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Data from: Persistent reproductive isolation between sympatric lineages of fall Chinook salmon in White Salmon River, Washington

Citation

Smith, Christian T.; Engle, Rod (2011), Data from: Persistent reproductive isolation between sympatric lineages of fall Chinook salmon in White Salmon River, Washington, Dryad, Dataset, https://doi.org/10.5061/dryad.jb01f

Abstract

Populations of fall Chinook salmon Oncorhynchus tshawytscha in the Columbia River are divided among two evolutionarily significant units: lower Columbia River fall Chinook salmon (or “tules”) in the lower portion of the river and upriver “brights” (URBs) in the upper portion. The two lineages migrate together through portions of the lower Columbia River but spawn allopatrically. Little White Salmon National Fish Hatchery has been releasing URBs adjacent to what was historically exclusively tule spawning habitat in the White Salmon River for approximately 22 years. Tules and URBs now spawn in sympatry in the adjacent White Salmon River, and potential introgression between these two lineages has been identified as a genetic risk of the hatchery program. To assess the extent of introgression, we analyzed 13 microsatellite loci in juveniles taken from the White Salmon River in three consecutive years. Assignment tests revealed that juveniles leaving the White Salmon River from March to early May resembled tules, while those leaving from late May to June resembled URBs. Model-based hybrid detection revealed that between 4.3% and 15.0% of the juveniles in each year were tule × URB hybrids. No hybrid adults were detected in any of the collections examined. The divergence between the tule and URB populations in the White Salmon River was comparable to that between allopatric populations representing the two lineages. Although hybrid juveniles are produced in the wild, we found no evidence that they survive to return as adults or successfully cross back into the parental populations. The separation between the two fall Chinook salmon lineages thus appears to be based on intrinsic as well as extrinsic factors.

Usage Notes

Location

White Salmon River
Columbia River