant and higher in areas where pythons were less abundant. Furthermore, the results of the study supported the hypothesis that the decreased mammal populations caused by python predation is positively effecting the abundance of the non-prey species of the Burmese python. The study also refuted the previously suggested alternative hypothesis that the recent increase in the abundance of coyotes in the Everglades is driving the observed decline in mammal populations. So based on the findings of the study, Dr. Willson and his team concluded that a trophic cascade, where Burmese pythons are having a positive indirect effect on the recruitment of small egg-laying species by suppressing mammal populations, is occurring in the Everglades National Park. What this means is that more egg laying species, such as turtles, are surviving to adulthood because the pythons have eaten a large number of their predators.

            Based on the conclusions Dr. Willson and his team were able to draw from the findings of this study, I asked him what he believes needs to be done next in order to mitigate the issues Burmese pythons are causing in south Florida. At the current moment, Dr. Willson believes that more extensive research is still needed and states how, in his mind, there are currently no “tools that can be used at a large-scale to do anything about this problem” because of how widely distributed pythons are in south Florida and how difficult they are to detect. Right now, the most effective way to mitigate Florida’s python problem is to work at a “small-scale and do things such as protect key area’s used by wading birds, and to keep python populations low in the Florida Keys where there are a lot of endemic species like the key deer, the lower keys marsh rabbit, and the Key Largo wood rat” says Dr. Willson. But, before any large-scale management plan can be implemented Dr. Willson is adamant that more research on control methods, such as python traps, needs to be done. He goes on to explain how on the island of Guam where invasive brown tree snakes lead to a significant loss of native fauna, well funded research regarding basic control methods, like traps and visual searches to remove tree snakes, has allowed researchers on the island to begin large scale removals and the reintroduction of native birds; something he would have said was impossible ten to fifteen years ago. “The solid research on the very basic level of how to detect [brown tree snakes] using very simple techniques basically laid the groundwork for large scale removals and we are just not doing that with [south Florida] pythons” says Dr. Willson. The main problem he currently sees in Florida is that “there is more pressure to present the visual of doing something rather than doing things that are less glamorous but actually inform our knowledge of the situation better”.

            After gaining a better understanding of the current python problem in south Florida, I asked Dr. Willson if thinks Burmese pythons are affecting the Everglades ecosystem in ways that have not yet been examined. He mentions how, in his mind, pythons are most likely having some indirect effect on the area’s vegetation dynamics by suppressing populations of important herbivores such as rabbits and deer. Furthermore, he suspects that pythons are indirectly affecting the seed dispersal of fruit-forming plant species by reducing the abundance of seed dispersing mammals. In Guam, research regarding the invasive brown tree snake suggests that brown tree snake’s “are changing the forest by changing the recruitment, pollination, and seed dispersal of trees” says Dr. Willson. If a similar phenomenon is occurring in the Everglades, its very likely that the forest structure of the park will be different in future than how it has been historically which could have far reaching implications that can not yet be predicted. However, if wildlife managers in the Everglades take what has been learned on Guam, in regards to invasive snake management, in to account as the come up with there own python management strategies it is possible that further large scale changes to the ecosystem dynamics of the Everglades can be prevented. Lastly, Dr. Willson mentioned how there is a lack of knowledge regarding the effects pythons have on wading birds because of how hard it is to keep track of there populations. The knowledge gaps that still exists regarding the effects pythons have on vegetation and other organisms will be a major hurdle researchers and wildlife managers will have to get over before any large scale management plan can be implemented

            To conclude the interview, Dr. Willson mentioned how the greatest challenge, when it comes to carrying out large-scale studies such as this one, is overcoming the very complex political and regulatory environment of south Florida. Since pythons are now so widely distributed across the region, to test his hypothesis meant he needed to include sites located on lands that are managed by several different entities. This made “the permitting required to conduct this study astronomically difficult to get organized” says Dr. Willson.

Dr. Willson’s full journal article can be found in volume 54 of the Journal of Applied Ecology on page 1251 or at https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.12844.

Work Cited

Gibbons, J. (2011) Invasive Burmese Pythons Are Taking a Toll on Florida’s Native Birds. Smithsonian Insider. Retrieved from https://insider.si.edu/2011/03/burmese-pythons-are-taking-a-toll-on-floridas-native-birds/

Willson, J. D. (2017) Indirect Effects of Invasive Burmese Pythons on Ecosystems in Southern Florida. Journal of Applied Ecology, 54, 1251-1258

Garcia, S. E. (2019) A 17-Foot Burmese Python Was Found in Florida. What Was It Even Doing There? The New York Times. Retrieved from https://www.nytimes.com/2019/04/08/us/python-florida.html

By Raymond Looney

Humans are naturally devastated by short-term weather events such as hurricanes, but the news tends to overlook the implications of these storms on natural flora and fauna in the devastated areas. If a changing climate is only going to intensify the impact and frequency of short-term climatic events like hurricanes, we need to find ways to adapt to our changing world or else we are toast. In September 2017, the West Indies and the Alantic coast were devastated by Hurricanes Irma and Maria. The two category five storms, brought with them winds upwards of 150 miles per hour, causing more than $65 billion in damages and caused an estimated death toll of 2,982 in Puerto Rico.

In a paper published in Nature in 2018, scientist Colin Donihue provided evidence for a species of anole lizards to have adapted due to two catastrophic short-term climate events, hurricane Maria, and hurricane Irma. Within a 6-week period, he found evidence that surviving individuals developed stronger grips by selection for larger toepads and forelimbs. This paper received a massive response as it is the first study to test how short-term climate events can cause long-term changes in native populations and cause immediate evolutionary shifts.

            Donihue and his team originally went to Turks and Caicos in order to study the impacts of an invasive rat on the endemic species of nearby islands (Pine Cay and Water Cay). In order to do this, he was set to take baseline natural history data of Anolis scriptus (A. scriptus) like body length, toe pad size, forelimb, and hindlimb length. Donihue describes the progression of their research as simply “being in the right place at the right time”, as right after they left the two islands were battered by hurricane Maria and Irma within a two-week period. These two storms caused immense damage to natural flora and fauna as well as human communities. If these events have catastrophic effects on humans, one can only imagine the damage that is put on natural biodiversity. The team initially had no plan to look into the impact of hurricanes on selection, however, were given a rare opportunity to put a very important question to the test.

            Three weeks after the effects of Hurricane Maria, Donihue returned to Pine Cay and Water Cay to resurvey the islands for surviving lizards measured forelimb and toepad size to determine if they had differed from their first visit not long ago. They looked for changes in toepad surface area, as an increase in this trait would indicate better clinging ability in A. scriptus. To determine the significance of their results, they questioned whether changes in toepad size of the surviving anoles’ were random, or whether the change was explained by the catastrophic events of the hurricanes.

After  an extremely busy two months, the team found evidence for shifts in morphological traits that may have given the lizards a survival advantage during the catastrophic storms. Surviving lizards had significantly larger toepads and forelimb size than the ones originally measured. These results suggest that natural selection has operated to deliver a survival advantage to the individuals with characteristic that helped them to cling tighter to their environment during strong storms.

            The findings of this study are imperative to the future of studying climatic effects on natural biodiversity. Most of the studies coming out regarding a warming climate on ecosystem processes focus on long-term processes such as droughts and excessive warming and don’t focus on short-term disturbances like hurricanes. Extreme climate events are only going to increase in frequency and severity in the future and we do not know how the implications of a rapidly warming climate will impact not only humans but natural flora and fauna of the world. Normally we only hear the negatives on climate change, however this study may give a positive view on how some organisms are adapting in real time to our new reality.

By Erica Leiserowitz

Over a century ago, the Sierra Nevada yellow-legged frog (Rana sierrae) was abundant throughout the watersheds of the Sierra Nevada mountains, located on the East side of California. But soon, this frog’s life took a dramatic turn. With the increase of humans living in the area, and more and more visitors to Yosemite National Park, the landscape began to change. There was more development, more pollution, and some of their habitat was destroyed due to construction and pollution. Perhaps most damaging was the decision to stock naturally fishless habitats with nonnative fish (usually trout) so that anglers could fish for recreation.  Those fish predate on tadpoles of native amphibians, including R. sierrae, which did not evolve with fish as predators. Then, in the 1970’s, Bd (Batrachochytrium dendrobatidis), a fungal pathogen that causes Chytridiomycosis, a very devastating and lethal infectious disease, emerged in the Sierra Nevadas. All of these factors, and possibly more, led to R. sierrae disappearing from >93% of its historical distribution. This story is, unfortunately, not a rare one, and is shared by many amphibian species around the world. But this is where the Sierra Nevada yellow-legged frog’s story becomes unique. Despite the presences of disease, new predators, habitat loss, and more, the R. sierrae is showing signs of recovery.

              In a scientific article published in 2016, researchers studying R. sierrae in Yosemite have found data that shines a ray of hope on the world of amphibian conservation. The article is called “Large-scale recovery of an endangered amphibian despite ongoing exposure to multiple stressors.” Over a 20 year study period surveying the total population of R. sierrae, they determined that the population increased by an average of 11% annually, which is a more than sevenfold increase in abundance over 20 years. These surveys involve researchers and technicians hiking and backpacking all over Yosemite to get to various ponds and lakes, no matter how remote. At the sites, they walk around the edges of the pond, count what they see, and take notes. These population counts are compared to previous years, and allows researchers to notice trends in population size, but also how many individuals were infected with Bd, or how many frogs are at one pond compared to another. I interviewed one of the authors of this article, US Geological Survey Ecologist Patrick Kleeman. His research focuses on amphibians in Yosemite and the surrounding areas, and the results of this study were as much as a surprise to him as they were to me.

“It gives me a sense of hope!”

He explained to me that from a personal level, it is not just exciting, but also very gratifying. It shows that there is a chance for recovery for endangered species, and that protection policies have an impact.

              It is unclear why the R. sierrae population is increasing. It might be because the National Park Service (NPS) stopped introducing trout into the watershed, and the number of fishless lakes increased. It also might be that R. sierrae is becoming resistant to Bd, due to Bd’s now long-term presence in the area. Because there are so many factors causing declines, it is often hard to pinpoint exactly what is causing an increase.

Patrick Kleeman says that this is why keeping up long-term surveys is so important.

“We might not have noticed this trend if we hadn’t been conducting large scale surveys in Yosemite since 1993. It allows you to compare your data to the previous years, and notice changes or patterns in population.”

I asked Kleeman why the public should care about this increase in R. sierra. He explained that even though frogs like R. sierrae may not be the most charismatic animals, they are still important. Even people who don’t like frogs should pay attention to global amphibian declines. Amphibians like R. sierra are important parts of the ecosystem. They prey on organisms and in turn are prey for other animals. Their presence is woven into the food web. Amphibians have also benefitted humans directly, as they have been used in medical research.  While there are increases in R. sierrae in Yosemite, complete recovery is still a long way off, so the policies used to protect this species, like preventing dumping pollutants into watersheds, or preventing stocking fish into naturally fishless areas still need to remain in place. In the meantime, we are still cheering for the Sierra Nevada yellow-legged frog, and hope that other amphibians will also take their lead.

By Hannah Ladner

Everyone has heard their fair share of ghost stories but here is a story that you may not have heard.  In the Salinas Valley in California, there are seemingly endless agriculture fields that are plagued by an unstoppable horde.  On dark misty nights, these creatures will emerge from the irrigation canals and ditches lining the fields and move into the vast fields of lettuce and spinach.  When the sun comes up, these creatures take refuge in the greens and the growers return to their crops.  Then, they are unknowingly harvested, packaged, and sent to terrorize unwitting, innocent consumers! 

While this tale is an exaggeration, its basis lies in fact.  Every year, there are a number of cases where people purchase pre-packaged vegetables from stores only to discover that an animal, often a frog, toad, or lizard, is also enclosed.  This isn’t a common occurrence, there are only a couple of incidents a year, but when mainstream news hears about it, it often goes viral.  Between 2004 and 2018, there have been at least 40 incidents where an animal has been found, with most of these (75%) being amphibians or reptiles.  In 9 of these cases, the stowaways were alive and intact, allowing for the people who found them to release them or keep them as pets.  This is a serious issue because of the risks of spreading disease to naïve wildlife populations or even cross breed with native species.

Despite lacking hard data on the true scale of the issue, the Salinas Valley lettuce growers knew something had to be done and they assembled a team.  Dr. Danny Hughes was one of these researchers brought in to determine how to reduce the frequency of these incidents.  In the past, Dr. Hughes has been involved in research on evolution and ecology studying species including leopard frogs, African burrowing snakes, and the Central African forest chameleon.  The main concerns that he had were how to keep tree frogs out of the salad fields, how to apply knowledge of frog ecology to develop better harvesting practices, how this issue may be contributing to the spread of disease, and how to better keep track of future incidents.

Frogs: Keep Out!

So how would Dr. Hughes keep the treefrogs, the main offenders, out of the salad fields; mini frog fences?  After a brief study, they found that this was in fact true! Of the many fences they developed, two of the novel fence ideas were effective at keeping out frogs most of the time.  One of these was a fence made of sandpaper with a grit matching the size of tree frog toe-pads preventing them from gripping the surface while the other design was a solid fence with a lip on top.  This second design prevented frogs from passing the fence 100% of the time.  If you’ve ever encountered a treefrog yourself, you may know first-hand what good jumpers and climbers they are so you can imagine what an impressive feat this is!

Using Frog Cycles.

Dr Hughes’ idea is to show growers a cost-effective solution combined with knowledge of frog phenology, or the seasonal cycles of frog movements and habits.  Frogs often migrate during wet, rainy nights and during mating season.  Foresight of these events will provide growers with the knowledge to prevent accidentally harvesting frogs hiding in their lettuce.  This would include what weather events are likely to trigger the animals to leave the irrigation canals as well as what times of the year certain frog species breed and migrate.  This knowledge combined with a cost-effective fence may be the best way of preventing the accidental harvest of wildlife. 

Flattening the Frog Curve.

Another concern that the public had was the risk of bacterial diseases being spread by these frogs.  Dr. Hughes said that the chances of a frog being a reservoir or host for diseases such as E. coli is extremely low.  He was more concerned about frogs transmitting diseases to other amphibians throughout the country because in many cases where animals were found alive, they were often released.  These non-native species have the potential to be extremely damaging to native species.  The Pacific Tree Frog was one of these commonly found species and is known to carry the Chytrid fungus without showing any symptoms.  Chytrid is a fungal pathogen that is currently threatening many of the world’s frog species.  By releasing these animals, this disease may be able spread to areas previously unaffected by the fungus. 

Future Incidents.

In the future, Dr. Hughes said that he hopes to develop an online portal for consumers to report any future wildlife findings.  This would allow for a greater amount of transparency to the public and enable researchers to find larger patterns of these incidents.  With the limited data that is available now, the true extent of this issue isn’t able to be determined.  The data that this study was able to analyze were only the incidents from popular Google-search results that “blew up” and there’s no way of knowing how many people discovered animals and simply didn’t make a fuss about it.  If this portal were to be developed, differences between conventional and organic crops could be studied as well as to see if there are any patterns in when these incidents occur.

The truth of the matter is that there isn’t “actually” a horde that wants to get into your salad bag, just a little tree frog in the wrong place at the wrong time. We simply need more research to be conducted, published, and brought to the attention of salad eaters worldwide to address the problems outlined in this article.

By Sophie Kogut

Introduction:

There’s a new threat looming over amphibian populations – Ranavirus. Ranaviruses are a class of virus that pose an increasing threat to aquatic ecosystems, as infection can lead to devastating mass mortality events. A ranavirus is a large, double-stranded DNA virus that causes a hemorrhagic response, or excessive bleeding,  in young toads and frogs which is often fatal. Ranavirus outbreaks may result in the decimation of entire generations of amphibian larvae. Even more concerning is that these viruses are not picky – they are capable of infecting amphibians, fish, and reptiles. Infection spreads rapidly through aquatic ecosystems because the virus is relatively stable. This is bad news, because according to disease ecologist Erin Sauer, “amphibians around the globe are already in peril”. Climate change, habitat destruction, the pet trade—the odds are stacked against many amphibian species, and it looks like ranavirus is just another enemy amphibians are up against.

What is behavioral fever?

When we get infected with a virus, one of our body’s immediate responses is to increase the body’s temperature, which results in uncomfortable sweating and chills: a fever. This signals to your immune system that something is wrong, and the immune system responds by kicking into overdrive: all hands on deck in an effort to destroy the pathogen. The initial fever is detected by the hypothalamus, which then directs your body to warm itself up.  Unlike mammals, toads are ectothermic, meaning they must rely on their environment to regulate their body temperature. This is why you frequently see lizards basking in the sun, or salamanders cooling off under a log. When infected by a virus, toad immune systems are incapable of inducing a fever on their own. However, Sauer has been studying a clever adaptation that may allow herps to fight viruses: a behavioral fever.

A behavioral fever occurs after the immune system detects the invasion of a pathogen, much like how a home security system detects an intruder. When the sensors on a home security system are triggered, a command center is alerted to the presence of the intruder; the command center will then alert the homeowner and provide instructions on how to respond. The hypothalamus in the brain of a toad acts like a command center, which, upon viral intrusion, instructs the toad to move to a warmer location, thus increasing its body temperature. This process is summarized below:

This phenomenon has been observed in many ectothermic species, but it does not occur with all types of pathogens. For example, infection by another infamous pathogen, chytrid fungus, does not induce toads to exhibit a behavioral fever. A behavioral fever is thought to kickstart the immune system in a similar way to fever in endotherms, where the fever acts as a messenger that facilitates a longer immune response, rather than a method to destroy the pathogens.

Dr. Sauer and her team designed an experiment to quantify the effects of behavioral fever on ranavirus. Their experiment yielded that adult Anaxyrus terrestris, or southern toads, are able to successfully reduce their viral load using this method, which is encouraging – to a point. Ranavirus is most deadly to younger animals, where large quantities of the virus may overwhelm the developing amphibian and result in a quicker death. Adult toads were tested using a method similar to COVID-19 testing: a swab sample was used to determine the presence of the virus, based on the quantity of viral DNA present. Unfortunately, the mouths of the younger toads were too small to be swabbed, so these frogs had to be analyzed post-mortem to determine viral presence; therefore, the results of this study apply more to adult toads.

Why should I care?

The changing climate may increase the frequency of disease outbreaks, so learning the strategies by which other animals fight these pathogens may prove to be extremely important in the context of endangered or threatened species. Also, there are serious economic and public health concerns when it comes to outbreaks—according to Sauer, there are “direct impacts on people getting sick, economic impacts on our [livestock] getting sick,” not to mention, “ these epidemic events could be an indicator that there’s something else going on in the ecosystem”. The current global pandemic is indeed a good example of how disruptive a microscopic virus can be. SARS-CoV-2 jumped from animals to humans and has since brought the world to  its knees. Regardless of whether a pathogen is capable of affecting humans right now, it is essential that we continue to monitor the ecological patterns and consequences of these outbreaks.

Bottom line:

This study concluded that while cold-blooded toads could not fight infections like mammals do, they are able to change their behavior in a way that enhances their ability to combat disease.

What’s next:

More research is needed before we can determine if other species can use this mechanism to fight ranavirus in the way A. terrestris has. As the virus mutates and infects other species, behaviors and responses may shift, and it is imperative to keep studying them. In Wisconsin, Sauer is continuing to study the effects of urbanization on amphibian populations with respect to other diseases.

Where to find it: Sauer, E. L., Trejo, N., Hoverman, J. T., & Rohr, J. R. (2019). Behavioural fever reduces ranaviral infection in toads. Functional Ecology, 33(11), 2172-2179