Earth Week: The ‘shrewd’ facts

UND parasitologist’s focus on small mammal gains international attention in NOAA’s latest Arctic Report Card


UND biologist Vasyl Tkach and team study shrews (above) in the Arctic as an indicator of changes in climate and ecology. Their research was featured in the most recent National Oceanic and Atmospheric Administration Arctic Report Card.

UND Associate Professor of Biology Vasyl Tkach has discovered dozens of new species. He’s traveled to all areas of the world—from Brazil to Kenya and beyond—and has published endless articles on his global findings.

But the research that took him and his colleagues to icy northern Alaska to examine the changing habitats of shrews may be his biggest public hit.

Vasyl Tkach

UND Professor of Biology Vasyl Tkach

Tkach is a part of a collaborative cross-country team whose research was included in 2016’s National Oceanic and Atmospheric Administration (NOAA) Arctic Report Card. The well-known annual peer-reviewed report brings together findings from scientists across the world to create a picture of ecosystem variations due to climate change.

“The invitation to contribute to the Arctic Report Card was evidence of the importance of the research,” Tkach said. “This is a good piece to put UND on the national and international map. It’s another opportunity for people to see our work here.”

The team’s focus on shrews is a deviation from the Arctic’s iconic polar bears, caribou, and muskoxen—all “poster children” for climate change studies.

“It’s only the second time a small mammal has been featured in the Arctic Report Card through its whole history,” Tkach noted. “The only other small mammal that got the honor in the history of the publication were lemmings. Everyone wants to hear about those,” he added with a laugh.

So why shrews? Tkach explained that since these small animals don’t migrate, any changes in climate and ecology affect them more directly. And since there are high numbers of them, scientists can more accurately take sample sizes and assess them.

The researchers in Tkach’s study followed the masked shrew, an animal that can be found here in North Dakota. But the masked shrews typically found in forests just below the Arctic tundra are pushing farther and farther north into the Arctic—an hypothesized indication of climate change—and are working their way into the habitat of the barren ground shrew, which can cause problems.

“The barren ground shrew populations have expanded and shrunk before due to glaciation. But that happened over hundreds, even thousands of years, so they had time to adjust and adapt,” Tkach said. “But right now, the change is so quick that it’s a challenge to their adaptability, and whether they are capable of coexisting with another species (the masked shrew) that essentially occupies the same ecological niche.”

Role of parasites

But Tkach’s involvement in this shrew-based research gets to the very core of the problem—to the guts, you could say.

“Environment is one thing, the vertebrate animal is another—and then there are the parasites. Of course, as a parasitologist, they’re my favorite objects,” Tkach smiled. “They are ideal targets to look at, because they’re not only found in shrews, but the majority of them have this complex life cycle, so in order to circulate in the environment, they need to find at least another host—sometimes more than one.”

Masked shrews and barren ground shrews are related, so they have the ability to hybridize and potentially exchange parasites when they coexist. “So we can look at how much was shared—or not shared—before, and what’s happening now as a result of climate change and the progressively overlapping distribution area,” Tkach explained.

Shrews are food to larger predators like arctic foxes and owls, and they may contain larval stages of parasites that will infect the predator. By looking at which parasites are found in the shrews and the animals that eat them, researchers can directly asses their situation within the whole community.

“That’s why we look to them as a maybe less flashy, but much more convenient system of assessing what’s happening,” he said.

Stephen Greiman

Stephen Greiman, a UND Ph.D. alumnus and current biology faculty member at Georgia Southern University, collaborated with Tkach on the shrew study that landed in the 2016 NOAA report. (Above) Greiman conducts field work on shrews and their parasites in the Yukon, Canada in 2014. Photo courtesy of Stephen Greiman.

Collaborative alum

This kind of parasite examination would not be possible without the ability to look to the past.

“If you go to the site and collect something, that’s a good starting point. But what you get is today’s slice of what happens in this environment,” Tkach said. “We can go to a museum, take a specimen that was collected a couple of decades ago, and then the specimens we have collected at a later time can be used in comparisons in the future. This way, we will have a clearer picture of what is happening.”

For his continuing research in this area, Tkach has had the opportunity to work extensively with his former UND graduate student Stephen Greiman, now a biology faculty member at Georgia Southern University.

During Greiman’s post-doctoral studies, he worked closely with renowned mammologist Joseph Cook—another of the shrew research collaborators—utilizing the shrew and parasite collections at the Museum of Southwestern Biology, which has been an important component in their collective Arctic studies.

Tkach says that the success of his research with Greiman and the rest of the team is a testament to not only a strong UND biology program, but a strong university as a whole.

“When students see what is done right here in this building where they take classes, and they see that it has national and international exposure, it helps them feel like a part of something really larger—a part of a greater scientific community that cares about things beyond this neighborhood,” he said.