Genetic Components in Life History Traits Contribute to Population Structure

Abstract

The most important salmonid genetic resource is genetic variation. That variation is observed among populations throughout the range of Pacific salmon (Oncorhynchus sp.) as well as among the individuals within each population. Numerous electrophoretic studies of allozyme variation document the existence of both inter- and intra- populational genetic variation in Pacific salmon (e.g., Gharrett et al., 1987; Gharrett et al., 1988; Beacham et al., 1988). Much of the phenotypic variation observed also has a genetic basis (e.g., Ricker, 1972; Beacham et al., 1988); however, because the phenotype expressed is a result of both genetic and environmental influences, it is usually not straightforward to identify the genetic component. In addition, multiple genetic loci are often involved in expression of interesting and important life history traits such as morphology, development, and behavior.