Hibernating little brown bats inside an abandoned copper mine in Michigan's Upper Peninsula. Photo by John DePue.

A new study from University of Michigan biologists presents the first genetic evidence of resistance in some bats to white-nose syndrome, a deadly fungal disease that has decimated some North American bat populations.

The study involved northern Michigan populations of the little brown bat, one of the most common bats in eastern North America prior to the arrival of white-nose syndrome in 2006. Since then, some populations of the small, insect-eating bat have experienced declines of more than 90 percent.

U-M researchers collected tissue samples from wild little brown bats that survived the disease, as well as individuals killed by the fungal pathogen. They compared the genetic makeup of the two groups and found differences in genes associated with regulating arousal from hibernation, the breakdown of fats and echolocation.

“Because we found differences in genes associated with regulating hibernation and breakdown of fats, it could be that bats that are genetically predisposed to be a little bit fatter or to sleep more deeply are less susceptible to the disease,” said U-M’s Giorgia Auteri, first author of a paper published Feb. 20, 2020 in the journal Scientific Reports.

U-M doctoral student Giorgia Auteri rappelling into an abandoned Upper Peninsula copper mine to study hibernating little brown bats, one of species known to be affected by white-nose syndrome. Image: John DePue.

“Changes at these genes are suggestive of evolutionary adaptation, given that white-nose syndrome causes bats to arouse with unusual frequency from winter hibernation, contributing to premature depletion of fat reserves,” said Auteri, a doctoral student in the Department of Ecology and Evolutionary Biology who conducted the study for her dissertation.

The other author of the Scientific Reports paper is U-M biologist Lacey Knowles, Auteri’s faculty adviser.

While the study was small – involving tissue samples from 25 little brown bats killed by white-nose syndrome and nine bats that survived the disease – the authors say their sample size is large enough to detect genetic changes driven by natural selection. A larger follow-up study is underway, expanding both the number of bats and the areas affected by the disease, to develop a fuller picture of adaptive change that may be key to the species’ survival.

The fungal pathogen that causes white-nose syndrome was inadvertently introduced in the northeastern United States in 2006 and is currently spreading across the continent.

Thirteen species of North American bats are currently affected, with some populations experiencing losses of 90-100 percent. The disease is named for a distinctive fungal growth around the muzzles and on the wings of hibernating bats.

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The paper is receiving widespread media attention including on Michigan Public Radio and by The Wildlife Society.