Genetic mapping of quantitative trait loci influencing growth, development and morphology in Atlantic salmon (Salmo salar, L.)
The molecular basis for heritable variation in quantitative traits is poorly understood in most species of fish. This is the case even for salmonids such as the Atlantic salmon (Salmo salar L.), one the most intensively studied and economically important aquaculture species. Quantitative genetic studies tell us that traits such as growth, development and morphology are likely to be controlled by a large number of genes, but to date there have only been two loci, the allozyme loci MEP-2* and TRP-2*, which have been shown to consistently influence the salmon phenotype. This thesis sets out to increase understanding of the molecular basis of phenotypic variation in growth performance, development and morphology in the Atlantic salmon. Experiments were performed to look for associations of phenotypic variation with genotypic variation at the molecular level and, thereby, to identify molecular markers linked to regions of the salmon genome containing genes influencing these quantitative traits. This was achieved by analysing phenotypic performance in two F2 backcross families derived from crosses of two outbred wild salmon populations, one from Scotland and one from Canada, which are divergent with respect to growth, development and morphology. The study began with an examination of the relationship between growth prior to first-feeding, utilising endogenous energy supplies, and growth post first-feeding, utilising exogenous energy supplies. The study then focused on growth, development and morphology in individually fish post first-feeding.