A century of anthropogenic perturbations impact genomic signatures of the iconic migratory Atlantic cod (2)

Anthropogenic stressors have led to dramatic ecosystem perturbations, including population declines and shifts in habitat range for key marine fish species. Understanding how these changes impact genome-wide characteristics, causing long-term evolutionary responses, is still in its infancy. Genome-wide retrospective assessment of the iconic migratory Atlantic cod (Gadus morhua) from the Barents Sea, unravelled varying degree of admixture with the non-migratory coastal ecotype throughout the 20th century, and intriguingly more intensified during recent decades. These genomic changes were supported by an increased number of individuals displaying the heterozygous state of the chromosomal inversion coupled to migratory behaviour in Atlantic cod. Ecological models and genome-wide scans identified that some of the observed frequency shifts – coupled to neural development, metabolic and growth regulation – covaried with intensified fisheries, reduced generation time as well as ocean warming. Our results demonstrate how anthropogenic perturbations impact the dynamics between two well-known ecotypes of Atlantic cod, and thus, their genomic signatures, with potential implications for future management programmes.