The fungal disease known as white-nose syndrome has absolutely obliterated certain species of North American bats, as I’m sure you know. One hope has been that it would cause a winged-mammal version of population resistance, where removing all the competing bats allows a few genetic variants who are less affected by the disease to thrive, spreading their resistance to future generations.
That’s what happens when we blast germs with antibiotics, so why couldn’t it happen when bats get blasted by fungal disease?
Alas, mammals are not bacteria. A Forest Service study (see it here) found no evidence that bats are evolving resistance.
So what is causing the apparent survival of a few scattered populations of little brown bats, which is the most affected species? “We propose that mechanisms other than adaptive immunity are more likely driving current persistence of little brown bats in affected regions,” the authors note.
Basically, some bats are changing habits to cope with the disease. The fungus mostly kills bats by waking them up during their long winter torpor, which depletes energy and keeps them from surviving until insect food appears in the spring. Bats that survive the fungus manage to shrug off at least some of these waking impulses, or else they have the habit of eating more in the fall so they have better fat supplies to make it through the winter.
Either way, no magic DNA bullet is going to save them.