Genome architecture enables local adaptation of Atlantic cod despite high connectivity |
| |
Authors: | Julia M I Barth Paul R Berg Per R Jonsson Sara Bonanomi Hanna Corell Jakob Hemmer‐Hansen Kjetill S Jakobsen Kerstin Johannesson Per Erik Jorde Halvor Knutsen Per‐Olav Moksnes Bastiaan Star Nils Chr Stenseth Henrik Svedäng Sissel Jentoft Carl André |
| |
Institution: | 1. Department of Biosciences, Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo, Oslo, Norway;2. Faculty of Medicine, Centre for Molecular Medicine Norway (NCMM), University of Oslo, Oslo, Norway;3. Department of Marine Sciences – Tj?rn?, University of Gothenburg, Str?mstad, Sweden;4. Section 5. for Marine Living Resources, National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark;6. National Research Council (CNR), Fisheries Section, Institute of Marine Sciences (ISMAR), Ancona, Italy;7. Institute of Marine Research, Fl?devigen, His, Norway;8. Department of Natural Sciences, Centre for Coastal Research, University of Agder, Kristiansand, Norway;9. Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden;10. Swedish Institute for the Marine Environment (SIME), Gothenburg, Sweden |
| |
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. |
| |
Keywords: | chromosomal inversion ecological adaptation Gadus morhua gene flow population divergence |
|
|