| 11. |
- Leppälä, Johanna, et al.
(författare)
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Investigating incipient speciation in Arabidopsis lyrata from patterns of transmission ratio distortion
- 2013
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Ingår i: Genetics. - : Oxford University Press (OUP). - 0016-6731 .- 1943-2631. ; 194:3, s. 697-708
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Tidskriftsartikel (refereegranskat)abstract
- Our understanding of the development of intrinsic reproductive isolation is still largely based on theoretical models and thorough empirical studies on a small number of species. Theory suggests that reproductive isolation develops through accumulation of epistatic genic incompatibilities, also known as Bateson-Dobzhansky-Muller (BDM) incompatibilities. We can detect these from marker transmission ratio distortion (TRD) in hybrid progenies of crosses between species or populations, where TRD is expected to result from selection against heterospecific allele combinations in hybrids. TRD may also manifest itself because of intragenomic conflicts or competition between gametes or zygotes. We studied early stage speciation in Arabidopsis lyrata by investigating patterns of TRD across the genome in F-2 progenies of three reciprocal crosses between four natural populations. We found that the degree of TRD increases with genetic distance between crossed populations, but also that reciprocal progenies may differ substantially in their degree of TRD. Chromosomes AL6 and especially AL1 appear to be involved in many single- and two-locus distortions, but the location and source of TRD vary between crosses and between reciprocal progenies. We also found that the majority of single- and two-locus TRD appears to have a gametic, as opposed to zygotic, origin. Thus, while theory on BDM incompatibilities is typically illustrated with derived nuclear alleles proving incompatible in hybrid zygotes, our results suggest a prominent role for distortions emerging before zygote formation.
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| 12. |
- Mackay, John, et al.
(författare)
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Towards decoding the conifer giga-genome
- 2012
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Ingår i: Plant Molecular Biology. - : Springer. - 0167-4412 .- 1573-5028. ; 80:6, s. 555-569
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Forskningsöversikt (refereegranskat)abstract
- Several new initiatives have been launched recently to sequence conifer genomes including pines, spruces and Douglas-fir. Owing to the very large genome sizes ranging from 18 to 35 gigabases, sequencing even a single conifer genome had been considered unattainable until the recent throughput increases and cost reductions afforded by next generation sequencers. The purpose of this review is to describe the context for these new initiatives. A knowledge foundation has been acquired in several conifers of commercial and ecological interest through large-scale cDNA analyses, construction of genetic maps and gene mapping studies aiming to link phenotype and genotype. Exploratory sequencing in pines and spruces have pointed out some of the unique properties of these giga-genomes and suggested strategies that may be needed to extract value from their sequencing. The hope is that recent and pending developments in sequencing technology will contribute to rapidly filling the knowledge vacuum surrounding their structure, contents and evolution. Researchers are also making plans to use comparative analyses that will help to turn the data into a valuable resource for enhancing and protecting the world's conifer forests.
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| 13. |
- Martinez-Sancho, Elisabet, et al.
(författare)
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The GenTree Dendroecological Collection, tree-ring and wood density data from seven tree species across Europe
- 2020
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Ingår i: Scientific Data. - : NATURE PUBLISHING GROUP. - 2052-4463. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- The dataset presented here was collected by the GenTree project (EU-Horizon 2020), which aims to improve the use of forest genetic resources across Europe by better understanding how trees adapt to their local environment. This dataset of individual tree-core characteristics including ring-width series and whole-core wood density was collected for seven ecologically and economically important European tree species: silver birch (Betula pendula), European beech (Fagus sylvatica), Norway spruce (Picea abies), European black poplar (Populus nigra), maritime pine (Pinus pinaster), Scots pine (Pinus sylvestris), and sessile oak (Quercus petraea). Tree-ring width measurements were obtained from 3600 trees in 142 populations and whole-core wood density was measured for 3098 trees in 125 populations. This dataset covers most of the geographical and climatic range occupied by the selected species. The potential use of it will be highly valuable for assessing ecological and evolutionary responses to environmental conditions as well as for model development and parameterization, to predict adaptability under climate change scenarios.
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| 14. |
- Mattila, Tiina M., et al.
(författare)
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Impact of demography on linked selection in two outcrossing Brassicaceae species
- 2019
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 9:17, s. 9532-9545
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Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity is shaped by mutation, genetic drift, gene flow, recombination, and selection. The dynamics and interactions of these forces shape genetic diversity across different parts of the genome, between populations and species. Here, we have studied the effects of linked selection on nucleotide diversity in outcrossing populations of two Brassicaceae species, Arabidopsis lyrata and Capsella grandiflora, with contrasting demographic history. In agreement with previous estimates, we found evidence for a modest population size expansion thousands of generations ago, as well as efficient purifying selection in C. grandiflora. In contrast, the A. lyrata population exhibited evidence for very recent strong population size decline and weaker efficacy of purifying selection. Using multiple regression analyses with recombination rate and other genomic covariates as explanatory variables, we can explain 47% of the variance in neutral diversity in the C. grandiflora population, while in the A. lyrata population, only 11% of the variance was explained by the model. Recombination rate had a significant positive effect on neutral diversity in both species, suggesting that selection at linked sites has an effect on patterns of neutral variation. In line with this finding, we also found reduced neutral diversity in the vicinity of genes in the C. grandiflora population. However, in A. lyrata no such reduction in diversity was evident, a finding that is consistent with expectations of the impact of a recent bottleneck on patterns of neutral diversity near genes. This study thus empirically demonstrates how differences in demographic history modulate the impact of selection at linked sites in natural populations.
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| 15. |
- Opgenoorth, Lars, et al.
(författare)
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The GenTree Platform : growth traits and tree-level environmental data in 12 European forest tree species
- 2021
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Ingår i: GigaScience. - : Oxford University Press. - 2047-217X. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Background: Progress in the field of evolutionary forest ecology has been hampered by the huge challenge of phenotyping trees across their ranges in their natural environments, and the limitation in high-resolution environmental information.Findings: The GenTree Platform contains phenotypic and environmental data from 4,959 trees from 12 ecologically and economically important European forest tree species: Abies alba Mill. (silver fir), Betula pendula Roth. (silver birch), Fagus sylvatica L. (European beech), Picea abies (L.) H. Karst (Norway spruce), Pinus cembra L. (Swiss stone pine), Pinus halepensis Mill. (Aleppo pine), Pinus nigra Arnold (European black pine), Pinus pinaster Aiton (maritime pine), Pinus sylvestris L. (Scots pine), Populus nigra L. (European black poplar), Taxus baccata L. (English yew), and Quercus petraea (Matt.) Liebl. (sessile oak). Phenotypic (height, diameter at breast height, crown size, bark thickness, biomass, straightness, forking, branch angle, fructification), regeneration, environmental in situ measurements (soil depth, vegetation cover, competition indices), and environmental modeling data extracted by using bilinear interpolation accounting for surrounding conditions of each tree (precipitation, temperature, insolation, drought indices) were obtained from trees in 194 sites covering the species' geographic ranges and reflecting local environmental gradients.Conclusion: The GenTree Platform is a new resource for investigating ecological and evolutionary processes in forest trees. The coherent phenotyping and environmental characterization across 12 species in their European ranges allow for a wide range of analyses from forest ecologists, conservationists, and macro-ecologists. Also, the data here presented can be linked to the GenTree Dendroecological collection, the GenTree Leaf Trait collection, and the GenTree Genomic collection presented elsewhere, which together build the largest evolutionary forest ecology data collection available.
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| 16. |
- Paananen, A, et al.
(författare)
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Genetic and phenotypic diversity of echovirus 30 strains and pathogenesis of type 1 diabetes
- 2007
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Ingår i: Journal of Medical Virology. - : Wiley. - 0146-6615 .- 1096-9071. ; 79:7, s. 945-955
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Tidskriftsartikel (refereegranskat)abstract
- Several enterovirus serotypes should be considered as potentially diabetogenic. The capacity of an enterovirus to kill or impair the functions of human -cells can vary among the strains within a given serotype as shown previously for echovirus 9 and 30 (E-30). The evolution of E-30 has also shown patterns correlating with the global increase of type 1 diabetes incidence. In the present study, antigenic properties of a set of E-30 isolates were investigated and the results correlated with the previously documented -cell destructive phenotype of the strains, or to genetic clustering of the strains. No simple correlation between the three properties was observed. A full-length infectious clone was constructed and sequenced from one of the isolates found to be most destructive to -cells (E-30/14916net87). Phylogenetic analyses demonstrated that this strain was closely related to the E-30 prototype strain at the capsid coding region while outside the capsid region prototype strains of several other human enterovirus B serotypes clustered more closely. This suggests that the relatively greater pathogenicity of the strain might be based on properties of the genome outside of the structural protein coding region. Neutralizing antibody assays on sera from 100 type 1 diabetic patients and 100 controls using three different E-30 strains did not reveal differences between the groups. This finding does not support a previous proposition of aberrant antibody responses to E-30 in diabetic patients. It is concluded that identification of the genetic counterparts of pathogenicity of E-30 strains requires further studies.
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| 17. |
- Palmé, Anna, 1973-, et al.
(författare)
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Patterns of Divergence among Conifer ESTs and Polymorphism in Pinus sylvestris Identify Putative Selective Sweeps
- 2008
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Ingår i: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 25:12, s. 2567-2577
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Tidskriftsartikel (refereegranskat)abstract
- Finding genes that are under positive selection is a difficult task, especially in non-model organisms. Here, we haveanalyzed expressed sequence tag (EST) data from 4 species (Pinus pinaster, Pinus taeda, Picea glauca, and Pseudotsugamenziesii) to investigate selection patterns during their evolution and to identify genes likely to be under positiveselection. To confirm selection, population samples of these genes have been sequenced in Pinus sylvestris, a species thatwas not included in the EST data set. The estimates of branch-specific Ka/Ks (nonsynonymous/synonymous substitutionrates) across all genes in the EST data set were similar or smaller than estimates from other higher plant species. Therewas no evidence for the traditional indication of positive selection, Ka/Ks above 1. However, several lines of evidencebased on polymorphism patterns suggest that genes with high Ka/Ks (0.20–0.52) in the EST data set are in fact moreaffected by positive selection in P. sylvestris than genes with low Ka/Ks (0.01–0.04). The high Ka/Ks genes have a lowerlevel of polymorphism and more negative Tajima’s D than the low Ka/Ks genes. Further, in the high Ka/Ks group, theHudson–Kreitman–Aguade test is significant. This suggests that the EST data set is a good starting point for findinggenes under positive selection in conifers and that even moderate Ka/Ks values could be indicative of selection. A groupof 5 genes with high Ka/Ks collectively show evidence for positive selection within P. sylvestris.
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| 18. |
- Palmé, Anna, 1973-, et al.
(författare)
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Selection on Nuclear Genes in a Pinus Phylogeny
- 2009
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Ingår i: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 26:4, s. 893-905
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we investigate natural selection in a pine phylogeny. DNA sequences from 18 nuclear genes were used toconstruct a very well-supported species tree including 10 pine species. This tree is in complete agreement witha previously reported supertree constructed from morphological and molecular data, but there are discrepancies withprevious chloroplast phylogenies within the section Pinus. A significant difference in evolutionary rate between Piceaand Pinus was found, which could potentially indicate a lower mutation rate in Picea, but other scenarios are alsopossible. Several approaches were used to study selection patterns in a set of 21 nuclear genes in pines and in some casesin Picea and Pseudotsuga. The overall pattern suggests efficient purifying selection resulting in low branch-specific dn/dsratios with an average of 0.22, which is similar to other higher plants. Evidence for purifying selection was common andfound on at least 55% of the branches. Evidence of positive selection at several sites was found in a phytocyanin homologand significant differences in dn/ds among the branches in the gene tree in dehydrin 1. Several genes suitable for furtherphylogenetic analysis at various levels of divergence were identified.
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| 19. |
- Quilot-Turion, Bénédicte, et al.
(författare)
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Genetic changes in flowering and morphology in response to adaptation to a high-latitude environment in Arabidopsis lyrata
- 2013
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Ingår i: Annals of Botany. - : Oxford University Press. - 0305-7364 .- 1095-8290. ; 111:5, s. 957-968
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims The adaptive plastic reactions of plant populations to changing climatic factors, such as winter temperatures and photoperiod, have changed during range shifts after the last glaciation. Timing of flowering is an adaptive trait regulated by environmental cues. Its genetics has been intensively studied in annual plants, but in perennials it is currently not well characterized. This study examined the genetic basis of differentiation in flowering time, morphology, and their plastic responses to vernalization in two locally adapted populations of the perennial Arabidopsis lyrata: (1) to determine whether the two populations differ in their vernalization responses for flowering phenology and morphology; and (2) to determine the genomic areas governing differentiation and vernalization responses.Methods Two A. lyrata populations, from central Europe and Scandinavia, were grown in growth-chamber conditions with and without cold treatment. A QTL analysis was performed to find genomic regions that interact with vernalization.Key Results The population from central Europe flowered more rapidly and invested more in inflorescence growth than the population from alpine Scandinavia, especially after vernalization. The alpine population had consistently a low number of inflorescences and few flowers, suggesting strong constraints due to a short growing season, but instead had longer leaves and higher leaf rosettes. QTL mapping in the F2 population revealed genomic regions governing differentiation in flowering time and morphology and, in some cases, the allelic effects from the two populations on a trait were influenced by vernalization (QTL × vernalization interactions).Conclusions The results indicate that many potentially adaptive genetic changes have occurred during colonization; the two populations have diverged in their plastic responses to vernalization in traits closely connected to fitness through changes in many genomic areas.
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| 20. |
- Sandring, Saskia, et al.
(författare)
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Selection on flowering time and floral display in an alpine and a lowland population of Arabidopsis lyrata
- 2007
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 20:2, s. 558-567
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Tidskriftsartikel (refereegranskat)abstract
- To determine whether population differentiation in flowering time is consistent with differences in current selection, we quantified phenotypic selection acting through female reproductive success on flowering phenology and floral display in two Scandinavian populations of the outcrossing, perennial herb Arabidopsis lyrata in two years. One population was located in an alpine environment strongly affected by grazing, whereas the other was close to sea level and only moderately affected by herbivory. Multiple regression models indicated directional selection for early end of flowering in one year in the lowland population, and directional selection for early start of flowering in one year in the alpine population. As expected, there was selection for more inflorescences in the lowland population. However, in the alpine population, plants with many inflorescences were selectively grazed and the number of inflorescences produced was negatively related to female fitness in one year and not significantly related to female fitness in the second year. The results are consistent with the hypothesis that genetic differentiation in flowering phenology between the study populations is adaptive, and indicate that interactions with selective grazers may strongly influence selection on floral display in A. lyrata.
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