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- Feng, Shaohong, et al.
(författare)
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Dense sampling of bird diversity increases power of comparative genomics
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 587:7833
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Tidskriftsartikel (refereegranskat)abstract
- Whole-genome sequencing projects are increasingly populating the tree of life and characterizing biodiversity(1-4). Sparse taxon sampling has previously been proposed to confound phylogenetic inference(5), and captures only a fraction of the genomic diversity. Here we report a substantial step towards the dense representation of avian phylogenetic and molecular diversity, by analysing 363 genomes from 92.4% of bird families-including 267 newly sequenced genomes produced for phase II of the Bird 10,000 Genomes (B10K) Project. We use this comparative genome dataset in combination with a pipeline that leverages a reference-free whole-genome alignment to identify orthologous regions in greater numbers than has previously been possible and to recognize genomic novelties in particular bird lineages. The densely sampled alignment provides a single-base-pair map of selection, has more than doubled the fraction of bases that are confidently predicted to be under conservation and reveals extensive patterns of weak selection in predominantly non-coding DNA. Our results demonstrate that increasing the diversity of genomes used in comparative studies can reveal more shared and lineage-specific variation, and improve the investigation of genomic characteristics. We anticipate that this genomic resource will offer new perspectives on evolutionary processes in cross-species comparative analyses and assist in efforts to conserve species. A dataset of the genomes of 363 species from the Bird 10,000 Genomes Project shows increased power to detect shared and lineage-specific variation, demonstrating the importance of phylogenetically diverse taxon sampling in whole-genome sequencing.
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- Liedvogel, Miriam, et al.
(författare)
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Chemical magnetoreception: Bird cryptochrome 1a is excited by blue light and forms long-lived radical-pairs
- 2007
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Ingår i: PLoS ONE.
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Tidskriftsartikel (refereegranskat)abstract
- Cryptochromes (Cry) have been suggested to form the basis of light-dependent magnetic compass orientation in birds. However, to function as magnetic compass sensors, the cryptochromes of migratory birds must possess a number of key biophysical characteristics. Most importantly, absorption of blue light must produce radical pairs with lifetimes longer than about a microsecond. Cryptochrome 1a (gwCry1a) and the photolyase-homology-region of Cry1 (gwCry1-PHR) from the migratory garden warbler were recombinantly expressed and purified from a baculovirus/Sf9 cell expression system. Transient absorption measurements show that these flavoproteins are indeed excited by light in the blue spectral range leading to the formation of radicals with millisecond lifetimes. These biophysical characteristics suggest that gwCry1a is ideally suited as a primary light-mediated, radical-pair-based magnetic compass receptor.
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- Midtbøen, Arnfinn H., et al.
(författare)
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Assessments of citizenship criteria : are immigrants more liberal?
- 2020
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Ingår i: Journal of ethnic and migration studies. - : Routledge. - 1369-183X .- 1469-9451. ; 46:13, s. 2625-2646
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Tidskriftsartikel (refereegranskat)abstract
- The literature on citizenship policies is flourishing, yet we know little of which naturalisation requirements majorities and minorities find reasonable, and how they view existing citizenship regimes. Drawing on original survey data with young adults in Norway (N = 3535), comprising immigrants and descendants with origins from Iraq, Pakistan, Poland, Somalia and Turkey, as well as a non-immigrant majority group, this article examines whether perceptions of ideal citizenship criteria and assessments of Norway's current rules differ between groups. In terms of ideal citizenship criteria, we find a striking similarity across groups when looking at six different dimensions of citizenship policy. When merged into an index and estimated in a multivariate regression model, we find that both immigrants and descendants are significantly more liberal than natives are, yet the differences are small. When assessing the semi-strict citizenship regime in Norway, we find that immigrants are significantly more positive towards the current rules than natives. The results lend little support to recent work on 'strategic' and 'instrumental' citizenship and point instead to a close to universal conception of the terms of membership acquisition in Norway. This suggests that states may operate with moderate integration requirements while maintaining the legitimacy of the citizenship institution.
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- Piersma, T, et al.
(författare)
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Is there a "migratory syndrome" common to all migrant birds?
- 2005
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Ingår i: Annals of the New York Academy of Sciences. - : Wiley. - 0077-8923. ; 1046, s. 282-293
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Tidskriftsartikel (refereegranskat)abstract
- Bird migration has been assumed, mostly implicitly, to represent a distinct class of animal behavior, with deep and strong homologies in the various phenotypic expressions of migratory behavior between different taxa. Here the evidence for the existence of what could be called a "migratory syndrome," a tightly integrated, old group of adaptive traits that enables birds to commit themselves to highly organized seasonal migrations, is assessed. A list of problems faced by migratory birds is listed first and the traits that migratory birds have evolved to deal with these problems are discussed. The usefulness of comparative approaches to investigate which traits are unique to migrants is then discussed. A provisional conclusion that, perhaps apart from a capacity for night-time compass orientation, there is little evidence for deeply rooted co-adapted trait complexes that could make up such a migratory syndrome, is suggested. Detailed analyses of the genetic and physiological architecture of potential adaptations to migration, combined with a comparative approach to further identify the phylogenetic levels at which different adaptive traits for migration have evolved, are recommended.
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