Genetic variation and fitness in salmonids

Abstract

Over the last quarter century, many studieshave attempted to clarify the relationshipbetween genetic variability and fitness, butfew of these have involved salmonid fishes. Examination of studies of salmonids revealsthat such a relationship varies both among andwithin species. A correlation between geneticvariability and fitness can be affected bygenetic background, environment, and age, andit also depends upon the genetic markers andphenotypes evaluated. The relationshipsbetween molecular genetic variation,quantitative genetic variation, and phenotypicvariation may be more relevant to conservationissues than those between genetic variation andaverage fitness or performance. Consequently,future work in salmonids should include moreintensive investigation of the correspondenceof molecular genetic variation within and amongpopulations to quantitative genetic andphenotypic variation for traits affectingfitness. In the absence of a more completeunderstanding of the relationship betweengenetic variation and fitness, maintenance ofgenetic and phenotypic variation within andamong conspecific populations should beconsidered a primary goal of conservingsalmonid fishes.