| 1. |
- Khosrawi, F., et al.
(författare)
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Sensitivity of polar stratospheric cloud formation to changes in water vapour and temperature
- 2016
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 16:1, s. 101-121
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Tidskriftsartikel (refereegranskat)abstract
- More than a decade ago it was suggested that a cooling of stratospheric temperatures by 1 K or an increase of 1 ppmv of stratospheric water vapour could promote denitrification, the permanent removal of nitrogen species from the stratosphere by solid polar stratospheric cloud (PSC) particles. In fact, during the two Arctic winters 2009/10 and 2010/11 the strongest denitrification in the recent decade was observed. Sensitivity studies along air parcel trajectories are performed to test how a future stratospheric water vapour (H2O) increase of 1 ppmv or a temperature decrease of 1K would affect PSC formation. We perform our study based on measurements made during the Arctic winter 2010/11. Air parcel trajectories were calculated 6 days backward in time based on PSCs detected by CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder satellite observations). The sensitivity study was performed on single trajectories as well as on a trajectory ensemble. The sensitivity study shows a clear prolongation of the potential for PSC formation and PSC existence when the temperature in the stratosphere is decreased by 1K and water vapour is increased by 1 ppmv. Based on 15 years of satellite measurements (20002014) from UARS/HALOE, Envisat/MIPAS, Odin/SMR, Aura/MLS, Envisat/SCIAMACHY and SCISAT/ACE-FTS it is further investigated if there is a decrease in temperature and/or increase of water vapour (H2O) observed in the polar regions similar to that observed at midlatitudes and in the tropics. Performing linear regression analyses we derive from the Envisat/MIPAS (2002-2012) and Aura/MLS (2004-2014) observations predominantly positive changes in the potential temperature range 350 to 1000 K. The linear changes in water vapour derived from Envisat/MIPAS observations are largely insignificant, while those from Aura/MLS are mostly significant. For the temperature neither of the two instruments indicate any significant changes. Given the strong inter-annual variation observed in water vapour and particular temperature the severe denitrification observed in 2010/11 cannot be directly related to any changes in water vapour and temperature since the millennium. However, the observations indicate a clear correlation between cold winters and enhanced water vapour mixing ratios. This indicates a connection between dynamical and radiative processes that govern water vapour and temperature in the Arctic lower stratosphere.
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| 2. |
- Alonso-Blanco, Carlos, et al.
(författare)
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1,135 Genomes Reveal the Global Pattern of Polymorphism in Arabidopsis thaliana
- 2016
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Ingår i: Cell. - : Elsevier. - 0092-8674 .- 1097-4172. ; 166:2, s. 481-491
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Tidskriftsartikel (refereegranskat)abstract
- Arabidopsis thaliana serves as a model organism for the study of fundamental physiological, cellular, and molecular processes. It has also greatly advanced our understanding of intraspecific genome variation. We present a detailed map of variation in 1,135 high-quality re-sequenced natural inbred lines representing the native Eurasian and North African range and recently colonized North America. We identify relict populations that continue to inhabit ancestral habitats, primarily in the Iberian Peninsula. They have mixed with a lineage that has spread to northern latitudes from an unknown glacial refugium and is now found in a much broader spectrum of habitats. Insights into the history of the species and the fine-scale distribution of genetic diversity provide the basis for full exploitation of A. thaliana natural variation through integration of genomes and epigenomes with molecular and non-molecular phenotypes.
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| 3. |
- Kawakatsu, Taiji, et al.
(författare)
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Epigenomic Diversity in a Global Collection of Arabidopsis thaliana Accessions
- 2016
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Ingår i: Cell. - : Elsevier. - 0092-8674 .- 1097-4172. ; 166:2, s. 492-505
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Tidskriftsartikel (refereegranskat)abstract
- The epigenome orchestrates genome accessibility, functionality, and three-dimensional structure. Because epigenetic variation can impact transcription and thus phenotypes, it may contribute to adaptation. Here, we report 1,107 high-quality single-base resolution methylomes and 1,203 transcriptomes from the 1001 Genomes collection of Arabidopsis thaliana. Although the genetic basis of methylation variation is highly complex, geographic origin is a major predictor of genome-wide DNA methylation levels and of altered gene expression caused by epialleles. Comparison to cistrome and epicistrome datasets identifies associations between transcription factor binding sites, methylation, nucleotide variation, and co-expression modules. Physical maps for nine of the most diverse genomes reveal how transposons and other structural variants shape the epigenome, with dramatic effects on immunity genes. The 1001 Epigenomes Project provides a comprehensive resource for understanding how variation in DNA methylation contributes to molecular and non-molecular phenotypes in natural populations of the most studied model plant.
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| 4. |
- Novikova, P. Y., et al.
(författare)
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Sequencing of the genus Arabidopsis identifies a complex history of nonbifurcating speciation and abundant trans-specific polymorphism
- 2016
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 48:9, s. 1077-1082
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Tidskriftsartikel (refereegranskat)abstract
- The notion of species as reproductively isolated units related through a bifurcating tree implies that gene trees should generally agree with the species tree and that sister taxa should not share polymorphisms unless they diverged recently and should be equally closely related to outgroups. It is now possible to evaluate this model systematically. We sequenced multiple individuals from 27 described taxa representing the entire Arabidopsis genus. Cluster analysis identified seven groups, corresponding to described species that capture the structure of the genus. However, at the level of gene trees, only the separation of Arabidopsis thaliana from the remaining species was universally supported, and, overall, the amount of shared polymorphism demonstrated that reproductive isolation was considerably more recent than the estimated divergence times. We uncovered multiple cases of past gene flow that contradict a bifurcating species tree. Finally, we showed that the pattern of divergence differs between gene ontologies, suggesting a role for selection. © 2016 Nature America, Inc. All rights reserved.
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| 5. |
- Pedersen, M. W., et al.
(författare)
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Trends in marine climate change research in the Nordic region since the first IPCC report
- 2016
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Ingår i: Climatic Change. - : Springer Science and Business Media LLC. - 0165-0009 .- 1573-1480. ; 134:1-2, s. 147-161
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Tidskriftsartikel (refereegranskat)abstract
- Oceans are exposed to anthropogenic climate change shifting marine systems toward potential instabilities. The physical, biological and social implications of such shifts can be assessed within individual scientific disciplines, but can only be fully understood by combining knowledge and expertise across disciplines. For climate change related problems these research directions have been well-established since the publication of the first IPCC report in 1990, however it is not well-documented to what extent these directions are reflected in published research. Focusing on the Nordic region, we evaluated the development of climate change related marine science by quantifying trends in number of publications, disciplinarity, and scientific focus of 1362 research articles published between 1990 and 2011. Our analysis showed a faster increase in publications within climate change related marine science than in general marine science indicating a growing prioritisation of research with a climate change focus. The composition of scientific disciplines producing climate change related publications, which initially was dominated by physical sciences, shifted toward a distribution with almost even representation of physical and biological sciences with social sciences constituting a minor constant proportion. These trends suggest that the predominantly model-based directions of the IPCC have favoured the more quantitatively oriented natural sciences rather than the qualitative traditions of social sciences. In addition, despite being an often declared prerequisite to successful climate science, we found surprisingly limited progress in implementing interdisciplinary research indicating that further initiatives nurturing scientific interactions are required.
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