Heritability and Genomic Basis of Age-at-maturity in Chinook Salmon
Abstract
Intra-population variation in the age at return and reproduction of Chinook Salmon (Oncorhynchus tshawytscha), or age-at-maturity, acts as a buffer against stochastic environmental variation. We investigated the genetic component of this trait by estimating heritability of age-at-maturity and the genomic basis of both sex and age-at-maturity in stocks representing the three major lineages of the Columbia River Basin. We found that heritability of age-at-maturity was generally stronger for fathers with male offspring (mean h2 = 0.37, SD = 0.164) than mothers with female offspring (mean h2 = 0.29, SD = 0.077), fathers with female offspring (mean h2 = 0.29, SD = 0.155), or mothers with male offspring (mean h2 = 0.25, SD = 0.100). We identified several regions of the genome that were consistently associated with sex across all three lineages that included expected sex-chromosomes (Chr17, 18), but also putative copies of sex-linked regions in several autosomal chromosomes. Further, large regions of the same two chromosomes (17 and 18) were associated with age-at-maturity in a lineage-specific manner. Patterns of genotype by phenotype with multi-marker haplotypes confirmed the association of SNPs on chromosome 17 with both size (fork length) in natural-origin males from the two interior lineages, and age-at-maturity (ocean-age) in interior ocean-type males, but not in females. Further studies will be necessary to verify other candidate regions and polygenic effects on size and age-at-maturity in this species. While rearing environment and growth play a major role in age-at-maturity, these results provided evidence for genetic heritability and candidate genes associated with this trait that will assist in monitoring genetic variation to maintain life history variation in Chinook Salmon.
Authors
Citation
Willis, S.C., R.L. Horn, J.E. Hess, J.K. Fryer, J.M. Whiteaker, and S.R. Narum. 2025.Heritability and genomic basis of age-at-maturity in Chinook Salmon. Journal of Heredity:esaf021. Online at https://doi.org/10.1093/jhered/esaf021.