60-years of genetic studies to unravel the best management units in Atlantic cod

Image Svanhildur Egilsdóttir.

A recent study published by scientists at MFRI summarized the genetic studies which have been performed on Atlantic cod in Icelandic waters. Pampoulie et al. (2022) provide a review of genetic from the early allozyme approaches carried out in the 1960’s to the genomic work currently on-going. This review highlights the importance of the recent generation of a chromosome anchored genome assembly together with whole-genome population data, which drastically changed the perception of the possible management units to consider. After nearly 60 years of genetic investigation of Atlantic cod structure in Icelandic waters, genetic (and later genomic) data combined with behavioural monitoring using Data Storage Tags (DSTs) shifted the attention of scientists from geographical population structures previously published to behavioural ecotypes recently discovered.

In the last 7 years, MFRI scientists have been investigating the genomic structure of potential ecotypes of Atlantic cod, revealed by early tagging studies using Data Storage Tags (Pálsson & Thorsteinsson, 2003). Together with their colleagues of CEES in Norway, they revealed an unexpected within species genomic diversity in Atlantic cod. The recent use of reference genomes of coastal vs. frontal Icelandic cod and of stationary vs. migratory individuals of cod across the North Atlantic has confirmed the presence of supergenes under natural selection, which shaped the architecture of local adaptation of the species in Icelandic waters for the last 30,000 years and in the North Atlantic for the last 0.4 to 1.66 million years (Matschiner et al., 2022). This review paper demonstrates the importance of reference genomes to detect the presence of an unexpected within-species diversity related to large supergenes.

Access to the paper.