Skip to main content
Dryad

A stepwise genomic analysis of sugar kelp population structure in Atlantic Canada using DArTseq to whole genome sequencing

PUNCHER, GREGORY NEILS12; Le Cam, Sabrina1; O’Leary, Stephen J.B.3; Salvo, Flora2; Dufresne, France1

Published Jul 21, 2026 on Dryad. https://doi.org/10.5061/dryad.qjq2bvqx5

Data files

Jul 21, 2026 version files 403.60 MB

Click names to download individual files

Abstract

Saccharina latissima (sugar kelp) is a foundation species of growing commercial interest, yet its population genetic structure in Atlantic Canada remains poorly resolved. A two-tiered genomic approach was used to characterize regional patterns of diversity and connectivity across the Estuary and Gulf of St. Lawrence and the coast of Nova Scotia. Reduced-representation genotyping by DArTseq provided broad spatial coverage (603 individuals, 23 sites, 4,386 SNPs), while low-coverage whole-genome sequencing (WGS) of a representative subset of populations generated high-resolution datasets using both GATK- and ANGSD-based pipelines (105–106 variants). Population structure was congruent across datasets. Nova Scotia populations were clearly differentiated from those in Québec, and finer-scale structure was evident among the Gaspé Peninsula, Baie-des-Chaleurs, North Shore and Miquelon. Neutral WGS datasets revealed moderate differentiation and predominantly negative FIS values. Outlier loci showed elevated FST, indicating that adaptive divergence amplifies underlying demographic structure. Although DArTseq produced higher and more variable FST estimates, it recovered the same major groupings, underscoring robustness across marker systems. Lower diversity in estuarine populations and a higher number of private-alleles in Nova Scotia are consistent with serial founder effects during postglacial range expansion, while the Gulf of St. Lawrence likely represents a suture zone where distinct lineages have admixed. These results reveal strong, hierarchical population structure in S. latissima shaped by limited dispersal, environmental heterogeneity and historical colonization processes. The convergence across genomic approaches provides a robust foundation for delineating management units and supporting germplasm banking and selective breeding for sustainable kelp aquaculture in the Northwest Atlantic.