| 1. |
- Segelbacher, Gernot, et al.
(författare)
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Analyses of historical and current populations of black grouse in Central Europe reveal strong effects of genetic drift and loss of genetic diversity
- 2014
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Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 15:5, s. 1183-1195
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Tidskriftsartikel (refereegranskat)abstract
- Black grouse (Tetrao tetrix) in Central Europe have undergone a severe contraction of their range in recent decades with only a few small isolated remaining populations. Here we compare genetic diversity of two contemporary isolated populations (Sallandse Heuvelrug, Netherlands and Lüneburger Heide, Germany) with historical samples from the same region collected within the last one hundred years. We use markers with both putatively neutral and functional variation to test whether the present small and highly fragmented populations hold lower genetic diversity compared to the former larger population. For this we applied three different types of genetic markers: nine microsatellites and 21 single nucleotide polymorphisms (SNPs), both sets which have been found to be neutral, and two functional major histocompatibility complex (MHC) genes for which there is evidence they are under selection. The contemporary small isolated populations displayed lower neutral genetic diversity compared to the corresponding historical samples. Furthermore, samples from Denmark showed that this now extinct population displayed lower genetic variation in the period immediately prior to the local extinction. Population structure was more pronounced among contemporary populations compared to historical populations for microsatellites and SNPs. This effect was not as distinct for MHC which is consistent with the possibility that MHC has been subjected to balancing selection in the past, a process which maintains genetic variation and may minimize population structure for such markers. Genetic differentiation among the present populations highlights the strong effects of population decline on the genetic structure of natural populations, which can be ultimately attributed to habitat loss following anthropogenic land use changes.
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| 2. |
- Segelbacher, Gernot, et al.
(författare)
-
Historic and current populations of black grouse in central Europe – evidence for rapid loss of genetic diversity
- 2011
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Black grouse (Tetrao tetrix) in central Europe have undergone a severe contraction of their range with only a few small isolated remaining populations. We here compare genetic diversity of two contemporary populations (Sallandse Heuvelrug, Netherlands and Lüneburger Heide, Germany) with historic samples from the same range collected decades ago. We use both neutral and MHC markers to test whether present small and highly fragmented populations hold lower genetic diversity compared to the former larger population. For this we applied three different types of genetic markers: nine microsatellites and 21 SNPs (Single Nucleotide Polymorphisms) which both have been found to be neutral, and two functional MHC (Major Histocompatibility Complex) genes that are presumably under selection. The contemporary small isolated populations displayed lower neutral genetic diversity compared to the historic samples. A similar trend was found for genotypes at MHC class II loci. Furthermore, population structure was more pronounced among contemporary populations compared to historic populations for microsatellites and SNPs. This effect was not as distinct for MHC which suggests that MHC has been subjected to balancing selection in the past, a process upholding genetic variation and minimizing population structure for such markers. As predicted from theory, drift is the most potent evolutionary processes affecting genetic variation at small population sizes. Genetic differentiation among present populations highlights the strong affects of population decline and habitat loss due to anthropogenic land use changes on genetic structure of natural populations.
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| 3. |
- Strand, Tanja, 1978-, et al.
(författare)
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Can balancing selection on MHC loci counteract genetic drift in small fragmented populations of black grouse?
- 2012
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 2:2, s. 341-353
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Tidskriftsartikel (refereegranskat)abstract
- The ability of natural populations to adapt to new environmental conditions is crucial for their survival and partly determined by the standing genetic variation in each population. Populations with higher genetic diversity are more likely to contain individuals that are better adapted to new circumstances than populations with lower genetic diversity. Here we use both neutral and MHC markers to test whether small and highly fragmented populations hold lower genetic diversity than large ones. We use black grouse as it is distributed across Europe and found in populations with varying degrees of isolation and size. We sampled eleven different populations; five continuous, three isolated and three small and isolated. We tested patterns of genetic variation in these populations using three different types of genetic markers: nine microsatellites and 21 SNPs (Single Nucleotide Polymorphisms) which both were found to be neutral, and two functional MHC (Major Histocompatibility Complex) genes that are presumably under selection. The small isolated populations displayed significantly lower neutral genetic diversity compared to continuous populations. A similar trend, but not as pronounced, was found for genotypes at MHC class II loci. Populations were less divergent at MHC genes compared to neutral markers. Measures of genetic diversity and population genetic structure were positively correlated among microsatellites and SNPs, but none of them were correlated to MHC when comparing all populations. Our results suggest that balancing selection at MHC loci does not counteract the power of genetic drift when populations get small and fragmented.
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