| 1. |
- Knutsen, H., et al.
(författare)
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Stable coexistence of genetically divergent Atlantic cod ecotypes at multiple spatial scales
- 2018
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Ingår i: Evolutionary Applications. - : Wiley. - 1752-4571. ; 11:9, s. 1527-1539
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Tidskriftsartikel (refereegranskat)abstract
- Coexistence in the same habitat of closely related yet genetically different populations is a phenomenon that challenges our understanding of local population structure and adaptation. Identifying the underlying mechanisms for such coexistence can yield new insight into adaptive evolution, diversification and the potential for organisms to adapt and persist in response to a changing environment. Recent studies have documented cryptic, sympatric populations of Atlantic cod (Gadus morhua) in coastal areas. We analysed genetic origin of 6,483 individual cod sampled annually over 14 years from 125 locations along the Norwegian Skagerrak coast and document stable coexistence of two genetically divergent Atlantic cod ecotypes throughout the study area and study period. A "fjord" ecotype dominated in numbers deep inside fjords while a "North Sea" ecotype was the only type found in offshore North Sea. Both ecotypes coexisted in similar proportions throughout coastal habitats at all spatial scales. The size-at-age of the North Sea ecotype on average exceeded that of the fjord ecotype by 20% in length and 80% in weight across all habitats. Different growth and size among individuals of the two types might be one of several ecologically significant variables that allow for stable coexistence of closely related populations within the same habitat. Management plans, biodiversity initiatives and other mitigation strategies that do not account for the mixture of species ecotypes are unlikely to meet objectives related to the sustainability of fish and fisheries.
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| 2. |
- Jansson, E., et al.
(författare)
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Genetic analysis of goldsinny wrasse reveals evolutionary insights into population connectivity and potential evidence of inadvertent translocation via aquaculture
- 2017
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Ingår i: Ices Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 74:8, s. 2135-2147
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Tidskriftsartikel (refereegranskat)abstract
- The salmon industry is heavily dependent on wrasse for delousing infected fish. The goldsinny wrasse is numerically the most important, and each year, millions are harvested from the wild and transported large distances into fish farms. Population genetic knowledge is required to sustainably exploit this species. Here, 1051 goldsinny wrasses from 16 locations across Scandinavia, the British Isles, and Spain were genotyped with 14 microsatellite and 36 SNP markers. Within-population genetic diversity decreased towards north, and a genetic break was observed across the North Sea. Samples from Northern Norway differed from rest of the Scandinavian samples, and samples from the British Isles differed from the Spanish ones. Within Scandinavia, isolation-by-distance was detected. Observed genetic patterns fitted well with expectations derived from oceanographic drift simulations. A sample from mid-Norway deviated from these patterns however, and was genetically very similar to southern Scandinavian samples. We conclude that the population structure of this species is primarily determined by the opposing evolutionary forces of passive drift, limited adult migration and spawning-site fidelity, whereas the deviation in isolation-by-distance observed in mid-Norway is potentially caused by inadvertent translocations of wrasse from southern Scandinavia via current aquaculture practise. Inclusion of outlier loci gave greater resolution, suggesting that diversifying selection may also affect population structuring among goldsinny wrasses.
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| 3. |
- Jorde, P. E., et al.
(författare)
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Genetically distinct populations of northern shrimp, Pandalus borealis, in the North Atlantic: adaptation to different temperatures as an isolation factor
- 2015
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083. ; 24:8, s. 1742-1757
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Tidskriftsartikel (refereegranskat)abstract
- The large-scale population genetic structure of northern shrimp, Pandalus borealis, was investigated over the species' range in the North Atlantic, identifying multiple genetically distinct groups. Genetic divergence among sample localities varied among 10 microsatellite loci (range: F-ST=-0.0002 to 0.0475) with a highly significant average (F-ST=0.0149; P<0.0001). In contrast, little or no genetic differences were observed among temporal replicates from the same localities (F-ST=0.0004; P=0.33). Spatial genetic patterns were compared to geographic distances, patterns of larval drift obtained through oceanographic modelling, and temperature differences, within a multiple linear regression framework. The best-fit model included all three factors and explained approximately 29% of all spatial genetic divergence. However, geographic distance and larval drift alone had only minor effects (2.5-4.7%) on large-scale genetic differentiation patterns, whereas bottom temperature differences explained most (26%). Larval drift was found to promote genetic homogeneity in parts of the study area with strong currents, but appeared ineffective across large temperature gradients. These findings highlight the breakdown of gene flow in a species with a long pelagic larval phase (up to 3months) and indicate a role for local adaptation to temperature conditions in promoting evolutionary diversification and speciation in the marine environment.
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| 4. |
- S, Mortensen, et al.
(författare)
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Summer mortalities and detection of ostreid herpesvirus microvariant in Pacific oysterCrassostrea gigasin Sweden and Norway
- 2016
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Ingår i: Diseases of Aquatic Organisms. - : Inter-Research Science Center. - 0177-5103 .- 1616-1580. ; 117:3, s. 171-176
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Tidskriftsartikel (refereegranskat)abstract
- The Pacific oyster Crassostrea gigas has recently expanded its range in Scandinavia. The expansion is presumably a result of northwards larval drift. Massive settlements were recorded in many areas along the Swedish west coast and southern Norway in 2013 and 2014. After the spawning season in 2014, the temperature of the surface water peaked at 24−26°C. After this period, high and sudden mortalities occurred in a Swedish hatchery and in wild populations along the Swedish west coast and south coast of Norway. Surveys and collected data showed that mortalities mainly occurred during 3 wk in September. All size classes were affected, and affected populations displayed a patchy distribution with heavily affected and unaffected populations in close proximity. Flat oysters Ostrea edulis and blue mussels Mytilus edulis were unaffected. Ostreid herpesvirus (OsHV) was detected in moribund Pacific oyster spat as well as in surviving adults. The virus was identified as OsHV-1 μvar. This is the first detection of this variant in Scandinavia, showing that OsHV-1 μvar is present in areas with recent establishments of Pacific oysters, and where there is no aquaculture of this species.
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| 5. |
- Sodeland, M., et al.
(författare)
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Stabilizing selection on Atlantic cod supergenes through a millennium of extensive exploitation
- 2022
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 119:8
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Tidskriftsartikel (refereegranskat)abstract
- Life on Earth has been characterized by recurring cycles of ecological stasis and disruption, relating biological eras to geological and climatic transitions through the history of our planet. Due to the increasing degree of ecological abruption caused by human influences many advocate that we now have entered the geological era of the Anthropocene, or “the age of man.” Considering the ongoing mass extinction and ecosystem reshuffling observed worldwide, a better understanding of the drivers of ecological stasis will be a requisite for identifying routes of intervention and mitigation. Ecosystem stability may rely on one or a few keystone species, and the loss of such species could potentially have detrimental effects. The Atlantic cod (Gadus morhua) has historically been highly abundant and is considered a keystone species in ecosystems of the northern Atlantic Ocean. Collapses of cod stocks have been observed on both sides of the Atlantic and reported to have detrimental effects that include vast ecosystem reshuffling. By whole-genome resequencing we demonstrate that stabilizing selection maintains three extensive “supergenes” in Atlantic cod, linking these genes to species persistence and ecological stasis. Genomic inference of historic effective population sizes shows continued declines for cod in the North Sea-Skagerrak-Kattegat system through the past millennia, consistent with an early onset of the marine Anthropocene through industrialization and commercialization of fisheries throughout the medieval period. © 2022 National Academy of Sciences. All rights reserved.
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