Steelhead (Oncorhynchus mykiss) lineages and sexes show variable patterns of association of adult migration timing and age‐at‐maturity traits with two genomic regions

Abstract

For protected species under management, ensuring that genetic and phenotypic diversity is maintained above critical levels is one of the primary goals of conservation (Funk, McKay, Hohenlohe, &

The Impacts of Dam Construction and Removal on the Genetics of Recovering Steelhead (Oncorhynchus mykiss) Populations across the Elwha River Watershed

“…Taking into account that the first dam removal began in 2011, one to two generations at most have passed since our last sample was collected for the in-between-dam population. The three-year delay until the removal of the upriver dam coupled with the significant variation in O. mykiss age-to-maturity [ 49 , 97 ], however, suggests that this may be a generous estimate. Significant, sustained, shifts in effective population size for several generations is required in order to observe significant shifts in genetic diversity [ 98 ].…”

“…Previous work in O. mykiss found a major-effect locus for migration return timing in the GREB1L gene on chromosome 28 [ 44 , 45 , 46 ]. Variation in the GREB1L gene has also been identified as a candidate for adult run timing in Chinook salmon [ 45 , 47 , 48 ]; however, there is uncertainty regarding the extent to which variation in this gene explains run timing outside of coastal populations [ 49 ]. For example, in the Columbia River Basin, all inland steelhead are freshwater-maturing fish that would be predicted to possess the “summer-run” alleles observed in coastal populations [ 50 ].…”

“…However, both summer- and winter-run timing alleles have been detected in inland migrating populations and appear to be more strongly associated with arrival timing at spawning grounds rather than ocean migration timing [ 46 ]. Fragmentation of aquatic corridors and removal of natural barriers to migration have been implicated in the deviation of this genotypic–phenotypic association, indicating the importance of landscape connectivity for maintenance of run timing life histories [ 47 , 49 , 51 , 52 ]. Disruption to gene flow by barriers, therefore, could significantly impact the distribution of adaptive genetic variation underlying diverse migratory phenotypes.…”

Genome‐wide analysis reveals demographic and life‐history patterns associated with habitat modification in landlocked, deep‐spawning sockeye salmon (Oncorhynchus nerka)

“…Recent work has further demonstrated significant associations between six6 and age at maturity in both sockeye salmon and steelhead trout (Waters et al, 2021;Willis et al, 2020).…”

Maturation in Atlantic salmon (Salmo salar, Salmonidae): a synthesis of ecological, genetic, and molecular processes

“…This may suggest that the region is associated with a correlated trait (e.g., body size or return migration timing) that is also associated with an environmental factor [e.g., river catchment area, (Pritchard et al 2018)]. The six6 locus has also been linked with the timing of maturation in several species of Pacific salmon (Waters et al 2021;Willis et al 2020) indicating that this genomic region plays a role in maturation and sexual reproduction in other salmonids. The six6 locus is also associated with variation in return migration timing among Scottish Atlantic salmon populations (Cauwelier et al 2018).…”