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- Söderquist, Pär, et al.
(author)
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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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In: European Biophysics Journal. - : Springer Verlag (Germany). - 0175-7571 .- 1432-1017. ; 63
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Journal article (peer-reviewed)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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| 5. |
- Elmberg, Johan, et al.
(author)
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Farmed European mallards are genetically different and cause introgression in the wild population following releases
- 2016
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Conference paper (peer-reviewed)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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| 6. |
- Elmberg, Johan, et al.
(author)
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Farmed European mallards are genetically different and cause introgression in the wild population following releases
- 2016
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Conference paper (other academic/artistic)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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| 8. |
- Garrido, Pablo, et al.
(author)
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Experimental rewilding enhances grassland functional composition and pollinator habitat use
- 2019
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In: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 56, s. 946-955
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Journal article (peer-reviewed)abstract
- Semi-natural grasslands are rich in biodiversity and thus important habitats for conservation, yet they are experiencing rapid declines due to agricultural intensification and abandonment. Promoting a more diverse mammalian herbivore community, including large and megaherbivores, may result in positive cascade effects for biodiversity and ecosystem functioning. Therefore, reintroducing an ecologically functional substitute of an extinct large herbivore could mitigate current biodiversity declines and foster semi-natural grassland conservation. To test this hypothesis, we set up a 3-year rewilding experiment where 12 feral horses were introduced in three 10-hectare enclosure replicates (four horses per enclosure). We used community-weighted mean plant functional traits to elucidate plant community changes induced by grazing through time. We also investigated the effects of this experimental treatment on insect pollinated plants and on pollinator habitat use. The grassland community exerted a mixed tolerance/avoidance response to grazing. This resulted in plant functional compositional changes which favoured prostrate plant species with higher specific leaf area, characteristic of ruderal communities. Plant species richness was higher in grazed compared to ungrazed areas. Butterfly and bumblebee habitat use, as well as feeding and resting activities were also higher in grazed areas. Moreover, the number of pollinators increased with plant species richness.Synthesis and applications. This study demonstrates that, to enhance the diversity of a given herbivore community with ecological replacements of extinct wild horses can have significant effects on the functional composition of grasslands. It can also mitigate plant species declines, in particular bee-dependent plants, and boost pollinator habitat use. Novel management alternatives are urgently needed to reverse the negative effect of land abandonment in European agricultural landscapes. Thus, rewilding interventions with large mammalian herbivores may offset current biodiversity declines by maintaining important functional links between plants and pollinators in grassland ecosystems.Foreign Language AbstractSammanfattningNaturbetesmarker ar rika pa biologisk mangfald och ar darmed av stor betydelse for naturvarden. Tyvarr minskar arealen av dessa marker pa grund av intensifieringar inom jordbruket och andrad djurhallning. En variationsrik djurhallning med stora daggdjur kan resultera i positiva foljdeffekter for biologisk mangfald och mer funktionella ekosystem. Genom att aterinfora ekologiskt funktionella ersattare for utdoda stora vaxtatare kan vi pa sa vis minska forlusten av biologisk mangfald och gynna bevarandet av naturbetesmarker. For att testa detta genomfordes ett trearigt faunarestaurerings-forsok med 12 hastar som fick beta i tre stycken 10-hektar stora hagn (fyra hastar i varje). Vi anvande medelvarden av vaxtsamhallets funktionella egenskaper for att studera hur hastarnas bete forandrade vaxtsamhallet over tid. Vi studerade aven effekter pa insektpollinerade vaxter och hur pollinerande insekter nyttjade forsoksytorna. Vaxterna uppvisade en blandning av tolerans och undvikande som respons mot betandet, vilket resulterade i funktionella forandringar som gynnade lagvaxande arter med stora blad, sa kallade ruderatvaxter. Vaxtrikedomen var hogre pa betade ytor an pa obetade. Det var aven storre forekomst av fodosokande och vilande fjarilar och humlor pa betade ytor. Antalet pollinerande insekter okade med vaxtrikedomen.Syntes och tillampning. Var studie visar att vi genom en vildare djurhallning kan aterskapa hastens ekosystemfunktion och att det ger positiva effekter pa vaxtsamhallets funktionella sammansattning. En vildare djurhallning kan aven motverka forlusten pollinerade vaxter och oka mangden pollinerande insekter. Nya forvaltningsmetoder behovs for att vanda den genomgripande utvecklingen kopplat till igenvaxning av det europeiska jordbrukslandskapet. angstrom terforandet av stora vaxtatande daggdjur kan forhindra forlusten av biologisk mangfald och uppratthalla viktiga funktionella kopplingar mellan vaxter och dess pollinatorer i naturbetesmarker.This study demonstrates that, to enhance the diversity of a given herbivore community with ecological replacements of extinct wild horses can have significant effects on the functional composition of grasslands. It can also mitigate plant species declines, in particular bee-dependent plants, and boost pollinator habitat use. Novel management alternatives are urgently needed to reverse the negative effect of land abandonment in European agricultural landscapes. Thus, rewilding interventions with large mammalian herbivores may offset current biodiversity declines by maintaining important functional links between plants and pollinators in grassland ecosystems.
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- Jansson, Anna, et al.
(author)
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Shaping the Swedish landscape: a future for the Gotland russ
- 2016
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Conference paper (other academic/artistic)abstract
- Tree encroachment and abandonment of pastures is an important cause of biodiversity loss in Sweden. In thisstudy, we evaluate the impact of all-year-around grazing by an ancient horse breed, the Gotland russ (GR),on tree encroachment. Twelve GR stallions were kept in 3 enclosures (lat: 59, long: 17, 4 GR/enclosure, 7ha forest and 3 ha open fields/enclosure) from May 2014 (age 1 yrs) until February 2016. Prior to the study,3 exclosures (EX, 5×42.5 m) where GR grazing was excluded were centered with the long side at the borderbetween forest and field. The field part of EX were further divided into four 5×5 m sections starting from theforest (1 to 4). Tree type (deciduous, spruce or pine), number and height were registered in the sections and theequivalent, grazed area adjacent to the EX on the 25th of February 2016. Body condition (BC) was assessedweekly using a 9 leveled scoring system. Individuals <4 were withdrawn, fed and reintroduced when BC was>4. Analysis of tree heights and numbers were made by procGLM in SAS. There was no difference in the totalnumber of deciduous trees (21±8 vs 25±8), spruces (2±1 vs 3±1) and pines (0.2±0.2 vs 0.8±0.2) between EXand grazed areas (P>0.05). In the grazed areas, the deciduous trees were shorter compared to the trees in EX(330±57 vs 780±70 mm, P<0.0001). There was no difference in spruce height (EX: 920±110 vs grazed areas:780±130 mm, P=0.31). In the grazed areas, tree height decreased from quarter 1 to 4 (1: 610±60, 2: 230±110, 3:140±90 and 4: 60±100 mm, P<0.0001) whereas in EX, the height increased (1: 740±60, 2: 570±150, 3: 810±90and 4: 960±100 mm, P<0.02). Four individuals (3 from the same enclosure) were withdrawn temporarily inFebruary 2015 due to BC <4. The study show that grazing by GR may inhibit encroachment by deciduoustrees and that BC was maintained in most individuals, despite the semi-feral conditions. The results providea new use for a threatened, ancient breed in landscape management.
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