LBBs Fighting Hard

Little brown bats, (Myotis lucifugus), are fighting back against the white nose syndrome caused by the P. destructans fungus.  The disease has wiped out colony after colony of the indigenous specie in North America {26.05.22)  90% of the endangered bats have succumbed to the fungus which robs them of hibernation and thereby depletes their fat reserves.  New research shows survivors have developed adaptive gene changes that regulate arousal from hibernation (GABARB1) and breakdown of fats (cGMP-PK1). Whether these apparent adaptations will allow the specie's survival of the plague remains unknown.  The disease was introduced to bats by humans in the northeast of the US in 2006, probably by spelunkers who tracked the fungus into their roosting caves.

The researchers found a large amount of genetic drift in surviving populations  of bats.  Genetic drift is non-adaptive genome changes associated with declining populations affected by the disease.  This result indicates a very strong selective process acting on standard gene variation. Such rapid evolution is not unprecedented in nature.  Steelhead trout, an ocean going fish introduced into the central US, have rapidly become adapted to fresh water despite small founder populations.

Two of the four genes mapped in the study regulate histamine response, which are released in response to tissue damage caused by the fungus. The researchers think that bats genetically predisposed to release fewer histamines, or prevent arousal induced by histamines, are better able to conserve their energy stores during winter and survive a fungal infection.  The fat metabolism gene studied is linked to obesity in animals; bats with this gene variation might allow bats faced with premature energy depletion during winter to survive.  These findings suggest that little brown bats are developing tolerances to the disease through evolutionary genetic changes.  More research is needed to determine if genomic changes in little brown bats provide tolerance to the P.destructans fungus, or if the survivors are developing resistance to the disease.