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- Alshwairikh, Yara A., et al.
(författare)
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Influence of environmental conditions at spawning sites and migration routes on adaptive variation and population connectivity in Chinook salmon
- 2021
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Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 11:23, s. 16890-16908
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Tidskriftsartikel (refereegranskat)abstract
- Many species that undergo long breeding migrations, such as anadromous fishes, face highly heterogeneous environments along their migration corridors and at their spawning sites. These environmental challenges encountered at different life stages may act as strong selective pressures and drive local adaptation. However, the relative influence of environmental conditions along the migration corridor compared with the conditions at spawning sites on driving selection is still unknown. In this study, we performed genome–environment associations (GEA) to understand the relationship between landscape and environmental conditions driving selection in seven populations of the anadromous Chinook salmon (Oncorhynchus tshawytscha)—a species of important economic, social, cultural, and ecological value—in the Columbia River basin. We extracted environmental variables for the shared migration corridors and at distinct spawning sites for each population, and used a Pool-seq approach to perform whole genome resequencing. Bayesian and univariate GEA tests with migration-specific and spawning site-specific environmental variables indicated many more candidate SNPs associated with environmental conditions at the migration corridor compared with spawning sites. Specifically, temperature, precipitation, terrain roughness, and elevation variables of the migration corridor were the most significant drivers of environmental selection. Additional analyses of neutral loci revealed two distinct clusters representing populations from different geographic regions of the drainage that also exhibit differences in adult migration timing (summer vs. fall). Tests for genomic regions under selection revealed a strong peak on chromosome 28, corresponding to the GREB1L/ROCK1 region that has been identified previously in salmonids as a region associated with adult migration timing. Our results show that environmental variation experienced throughout migration corridors imposed a greater selective pressure on Chinook salmon than environmental conditions at spawning sites.
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| 2. |
- Hedmark, Eva, 1972-
(författare)
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Conservation Genetics of Scandinavian Wolverines
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, genetic methods for individual identification and sex determination of wolverines from non-invasive samples were developed and applied in genetic monitoring of Scandinavian wolverine populations. Paternity and mating system of wolverines were studied by combining genetic analysis with telemetry data. Moreover, the possibility to obtain DNA from claws left on tanned carnivore hides was investigated.Non-invasive genetic sampling was effective in revealing important population parameters. For the subpopulation in southern Norway, a population size of approximately 90 individuals, an equal sex ratio and similar levels of genetic diversity as in the main Scandinavian population were revealed. Genetic erosion in this small population has likely been counteracted by immigration of individuals from the main population since its re-establishment around 1970.During the 1990s, two areas in east-central Sweden were colonised by wolverines. In a survey comprising 400 non-invasive samples collected during five winters, a total of 22 wolverines were detected. Genetic data suggest that inbreeding has occurred in both areas and that the two populations were founded by as few as 2-4 individuals. These findings suggest that gene flow from the main population is crucial for their survival even in a short time perspective. The detection of occasional stray individuals from the main population shows that this is indeed feasible. Paternity analysis of 145 wolverine offspring in northern Sweden and southern Norway confirmed a polygamous mating system in wolverines. Breeding pair formation was generally consistent with the territories held by males and females, i.e. breeding pairs had overlapping territories. In the majority of litters, siblings were assigned the same father, thus indicating that multiple paternity is rare. Tanning is a common form of preservation of mammalian specimens that normally precludes genetic analysis. Nevertheless, I demonstrate the possibility to successfully extract and amplify DNA from claws left on tanned carnivore hides.
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| 3. |
- Hoban, Sean, et al.
(författare)
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Genetic diversity targets and indicators in the CBD post-2020 Global Biodiversity Framework must be improved
- 2020
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 248
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Tidskriftsartikel (refereegranskat)abstract
- The 196 parties to the Convention on Biological Diversity (CBD) will soon agree to a post-2020 global framework for conserving the three elements of biodiversity (genetic, species, and ecosystem diversity) while ensuring sustainable development and benefit sharing. As the most significant global conservation policy mechanism, the new CBD framework has far-reaching consequences- it will guide conservation actions and reporting for each member country until 2050. In previous CBD strategies, as well as other major conservation policy mechanisms, targets and indicators for genetic diversity (variation at the DNA level within species, which facilitates species adaptation and ecosystem function) were undeveloped and focused on species of agricultural relevance. We assert that, to meet global conservation goals, genetic diversity within all species, not just domesticated species and their wild relatives, must be conserved and monitored using appropriate metrics. Building on suggestions in a recent Letter in Science (Laikre et al., 2020) we expand argumentation for three new, pragmatic genetic indicators and modifications to two current indicators for maintaining genetic diversity and adaptive capacity of all species, and provide guidance on their practical use. The indicators are: 1) the number of populations with effective population size above versus below 500, 2) the proportion of populations maintained within species, 3) the number of species and populations in which genetic diversity is monitored using DNA-based methods. We also present and discuss Goals and Action Targets for post-2020 biodiversity conservation which are connected to these indicators and underlying data. These pragmatic indicators and goals have utility beyond the CBD; they should benefit conservation and monitoring of genetic diversity via national and global policy for decades to come.
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| 4. |
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| 5. |
- Nyström, Veronica, 1979-
(författare)
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Studies of declining populations - temporal genetic analyses of two arctic mammals
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many populations and species are threatened with extinction today. Understanding the extinction process and the factors behind population decline is therefore important. In this thesis, genetic analyses were performed on temporally spaced samples to investigate the demographic history and genetic effects of population reduction of two species: the arctic fox (Vulpes lagopus) and the woolly mammoth (Mammuthus primigenius). We used ancient DNA techniques to measure genetic variation in both mitochondrial DNA and microsatellites. In paper I, we investigated the genetic consequences of a human-induced demographic bottleneck in the Scandinavian arctic fox population. By comparing genetic data from museum specimens with genetic data from the contemporary population, we found a loss of genetic variation. However, the loss was less than expected, probably due to gene flow from North Russia. Using the same approach, we also found that Pleistocene arctic foxes from midlatitude Europe do not seem to have contributed to the genetic composition of contemporary populations (paper II). This suggests that they went extinct rather than track their habitat when it shifted northwards at the end of Pleistocene. Further, by analysing genetic data from radiocarbon dated fossils, we also found that the woolly mammoth lost genetic variation in connection to a marked decline in population size at the end of Pleistocene (paper III and IV). However, no further losses were detected during the time that mammoths were isolated on Wrangel Island, which suggests a rapid extinction process possibly caused by the arrival of humans or a short-term change in climate (paper III and IV). The results in this thesis demonstrate the usefulness of temporal genetic analyses for identifying population decline and evaluating its consequences.
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