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Simberloff Receives Honorary Doctorate

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Simberloff Receives Honorary Doctorate

Tel Aviv President Ariel Porat, from left, congratulates University of Tennessee Professor Daniel Simberloff, along with TAU Rector Mark Shtaif on stage while in black and red regalia
Tel Aviv President Ariel Porat, from left, congratulates University of Tennessee Professor Daniel Simberloff, along with TAU Rector Mark Shtaif. TAU presented an honorary doctorate on May 30, 2024, to Simberloff, the Gore Hunger Professor of Environmental Science in UT’s Department of Ecology and Evolutionary Biology. The honor cites Simberloff’s “legendary achievements as an ecologist, conservation biologist and invasive species expert.”

by Amy Beth Miller

Daniel Simberloff’s contributions to ecology and conservation biology as a researcher, educator, and mentor received recognition this spring from Tel Aviv University (TAU).

Simberloff, the Gore Hunger Professor of Environmental Studies in the University of Tennessee, Knoxville’s Department of Ecology and Evolutionary Biology, received an honorary doctorate during a May 30 ceremony at TAU. The certificate cites Simberloff’s “legendary achievements as an ecologist, conservation biologist and invasive species expert.”

Simberloff is the first ecologist to receive an honorary degree from Tel Aviv University, and the university also asked him to open a symposium that week that brought together scientists from across Israel studying biological invasions and government policymakers. 

Simberloff first served as a visiting professor at Tel Aviv University in 1996 and before that had co-advised a TAU doctoral student, with whom he continued to collaborate. He also was involved in planning for the university’s Steinhardt Museum of Natural History. 

The honorary degree presented to Simberloff notes that his work “is studied by virtually every undergraduate student in the field worldwide” and is “helping to prevent extinctions and protect biodiversity.”

“It’s really gratifying,” he said of the honor, “because it’s a nation with a lot of ecologists doing world-class work and publishing in all the leading journals, and people working right in my major area of biological invasions and much concerned with conservation in a very challenging environment.”

The honorary degrees were presented during the annual meeting of TAU’s Board of Governors, which includes representatives from around the world.

The eight other honorees included the co-founder of WhatsApp and the first Jewish woman appointed to the Supreme Court of Canada, as well as others recognized for academics, contributions to the arts, activism, and entrepreneurship.

During the ceremony, TAU President Ariel Porat said, “Even in wartime, we must maintain our way of life. Especially for a university, it is crucial to continue researching, teaching, and contributing to society. Today’s honorary degrees ceremony shows that the pursuit of science and knowledge never stops.”

Simberloff’s contributions to understanding the natural world also were recognized in August 2023 by the British Ecological Society (BES). The honorary membership he received in the BES is the highest honor it bestows, recognizing exceptional contribution at the international level to the generation, communication, and promotion of ecological knowledge and solutions.

McGill University awarded Simberloff an honorary Doctor of Science degree in June 2023, calling him a pioneer and renowned scholar in ecology and conservation biology. “Studying the susceptibility of ecosystems to biological invasions years before the phenomenon became a thriving subdiscipline, Simberloff is a world leader in this research area,” McGill said in honoring him.

Jacob Suissa in ‘The Conversation’: “Ferns and flowers bribe helpful ant defenders with nectar, but ferns developed this ability much later – our study shows why”

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Ferns and flowers bribe helpful ant defenders with nectar, but ferns developed this ability much later – our study shows why

Ants foraging for nectar on a Bracken fern (Pteridium aquilinum). Jacob S. Suissa, CC BY-ND
Jacob S. Suissa, University of Tennessee

Look closely at a plant in your local park, your garden or even your kitchen, and you’re likely to see some damage. Whether a caterpillar has chewed away part of a leaf or a mealybug is sucking on sap, animals are constantly feeding on plants.

Of course, herbivory, or plant predation, is not ideal for a plant’s survival. So plants have evolved many different defense mechanisms to inhibit this threat, including physical and chemical weapons. For example, cactuses arm their bodies with skin-piercing spines. Herbs such as mint, lavender and rosemary produce volatile scent compounds that can help deter herbivores.

Other plants resort to bribing personal bodyguards by secreting thick, sweet nectar.

Nectar is most commonly associated with flowers, where it is used to entice bees, birds or butterflies to move pollen from one flower to another. But other plants produce different types of nectar glands called extrafloral nectaries. Plants produce these glands to bribe ants with a sweet reward; in return, ants will defend the plant from insect herbivores.

I study plant evolutionary biology, and recently worked with fern biologist Fay-Wei Li at the Boyce Thompson Institute and Cornell University ant biologist Corrie Moreau to examine the evolution of ant-bribing defense mechanisms in plants.

We found something striking: nearly 130 million years ago, during the Cretaceous geologic period, ferns and flowering plants independently evolved ant-bribing nectar glands at roughly the same time. We figured this out by using complex algorithms to estimate the evolutionary origin and history of ferns, flowering plants and ants.

This timing is quite interesting because it was very early in flowering plant evolutionary history, but quite late in fern evolutionary history. Our work demonstrated that old dogs can learn some new tricks – and, even more importantly, how it happened in ferns.

Meeting above the ground

Plants are the primary producers of nearly all of the food supply on Earth, so virtually all living creatures rely on them for survival. For this reason, herbivory is part of life. But it also creates serious costs for many industries, from house plants to agricultural crops. Major pest outbreaks can even threaten global food security.

For all of these reasons, understanding how plants defend themselves against predators is a critical challenge.

The evolution of ant-mediated defense strategies inexorably linked two lineages across the kingdom of life. It meant that ants and plants would eventually evolve together – a process called coevolution. As one species changes, the other may change in response, and these changes can even become encoded in their genes.

Flowering plants originated in the Cretaceous period, around 150 million years ago, and our analyses demonstrated that they formed tight associations with ants early on. These flowering plants and their ant partners seemingly evolved together over time.

But ferns didn’t. While they had the potential to develop nectaries at the same time as flowering plants, they didn’t start to evolve nectaries at fast rates until they learned to live among the trees.

Ferns originally were terrestrial plants, but after flowering plants evolved into large trees, ferns jumped onto their branches as epiphytes – plants that grow on other plants, often with no attachment to the ground.

A drop of moisture on a fern leaf where it joins the stem
Drynaria pilosa, commonly known as basket fern, secretes nectar. Jacob Suissa, CC BY-ND

Ferns can also climb up trees, as ivy does, or create their own trunks in the case of tree ferns. This also helped ferns get into the canopy.

The fact that ferns didn’t start producing nectar for ants until they moved up into trees confused me as a fern biologist. That was, until my coauthor Corrie Moreau pointed out that most ants lived in treetops.

This made perfect sense. As ferns became canopy dwellers, they began to grow closer to ants that were already associated with nectary-bearing trees. Comingling with these ants, ferns eventually tapped into the established mutually beneficial relationship between the ants and flowering plants.

The evolution and ecology of fern-ant relationships

While our study discovered new aspects of ant-mediated plant defense, it left many questions unanswered. For instance, are some ants specializing on ferns, or are they generalists that can feed on nectar from a wider range of plants? How, exactly, did plants originally develop the physical capacity to produce extra-floral nectar? Are the genes that encode for nectary development the same between ferns and flowering plants? Is the chemistry of fern and flowering plant nectar the same?

Our study lays the foundation for further research into the evolution and ecology of these nectaries. This is important foundational science. It’s also conceivable that research in this area could contribute to breeding programs that promote nectary-mediated ant defense, reducing the need for pesticides to protect plants from predators.The Conversation

Jacob S. Suissa, Assistant Professor of Plant Evolutionary Biology, University of Tennessee

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Ecological Society of America Awards UT Researchers

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Ecological Society of America Awards UT Researchers

Michael Blum headshot photo
Michael Blum
Alivia Nytko

by Randall Brown

Two Vol researchers from the UT Department of Ecology and Evolutionary Biology (EEB) earned honors in the 2024 Ecological Society of America (ESA) Awards. These awards recognize outstanding contributions to ecology in new discoveries, teaching, sustainability, diversity, and lifelong commitment to the profession.

EEB Professor Michael Blum, associate dean for research and creative activity in the College of Arts and Sciences, shared in the ESA’s George Mercer Award, given annually for an outstanding ecological research paper published within the past two years with an early-career lead author. 

EEB PhD student Alivia Nytko earned the E. Lucy Braun Award for Excellence in Ecology for her poster presentation at the 2023 ESA Annual Meeting titled, “Plant rarity related to phylogenetic divergence in biomass: Implications for ecosystem function.” 

“We are so pleased that our EEB researchers have been recognized by ESA for their scientific achievements,” said College of Arts and Sciences Interim Executive Dean Robert Hinde.

Blum collaborated with lead author Megan Vahsen, a postdoctoral fellow at Utah State University, Associate Professor Scott Emrich from UT’s Tickle College of Engineering, and others on the study “Rapid plant trait evolution can alter coastal wetland resilience to sea level rise,” published in Science in January 2023. Their work calls attention to the significant role of rapid evolution in shaping how ecosystems respond to global change.

They examined a dominant coastal marsh sedge to reveal how genetically based variation in a plant’s traits can evolve rapidly and influence a marsh’s resilience to sea level rise. The team used a unique approach, growing “resurrected” plants from decades-old seeds recovered from marsh soils and employing an ecosystem modeling approach. Bridging quantitative genetics and ecosystem modeling, their study highlights the need to consider evolutionary processes in ecological forecasting. 

Nytko’s winning research challenges conventional views on plant rarity by suggesting that rarity might often be an evolutionary adaptation rather than a result of environmental constraints. She used data from 25 Eucalyptus species to examine how natural selection influences plant traits that in turn shape plants’ range sizes and habitat needs. Her findings reveal that rare species are consistently smaller than their more common counterparts and that this trait has evolved multiple times across different groups. Her work highlights potential pathways for promoting conservation of rare plant populations.

“This excellence in ecology award from ESA for Alivia is fitting and well-deserved,” said Professor and EEB Department Head Jennifer Schweitzer. “Alivia is such a creative graduate student and this rarity work with Professor Bailey is innovative and has the potential to change how we think about, predict and manage rare species in nature.”

Nytko’s award is named for E. Lucy Braun, an eminent plant ecologist and one of the charter members of the ESA, studied and mapped North American forests and described them in her book, The Deciduous Forests of Eastern North America.

“It is such an achievement that two researchers in the EEB department have been honored for their work in ecology on the national stage,” said Professor Kate Jones, divisional dean for math and natural sciences. “Alivia Nytko winning the Braun Award for Excellence in Ecology and being singled out for her poster presentation at the Ecological Society of America’s annual meeting is a huge honor. It is also fantastic to see my colleague Mike Blum’s work with Megan Vahsen being recognized in this way.”

ESA will present the 2024 awards during a ceremony at the society’s upcoming annual meeting, August 4–9 in Long Beach, California.

Learn more about the 2024 ESA awards.

Suissa Study Has High Hopes For Plant-Ant Partnerships

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Ants crawling on a green stem

by Randall Brown

Collaborations across research disciplines can lead to unexpected breakthroughs and discoveries. Collaborations across species lead to unexpected evolutionary paths of mutual benefit.

For example, some plants have managed to recruit ant bodyguards. They produce sugary nectar on their leaves that attracts the ants, then these very territorial and aggressive ant mercenaries patrol “their” plant and sting or bite herbivores that try to eat it.

These relationships are well-documented in flowering plants, but they also occur in non-flowering ferns. This is weird news for researchers, as it has long been thought that ferns lack the nectaries for such complex biotic interactions.

Jacob Suissa, assistant professor in the UT Department of Ecology and Evolutionary Biology, worked with colleagues at Cornell University, including fern expert Fay-Wei li and ant expert Corrie Moreau, to investigate how this phenomenon developed over the millennia. They recently published findings in Nature Communications about the evolutionary timeline and underlying factors of this interspecies partnership.

“The new elements of this work are twofold,” explained Suissa. “First, we discovered that nectaries—the structures that produce sugary nectar to attract ant bodyguards—evolved in ferns and flowering plants around the same time.”

This happened some 135 million years ago, coinciding with the rise of plant-ant associations in the Cretaceous period. 

“This timing is quite spectacular given that it is very late in fern evolutionary history, nearly 200 million years after their origin,” said Suissa. “But it’s very early in flowering plant evolutionary history, nearly at the start of their origin in the Cretaceous.”

The second new element is how it all happened. Ferns originally flourished as terrestrial plants, growing on the forest floor. They transitioned in a major way in the Cenozoic Era, around 60 million years ago, becoming epiphytic, or tree dwelling, plants.

They learned some new habits on their way up.

“We discovered that as ferns left the forest floor and moved into the canopies, either as epiphytes, climbers, or tree ferns, they tapped into the existing ant-flowering plant interactions and evolved nectaries,” said Suissa.

This presents a curious dynamic in the ecological and evolutionary history of these two plant lineages. Ferns and flowering plants diverged from a common ancestor more than 400 million years ago, but then hit their stride in parallel with their nectary evolution and the mutually beneficial ant-plant tradeoff.

“This suggests that there may be some ‘rules of life’ governing the evolution of non-floral nectaries and ant-plant mutualism,” said Suissa. “This work can help future investigations by providing the evolutionary framework or backdrop for ecological, developmental, or genomic analyses.”

Read Suissa’s full paper, “Convergent evolution of nectaries in ferns facilitated the independent recruitment of ant-bodyguard from flowering plants,” in Nature Communications.

UT Researchers Dig Up Good News For Microbial Studies

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UT Researchers Dig Up Good News For Microbial Studies

by Randall Brown

Post-doctoral researcher Joe Edwards and graduate student Sarah Love, both in the Department of Ecology and Evolutionary Biology, published findings this spring that can save fellow researchers a lot of time and energy when storing soil samples for later study of their microbial content.

The preferred method for storing soil samples for the study of microbes has long been to freeze them to keep the DNA intact for studies that might need to extract information years down the road. The downside is the need to power these freezers and maintain facilities to house them.

Headshot photo of Sarah Love outdoors with mountains behind her
Outdoor headshot photo of Joe Edwards

Edwards and Love examined a wide array of soil samples in a project funded by the National Science Foundation and the US Forest Service. Their analysis indicates that soil stored under refrigerated or air-dried conditions can still retain the needed information for understanding microbial community composition and structure for many years.

“We wanted to show that these air-dried soils were still useful for understanding soil microbial communities,” said Edwards. “We’re using dried soil microbes from an archived national database to look at long-term, continent-wide spatial patterns in fungal communities and compare those with forest census data from all of those same plots.”

This soil database stores a history of the ecological changes in an area over long periods of time. Researchers want to study these soils with relatively new methods to build a timeline of ecological changes in fungi at the microbial level.

“This microbial sequencing technology has only been around for maybe the last 10 to 15 years or so,” said Edwards. “We don’t have very long-term trajectories for these microbiomes. The cool thing about these archives is that they were sampled more than once, so we have multiple resampling. We can look at how much of that community changes over time and get historical patterns for them, which is something really nobody has done yet.”

The results that Edwards and Love found show that dry-storage soil samples can be extremely useful for studying how soil properties and fungal communities change over longer periods, potentially up to decades. 

“What we were saying in the paper is a little nuanced,” said Edwards. “We managed to maintain the environmental variance that was explained in the microbial community. The method isn’t quite as reliable if you’re just trying to track specific taxa of fungi across time. But for looking at broad patterns in community diversity and community composition, it’s useful. We can get a good idea of the overall shape of these communities as they change over space and time.”

Knowing the reliability of available archived information can help future researchers know that their samples will give them the accurate data they need. 

Edwards and Love will apply the findings themselves to the next phase of their own soil research: sequencing thousands of air-dried soils from across the country. The information they find can offer important new understanding of long-term, global patterns of change.

Departmental Support Boosts NSF Awards For Graduate Students

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Departmental Support Boosts NSF Awards For Graduate Students

by Randall Brown

Sam Wilhelm’s winning proposal looked at how flowering plants and pollinating bees in the southeast respond and rebound to annual wildfires.

An increasing number of Vols in the Department of Ecology and Evolutionary Biology (EEB) earned awards through the National Science Foundation (NSF) Graduate Research Fellowship Program (GRFP). It marks a successful effort from the department to support researchers at the graduate level.

EEB winners are Sam Wilhelm, Kate Loveday, and Keelee Pullum. Other 2024 fellowship winners across the UT College of Arts and Sciences include Gage Coon from the Department of Microbiology and Charles Bell from the Department of Physics and Astronomy. 

“These are some of the most distinguished fellowships that a grad student can get,” said Stephanie Kivlin, associate professor and director of graduate studies in EEB. “It shows that our students are performing at a high level, really going above and beyond.”

The GRFP helps ensure the quality, vitality, and diversity of the US scientific and engineering workforce by supporting outstanding graduate students who are pursuing full-time, research-based graduate degrees in science, technology, engineering, and mathematics (STEM) or in STEM education.

The three new awardees this year make a total of six EEB students with GRFP fellowships, representing about 10% of the department’s current graduate students. Kivlin is excited that their student-support initiatives have garnered this high number of fellowships. 

“It’s nice to see the professional development training that we’re doing in the department is really paying off for our students,” she said. “We started a mock panel to review proposals before they are submitted in 2019. Since then, we’ve had so many more proposals funded. We also have writing and presentation classes, so our students are trained in multiple skills for the workforce.”

The GRFP provides three years of support over a five-year fellowship period for the graduate education of students who have demonstrated their potential for significant research achievements.

“If you have your own funding as a graduate student, you can pursue whatever question you want,” said Kivlin. “Often those are independent of the principal investigators of the graduate labs. It springboards students’ careers then because everyone can see that they have already started doing independent research.”

Wilhelm’s winning proposal looked at how flowering plant communities in the southeast respond and rebound to annual wildfires, and how that in turn might mediate the associated bee community in the area.

“I used metacommunity theory to hypothesize that different fire regimes may support a mosaic of different plant-bee ‘interaction metacommunities’ at the landscape scale,” said Wilhelm. “I proposed to test this by comparing plant-bee interaction dynamics across multiple annual fire treatments that differ in seasonality. I am thrilled to receive this award that will allow me to continue studying native bees and conservation of the ecosystems that sustain them.”

Loveday’s proposal looked into the mechanisms that allow invasive plant species to outcompete native herbaceous understories of forests.

“The GRFP is great because the NSF funds the potential of the applicant to do research effectively, not the specific projects you write up, which reinforces my confidence in doing research,” said Loveday. “The grant gives me the opportunity to pursue research questions I am passionate to answer.”

Pullum’s project aims to test how sickness behavior and parental care are traded off in the wild and how both parent and offspring fitness are affected.

“I plan to carry out these experiments for snow buntings, a species of arctic-breeding songbirds that migrate yearly to Utkiagvik, Alaska,” said Pullum. “The funding from the NSF GRFP will allow me to focus on research and community outreach during my graduate studies.”

EEB students Dusty Prater and Trina Chou earned honorable mentions for their proposals.

In microbiology, Gage Coon’s successful GRFP project aims to develop a microbial cycle that would turn atmospheric CO2 into calcium carbonate (rocks). Charles Bell, GRFP winner in physics, proposed novel ways to detect and investigate dark matter.

Faculty Recognized for Excellence in Teaching, Service, and Academic Outreach

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Faculty Recognized for Excellence in Teaching, Service, and Academic Outreach

During the 2023 UT College of Arts and Sciences faculty convocation, EEB faculty received awards for excellence in teaching, research, and academic outreach. 

Benjamin Keck, Lecturer – Excellence in Teaching Awards: Lecturer

Benjamin Keck is presented with an award by Liem Tran at the Faculty Awards Ceremony

Ben Keck is an outstanding and dedicated lecturer for the University of Tennessee who has supported student learning in the classroom, in the field, and in the lab for many years. His teaching practice stands out for his high level of innovation, enthusiasm, and positive course climate.

Keck is a dedicated undergraduate teacher of both introductory biology courses and upper-level majors courses. His appointment is across two units—general biology and EEB—and he makes a huge contribution both as a teacher and a mentor to students. As the Director of the Ichthyology Collection at UT, Keck also makes outstanding contributions to community outreach efforts to highlight the diversity and importance of fishes in Eastern Tennessee.


Randy Small, Professor – Excellence in Teaching Awards: Senior

Randy Small is presented with an award by Liem Tran at the Faculty Awards Banquet

Randy Small is a full professor in EEB and has been the director for Teaching and Learning in the Division of Biology since 2019. His first rate and long-standing contributions to the educational mission of the College of Arts and Sciences makes him the perfect winner of this award. Legions of students in EEB as a department and the whole Division of Biology have benefited from Small’s dedication to student success, outstanding teaching practice, and educational vision and leadership. This award is long overdue.


Laura Alexandra Russo, Assistant Professor – Faculty Academic Outreach Award: Research & Creative Activity

Laura Alexandra Russo is presented with an award at the Faculty Awards Ceremony

Russo is an outstanding faculty member in the Department of Ecology and Evolutionary Biology whose outreach has raised the profile of UT Knoxville scientifically and to the public. Her research engages the public, community groups, state agencies, students, and others to tackle declines in bee species and other pollinators and what can be done to reverse these trends. Her approach exemplifies engaged scholarship that is conducted with and in communities.

Russo regularly leads outreach events at state parks like Seven Islands and Roan Mountain and national parks like the Great Smoky Mountains, including pollinator and plant hikes and bioblitzes in which community members find, identify, and document biodiversity. She actively engages with UT Extension, giving seminars and running outreach events at UT’s research and education centers across the state.


Elisabeth Schussler, Professor – Outstanding Service Award

Elisabeth Schussler is presented an award by Robert Hinde at the Faculty Awards Ceremony

In her role as Director of Biology Teaching and Learning, Professor Schussler ensures our students in the lower-division biology courses receive excellence instruction from our graduate teaching assistants and nontenure-track faculty. 

She provides professional development opportunities for instructors to be at the top of their teaching game and it is this passion for high-quality teaching across the natural sciences that led her to build teams of faculty members across the college and university who also want high-quality instruction in lower-level courses. As Faculty Senate president, she supported the ideas of liberal arts learning through cultivation of a strong shared governance process. 

Graduate Student Wieteke Holthuijzen Published in ‘The Conversation’

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Murderous mice attack and kill nesting albatrosses on Midway Atoll − scientists struggle to stop this gruesome new behavior

Their ‘island naïveté’ means these seabirds are easy pickings when mice attack. USFWS – Pacific Region/Flickr, CC BY-NC
Wieteke Holthuijzen, University of Tennessee

At the far end of the Northwestern Hawaiian Islands lies Kuaihelani – also known as Midway Atoll – a small set of islands home to the world’s largest albatross colony. Over a million albatrosses return to Kuaihelani each year to breed. These seemingly pristine islands appear safe, but there’s a predator lurking among the seabirds.

House mice (Mus musculus) — the same kind that may be in your residence — have started to attack and kill albatrosses, eating them alive as they sit on their nests. I’m an ecologist who’s been studying the mystery behind these murderous mice.

A predator hiding in plain sight

Once the site of intense warfare during World War II, Kuaihelani is now a national wildlife refuge.

Without predators such as cats, rats or mongooses, Kuaihelani provides a safe haven for millions of nesting and migratory birds, including mōlī (Phoebastria immutabilis), also known as Laysan albatrosses. These seabirds, each about the size of a goose, nest in nearly the exact same spot each year, producing only one egg annually.

One person holds a large bird while another, wearing medical gloves, inspects a bloody wound on its back.
Biologists examine wounds on an adult mōlī caused by invasive house mice. USFWS – Pacific Region/Flickr, CC BY-NC

In the winter nesting season of 2015, bird-counting volunteers and biologists began seeing gruesome bloody wounds on nesting mōlī. At first, they found only a few mōlī with these mysterious injuries, which included severe chewing along the neck and even scalping. In the weeks that followed, they found dozens of injured mōlī, then hundreds.

Biologists were stumped. Had a black rat escaped off a docked boat? Had a peregrine falcon blown in with the latest winter storm? Desperate to identify the culprit, biologists set up game cameras around nesting mōlī.

Time-lapse night vision footage shows a mouse attacking the head and body of a nesting mōlī.

The cameras captured bizarre nighttime footage of mice crawling and chewing on the backs and heads of mōlī. It was the first time a house mouse had ever been observed attacking a live adult, nesting albatross.

Mōlī, like many seabirds, have evolved without predators on remote islands. As a result, such seabirds are often oddly unafraid and curious – pulling on researchers’ shoelaces or nibbling at our clipboards. This phenomenon is called “island naïveté” and, however charming, can spell disaster when nonnative predators such as rats and cats are introduced to islands. Lacking innate caution, even the largest seabirds can become the defenseless prey of predators as small as a mouse.

A black and white aerial photo of two small island. The one in the foreground has three intersecting landing strips.
The World War II military base on Midway Atoll including an airfield on Eastern Island and more facilities on Sand Island, across the channel. U.S. Navy/Wikimedia Commons

Developing a taste for flesh

During World War II, the islands of Kuaihelani were cleared and covered with wartime infrastructure. Both black rats and house mice were inadvertently introduced at this time. Soon, the rats began decimating populations of burrowing seabirds.

When the military importance of Kuaihelani faded in the 1990s, management of the atoll was transferred to the U.S. Fish and Wildlife Service. Rats were successfully eradicated in 1996, but mice remained. Thought to be small and harmless, they didn’t generate much concern until 2015.

Although scientists may never know exactly why mice began to attack and kill mōlī, we have some ideas.

Due to climate change, Kuaihelani has experienced increasingly erratic precipitation, sometimes resulting in long dry spells or intense downpours. During dry periods, vegetation quickly dies back. It’s likely the usual food items for mice, namely seeds and bugs, decline during these periods. In order to survive, mice need to find a different food source.

On an island with millions of birds, seabird carcasses are plentiful and attract a rich community of bugs, including cockroaches, isopods and maggots. Mice appear to have quite an appetite for these critters and likely feed on seabird carcasses at the same time. The transition from scavenging dead seabirds to attacking live ones that don’t fight back is only a small step.

As mouse attacks on nesting mōlī escalated from 2015 on, it was clear something needed to be done – and fast. The solution was to get rid of the mice, which, unfortunately, is much easier said than done.

Die-hard mice

Mouse eradication is a challenging and risky conservation endeavor that requires years of research and careful planning. Ideally, rodenticide, a type of poison used to kill rodents, should be offered when mice are most hungry and likely to eat it. This requires knowing exactly what they are eating and when those food sources are scarce.

By extracting and sequencing DNA from mouse poop and analyzing stable isotopes – a technique that identifies unique chemical fingerprints of organisms – my colleagues and I could figure out what organisms mice were eating and in what quantities. We found that mice on Sand Island of Kuaihelani mainly eat bugs (about 62% of their diet), followed by plants (27%) and finally albatross (likely mōlī, about 12%). The Fish and Wildlife Service identified July as the best time for the eradication attempt, since seabird density is typically lowest then.

Because of COVID-19 disruptions, the eradication attempt was delayed until July 2023, when the nonprofit organization Island Conservation and the Fish and Wildlife Service meticulously applied rodenticide in multiple rounds. At first, it seemed to be working. But in the weeks that followed, a few mice were spotted – then more. By September 2023, the eradication was declared unsuccessful.

Some conservation practitioners believe eradication should be attempted again, but others worry about creating mice resistant to rodenticide. When generations of rodents are exposed to rodenticide repeatedly, they may start to carry genetic mutations resulting in resistance to the poison, making future eradication efforts ineffective.

Without a doubt, mice on Kuaihelani have already been exposed to rodenticide for a long time. When Kuaihelani – or Midway Atoll – was a naval base, rodenticide was likely applied in and around buildings and residences. The rat eradication in 1996 was another exposure. I’m currently researching whether the mice on Kuaihelani already have these genetic mutations.

The worries about rodenticide-resistant mice aren’t limited to Kuaihelani. Around the world, especially in Europe, there are more and more cases of rodents carrying resistance. Rodents continue to have severe and widespread ecological effects on islands worldwide.

For now, I’m focused on helping the mōlī of Kuaihelani survive. But our research may also help inform the growing challenge of resistant mice around the world.The Conversation

Wieteke Holthuijzen, Ph.D. Candidate in Ecology and Evolutionary Biology, University of Tennessee

This article is republished from The Conversation under a Creative Commons license. Read the original article.