According to a new study, the microbial ecosystem in the guts of wild martens (Martes americana) living in relatively pristine natural habitats differs from the gut microbiome of wild martens living in areas more heavily impacted by human activity. The discovery highlights a new tool that will enable researchers and wildlife managers to assess the health of wild ecosystems.
"Specifically, we discovered that wild martens in relatively undisturbed environments have more carnivorous diets than martens in human-affected areas," explains Erin McKenney, co-lead author of the study and assistant professor of applied ecology at North Carolina State University. Marten are small mammals that are closely related to weasels, ferrets, and mink.
"This finding, together with our other work on carnivore microbiomes, tells us that the microbial ecosystems in carnivore guts can vary significantly, reflecting a carnivore's environment," McKenney says. "This means, among other things, that we can assess the gut microbiomes of carnivores that live in a given area, which can be done by testing wild animal feces. In practice, this research reveals a useful tool for assessing the health of wild ecosystems."
"Our goal here was to determine how if at all, human disturbance of a landscape affects the gut microbiome of American martens that live in that landscape," says Diana Lafferty, co-lead author and assistant professor of biology at Northern Michigan University. "And the answers were pretty clear here."
The researchers collected gut microbiome data from 21 martens for the study. During a legal trapping season, sixteen martens were caught. The remaining five were safely trapped and released in the Huron Mountain Club in Michigan's Upper Peninsula.
"The Huron Mountain Club is especially important for this study because it's relatively pristine—one of the largest, primeval forests in the eastern United States," says Lafferty. "This makes it an excellent contrast to the 16 martens harvested, which were collected in areas more impacted by human activity."
The researchers discovered that the gut microbiomes of marten harvested in the Huron Mountain Club's pristine forest were clearly distinct from marten harvested elsewhere.
"This reflects the fact that marten in the relatively pristine forest can forage at a higher trophic level, which means they occupy a higher position in the food web," Lafferty explains. "In other words, martens in relatively pristine forests eat more carnivorous foods, whereas martens in more populated areas eat more omnivorous foods. Essentially, the findings show that a disturbed landscape causes a significantly different diet, which is reflected in their gut microbiomes."
"It's also worth noting that we were able to trap and release the marten in Huron Mountain Club during the dead of winter because we designed and built custom box traps to protect them from the elements," says Chris Kailing, a co-author of the paper and former Northern Michigan University student who worked on the project. "This is interesting because it allows for winter sampling for future wildlife research even in harsh winter conditions."
"This is the most recent chapter in a body of research that is assisting us in understanding carnivore gut microbiomes," McKenney says. "Carnivore gut microbiomes are inherently more variable than other animals' gut microbiomes. This study adds to the emerging picture that all of this variation is not just noise. Rather, this variability stems from the nutritional landscape to which carnivores have access—which, in turn, reflects the health of the ecosystem in which carnivores live. This means that studying the gut microbiome of wild carnivores can provide us with valuable information about the ecosystems in which they live."
The paper, titled "The gut microbiome of a wild American marten in Michigan's Upper Peninsula," will be published on November 3 in the open-access journal PLOS ONE. Sierra Gillman of the University of Washington, Miles Walimaa of Northern Michigan University, Macy Kailing of Virginia Tech University, and Brian Roell of the Michigan Department of Natural Resources all contributed to the paper.
Journal information: PLoS ONE