The MSU EEB Presidential Postdoctoral Fellowship is a two-year position that includes a generous salary and research stipend. Fellows are fully participating members of EEB with cutting-edge research programs and innovative community engagement initiatives, mentored by two or more EEB faculty members.
The Volunteer of Distinction awards celebrate academic excellence among undergraduate and graduate students. Students are selected to be honored as Volunteers of Distinction in recognition of their extraordinary academic achievement, professional promise, teaching (graduate students), or research.
Biologist Charles Darwin would be 216 years-old this month, and museum educators and UT scientists at the McClung Museum of Natural History and Culture are celebrating with Darwin Day on February 23.
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.
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.
In Water Canyon, New Mexico, there is a small, 18-mile-long, high-elevation area called the Magdalena Mountains, surrounded by desert. The isolated peaks host a scrubby collection of plants, including a tiny cluster of about 20 cottonwood trees. They are trapped, as if on an island, unable to escape by migration or pollen flow across the surrounding inhospitable lowland to any faraway, or even nearby, high-elevation area.
It is one of the hottest and driest “sky island” sites that we study, far hotter than any adjacent large mountain chain, and a great place to look for climate-adapted traits.
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.
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.
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.
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.
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.
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.
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.
Read the article here: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0293092
Faculty, staff and students from EEB gathered on May 18, 2023 to celebrate the end of the semester, recognize award-winners, and honor retirees. Check out this YouTube video to see all of the winners, along with some photos from the celebration.
Read about Dr. David Etnier’s Snail Darter legacy here:
.jpg){kind=link}