The fungal pathogen Batrachochytrium salamandrivorans (Bsal) poses a severe threat to amphibians, driving biodiversity declines across Europe and urgently requiring research to understand and mitigate its impacts. In the Gorssel outbreak zone in the Netherlands, Bsal has been spreading slowly since its introduction in 2018, creating a rare natural laboratory where infected and naïve populations coexist. This provides an unprecedented opportunity to study evolutionary processes in real time in a natural setting. This project leverages this unique system to study the biological relevance of the candidate resistance genes identified in the laboratory studies of Triturus newts in the previous FWO junior, and investigate real-time adaptive responses to Bsal. By combining spatial, temporal, and individual-level genomic analyses, the study aims to uncover the genetic basis and functional relevance of resistance and assess its evolutionary implications across the salamander tree of life through subsequent comparative phylogenetics. This research will providing critical insights into host-pathogen co-evolution and the findings will inform conservation efforts by identifying resistant genotypes for breeding programs and habitat management strategies. By bridging laboratory and field studies, this project fills critical knowledge gaps in disease resistance evolution and the evolutionary implications of disease outbreaks.