Heritability and genomic basis of age-at-maturity in Chinook Salmon

Life history variation acts as a buffer against stochastic environmental variation. When these variations represent distinct phenotypic optima for males and females there may be sexually antagonistic selection, and with high heritability, the opportunity for intralocus sexual conflict. The age at return migration for Chinook Salmon (Oncorhynchus tshawytscha), or age-at-maturity, is one such trait, since male age-at-maturity appears to experience a divergent selective landscape from females. We investigated the heritability of age-at-maturity, genomic basis of both sex and age-at-maturity, and potential for intralocus sexual conflict regarding age-at-maturity in stocks of Chinook Salmon from the Columbia River Basin representing the three major lineages present there. We found that heritability of age-at-maturity was positive for both sexes as well as in opposite sex comparisons but was generally stronger for males. We identified regions of the genome associated with sex across all three..., GT-seq on Illumina NextSeq 4000, , # Heritability and genomic basis of age-at-maturity in Chinook Salmon

[https://doi.org/10.5061/dryad.08kprr5c3](https://doi.org/10.5061/dryad.08kprr5c3)

## Description of the data and file structure

DNA was extracted using nondenatured Chelex protocols from the manufacturer (Sigma-Aldrich). Fish were genotyped using a genotyping-in-thousands panel (GT-seq; Campbell et al. 2015) consisting of dozens (hatchery-origin grandparents) to hundreds (natural-origin and 2018/2022 hatchery-origin broodstock) of SNP markers. NOR fish were initially genotyped and reported in Willis et al. (2021), while hatchery-origin broodstock from 2018 and 2022 were genotyped in those years and reported in PBT baselines utilized in Hess et al. (2024). The NOR and 2018 hatchery-origin broodstock fish, utilized in genomic analyses below, were genotyped a second time on an Illumina HiSeq 4000 using a panel of 359 markers plus sex marker to confirm that the correct sample was chosen for sequencing and that sex was...,