IL31RA and infection: This apparent difference in virulence of Bd genotypes could have resulted through a number of mechanisms, including: historical coevolution between Bd and local amphibian hosts has led to a stable state of hypovirulence in endemic Bd lineages; genomic changes have resulted in hypervirulence in Bd-GPL; and/or, as a recently emerged lineage of Bd, Bd-GPL has escaped host defense mechanisms such that even hosts that have a long co-evolutionary history with endemic Bd are functionally naïve to Bd-GPL infections.