Genome architecture enables local adaptation of Atlantic cod despite high connectivity

Citations Over TimeTop 1% of 2017 papers

Abstract

Adaptation to local conditions is a fundamental process in evolution; however, mechanisms maintaining local adaptation despite high gene flow are still poorly understood. Marine ecosystems provide a wide array of diverse habitats that frequently promote ecological adaptation even in species characterized by strong levels of gene flow. As one example, populations of the marine fish Atlantic cod (Gadus morhua) are highly connected due to immense dispersal capabilities but nevertheless show local adaptation in several key traits. By combining population genomic analyses based on 12K single nucleotide polymorphisms with larval dispersal patterns inferred using a biophysical ocean model, we show that Atlantic cod individuals residing in sheltered estuarine habitats of Scandinavian fjords mainly belong to offshore oceanic populations with considerable connectivity between these diverse ecosystems. Nevertheless, we also find evidence for discrete fjord populations that are genetically differentiated from offshore populations, indicative of local adaptation, the degree of which appears to be influenced by connectivity. Analyses of the genomic architecture reveal a significant overrepresentation of a large ~5 Mb chromosomal rearrangement in fjord cod, previously proposed to comprise genes critical for the survival at low salinities. This suggests that despite considerable connectivity with offshore populations, local adaptation to fjord environments may be enabled by suppression of recombination in the rearranged region. Our study provides new insights into the potential of local adaptation in high gene flow species within fine geographical scales and highlights the importance of genome architecture in analyses of ecological adaptation.

Related Papers

• → Feeding opportunities of larval and juvenile cod (Gadus morhua) in a Greenlandic fjord: temporal and spatial linkages between cod and their preferred prey(2014)31 cited
• → Searching for Atlantic cod (Gadus morhua) spawning sites in the northwest Gulf of St Lawrence (Canada) using molecular techniques(2011)18 cited
• → The complete amino acid sequences to two variants of growth hormone from Atlantic cod (Gadus morhua)(1991)18 cited
• → Erratum: Effect of the North Atlantic Oscillation on recruitment of Atlantic cod (Gadus morhua)(2004)1 cited
• Towards an understanding of the spawning ecology of Atlantic cod (Gadus morhua) in the Northern Atlantic(2024)