Some bats are adapting to white-nose syndrome, study finds

Some bats are developing adaptations to white-nose syndrome that allow them to survive the deadly disease, according to a recent study.

Comparing little brown bats (Myotis lucifugus) that died from the disease with those that survived it, researchers found differences in key genes associated with regulating hibernation and fat metabolism. Those functions are particularly relevant, because white-nose syndrome kills by causing bats to wake up frequently from hibernation and deplete their fat reserves.

Researchers say this is the first published study to document genetic changes related to survival advantages.

“This means that maybe, hopefully, later generations of bats may be better able to deal with the disease,” said Giorgia Auteri, a PhD candidate at the University of Michigan Department of Ecology and Evolutionary Biology, who led the study published in Scientific Reports.

“But it’s a little but too soon to say,” Auteri said, because even if some individuals have a genetic edge, it may not be strong enough to create a viable population to face off the disease in the long run.

Auteri conducted the research after finding Michigan caves covered with bats that had died from white-nose syndrome. The fungus was first detected in Michigan in 2014 and has since decimated their populations. She began collecting carcasses, hoping to do something with them to help the species. “They died, but they might as well have died for a reason,” she said.

Auteri wondered if after a horrible first rush of deaths, remaining individuals — and their offspring — might be better adapted to the disease, “or is this something we’re really in for the long haul if they have not adapted to it at all?”

She and her colleagues had a clue about what they may find from the history of Eurasian bats that have lived with the fungus for thousands of years. The fungus still grows on them, but it doesn’t cause many deaths. Since little brown bats in North America aren’t that genetically different from many Eurasian bats, Auteri thought, maybe some genetic variants can allow them to better cope with it.

She put the bat carcasses she collected to use by studying their genes and comparing them to bats that had been infected and survived. “I was thinking that whether or not bats are potentially evolving to better cope with this disease, this can impact the tempo and types of management decisions,” she said.

Researchers collected dead bats from inside and outside caves as well as individuals that had been infected by the disease, but were still alive. Survivors are rare, but Auteri and her colleagues used nets to catch bats in the summer, when they were actively flying around, looking for scars or lesions caused by the fungus. They also used samples of healthy bats that had been sent in for rabies testing.

When they compared the genes of dead bats with those from survivors, they found differences in genes associated with regulating hibernation and fat metabolism that could affect whether or not they can live with white-nose syndrome — differences they seemed to have developed over just the few years since the disease reached Michigan. “It could be the survivors are predisposed to be deep sleepers with more fat reserves compared to ones that weren’t surviving the disease,” she said.

She and her colleagues plan to broaden the study to look at populations of bats outside Michigan. They also plan to complete a full genome sequencing of some individuals and possibly look more at immune genes that may be fighting off the fungus.

“The best-case scenario is that for this species, eventually populations will be able to increase in size even with the fungus present,’ she said. “In the interim, my hope for this study is that the information is useful to wildlife managements on the ground making conservation decisions.”