| 1. |
- Barth, Julia M.I., et al.
(author)
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Genome architecture enables local adaptation of Atlantic cod despite high connectivity
- 2017
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In: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 26:17, s. 4452-4466
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Journal article (peer-reviewed)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.
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| 2. |
- Patrinos, George P., et al.
(author)
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Human variome project country nodes: Documenting genetic information within a country
- 2012
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In: Human Mutation. - : Hindawi Limited. - 1059-7794. ; 33:11, s. 1513-1519
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Journal article (peer-reviewed)abstract
- The Human Variome Project (http://www.humanvariomeproject.org) is an international effort aiming to systematically collect and share information on all human genetic variation. The two main pillars of this effort are gene/disease-specific databases and a network of Human Variome Project Country Nodes. The latter are nationwide efforts to document the genomic variation reported within a specific population. The development and successful operation of the Human Variome Project Country Nodes are of utmost importance to the success of Human Variome Project's aims and goals because they not only allow the genetic burden of disease to be quantified in different countries, but also provide diagnosticians and researchers access to an up-to-date resource that will assist them in their daily clinical practice and biomedical research, respectively. Here, we report the discussions and recommendations that resulted from the inaugural meeting of the International Confederation of Countries Advisory Council, held on 12th December 2011, during the 2011 Human Variome Project Beijing Meeting. We discuss the steps necessary to maximize the impact of the Country Node effort for developing regional and country-specific clinical genetics resources and summarize a few well-coordinated genetic data collection initiatives that would serve as paradigms for similar projects. Hum Mutat 33:15131519, 2012. (c) 2012 Wiley Periodicals, Inc.
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| 4. |
- Hjalmarsen, A, et al.
(author)
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Effect of long-term oxygen therapy on cognitive and neurological dysfunction in chronic obstructive pulmonary disease
- 1999
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In: European neurology. - : S. Karger AG. - 0014-3022 .- 1421-9913. ; 42:1, s. 27-35
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Journal article (peer-reviewed)abstract
- The aim of this study was to assess effect of long-term oxygen therapy (LTOT) on the function of central and autonomic nervous system in patients with hypoxaemic chronic obstructive pulmonary disease (COPD). A battery of neuropsychological tests was used together with the Short Test of Mental Status in addition to transcranial Doppler ultrasonography, and five cardiovascular tests as well as a questionnaire on autonomic function. Ten COPD patients, 4 males and 6 females, with a mean age of 65.9 ± 7.3 (SD) years, were studied at the beginning and after 3 months of LTOT. At start PaO<sub>2</sub> was 6.7 ± 1.1 kPa without oxygen and 9.9 ± 1.5 kPa after 3 months with oxygen. Our results demonstrate that neuropsychological function, cerebral blood flow velocity and autonomic function were positively influenced after 3 months of LTOT although the changes did not reach statistical significance. The COPD patients were cognitively impaired as compared to age-matched healthy controls. Our findings were consistent with the previous notion of improvement of hypoxic cognitive dysfunction by LTOT.
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| 6. |
- Knutsen, H., et al.
(author)
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Does population genetic structure support present management regulations of the northern shrimp (Pandalus borealis) in Skagerrak and the North Sea?
- 2015
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In: Ices Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 72:3, s. 863-871
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Journal article (peer-reviewed)abstract
- Population structuring in the northern shrimp (Pandalus borealis) in the North Sea area (including Fladen and Skagerrak) was studied by microsatellite DNA analyses. Screening 20 sample locations in the open ocean and Skagerrak fjords for nine loci revealed low, but significant genetic heterogeneity. The spatial genetic structure among oceanic samples of Skagerrak and the eastern North Sea was weak and non-significant, consistent with the current management regime of one single stock. However, Skagerrak fjord samples generally displayed elevated levels of genetic differentiation, and significantly so in several pairwise comparisons with other fjords and oceanic samples. Although the Skagerrak fjord populations are of less economic value, some of them are regulated separately (e.g. the Gullmarsfjord) and local stocks may prove important to uphold genetic variability and biocomplexity in a changing environment.
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| 9. |
- Ryman, N., et al.
(author)
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Power for detecting genetic divergence: differences between statistical methods and marker loci
- 2006
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In: Molecular Ecology. - 0962-1083. ; 15:8, s. 2031-2045
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Journal article (peer-reviewed)abstract
- Information on statistical power is critical when planning investigations and evaluating empirical data, but actual power estimates are rarely presented in population genetic studies. We used computer simulations to assess and evaluate power when testing for genetic differentiation at multiple loci through combining test statistics or P values obtained by four different statistical approaches, viz. Pearson's chi-square, the log-likelihood ratio G-test, Fisher's exact test, and an F-ST-based permutation test. Factors considered in the comparisons include the number of samples, their size, and the number and type of genetic marker loci. It is shown that power for detecting divergence may be substantial for frequently used sample sizes and sets of markers, also at quite low levels of differentiation. The choice of statistical method may be critical, though. For multi-allelic loci such as microsatellites, combining exact P values using Fisher's method is robust and generally provides a high resolving power. In contrast, for few-allele loci (e.g. allozymes and single nucleotide polymorphisms) and when making pairwise sample comparisons, this approach may yield a remarkably low power. In such situations chi-square typically represents a better alternative. The G-test without Williams's correction frequently tends to provide an unduly high proportion of false significances, and results from this test should be interpreted with great care. Our results are not confined to population genetic analyses but applicable to contingency testing in general.
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| 10. |
- Sodeland, M., et al.
(author)
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Stabilizing selection on Atlantic cod supergenes through a millennium of extensive exploitation
- 2022
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In: 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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Journal article (peer-reviewed)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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