Evolutionary Genetics of Atlantic Salmon (Salmo salar L.) - Molecular Markers and Applications

Vasemägi, A. 2004. Evolutionary Genetics of Atlantic salmon (Salmo salar L.) Molecular Markers and Applications. ISSN 1401-6230, ISBN 91-576-6708-X This thesis deals with evolutionary genetics of Atlantic salmon populations, with the special emphasis on the roles of migration, random genetic drift, mutation and natural selection affecting the patterns of molecular variation across contemporary and historical time scales. Studies of mitochondrial DNA variation supported the hypothesis of multiple post-glacial colonization events of the Baltic Sea. The Eastern Atlantic populations differ from the geographically close southern Baltic populations, indicating absence of inward and limited outward gene flow through the Danish straits during the last 8000 years. Four common European mitochondrial haplotypes derive from the ancestral ND1-BBBA haplotype by one-step substitutions. Our results suggest that wild populations have an important role in re-colonization processes of the former salmon rivers where populations have been driven to extinction due to human activities. Spatio-temporal analysis over eighteen years provided genetic evidence of immigration from compensatory hatchery releases into one of the biggest wild Atlantic salmon population in the Gulf of Bothnia (R. Vindelälven) and emphasize the genetic risks associated with current large-scale stocking practices in the Baltic Sea. For restoration of former salmon rivers in the Gulf of Finland we recommend that two closest native salmon populations should be preferred to help to fill in the currently missing “building blocks” that are important for the persistence of genetic variation and long-term survival of salmon populations in Estonia. We identified several expressed sequence tag (EST) loci that are potentially affected by divergent selection demonstrating that EST-scans may provide suitable strategy to discover functionally important genetic variation both in model and non-model organisms.