Introgression and subtle population structure in Copper and Quillback rockfishes
Date
2024
Authors
Sykes, Nathan
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Abstract
Genomic methods are increasingly being applied in fisheries to promote effective management and sustainability. Pacific rockfishes, genus Sebastes, inhabit inshore, shelf, and slope habitats along the North American west coast. Among these, Copper and Quillback rockfishes (abbreviated to Copper and Quillback) are closely related species known to hybridize, particularly within the Salish Sea in North America’s Pacific Northwest. Here, I investigate genetic population structure and introgression patterns in Copper and Quillback rockfishes from Alaska to California. Using low-coverage whole-genome resequencing (lcWGS) across a broad geographic range, I seek to (1) describe genetic differentiation between the rockfish species, (2) assess population structure within each species, (3) identify regions of the genome with unique patterns of differentiation between species, and (4) look for signatures of introgression in the genomes of both species. My analyses reveal that Copper exhibit higher levels of population differentiation compared to Quillback, especially between coastal and Salish Sea populations. In contrast, Quillback populations appear to be more panmictic, with lower overall differentiation. Several large haploblocks are found to be segregating between the species, with introgression patterns varying across genomic regions. These findings provide novel insights into the range-wide genetic structure of these species and highlight the role of genomic architecture in local introgression.
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Keywords
Rockfish, Genomics, Fisheries