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| 2. |
- Burri, Reto, et al.
(författare)
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Linked selection and recombination rate variation drive the evolution of the genomic landscape of differentiation across the speciation continuum of Ficedula flycatchers
- 2015
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 25:11, s. 1656-1665
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Tidskriftsartikel (refereegranskat)abstract
- Speciation is a continuous process during which genetic changes gradually accumulate in the genomes of diverging species. Recent studies have documented highly heterogeneous differentiation landscapes, with distinct regions of elevated differentiation ("differentiation islands") widespread across genomes. However, it remains unclear which processes drive the evolution of differentiation islands; how the differentiation landscape evolves as speciation advances; and ultimately, how differentiation islands are related to speciation. Here, we addressed these questions based on population genetic analyses of 200 resequenced genomes from 10 populations of four Ficedula flycatcher sister species. We show that a heterogeneous differentiation landscape starts emerging among populations within species, and differentiation islands evolve recurrently in the very same genomic regions among independent lineages. Contrary to expectations from models that interpret differentiation islands as genomic regions involved in reproductive isolation that are shielded from gene flow, patterns of sequence divergence (d(XY) relative node depth) do not support a major role of gene flow in the evolution of the differentiation landscape in these species. Instead, as predicted by models of linked selection, genome-wide variation in diversity and differentiation can be explained by variation in recombination rate and the density of targets for selection. We thus conclude that the heterogeneous landscape of differentiation in Ficedula flycatchers evolves mainly as the result of background selection and selective sweeps in genomic regions of low recombination. Our results emphasize the necessity of incorporating linked selection as a null model to identify genome regions involved in adaptation and speciation.
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| 3. |
- Kopacova, Marcela, et al.
(författare)
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Blood pressure and stature in Helicobacter pylori positive and negative persons
- 2014
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Ingår i: World Journal of Gastroenterology. - : Baishideng Publishing Group Inc.. - 1007-9327 .- 2219-2840. ; 20:19, s. 5625-5631
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate vital signs and body indices in Helicobacter pylori (H. pylori) positive and negative persons. A total of 22 centres entered the study. They were spread over the whole country, corresponding well to the geographical distribution of the Czech population. A total of 1818 subjects (aged 5-98 years) took part in the study, randomly selected out of 38147 subjects. H. pylori infection was investigated by means of a 13C-urea breath test. Data on height, weight, systolic and diastolic blood pressure and heart rate were collected at the clinics of general practitioners. The overall prevalence of H. pylori infection was 30.4% (402/1321) in adults (>= 18 year-old) and 5.2% (26/497) in children and adolescents (<= 17 year-old). Once adjusted for age and gender, only a difference in body mass index remained statistically significant with H. pylori positive adults showing an increase of 0.6 kg/m(2) in body mass index. Once adjusted for age and gender, we found a difference in height between H. pylori positive and H. pylori negative children and adolescents. On further adjustment for place of residence, this difference became statistically significant, with H. pylori positive children and adolescents being on average 3.5 cm shorter. H. pylori positive adults were significantly older compared to H. pylori negative subjects. Once adjusted for age and gender, H. pylori infection had no impact on body weight, body mass index and vital signs either in adults or children and adolescents. Chronic H. pylori infection appeared to be associated with short stature in children. H. pylori infection did not influence blood pressure, body weight and body mass index either in adults or children and adolescents.
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| 4. |
- Lehtonen, Paula K., et al.
(författare)
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Geographic patterns of genetic differentiation and plumage colour variation are different in the pied flycatcher (Ficedula hypoleuca)
- 2009
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Ingår i: Molecular Ecology. - 0962-1083. ; 18:21, s. 4463-4476
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Tidskriftsartikel (refereegranskat)abstract
- The pied flycatcher is one of the most phenotypically variable bird species in Europe. The geographic variation in phenotypes has often been attributed to spatial variation in selection regimes that is associated with the presence or absence of the congeneric collared flycatcher. Spatial variation in phenotypes could however also be generated by spatially restricted gene flow and genetic drift. We examined the genetic population structure of pied flycatchers across the breeding range and applied the phenotypic Q(ST) (P(ST))-F(ST) approach to detect indirect signals of divergent selection on dorsal plumage colouration in pied flycatcher males. Allelic frequencies at neutral markers were found to significantly differ among populations breeding in central and southern Europe whereas northerly breeding pied flycatchers were found to be one apparently panmictic group of individuals. Pairwise differences between phenotypic (P(ST)) and neutral genetic distances (F(ST)) were positively correlated after removing the most differentiated Spanish and Swiss populations from the analysis, suggesting that genetic drift may have contributed to the observed phenotypic differentiation in some parts of the pied flycatcher breeding range. Differentiation in dorsal plumage colouration however greatly exceeded that observed at neutral genetic markers, which indicates that the observed pattern of phenotypic differentiation is unlikely to be solely maintained by restricted gene flow and genetic drift.
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| 5. |
- Rejchrt, Stanislav, et al.
(författare)
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Epidemiology of dyspepsia
- 2014
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Ingår i: Vnitr̆ní lékar̆ství. - : Czech Medical Association. - 0042-773X. ; 60:7-8, s. 649-656
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Tidskriftsartikel (refereegranskat)abstract
- Epidemiology of uninvestigated dyspepsia was studied in the Czech Republic for the first time in 2001. The aim of our current multi-centre prospective study was to evaluate dyspepsia using the same methods in a representative sample of general unselected population from the same geographical areas 10 years later. A total of 22 centres entered the study. A total of 1,836 subjects (aged 5-98 years) were enrolled. The overall prevalence of dyspepsia was 12 %; namely 3.5 % in subjects aged 5-24 years, 18 % among 25-64-year-old persons and 15 % in subjects 65 years. Despite the substantial decrease of Helicobacter pylori infection in the Czech Republic over the past 10 years, the prevalence and basic socio-demographic determinants of uninvestigated dyspepsia did not change significantly. Key words: Czech Republic - epidemiology - Helicobacter pylori - uninvestigated dyspepsia.
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| 6. |
- Rejchrt, Stanislav, et al.
(författare)
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The prevalence and sociodemographic determinants of uninvestigated dyspepsia in the Czech Republic : a multicentre prospective study accomplished 10 years after the first study from the same geographical areas
- 2018
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Ingår i: European Journal of Gastroenterology and Hepathology. - 0954-691X .- 1473-5687. ; 30:1, s. 76-82
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveThe epidemiology of uninvestigated dyspepsia was studied in the Czech Republic for the first time in 2001. The aim of the current multicenter prospective study was to evaluate dyspepsia using the same methods in a representative sample of general unselected population from the same geographical areas 10 years later.Participants and methodsA total of 38 147 individuals comprised the general population for a random two-step selection process. A total of 1836 participants (863 males and 973 females; aged 5–98 years) took part in the questionnaire-based study. Helicobacter pylori status was investigated in all participants by means of 13C-urea breath test.ResultsThe overall prevalence of dyspepsia was 2.6% among children and adolescents aged 5–17 years and 16.0% among adults aged 18–98 years. We did not detect any statistically significant sex differences in the prevalence of total dyspepsia or its subtypes. Overall, 2.4% of H. pylori-negative children and adolescents aged less than 18 years reported dyspepsia, and 16.8% of H. pylori-negative adults reported it. Among H. pylori-positive children and adolescents and adults, dyspepsia was present in 8.3 and 15.8%, respectively. Type A dyspepsia (as the only long-lasting symptom) was statistically significantly associated with H. pylori status among children and adolescents. Among adults aged 18 years or older, we noted a lower prevalence of dyspepsia in adults with elementary education compared with university education. Current use of antibiotics was associated with an increased prevalence of dyspepsia in adults.ConclusionDespite the substantial decrease of H. pylori infection in the Czech Republic over the past 10 years, the prevalence and sociodemographic determinants of uninvestigated dyspepsia did not change significantly.
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| 7. |
- Sirkiä, Päivi M., et al.
(författare)
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Fecundity selection does not vary along a large geographical cline of trait means in a passerine bird
- 2015
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066. ; 114:4, s. 808-827
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Tidskriftsartikel (refereegranskat)abstract
- Local environmental and ecological conditions are commonly expected to result in local adaptation, although there are few examples of variation in phenotypic selection across continent-wide spatial scales. We collected standardized data on selection with respect to the highly variable plumage coloration of pied flycatcher (Ficedula hypoleucaPall.) males from 17 populations across the species' breeding range. The observed selection on multiple male coloration traits via the annual number of fledged young was generally relatively weak. The main aim of the present study, however, was to examine whether the current directional selection estimates are associated with distance to the sympatric area with the collared flycatcher (Ficedula albicollisTemminck), a sister species with which the pied flycatcher is showing character displacement. This pattern was expected because plumage traits in male pied flycatchers are changing with the distance to these areas of sympatry. However, we did not find such a pattern in current selection on coloration. There were no associations between current directional selection on ornamentation and latitude or longitude either. Interestingly, current selection on coloration traits was not associated with the observed mean plumage traits of the populations. Thus, there do not appear to be geographical gradients in current directional fecundity selection on male plumage ornamentation. The results of the present study do not support the idea that constant patterns in directional fecundity selection would play a major role in the maintenance of coloration among populations in this species. By contrast, the tendency for relatively weak mosaic-like variation in selection among populations could reflect just a snapshot of temporally variable, potentially environment-dependent, selection, as suggested by other studies in this system. Such fine-grained variable selection coupled with gene flow could maintain extensive phenotypic variation across populations.(c) 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 808-827.
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| 8. |
- Smeds, Linnea, et al.
(författare)
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Evolutionary analysis of the female-specific avian W chromosome
- 2015
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The typically repetitive nature of the sex-limited chromosome means that it is often excluded from or poorly covered in genome assemblies, hindering studies of evolutionary and population genomic processes in non-recombining chromosomes. Here, we present a draft assembly of the non-recombining region of the collared flycatcher W chromosome, containing 46 genes without evidence of female-specific functional differentiation. Survival of genes during W chromosome degeneration has been highly non-random and expression data suggest that this can be attributed to selection for maintaining gene dose and ancestral expression levels of essential genes. Re-sequencing of large population samples revealed dramatically reduced levels of within-species diversity and elevated rates of between-species differentiation (lineage sorting), consistent with low effective population size. Concordance between W chromosome and mitochondrial DNA phylogenetic trees demonstrates evolutionary stable matrilineal inheritance of this nuclear-cytonuclear pair of chromosomes. Our results show both commonalities and differences between W chromosome and Y chromosome evolution.
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| 9. |
- Voeten, Dennis F. A. E., et al.
(författare)
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Wing bone geometry reveals active flight in Archaeopteryx
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Archaeopteryx is an iconic fossil taxon with feathered wings from the Late Jurassic of Germany that occupies a crucial position for understanding the early evolution of avian flight. After over 150 years of study, its mosaic anatomy unifying characters of both non-flying dinosaurs and flying birds has remained challenging to interpret in a locomotory context. Here, we compare new data from three Archaeopteryx specimens obtained through phase-contrast synchrotron microtomography to a representative sample of archosaurs employing a diverse array of locomotory strategies. Our analyses reveal that the architecture of Archaeopteryx's wing bones consistently exhibits a combination of cross-sectional geometric properties uniquely shared with volant birds, particularly those occasionally utilising short-distance flapping. We therefore interpret that Archaeopteryx actively employed wing flapping to take to the air through a more anterodorsally posteroventrally oriented flight stroke than used by modern birds. This unexpected outcome implies that avian powered flight must have originated before the latest Jurassic.
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