Genetic variation and fitness in salmonids

Over the last quarter century, many studies have attempted to clarify the relationship between genetic variability and fitness, but few of these have involved salmonid fishes. Examination of studies of salmonids reveals that such a relationship varies both among and within species. A correlation between genetic variability and fitness can be affected by genetic background, environment, and age, and it also depends upon the genetic markers and phenotypes evaluated. The relationships between molecular genetic variation, quantitative genetic variation, and phenotypic variation may be more relevant to conservation issues than those between genetic variation and average fitness or performance. Consequently, future work in salmonids should include more intensive investigation of the correspondence of molecular genetic variation within and among populations to quantitative genetic and phenotypic variation for traits affecting fitness. In the absence of a more complete understanding of the relationship between genetic variation and fitness, maintenance of genetic and phenotypic variation within and among conspecific populations should be considered a primary goal of conserving salmonid fishes.