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- Elmberg, Johan, et al.
(författare)
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Farmed European mallards are genetically different and cause introgression in the wild population following releases
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The practice of restocking already viable populations to increase harvest potential has since long been common in forestry, fisheries and wildlife management. The potential risks of restocking native species have long been overshadowed by the related issue of invasive alien species. However, during the last decade releases of native species with potentially non-native genome have received more attention. A suitable model to study genetic effects of large-scale releases of native species is the Mallard Anas platyrhynchos, being the most widespread duck in the world, largely migratory, and an important quarry species. More than 3 million unfledged hatchlings are released each year around Europe to increase local harvest. The aims of this study were to determine if wild and released farmed Mallards differ genetically, if there are signs of previous or ongoing introgression between wild and farmed birds, and if the genetic structure of the wild Mallard population has changed since large-scale releases started in Europe in the 1970s. Using 360 Single Nucleotide Polymorphisms (SNPs) we found that the genetic structure differed among historical wild, present-day wild, and farmed Mallards in Europe. We also found signs of introgression in the wild Mallard population, that is, individuals with a genetic background of farmed stock are part of the present free-living population. Although only a small proportion of the released Mallards appears to survive to merge with the free-living breeding population, their numbers are still so large that the genetic impact may have significance for the wild population in terms of individual survival and longterm fitness.
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| 4. |
- Stenmark, Bianca, 1987-, et al.
(författare)
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Complete genome and methylome comparison of two Neisseria meningitidis serogroup Y subtypes
- 2017
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Ingår i: 2nd ASM Conference on Rapid Applied Microbial Next-Generation Sequencing and Bioinformatic Pipelines. - Washington, DC : American Society for Microbiology. ; , s. 32-33
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: A significant increase in invasive meningococcal disease (IMD) due to serogroup Y Neisseria meningitidis (MenY) strains emerged in the United States during the 1990s spreading to Europe shortly thereafter. The largest increase was observed in Sweden with incidence proportions up to 53%. cgMLST of all MenY isolates causing IMD between 1995 to 2012 in Sweden revealed that a distinct strain (YI) and more specifically a subtype (1) of this strain was found to be responsible for the increase of MenY IMD in Sweden [1]. The aim was to compare the complete genome and methylome of subtype 1 to the less successful subtype 2 using Single Molecule Real-Time (SMRT) sequencing technology.Methods: Ten genomes belonging to subtype 1 (n=7) and 2 (n=3) and one MenY genome without connection to a specific strain were sequenced using SMRT sequencing on a PacBio®RS II. SMRT Portal v2 was used to identify modified positions and for the genome-wide analysis of modified motifs. DNA methyltransferase genes associated with the different methyltransferase recognition motifs identified were searched using the Restriction Enzyme Database REBASE (rebase.neb.com).Results: Genomic comparison of the two MenY subtypes revealed that these possessed highly similar genomes, only two genes encoding hypothetical proteins were present in subtype 2 but absent in subtype 1. There were 99 genes with allelic differences and non-synonymous differences were found in genes implicated in adhesion, lipooligosaccharides (LOS) production, pilin production and iron acquisition. The genome-wide analysis of the methylome identified three modified motifs: GATC, GGNNCC and CACNNNNNTAC, the latter was only found in isolates belonging to subtype 2 and a trans-posase was found inserted in the candidate enzyme: a type I restriction system specificity protein (NEIS2535). In general, modifications were found in both cytosine and adenine bases although the latter, 6mA, was the most frequent modification in all isolates and more predominant among subtype 2. Many inactive restriction modification systems were present; however, in order to reveal more active sys-tems, further analysis on 5mC is needed.Conclusion: Our preliminary results indicate that there is a difference in methylation motifs as well as positional distribution of modifications between the two MenY subtypes. Since no differences were found in the presence of genes potentially involved in pathogenicity between the two subtypes, and it has been previously established that there was rather a tendency of a milder clinical picture among IMD caused by subtype 1 [2], the emergence of subtype 1 was most probably due to increased transmission or that the human population was more immunologically naïve to this subtype.References: 1. Törös B et al. J Clin Microbiol 2015, 53(7):2154-2162. 2. Säll O et al.Epidemiol Infect 2017, 145(10):2137-2143.
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| 5. |
- Söderquist, Pär, et al.
(författare)
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Admixture between released and wild game birds: a changing genetic landscape in European mallards (Anas platyrhynchos)
- 2017
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Ingår i: European Biophysics Journal. - : Springer Verlag. - 0175-7571 .- 1432-1017. ; 63:6
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Tidskriftsartikel (refereegranskat)abstract
- Disruption of naturally evolved spatial patterns of genetic variation and local adaptations is a growing concern in wildlife management and conservation. During the last decade, releases of native taxa with potentially non-native genotypes have received increased attention. This has mostly concerned conservation programs, but releases are also widely carried out to boost harvest opportunities. The mallard, Anas platyrhynchos, is one of few terrestrial migratory vertebrates subjected to large-scale releases for hunting purposes. It is the most numerous and widespread duck in the world, yet each year more than three million farmed mallard ducklings are released into the wild in the European Union alone to increase the harvestable population. This study aimed to determine the genetic effects of such large-scale releases of a native species, specifically if wild and released farmed mallards differ genetically among subpopulations in Europe, if there are signs of admixture between the two groups, if the genetic structure of the wild mallard population has changed since large-scale releases began in the 1970s, and if the current data matches global patterns across the Northern hemisphere. We used Bayesian clustering (Structure software) and Discriminant Analysis of Principal Components (DAPC) to analyze the genetic structure of historical and present-day wild (n = 171 and n = 209, respectively) as well as farmed (n = 211) mallards from six European countries as inferred by 360 single-nucleotide polymorphisms (SNPs). Both methods showed a clear genetic differentiation between wild and farmed mallards. Admixed individuals were found in the present-day wild population, implicating introgression of farmed genotypes into wild mallards despite low survival among released farmed mallards. Such cryptic introgression would alter the genetic composition of wild populations and may have unknown long-term consequences for conservation.
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