Abstracts (first author)
Footprints of directional selection in wild populations of Atlantic salmon: evidence for parasite-driven evolution?
European populations of Atlantic salmon (Salmo salar) exhibit natural variance in susceptibility levels to the ectoparasite Gyrodactylus salaris, ranging from resistance to extreme susceptibility, and thus are a good model for studying the evolution of virulence and resistance. Advances in genome technologies provide new opportunities for obtaining a genome-scale view of the action of natural selection in wild populations. However, distinguishing the molecular signatures of genetic drift and environment-associated selection may challenge the search for specific pathogen driven selection. We used a novel genome-scan analysis approach aimed at i) identifying signals of selection in salmon populations affected by genetic drift at varying levels; and ii) separating the potentially selected loci identified into those affected by pathogen (G. salaris)-driven selection and salinity-driven selection. 4631 single nucleotide polymorphisms (SNPs) were screened in 472 salmon individuals from 12 different north European salmon populations. We identified several genomic regions potentially affected exclusively by parasite-driven selection, as well as several regions affected by salinity mediated directional selection. Functional annotation of candidate SNPs supported the participation of the detected genomic regions in immune defense and osmoregulation. These results provide new insights in genetic basis of pathogen susceptibility/resistance and adaptation to various salinity levels in Atlantic salmon, and open possibilities for specific candidate gene search.