Determining the Scale of Biologically Important Local Adaptation In Atlantic Salmon Using a Common Garden Experimental Approach

A series of common-garden experiments have been carried out in the Srahrevagh River, NW Ireland, over the last two decades. In these experiments, the relative fitness of different groups of Atlantic salmon (Salmo salar) have been compared using a genotype approach. A previous study suggested that large fitness differences can exist between populations at small local spatial scales (50Km).  No provision was made in this study, such as the establishment of inter-population hybrids, which could have allowed for a more definitive conclusion about the genetic basis of the result. Intermediate fitness values for the hybrids would provide convincing evidence that there was additive genetic explanation for the results. Here we report preliminary results on a follow up experiment which seeks to explore local adaptation using inter-specific hybrids as a genetic control.