Maya Saar (@mayasaar.bsky.social)

Two distinct host-specialized fungal species cause white-nose disease in bats | Nature The emergence of infectious diseases, particularly those caused by fungal pathogens, poses serious threats to public health, wildlife and ecosystem stability1. Host–fungus interactions and environmental factors have been extensively examined2–4. However, the role of genetic variability in pathogens is often less well-studied, even for diseases such as white-nose in bats, which has caused one of the highest disease-driven death tolls documented in nonhuman mammals5. Previous research on white-nose disease has primarily focused on variations in disease outcomes attributed to host traits or environmental conditions6–8, but has neglected pathogen variability. Here we leverage an extensive reference collection of 5,479 fungal isolates from 27 countries to reveal that the widespread causative agent is not a single species but two sympatric cryptic species, each exhibiting host specialization. Our findings provide evidence of recombination in each species, but significant genetic differentiat https://doi.org/10.1038/s41586-025-09060-5