| 1. |
- Lundregan, Sarah L., et al.
(författare)
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Infection by a helminth parasite is associated with changes in DNA methylation in the house sparrow
- 2022
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Ingår i: Ecology and Evolution. - : Wiley-Blackwell. - 2045-7758. ; 12:11
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Tidskriftsartikel (refereegranskat)abstract
- Parasites can exert strong selective pressures on their hosts and influence the evolution of host immunity. While several studies have examined the genetic basis for parasite resistance, the role of epigenetics in the immune response to parasites is less understood. Yet, epigenetic modifications, such as changes in DNA methylation, may allow species to respond rapidly to parasite prevalence or virulence. To test the role of DNA methylation in relation to parasite infection, we examined genome-wide DNA methylation before and during infection by a parasitic nematode, Syngamus trachea, in a natural population of house sparrows (Passer domesticus) using reduced representation bisulfite sequencing (RRBS). We found that DNA methylation levels were slightly lower in infected house sparrows, and we identified candidate genes relating to the initial immune response, activation of innate and adaptive immunity, and mucus membrane functional integrity that were differentially methylated between infected and control birds. Subsequently, we used methylation-sensitive high-resolution melting (MS-HRM) analyses to verify the relationship between methylation proportion and S. trachea infection status at two candidate genes in a larger sample dataset. We found that methylation level at NR1D1, but not CLDN22, remained related to infection status and that juvenile recruitment probability was positively related to methylation level at NR1D1. This underscores the importance of performing follow-up studies on candidate genes. Our findings demonstrate that plasticity in the immune response to parasites can be epigenetically mediated and highlight the potential for epigenetic studies in natural populations to provide further mechanistic insight into host-parasite interactions.
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| 2. |
- Lundregan, Sarah L., et al.
(författare)
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Inferences of genetic architecture of bill morphology in house sparrow using a high-density SNP array point to a polygenic basis
- 2018
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Ingår i: Molecular Ecology. - : WILEY. - 0962-1083 .- 1365-294X. ; 27:17, s. 3498-3514
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the genetic architecture of quantitative traits can provide insights into the mechanisms driving phenotypic evolution. Bill morphology is an ecologically important and phenotypically variable trait, which is highly heritable and closely linked to individual fitness. Thus, bill morphology traits are suitable candidates for gene mapping analyses. Previous studies have revealed several genes that may influence bill morphology, but the similarity of gene and allele effects between species and populations is unknown. Here, we develop a custom 200K SNP array and use it to examine the genetic basis of bill morphology in 1857 house sparrow individuals from a large-scale, island metapopulation off the coast of Northern Norway. We found high genomic heritabilities for bill depth and length, which were comparable with previous pedigree estimates. Candidate gene and genomewide association analyses yielded six significant loci, four of which have previously been associated with craniofacial development. Three of these loci are involved in bone morphogenic protein (BMP) signalling, suggesting a role for BMP genes in regulating bill morphology. However, these loci individually explain a small amount of variance. In combination with results from genome partitioning analyses, this indicates that bill morphology is a polygenic trait. Any studies of eco-evolutionary processes in bill morphology are therefore dependent on methods that can accommodate polygenic inheritance of the phenotype and molecular-scale evolution of genetic architecture.
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| 3. |
- Niskanen, Alina K., et al.
(författare)
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Consistent scaling of inbreeding depression in space and time in a house sparrow metapopulation
- 2020
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 117:25, s. 14584-14592
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Tidskriftsartikel (refereegranskat)abstract
- Inbreeding may increase the extinction risk of small populations. Yet, studies using modern genomic tools to investigate inbreeding depression in nature have been limited to single populations, and little is known about the dynamics of inbreeding depression in subdivided populations over time. Natural populations often experience different environmental conditions and differ in demographic history and genetic composition, characteristics that can affect the severity of inbreeding depression. We utilized extensive long-term data on more than 3,100 individuals from eight islands in an insular house sparrow metapopulation to examine the generality of inbreeding effects. Using genomic estimates of realized inbreeding, we discovered that inbred individuals had lower survival probabilities and produced fewer recruiting offspring than noninbred individuals. Inbreeding depression, measured as the decline in fitness-related traits per unit inbreeding, did not vary appreciably among populations or with time. As a consequence, populations with more resident inbreeding (due to their demographic history) paid a higher total fitness cost, evidenced by a larger variance in fitness explained by inbreeding within these populations. Our results are in contrast to the idea that effects of inbreeding generally depend on ecological factors and genetic differences among populations, and expand the understanding of inbreeding depression in natural subdivided populations.
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