Friday, March 22, 2024

PALEONTOLOGY

Researchers name prehistoric amphibian ancestor discovered in Smithsonian collection after Kermit the Frog

Discovery sheds light on the origin of living frogs and other amphibians and pays homage to the iconic muppet

SMITHSONIAN

The fossil skull of Kermitops. — IMAGE:
THE FOSSIL SKULL OF *KERMITOPS*.
THE SKULL POSSESSES A MISHMASH OF TRAITS THAT WERE DIFFERENT FROM FEATURES SEEN IN THE SKULLS OF OLDER TETRAPODS, THE ANCIENT ANCESTORS OF AMPHIBIANS AND OTHER LIVING FOUR-LEGGED VERTEBRATES. FOR EXAMPLE, THE REGION OF THE SKULL BEHIND THE ANIMAL’S EYES WAS MUCH SHORTER THAN ITS ELONGATED, CURVED SNOUT. THESE SKULL PROPORTIONS HELPED THE ANIMAL, WHICH LIKELY RESEMBLED A STOUT SALAMANDER, SNAP UP TINY GRUB-LIKE INSECTS.

SCIENTISTS HAVE UNCOVERED THE FOSSILIZED SKULL OF A 270-MILLION-YEAR-OLD ANCIENT AMPHIBIAN ANCESTOR IN THE COLLECTION OF THE Smithsonian’s National Museum of Natural History. IN A PAPER PUBLISHED TODAY, MARCH 21, IN THE *Zoological Journal of the Linnean Society*, THE TEAM OF RESEARCHERS DESCRIBED THE FOSSIL AS A NEW SPECIES OF PROTO-AMPHIBIAN, WHICH THEY NAMED *KERMITOPS GRATUS* IN HONOR OF THE ICONIC MUPPET, KERMIT THE FROG.
NOTE: USNM PAL 407585, DEPARTMENT OF PALEOBIOLOGY, SMITHSONIAN INSTITUTION.
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CREDIT: BRITTANY M. HANCE, SMITHSONIAN.

Scientists have uncovered the fossilized skull of a 270-million-year-old ancient amphibian ancestor in the collection of the Smithsonian’s National Museum of Natural History. In a paper published today, March 21, in the Zoological Journal of the Linnean Society, the team of researchers described the fossil as a new species of proto-amphibian, which they named Kermitops gratus in honor of the iconic Muppet, Kermit the Frog.

According to Calvin So, a doctoral student at the George Washington University and the lead author on the new paper, naming the new creature after the beloved frog character, who was created by puppeteer Jim Henson in 1955, is an opportunity to get people excited about the discoveries scientists make using museum collections.

“Using the name Kermit has significant implications for how we can bridge the science that is done by paleontologists in museums to the general public,” So said. “Because this animal is a distant relative of today’s amphibians, and Kermit is a modern-day amphibian icon, it was the perfect name for it.”

The fossilized skull—which measures just over an inch long and possesses large, oval-shaped eye sockets—was originally unearthed by the late paleontologist Nicholas Hotton III, who served as a curator in the museum’s paleobiology department for nearly 40 years. Hotton spent several field seasons excavating fossils from rock outcrops in north central Texas known as the Red Beds. The area’s rust-colored rocks date back to the early Permian period more than 270 million years ago and contain the fossilized remains of ancient reptiles, amphibians and sail-backed synapsids, the precursors to modern mammals.

Hotton and his team collected so many fossils that they were not able to study all of them in detail. This included a small proto-amphibian skull, which the team had unearthed in a rock layer known as the Clear Fork Formation in 1984. The skull was deposited in the Smithsonian’s National Fossil Collection, where it spent decades waiting for a researcher to take a closer look.

In 2021, Arjan Mann, a postdoctoral paleontologist at the museum and a former Peter Buck Fellow, was sifting through Hotton’s trove of Texas fossils when one specimen labeled as an early amphibian caught his eye.

“One fossil immediately jumped out at me—this really well preserved, mostly prepared skull,” said Mann, who serves as So’s mentor and is also a co-author on the new paper.

Mann and So teamed up to determine what kind of prehistoric creature the fossil belonged to. The skull possessed a mishmash of traits that were different from features seen in the skulls of older tetrapods, the ancient ancestors of amphibians and other living four-legged vertebrates. For example, the region of the skull behind the animal’s eyes was much shorter than its elongated, curved snout. These skull proportions helped the animal, which likely resembled a stout salamander, snap up tiny grub-like insects.

The researchers identified the fossil as a temnospondyl, a diverse group of primitive amphibian relatives that lived for over 200 million years from the Carboniferous to the Triassic periods. But because the animal’s skull sported such unique features, the scientists concluded that it belonged in an entirely new genus, which they named Kermitops. The moniker is a play on the creature’s cartoonishly wide-eyed face and is derived from a mashup of the words “Kermit” and the Greek suffix “-ops,” which means face. The researchers also christened the new animal with the species name gratus to represent their gratitude for Hotton and the rest of the team that originally unearthed the fossil.

Kermitops is notable for more than just its namesake puppet persona. The early fossil record of amphibians and their ancestors is largely fragmentary, which makes it difficult to understand how frogs, salamanders and their kin originated. Adding relatives like Kermitops into the fold is essential for fleshing out the early branches of the amphibian family tree.

“Kermitops offers us clues to bridge this huge fossil gap and start to see how frogs and salamanders developed these really specialized traits,” So said.

Mann agrees and hopes that the discovery of a previously unknown amphibian ancestor hiding in plain site will inspire other paleontologists to take a closer look at their own museum’s fossil collections.

“This is an active area of research that a lot more paleontologists need to dive back into,” Mann said. “Paleontology is always more than just dinosaurs, and there are lots of cool evolutionary stories and mysteries still waiting to be answered. We just need to keep looking.”

The new project is the latest example of the Smithsonian’s history of collaboration with George Washington University. This collaboration provides the university’s students with access to the collections and resources of the world’s largest museum and research complex. The new paper also includes a coauthor from the Field Museum of Natural History.

About the National Museum of Natural History

The National Museum of Natural History is connecting people everywhere with Earth’s unfolding story. It is one of the most visited natural history museums in the world. Opened in 1910, the museum is dedicated to maintaining and preserving the world’s most extensive collection of natural history specimens and human artifacts. The museum is open daily, except Dec. 25, from 10 a.m. to 5:30 p.m. Admission is free. For more information, visit the museum on its website, blog, Facebook, Twitter and Instagram.

The fossil skull of Kermitops (left) alongside a modern frog skull (Lithobates palustris, right).

Note: USNM PAL 407585, Department of Paleobiology (left), and USNM 230961, Division of Amphibians and Reptiles (right), Smithsonian Institution.

CREDIT

Brittany M. Hance, Smithsonian.

Arjan Mann (right), a Smithsonian postdoctoral paleontologist and former Peter Buck Fellow, and Calvin So (left), a doctoral student at George Washington University, holding the fossil skull of Kermitops in front of the Kermit the Frog puppet display in the “Entertainment Nation” exhibition at the National Museum of American History.

Note: Fossil skull of Kermitops; USNM PAL 407585, Department of Paleobiology, Smithsonian Institution.

Note: Kermit the Frog puppet; 1994.0037.01, Gift of Jim Henson Productions. From the collections at National Museum of American History, Smithsonian Institution.

CREDIT

James D. Tiller and James Di Loreto, Smithsonian.

Calvin So (left), a doctoral student at George Washington University, and Arjan Mann (right), a Smithsonian postdoctoral paleontologist and former Peter Buck Fellow, with the fossil skull of *Kermitops* in the Smithsonian’s National Museum of Natural History fossil collection.
“Using the name Kermit has significant implications for how we can bridge the science that is done by paleontologists in museums to the general public,” So said. “Because this animal is a distant relative of today’s amphibians, and Kermit is a modern-day amphibian icon, it was the perfect name for it.”
“This is an active area of research that a lot more paleontologists need to dive back into,” Mann said. “Paleontology is always more than just dinosaurs, and there are lots of cool evolutionary stories and mysteries still waiting to be answered. We just need to keep looking.”
Note: USNM PAL 407585, Department of Paleobiology, Smithsonian Institution.
CREDIT
Phillip R. Lee

JOURNAL

Zoological Journal of the Linnean Society

DOI

10.1093/zoolinnean/zlae012

METHOD OF RESEARCH

Observational study

ARTICLE TITLE

A new amphibamiform from the Early Permian of Texas elucidates patterns of cranial diversity among terrestrial amphibamiforms

ARTICLE PUBLICATION DATE

21-Mar-2024

Rays were more diverse 150 million years ago than previously thought

New fossil ray species discovered in Bavarica, Germany: Aellopobatis bavarica from the Late Jurassic

Peer-Reviewed Publication

UNIVERSITY OF VIENNA

Aellopobatis bavarica: The newly discovered species, complete fossils are only known from Germany. This species is also the largest species of all and can grow up to 170 cm in size. — IMAGE:
AELLOPOBATIS BAVARICA: THE NEWLY DISCOVERED SPECIES, COMPLETE FOSSILS ARE ONLY KNOWN FROM GERMANY. THIS SPECIES IS ALSO THE LARGEST SPECIES OF ALL AND CAN GROW UP TO 170 CM IN SIZE.
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CREDIT: TÜRTSCHER ET AL. (2024, FIGURE 4)

In a new study recently published in the journal Papers in Palaeontology, an international team of scientists led by palaeobiologist Julia Türtscher from the University of Vienna has explored the puzzling world of rays that lived 150 million years ago and discovered a previously hidden diversity – including a new ray species. This study significantly expands the understanding of these ancient cartilaginous fish and provides further insights into a past marine ecosystem.

In her new study, palaeobiologist Julia Türtscher from the Institute of Palaeontology at the University of Vienna examined 52 fossil rays from the Late Jurassic period. These rays are 150 million years old, from a time when Europe was largely covered by the sea, except for a few islands, comparable to today's Caribbean. The Late Jurassic specimens are particularly valuable to scientists because they are among the oldest known fully preserved ray specimens. As only the teeth of fossilised rays are usually preserved, such rare skeletal finds provide exciting insights into the early evolution of this group. Although the exceptionally well-preserved fossils (from Germany, France, and the UK) have been known for some time, they have been largely unexplored. Türtscher's study is the first comprehensive analysis of the variation in body shape in these rays.

The results show a greater diversity of holomorphic (fully preserved) rays in the Late Jurassic than previously thought. "Until now, only three holomorphic ray species have been confirmed from the Late Jurassic, but thanks to this study, a total of five species have now been identified," says Türtscher. Based on their analyses, the researchers were able to confirm a fourth species that had been discussed for some time, as well as documenting and introducing a new, previously undiscovered ray species: Aellopobatis bavarica. This species, which can grow up to 170 cm long, was previously thought to be a large form of the much smaller French Spathobatis bugesiacus, which is 60 cm long. However, by analysing the skeletal structures and body shapes in detail, the scientists were able to show that Aellopobatis bavarica is a separate species.

The new results also suggest that the five species occurred in very restricted areas, but the authors are reluctant to jump to conclusions about possible endemisms: "Further studies on the tooth morphology of the specimens and subsequent comparisons with isolated teeth from other sites may help to reconstruct the palaeogeographic distribution of Late Jurassic rays," explains Türtscher.

Insight into past marine ecosystems

The results of this new study not only contribute to the understanding of the biodiversity and evolution of rays in the Upper Jurassic, but also have direct implications on the identification of fossil ray species that are known from isolated teeth solely. Continual new discoveries about these fascinating animals provide insights into the dynamics of past marine ecosystems and highlight the importance of well-preserved fossils in the reconstruction of our geological past. "We can only draw accurate conclusions about living species if we also understand the past of a group, including its evolution, its adaptations to changing environmental factors over time, and the extinction this group has faced during its evolutionary history. Palaeobiological knowledge enables us to better understand the dynamics behind evolution and extinction of species and thus aids to develop more effective conservation measures for today's endangered species" says second author Patrick L. Jambura from the Institute of Palaeontology at the University of Vienna.

Palaeobiologist Julia Türtscher in the Bavarian State Collection of Palaeontology and Geology in Munich, where several specimens of the new ray species are on display.

CREDIT

Patrick L. Jambura

JOURNAL

Papers in Palaeontology

DOI

10.1002/spp2.1552

ARTICLE TITLE

Rostral and Body shape analyses reveal cryptic diversity of Late Jurassic batomorphs (Chondrichthyes, Elasmobranchii) from Europe.

ARTICLE PUBLICATION DATE

19-Mar-2024

New vaccine against a highly fatal tropical disease – and potential bioterror weapon – demonstrates efficacy in animal studies

UNIVERSITY OF CALIFORNIA - LOS ANGELES HEALTH SCIENCES

Burkholderia pseudomallei infecting a human cell — IMAGE:
BURKHOLDERIA PSEUDOMALLEI INFECTING A HUMAN CELL. THE BACTERIA (RED) ARE POLYMERIZING ACTIN (GREEN).
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CREDIT: PHOTO COURTESY OF CHRISTOPHER T. FRENCH

In a mouse study, UCLA researchers tested a vaccine against the bacterium that causes melioidosis and found it was highly protective against the disease, which is endemic in many tropical areas, causing approximately 165,000 cases with 89,000 fatalities around the world each year.

The bacterium, called Burkholderia pseudomallei, is spread through contact with contaminated soil and water through inhalation, ingestion or broken skin. It is so dangerous that it is categorized as a Tier 1 Select Agent of bioterrorism, and it can cause rapidly fatal pneumonia when inhaled in low doses. If aerosolized and unleashed in a terror attack, it could lead to widespread death.

To date there are no licensed vaccines against the bacterium, said senior author Dr. Marcus Horwitz, Distinguished Professor of Medicine, in the division of infectious diseases, and of Microbiology, Immunology and Molecular Genetics at the David Geffen School of Medicine at UCLA.

“A safe and effective vaccine is needed to prevent this disease as melioidosis is often difficult to diagnose, requires very lengthy treatment lasting three to six months, and has a high fatality rate even in high resource settings,” Horwitz said. “Such a vaccine would be of great benefit to people living in endemic regions, travelers, and military personnel stationed in these areas, and it would also reduce the risk from an intentional release of B. pseudomallei in a bioterrorist attack.”

The study is published in the peer-reviewed journal mBio.

The researchers developed the vaccine using a bacterial vector called LVS ΔcapB as a platform to express highly immunogenic proteins from B. pseudomallei that are able to induce an immune response that later protects the host from illness and death when infected with the pathogen. LVS ΔcapB, derived from a weakened form of a vaccine against tularemia, or “rabbit fever,” had been developed in Horwitz’s lab as a vector platform for creation of vaccines against other diseases caused by Tier 1 Select Agents such as anthrax and plague as well as tularemia.

They administered the new vaccine through both skin injection and intranasal delivery in a strain of mice that is particularly sensitive to B. pseudomallei lung infection. The researchers found that the vaccine was not only safe and non-toxic, but effective even against a highly lethal strain of the melioidosis bacteria. Intranasal administration provided better protection than skin injection, with just a single dose proving effective with long-lasting protection.

The next steps are to test the vaccine for protection against pneumonic melioidosis in a second animal model, which the Food and Drug Administration requires in the case of vaccines for which human efficacy studies cannot be conducted. If it passes that test, the vaccine would then become eligible for testing in humans for safety and immunogenicityS. The researchers will also evaluate the vaccine’s effectiveness against subcutaneous infection with B. pseudomallei, which is the way most cases of melioidosis are thought to be acquired naturally, and test it for efficacy against the closely related Tier 1 Select Agent pathogen Burkholderia mallei, which causes glanders in humans and animals.

Study co-authors are Michael Tullius, Peter Back, Saša Masleša-Galić, and Susana Nava of UCLA, and Richard Bowen of Colorado State University.

The study was funded by the National Institutes of Health (AI141390). Flow cytometry was performed in the UCLA Jonsson Comprehensive Cancer Center (JCCC) and Center for AIDS Research Flow Cytometry Core Facility that is supported by National Institutes of Health awards P30 CA016042 and 5P30 AI028697, and by the JCCC, the UCLA AIDS Institute, the David Geffen School of Medicine at UCLA, the UCLA Chancellor's Office, and the UCLA Vice Chancellor's Office of Research.

JOURNAL

mBio

DOI

10.1128/mbio.00186-24

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

LVS ΔcapB-vectored multiantigenic melioidosis vaccines protect against lethal respiratory Burkholderia pseudomallei challenge in highly sensitive BALB/c mice

ARTICLE PUBLICATION DATE

21-Mar-2024

Illinois study: Systematic review of agricultural injuries can help inform safety measures

Agricultural Injury Surveillance in the United States and Canada: A Systematic Literature Review

UNIVERSITY OF ILLINOIS COLLEGE OF AGRICULTURAL, CONSUMER AND ENVIRONMENTAL SCIENCES

Man posing with tractor — IMAGE:
UNIVERSITY OF ILLINOIS RESEARCHERS REVIEWED U.S. AND GLOBAL LITERATURE ON AGRICULTURAL INJURIES, HELPING TO INFORM SAFETY EDUCATION AND POLICIES.
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CREDIT: COLLEGE OF ACES

URBANA, Ill. – Agricultural occupations are hazardous with one of the highest rates of workplace injuries and fatalities in the U.S. The manual and often strenuous nature of the work, combined with the use of machinery and exposure to environmental hazards create a challenging work environment. Understanding the nature and causes of injuries can help improve safety guidelines and policy measures. However, obtaining a comprehensive overview of injuries is hindered by the absence of a central reporting system. Two new papers from the University of Illinois Urbana-Champaign provide a systematic review of academic literature on agricultural injuries in the U.S. and globally.

“When it comes to agriculture, there's no single source for injury data. In other occupations, work injuries in the U.S. must be reported to the Occupational Safety and Health Administration (OSHA), but farm work is often exempt from these requirements because many farms are small and have less than 10 full-time employees,” said Salah Issa, an assistant professor in the Department of Agricultural and Biological Engineering (ABE) and an Illinois Extension specialist; both units are part of the College of Agricultural, Consumer and Environmental Sciences (ACES) at Illinois. ABE is also part of The Grainger College of Engineering at Illinois.

“There have been a lot of grassroots efforts to track surveillance data, but they are based on different methods so it’s hard to get a complete look at agricultural injuries. Our work combines results into one large dataset, providing a comprehensive overview of previous research,” Issa explained.

In the first study, the researchers conducted a systematic literature review of 48 academic papers published in the U.S. and Canada from 1985 to 2022.

“We identified five different surveillance methods: newspaper clippings, surveys, death certificates, hospital records and emergency medical services (EMS) data, and multiple sources,” said Sihan Li, a doctoral student in ABE and lead author on the first paper.

The researchers also analyzed and categorized information such as the type and source of injury, the event leading up to it, and the gender of the victim.

Overall, vehicles (including tractors and ATVs) were the most common source of injury, with over 55,000 incidents reported, as well as the leading source of fatalities. Other significant causes of injury included machinery, slips and trips, animals, chemicals, and tools. Men were more than twice as likely as women to be victims of injury. Age varied by surveillance method, with newspaper clippings skewed to younger victims (22% of incidents) and death certificates skewed to older victims (30% over 65).

In the second study, the researchers reviewed 69 articles from 17 countries in North America, Europe, and Asia, including the U.S., Canada, Turkey, India, Pakistan, Austria, Italy, and others.

The main data sources identified in these studies were hospital records, followed by surveys, government records (including death certificates), insurance claims, and multiple sources.

“For the global perspective, we narrowed our scope to focus primarily on machine-related injuries, which involves tractors and farm equipment,” said Mian Muhammad Sajid Raza, a doctoral student in ABE and lead author on the second paper.

The researchers found that tractors stand out as the leading cause of fatal incidents, with tractor overturns accounting for 45% of all machinery-related incidents in North America. Furthermore, injuries linked overall to agricultural machinery significantly contribute to both fatal and non-fatal incidents.

“It is also interesting to look at other sources of injury. In North America and Europe, animals are the cause of less than 3% of all injuries. But in Asia, animals represent 7% of the total injuries and 35% of the fatalities. This is likely because farming is less automated and animals are still used extensively in some Asian countries,” Raza said.

The research shows agriculture is a dangerous occupation globally, with injuries reported in at least three continents. Overall trends are as expected, with vehicles and machinery playing a large role in injuries and fatalities, Issa noted.

“One of our most important findings is that the way you conduct injury surveillance will have an impact on your results,” he said. “For example, if you use newspaper clippings, your findings will skew towards a younger age group. The discrepancies are so large it’s clearly worth evaluating the type of surveillance methods employed, and it’s important to use multiple sources to get a good picture of what’s going on.”

Understanding the nature and source of injuries is important for developing educational programs and interventions, Issa concluded.

Both papers, “Agricultural Injury Surveillance in the United States and Canada: A Systematic Literature Review’ [DOI: 10.1080/1059924X.2024.2304699] and “Global Patterns of Agricultural Machine and Equipment Injuries- A Systematic Literature Review” [DOI: 10.1080/1059924X.2024.2304704] are published in the Journal of Agromedicine.

JOURNAL

Journal of Agromedicine

DOI

10.1080/1059924X.2024.2304699

METHOD OF RESEARCH

Literature review

ARTICLE TITLE

Agricultural Injury Surveillance in the United States and Canada: A Systematic Literature Review

Product that kills agricultural pests also deadly to native Pacific Northwest snail

OREGON STATE UNIVERSITY

CORVALLIS, Ore. – A product used to control pest slugs on farms in multiple countries is deadly to least one type of native woodland snail endemic to the Pacific Northwest, according to scientists who say more study is needed before the product gains approval in the United States.

Dee Denver of the Oregon State University College of Science led a 10-week laboratory project that showed the effect of a biotool marketed as Nemaslug on the Pacific sideband snail. The study was published today in PLOS One.

Nemaslug is based on the organism Phasmarhabditis hermaphrodita, a species of tiny, parasitic worm known as a nematode.

The speed of the Pacific sidebands’ demise depended on the concentration of Nemaslug exposure and the size and maturity of the snails, but by the end of the study all 90 were dead, whereas all 30 snails in a control group were still alive.

“This finding is a big deal because there are strong efforts to bring this commercialized nematode to U.S. markets to control invasive pests, such as the gray field slug, that cause damage to a variety of agricultural crops,” said Denver, who heads OSU’s Department of Integrated Biology and directs the university’s School of Life Sciences.

“Our research is the first to demonstrate that these nematodes infect and kill a non-target gastropod species in the Northwest, which due to its rainy climate is a land slug and snail biodiversity hotspot.”

If P. hermaphrodita were sold and released in Oregon and similar environments, Denver said, there is “strong potential” that the nematodes would infect and kill a range of non-target native species including the iconic Pacific banana slug, dealing a blow to biodiversity and creating other negative ecosystem impacts.

Before Nemaslug is made available in the United States, more research is needed to investigate the effects it might have on non-pest slugs and snails, including research in conditions that mimic those species’ natural environments, he added.

Presently, Nemaslug is sold in Canada, Kenya and the United Kingdom and throughout the European Union.

For it to be made available in the U.S., Denver said, it would need both the approval of the federal Department of Agriculture as well as the sign-off of regulators in individual states where it was distributed.

The nematodes sold as Nemaslug work by entering small openings in the bodies of host slugs and fatally infecting them. The nematodes then reproduce inside the dead host and disperse in search of new hosts.

Denver and his co-authors – biologists and crop and soil scientists at OSU – note that the history of biocontrol of agricultural pests is somewhat checkered, in part because unintended consequences for non-target species remain understudied and hard to predict.

One biocontrol effort involving the introduction of a non-native snail, they point out, led to the extinction of hundreds of native snail species on Hawai’i and other Pacific islands.

“Terrestrial slugs and snails make up more than one-third of the total documented animal species extinctions since the year 1500,” Denver said. “Beyond factors like rising global temperatures and habitat loss, gastropods have historically suffered greatly from poorly designed and executed biocontrol attempts.”

Collaborating on this research were Dana Howe of the Department of Integrative Biology and Andrew Colton, Casey Richart and Rory McDonnell of the Department of Crop and Soil Science in the College of Agricultural Sciences.

In 2018, a paper by some of the same collaborators described the first report of P. hermaphrodita in Oregon, and last year, another paper was the first report of a similar nematode, P. californica, in Washington state.

P. californica, discovered in 2013 as a species new to science, is sold in England, Scotland and Wales as Nemaslug 2.0; Denver and McDonnell found P. californica in Oregon for the first time during a 2018-19 nematode survey.

How widespread either species is in the Northwest has not been determined, Denver said.

JOURNAL

PLoS ONE

DOI

10.1371/journal.pone.0298165

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

The biocontrol nematode Phasmarhabditis hermaphrodita infects and increases mortality of Monadenia fidelis, a non-target terrestrial gastropod species endemic to the Pacific Northwest of North America, in laboratory conditions

ARTICLE PUBLICATION DATE

21-Mar-2024

Forest, stream habitats keep energy exchanges in balance, global team finds

PENN STATE

Sycamore Creek — IMAGE:
SYCAMORE CREEK FLOWS THROUGH AN ARID LANDSCAPE IN ARIZONA. IT WAS ONE OF THE STREAMS INCLUDED IN THE STUDY ON HOW STREAMS AND FORESTS EXCHANGE ENERGY.
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CREDIT: DANIEL ALLEN/PENN STATE

UNIVERSITY PARK, Pa. — Forests and streams are separate but linked ecosystems, existing side by side, with energy and nutrients crossing their porous borders and flowing back and forth between them. For example, leaves fall from trees, enter streams, decay and feed aquatic insects. Those insects emerge from the waters and are eaten by birds and bats. An international team led by Penn State researchers has now found that these ecosystems appear to keep the energy exchanges in balance — a finding that the scientists called surprising.

Scientists around the world who have conducted research on the exchange of energy, materials and organisms between these connected ecosystems have come to call the phenomenon “allochthony” — meaning the consumption of resources by organisms residing in one ecosystem, when that energy was produced in another ecosystem. The balance between aquatic and terrestrial ecosystems has been difficult to gauge and poorly understood at a global scale because it depends on an uneven flow of energy and nutrients that fluctuates across seasons and across different climates.

But findings of a new study recently published in Ecology Letters sheds new light on the relationship between forests and streams. The researchers, who analyzed data from 149 studies of coupled forest-stream ecosystems around the world, found that aquatic and terrestrial organisms consume the same amount of energy that comes from the opposite ecosystem.

“This was a really interesting and unexpected result because we know that there’s way more energy flowing into streams in the form of leaves that fall from trees than what comes out in the form of emergent aquatic insects,” said the study’s lead author Daniel Allen, assistant professor of aquatic ecology, Penn State College of Agricultural Sciences. “But the quality of the resources is vastly different, because the aquatic insects that emerge from streams are very nutritious.”

The researchers also found that consumer allochthony varies with feeding traits for aquatic invertebrates, fish and terrestrial arthropods — such as insects, beetles and spiders — but not for terrestrial vertebrates such as birds and rodents. Finally, they reported that allochthony is nearly twice as great in arid climates than tropical ones for aquatic invertebrates, but remains steady for fish across varied climates.

“Most people don’t think about streams and forests being interrelated, but the organisms those habitats support are dependent on energy and resources that come from outside their ecosystem,” Allen said. “This phenomenon is true around the world, and this study is important because we collected data across the planet, to look at how this fundamental process varies in different climates, seasons and from over 700 different stream and riparian species.”

Contributing to the research at Penn State were postdoctoral scholar Veronica Saenz, graduate student Kierstyn Higgins and recently graduated master’s degree student Alice Belskis, all in ecosystem science and management. Also contributing to the research were: James Larson, U.S. Geological Survey, Upper Midwest Environmental Sciences Center; Christina Murphy, U.S. Geological Survey, Maine Cooperative Fish and Wildlife Research Unit; Erica Garcia, Charles Darwin University, Australia; Kurt Anderson, University of California, Riverside; Michelle Busch, University of Kansas; Alba Argerich, University of Missouri; Brooke Penaluna, PNW Research Station, U.S. Forest Service; Jay Jones, University of Alaska, Fairbanks; and Matt Whiles, University of Florida.

The U.S. National Science Foundation supported this research.

JOURNAL

Ecology Letters

DOI

10.1111/ele.14401

METHOD OF RESEARCH

Meta-analysis

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Global patterns of allochthony in stream–riparian meta-ecosystems