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Ólafsdóttir GÁ, Turnbull S, Jónsdóttir IG, Nickel A, Karlsson H, Henke T, Nielsen EE, Pálsson S. Genetic assignment predicts depth of benthic settlement for 0-group Atlantic cod. PLoS One 2023; 18:e0292495. [PMID: 37792752 PMCID: PMC10550133 DOI: 10.1371/journal.pone.0292495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Accepted: 09/21/2023] [Indexed: 10/06/2023] Open
Abstract
Atlantic cod is a keystone species that remains among the most economically important demersal fish in the North Atlantic. Throughout its distribution range, Atlantic cod is composed of populations with varying environmental preferences and migratory propensities. This life-history variation is likely to have contributed to the niche width and large population sizes of Atlantic cod, and its relative resilience to environmental change and exploitation. The Icelandic cod stock is currently managed as a single unit, but early research indicates population variation by depth and temperature and distinct offshore and inshore spawning components. Pelagic 0-group juveniles from different spawning grounds coexist in nursery areas around Iceland, but their genetic composition or habitat partitioning had not been examined post benthic settlement. In the current study we examine the genetic composition of Atlantic cod juvenile aggregations at nearshore nursery grounds in NW-Iceland and report distinct segregation by the depth of offshore and inshore juvenile cod. The physiological mechanism of this segregation is not known, but the pattern demonstrates the need to consider population structure at nursery grounds in the application of marine spatial planning and other area-based conservation tools.
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Affiliation(s)
- Guðbjörg Ásta Ólafsdóttir
- University of Iceland, Research Centre of the Westfjords, Bolungarvík, Iceland
- Marine and Freshwater Research Institute, Hafnarfjörður, Iceland
| | - Shaun Turnbull
- University of Iceland, Research Centre of the Westfjords, Bolungarvík, Iceland
| | | | - Anja Nickel
- University of Iceland, Research Centre of the Westfjords, Bolungarvík, Iceland
| | - Hjalti Karlsson
- Marine and Freshwater Research Institute, Hafnarfjörður, Iceland
| | - Theresa Henke
- University of Iceland, Research Centre of the Westfjords, Bolungarvík, Iceland
| | - Einar Eg Nielsen
- DTU Aqua, National Institute of Aquatic Resources, Silkeborg, Denmark
| | - Snæbjörn Pálsson
- University of Iceland, Faculty of Life and Environmental Sciences, Reykjavík, Iceland
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Matschiner M, Barth JMI, Tørresen OK, Star B, Baalsrud HT, Brieuc MSO, Pampoulie C, Bradbury I, Jakobsen KS, Jentoft S. Supergene origin and maintenance in Atlantic cod. Nat Ecol Evol 2022; 6:469-481. [PMID: 35177802 PMCID: PMC8986531 DOI: 10.1038/s41559-022-01661-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 01/10/2022] [Indexed: 12/19/2022]
Abstract
Supergenes are sets of genes that are inherited as a single marker and encode complex phenotypes through their joint action. They are identified in an increasing number of organisms, yet their origins and evolution remain enigmatic. In Atlantic cod, four megabase-scale supergenes have been identified and linked to migratory lifestyle and environmental adaptations. Here we investigate the origin and maintenance of these four supergenes through analysis of whole-genome-sequencing data, including a new long-read-based genome assembly for a non-migratory Atlantic cod individual. We corroborate the finding that chromosomal inversions underlie all four supergenes, and we show that they originated at different times between 0.40 and 1.66 million years ago. We reveal gene flux between supergene haplotypes where migratory and stationary Atlantic cod co-occur and conclude that this gene flux is driven by gene conversion, on the basis of an increase in GC content in exchanged sites. Additionally, we find evidence for double crossover between supergene haplotypes, leading to the exchange of an ~275 kilobase fragment with genes potentially involved in adaptation to low salinity in the Baltic Sea. Our results suggest that supergenes can be maintained over long timescales in the same way as hybridizing species, through the selective purging of introduced genetic variation. Atlantic cod carries four supergenes linked to migratory lifestyle and environmental adaptations. Using whole-genome sequencing, the authors show that the genome inversions that underlie the supergenes originated at different times and show gene flux between supergene haplotypes.
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Affiliation(s)
- Michael Matschiner
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway. .,Department of Palaeontology and Museum, University of Zurich, Zurich, Switzerland. .,Natural History Museum, University of Oslo, Oslo, Norway.
| | - Julia Maria Isis Barth
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Ole Kristian Tørresen
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Bastiaan Star
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Helle Tessand Baalsrud
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Marine Servane Ono Brieuc
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | | | - Ian Bradbury
- Fisheries and Oceans Canada, St John's, Newfoundland and Labrador, Canada
| | - Kjetill Sigurd Jakobsen
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Sissel Jentoft
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway.
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