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- Dutoit, Ludovic, et al.
(författare)
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Covariation in levels of nucleotide diversity in homologous regions of the avian genome long after completion of lineage sorting
- 2017
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : ROYAL SOC. - 0962-8452 .- 1471-2954. ; 284:1849
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Tidskriftsartikel (refereegranskat)abstract
- Closely related species may show similar levels of genetic diversity in homologous regions of the genome owing to shared ancestral variation still segregating in the extant species. However, after completion of lineage sorting, such covariation is not necessarily expected. On the other hand, if the processes that govern genetic diversity are conserved, diversity may potentially covary even among distantly related species. We mapped regions of conserved synteny between the genomes of two divergent bird speciescollared flycatcher and hooded crow-and identified more than 600 Mb of homologous regions (66% of the genome). From analyses of whole-genome resequencing data in large population samples of both species we found nucleotide diversity in 200 kb windows to be well correlated (Spearman's rho = 0.407). The correlation remained highly similar after excluding coding sequences. To explain this covariation, we suggest that a stable avian karyotype and a conserved landscape of recombination rate variation render the diversity-reducing effects of linked selection similar in divergent bird lineages. Principal component regression analysis of several potential explanatory variables driving heterogeneity in flycatcher diversity levels revealed the strongest effects from recombination rate variation and density of coding sequence targets for selection, consistent with linked selection. It is also possible that a stable karyotype is associated with a conserved genomic mutation environment contributing to covariation in diversity levels between lineages. Our observations imply that genetic diversity is to some extent predictable.
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- Foote, Andrew D., et al.
(författare)
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Convergent evolution of the genomes of marine mammals
- 2015
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 47:3, s. 272-275
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Tidskriftsartikel (refereegranskat)abstract
- Marine mammals from different mammalian orders share several phenotypic traits adapted to the aquatic environment and therefore represent a classic example of convergent evolution. To investigate convergent evolution at the genomic level, we sequenced and performed de novo assembly of the genomes of three species of marine mammals (the killer whale, walrus and manatee) from three mammalian orders that share independently evolved phenotypic adaptations to a marine existence. Our comparative genomic analyses found that convergent amino acid substitutions were widespread throughout the genome and that a subset of these substitutions were in genes evolving under positive selection and putatively associated with a marine phenotype. However, we found higher levels of convergent amino acid substitutions in a control set of terrestrial sister taxa to the marine mammals. Our results suggest that, whereas convergent molecular evolution is relatively common, adaptive molecular convergence linked to phenotypic convergence is comparatively rare.
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- Foote, Andrew D., et al.
(författare)
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Genome-culture coevolution promotes rapid divergence of killer whale ecotypes
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Analysing population genomic data from killer whale ecotypes, which we estimate have globally radiated within less than 250,000 years, we show that genetic structuring including the segregation of potentially functional alleles is associated with socially inherited ecological niche. Reconstruction of ancestral demographic history revealed bottlenecks during founder events, likely promoting ecological divergence and genetic drift resulting in a wide range of genome-wide differentiation between pairs of allopatric and sympatric ecotypes. Functional enrichment analyses provided evidence for regional genomic divergence associated with habitat, dietary preferences and post-zygotic reproductive isolation. Our findings are consistent with expansion of small founder groups into novel niches by an initial plastic behavioural response, perpetuated by social learning imposing an altered natural selection regime. The study constitutes an important step towards an understanding of the complex interaction between demographic history, culture, ecological adaptation and evolution at the genomic level.
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5. |
- Knief, Ulrich, et al.
(författare)
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Epistatic mutations under divergent selection govern phenotypic variation in the crow hybrid zone
- 2019
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Ingår i: Nature Ecology & Evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 3:4, s. 570-576
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of genetic barriers opposing interspecific gene flow is key to the origin of new species. Drawing from information on over 400 admixed genomes sourced from replicate transects across the European hybrid zone between all-black carrion crows and grey-coated hooded crows, we decipher the interplay between phenotypic divergence and selection at the molecular level. Over 68% of plumage variation was explained by epistasis between the gene NDP and a similar to 2.8-megabase region on chromosome 18 with suppressed recombination. Both pigmentation loci showed evidence for divergent selection resisting introgression. This study reveals how few, large-effect loci can govern prezygotic isolation and shield phenotypic divergence from gene flow.
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9. |
- Poelstra, Jelmer W., et al.
(författare)
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The genomic landscape underlying phenotypic integrity in the face of gene flow in crows
- 2014
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 344:6190, s. 1410-1414
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Tidskriftsartikel (refereegranskat)abstract
- The importance, extent, and mode of interspecific gene flow for the evolution of species has long been debated. Characterization of genomic differentiation in a classic example of hybridization between all-black carrion crows and gray-coated hooded crows identified genome-wide introgression extending far beyond the morphological hybrid zone. Gene expression divergence was concentrated in pigmentation genes expressed in gray versus black feather follicles. Only a small number of narrow genomic islands exhibited resistance to gene flow. One prominent genomic region (<2 megabases) harbored 81 of all 82 fixed differences (of 8.4 million single-nucleotide polymorphisms in total) linking genes involved in pigmentation and in visual perception-a genomic signal reflecting color-mediated prezygotic isolation. Thus, localized genomic selection can cause marked heterogeneity in introgression landscapes while maintaining phenotypic divergence.
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10. |
- Poelstra, Jelmer W., et al.
(författare)
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Transcriptomics of colour patterning and coloration shifts in crows
- 2015
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 24:18, s. 4617-4628
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Tidskriftsartikel (refereegranskat)abstract
- Animal coloration is one of the most conspicuous phenotypic traits in natural populations and has important implications for adaptation and speciation. Changes in coloration can occur over surprisingly short evolutionary timescales, while recurrence of similar colour patterns across large phylogenetic distances is also common. Even though the genetic basis of pigment production is well understood, little is known about the mechanisms regulating colour patterning. In this study, we shed light on the molecular elements regulating regional pigment production in two genetically near-identical crow taxa with striking differences in a eumelanin-based phenotype: black carrion and grey-coated hooded crows. We produced a high-quality genome annotation and analysed transcriptome data from a 2 3 2 design of active melanogenic feather follicles from head (black in both taxa) and torso (black in carrion and grey in hooded crow). Extensive, parallel expression differences between body regions in both taxa, enriched for melanogenesis genes (e.g. ASIP, CORIN, and ALDH6), indicated the presence of cryptic prepatterning also in all-black carrion crows. Meanwhile, colour-specific expression (grey vs. black) was limited to a small number of melanogenesis genes in close association with the central transcription factor MITF (most notably HPGDS, NDP and RASGRF1). We conclude that colour pattern differences between the taxa likely result from an interaction between divergence in upstream elements of the melanogenesis pathway and genes that provide an underlying prepattern across the body through positional information. A model of evolutionary stable prepatterns that can be exposed and masked through simple regulatory changes may explain the phylogenetically independent recurrence of colour patterns that is observed across corvids and many other vertebrate groups.
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