Association Genetics of Migration and Residency in Rainbow and Steelhead Trout

Across their natural and introduced ranges, salmonids exhibit diverse life histories, from purely anadromous populations and species, to those that vary in the timing of their migration to the sea, to those that vary in whether or not they migrate or remain in freshwater for all of their lives.  In steelhead and rainbow trout (Oncorhynchus mykiss), we continue to dissect the genetic architecture of traits related to migration and residency.  In crosses between migratory and non-migratory O. mykiss from the Sashin Creek, Alaska system, we have identified several QTL for traits associated with smoltification, with some overlap with genome regions previously identified in the same species for similar traits.  To assess whether genome regions are the same or different among divergent natural systems, we are currently conducting genome-wide SNP association studies in the Sashin Creek, Alaska, and Little Sheep Creek, Oregon systems.  These studies will ultimately help us understand the genetic determinants of migration and residency in this species, and will be an important framework in which to study the evolution of migratory and resident life history diversity in the salmonid fishes.