Differences in growth between historical and contemporary isolates of a virulent fungal pathogen

Background/Question/Methods

Introduced pathogens can have devastating effects on native host populations. Following invasion, pathogens may adapt to local hosts and environmental conditions. Determining whether pathogens have adapted to local conditions may provide insights into potential changes in pathogen virulence and host-pathogen interactions. Here we examine whether the pathogen, Pseudogymnoascus destructans, that causes white-nose syndrome (WNS), has adapted to environmental conditions since its initial introduction into North America, where it has decimated bat populations. Previous work has shown that P. destructans reproduces clonally and has undergone little genetic change. However, phenotypic adaptations in the thermal niche of P. destructans remain unknown. To examine potential adaptations, we compared contemporary isolates (2018-2020) collected from hibernating bats to historical isolates (2007-2012) collected from museum specimens across a temporal and spatial gradient. We quantified growth of P. destructans isolates across a range of temperatures to determine whether there are differences in the thermal niche of P. destructans between historical and contemporary isolates.

Results/Conclusions

We did not observe clear differences in optimal thermal range for historical P. destructans isolates collected from the Northeastern, United States. Yet, we identified some differences in the optimal thermal niche of contemporary isolates across geographic regions. Our findings will further emphasize the impact of thermal conditions on pathogen niche breadth and highlight the need for future research on how this influences virulence associated with white-nose syndrome infections.