| While species introductions have been used for management, supplementation,
and conservation of natural populations, introduction practices can allow hybridization
between closely related species and genetically distinct populations. Many freshwater
fish species have a long history of supplementation and introductions that can lead to
hybridization and the loss of genetic integrity through outbreeding depression and
genetic swamping. I assessed introgression between native Redband Trout
(Oncorhynchus mykiss gairdneri) and stocked populations of coastal Rainbow Trout (O.
mykiss irideus) of the upper Owyhee River using single nucleotide polymorphisms. I
sampled individuals from ten streams and two reservoirs representing native and stocked
populations, and two outgroup references. I estimated levels of introgression in
populations, which ranged from 0 to 100% of the individuals sampled, and seven of ten
populations had ≥ 50% introgressed individuals. Distance to reservoirs and barriers to
hatchery fish dispersal likely influences both genetic structure and level of hybridization
observed.
Key Words: Introgression, Redband Trout, Rainbow Trout, hybridization, single
nucleotide polymorphisms |