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Reduced-Representation Sequencing Detects Trans-Arctic Connectivity and Local Adaptation in Polar Cod (Boreogadus
Sarah M Maes1,2, Marie L Verheye1, Caroline Bouchard3,4
1Laboratory of Biodiversity and Evolutionary Genomics, KU Leuven, Leuven, Belgium.
Molecular Ecology
|March 5, 2025
Summary
Polar cod exhibit distinct genetic structures across the Arctic, influenced by ocean currents and sea ice drift. Climate change may disrupt this connectivity, impacting polar cod populations.
Area of Science:
- Marine Biology
- Arctic Ecology
- Population Genetics
Background:
- Connectivity and genetic structure data for Arctic marine life are limited.
- The Arctic is experiencing rapid environmental changes.
- Polar cod (Boreogadus saida) are abundant, ice-associated Arctic fish.
Purpose of the Study:
- To investigate the spatial genetic structure of polar cod across the Arctic.
- To differentiate between neutral genetic variation (connectivity) and adaptive variation (local adaptation).
- To understand the drivers of genetic structure and potential impacts of climate change.
Main Methods:
- Reduced-representation sequencing to obtain single nucleotide polymorphism (SNP) markers.
- Genotyping of 611 polar cod using 922 high-quality SNP markers.
- Analysis of genomic variation to identify neutral and adaptive components.
Main Results:
- Broad-scale genetic differentiation was observed, defining three main groups: Beaufort-Chukchi Seas, Transpolar Drift region, and West Greenland.
- Neutral genetic structure aligns with major oceanographic features like the Beaufort Gyre and Transpolar Drift.
- Adaptive divergence was detected in West Greenland and Beaufort-Chukchi Seas populations, suggesting local adaptation to environmental conditions.
Conclusions:
- Oceanographic and sea ice drift patterns are key drivers of polar cod connectivity.
- Environmental conditions likely drive local adaptation in distinct polar cod populations.
- Climate change, including sea ice decline, poses a threat to polar cod connectivity and resilience.
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