Kess, Tony;
Einfeldt, Anthony;
Wringe, Brendan;
Lehnert, Sarah;
Layton, Kara;
McBride, Meghan;
Robert, Dominique;
Fisher, Jonathan;
Le Bris, Arnault;
den Heyer, Cornelia;
Shackell, Nancy;
Ruzzante, Daniel;
Bentzen, Paul;
Bradbury, Ian
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2021-02-19
<p class="western" style="text-indent:1.27cm;text-align:left;"><span style="background:transparent none 0% 0%;">Characterizing the nature of genetic differentiation among individuals and populations and its distribution across the genome is increasingly important to inform both conservation and management of exploited species. Atlantic Halibut (<i>Hippoglossus hippoglossus</i>) is an ecologically and commercially important fish species, yet knowledge of population structure and genomic diversity in this species remains lacking. Here, we use restriction-site associated DNA sequencing and a chromosome-level genome assembly to identify over 86,000 single nucleotide polymorphisms mapped to 24 chromosome-sized scaffolds, genotyped in 734 individuals across the Northwest Atlantic. We describe subtle but significant genome-wide regional structuring between the Gulf of St. Lawrence and adjacent Atlantic continental shelf. However, the majority of genetic divergence is associated with a large putative chromosomal rearrangement (5.74 megabases) displaying high differentiation and linkage disequilibrium, but no evidence of geographic variation. Demographic reconstructions suggest <font color="#000000">periods of expansion</font> coinciding with glacial retreat, and more recent declines in N<sub>e</sub>. This work highlights the utility of genomic data to identify multiple sources of genetic structure and genomic diversity in commercially exploited marine species. </span></p>
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