Eco-evolutionary responses of a cold-water fish (Salmo trutta) to the combined effects of an emerging pathogen and temperature

This dataset contains genetic, phenotypic, demographic, and environmental data from wild brown trout (Salmo trutta) populations sampled along natural gradients of water temperature and infection prevalence by Tetracapsuloides bryosalmonae, the parasite responsible for proliferative kidney disease (PKD). It includes single nucleotide polymorphisms (SNPs), genotypes at an immune-related gene (MHC-DAB), individual-level metrics of body condition and carotenoid-based coloration, as well as population density, infection prevalence, and water temperature records. Sampling was conducted both before and after seasonal disease outbreaks, enabling temporal comparisons. The dataset was used to investigate how pathogen pressure and thermal stress affect genetic and phenotypic variation, and to disentangle the roles of phenotypic plasticity and viability selection in wild populations. This resource is suitable for reuse in studies of eco-evolutionary dynamics, host–pathogen interactions, and climate-related stress responses in freshwater ecosystems. No identifiable human data are included, and all field sampling was conducted under appropriate ethical and legal permits.