| 1. |
- Clark, Andrew G., et al.
(författare)
-
Evolution of genes and genomes on the Drosophila phylogeny
- 2007
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 450:7167, s. 203-218
-
Tidskriftsartikel (refereegranskat)abstract
- Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.
|
|
| 2. |
- Seppä, H., et al.
(författare)
-
Spatial structure of the 8200 cal yr BP event in northern Europe
- 2007
-
Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 3:2, s. 225-236
-
Tidskriftsartikel (refereegranskat)abstract
- A synthesis of well-dated high-resolution pollen records suggests a spatial structure in the 8200 cal yr BP event in northern Europe. The temperate, thermophilous tree taxa, especially Corylus, Ulmus, and Alnus, decline abruptly between 8300 and 8000 cal yr BP at most sites located south of 61° N, whereas there is no clear change in pollen values at the sites located in the North-European tree-line region. Pollen-based quantitative temperature reconstructions and several other, independent palaeoclimate proxies, such as lacustrine oxygen-isotope records, reflect the same pattern, with no detectable cooling in the sub-arctic region. The observed patterns challenges the general view of the wide-spread occurrence of the 8200 cal yr BP event in the North Atlantic region. An alternative explanation is that the cooling during the 8200 cal yr BP event took place mostly during the winter and spring, and the ecosystems in the south responded sensitively to the cooling during the onset of the growing season. In contrast, in the sub-arctic area, where the vegetation was still dormant and lakes ice-covered, the cold event is not reflected in pollen-based or lake-sediment-based records.
|
|
| 3. |
- MacDonald, G. M., et al.
(författare)
-
Impacts of climate change on species, populations and communities : palaeobiogeographical insights and frontiers
- 2008
-
Ingår i: Progress in physical geography. - : SAGE Publications. - 0309-1333 .- 1477-0296. ; 32:2, s. 139-172
-
Forskningsöversikt (refereegranskat)abstract
- Understanding climate change and its potential impact on species, populations and communities is one of the most pressing questions of twenty-first-century conservation planning. Palaeobiogeographers working on Cenozoic fossil records and other lines of evidence are producing important insights into the dynamic nature of climate and the equally dynamic response of species, populations and communities. Climatic variations ranging in length from multimillennia to decades run throughout the palaeo-records of the Quaternary and earlier Cenozoic and have been shown to have had impacts ranging from changes in the genetic structure and morphology of individual species, population sizes and distributions, community composition to large-scale bio-diversity gradients. The biogeographical impacts of climate change may be due directly to the effects of alterations in temperature and moisture on species, or they may arise due to changes in factors such as disturbance regimes. Much of the recent progress in the application of palaeobiogegraphy to issues of climate change and its impacts can be attributed to developments along a number of still advancing methodological frontiers. These include increasingly finely resolved chronological resolution, more refined atmosphere-biosphere modelling, new biological and chemical techniques in reconstructing past species distributions and past climates, the development of large and readily accessible geo-referenced databases of biogeographical and climatic information, and new approaches in fossil morphological analysis and new molecular DNA techniques.
|
|
| 4. |
- McGuire, A.D., et al.
(författare)
-
Sensitivity of the carbon cycle in the Arctic to climate change
- 2009
-
Ingår i: Ecological Monographs. - : Wiley. - 0012-9615. ; 79:4, s. 523-555
-
Tidskriftsartikel (refereegranskat)abstract
- The recent warming in the Arctic is affecting a broad spectrum of physical, ecological, and human/cultural systems that may be irreversible on century time scales and have the potential to cause rapid changes in the earth system. The response of the carbon cycle of the Arctic to changes in climate is a major issue of global concern, yet there has not been a comprehensive review of the status of the contemporary carbon cycle of the Arctic and its response to climate change. This review is designed to clarify key uncertainties and vulnerabilities in the response of the carbon cycle of the Arctic to ongoing climatic change. While it is clear that there are substantial stocks of carbon in the Arctic, there are also significant uncertainties associated with the magnitude of organic matter stocks contained in permafrost and the storage of methane hydrates beneath both subterranean and submerged permafrost of the Arctic. In the context of the global carbon cycle, this review demonstrates that the Arctic plays an important role in the global dynamics of both CO2 and CH4. Studies suggest that the Arctic has been a sink for atmospheric CO2 of between 0 and 0.8 Pg C/yr in recent decades, which is between 0% and 25% of the global net land/ocean flux during the 1990s. The Arctic is a substantial source of CH4 to the atmosphere (between 32 and 112 Tg CH4/yr), primarily because of the large area of wetlands throughout the region. Analyses to date indicate that the sensitivity of the carbon cycle of the Arctic during the remainder of the 21st century is highly uncertain. To improve the capability to assess the sensitivity of the carbon cycle of the Arctic to projected climate change, we recommend that (1) integrated regional studies be conducted to link observations of carbon dynamics to the processes that are likely to influence those dynamics, and (2) the understanding gained from these integrated studies be incorporated into both uncoupled and fully coupled carbon–climate modeling efforts.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Hector, A. L., et al.
(författare)
-
An unusual magnetic structure in Sr2FeO3F and magnetic structures of K2NiF4-type iron(III) oxides and oxide halides, including the cobalt substituted series Sr2Fe 1-xCoxO3Cl
- 2005
-
Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 1364-5501 .- 0959-9428. ; 15:30, s. 3093-3103
-
Tidskriftsartikel (refereegranskat)abstract
- An unusual k = [1/2 1/2 1/2] magnetic structure is reported in Sr 2FeO3F at low temperature. The magnetic structures of LaBaFeO4, LaSrFeO4, LaCaFeO4, Ca 2FeO3Cl, Ca2FeO3Br, Sr 2FeO3F, Sr2FeO3Cl, Sr 2FeO3Br and solid solutions in the series Sr 2Fe1-xCoxO3Cl have been examined and only Sr2FeO3F exhibits this structure. The La 2CuO4-type spin arrangement dominates in all these phases, with antiferromagnetic ordering in the xy planes. The k = [1/2 1/2 1/2] magnetic phase in Sr2FeO3F occurs below 100 K and requires La2CuO4-type stacking across the SrO layers and La2NiO4-type stacking across the SrF layers. It has been possible to show that this phase grows in domains which have purely La 2CuO4-type stacking at higher temperatures. In the Sr 2Fe1-xCoxO3Cl series the La 2CuO4-type magnetic structure in Sr2FeO 3Cl and the La2NiO4-type structure in Sr 2CoO3Cl coexist and structural and magnetic behaviour indicate phase segregation into cobalt- and iron-rich regions.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Olomon, A. S., et al.
(författare)
-
Serum total cholesterol, statins and cognition in non-demented elderly
- 2009
-
Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 30:6, s. 1006-1009
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The association between serum total cholesterol (TC), lipid-lowering drugs and cognition in the elderly is currently controversial. Objective: To investigate the relationship between TC, lipid-lowering drugs and cognitive functions in non-demented elderly. Design and Setting: Participants of the Cardiovascular risk factors, aging and dementia (CAIDE) study were derived from random, population-based samples previously studied in 1972, 1977, 1982 or 1987. Analyses are based on 1382 non-demented participants re-examined in 1998 after an average follow-up of 21 years. Results: High midlife TC was associated with poorer late-life episodic memory and category fluency. TC decreased in most individuals over time. A more pronounced decrease was related to poorer late-life episodic memory and psychomotor speed, but not if subjects used statins. Conclusions: The TC-cognition relationship seems bidirectional. High midlife TC is associated with poorer late-life cognition, but decreasing TC after midlife may reflect poorer cognitive status. Statins may be beneficial for cognition in non-demented elderly.
|
|
