| 1. |
- Abramowicz, H., et al.
(författare)
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Conceptual design report for the LUXE experiment
- 2021
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Ingår i: European Physical Journal-Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 230:11, s. 2445-2560
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Tidskriftsartikel (refereegranskat)abstract
- This Conceptual Design Report describes LUXE (Laser Und XFEL Experiment), an experimental campaign that aims to combine the high-quality and high-energy electron beam of the European XFEL with a powerful laser to explore the uncharted terrain of quantum electrodynamics characterised by both high energy and high intensity. We will reach this hitherto inaccessible regime of quantum physics by analysing high-energy electron-photon and photon-photon interactions in the extreme environment provided by an intense laser focus. The physics background and its relevance are presented in the science case which in turn leads to, and justifies, the ensuing plan for all aspects of the experiment: Our choice of experimental parameters allows (i) field strengths to be probed where the coupling to charges becomes non-perturbative and (ii) a precision to be achieved that permits a detailed comparison of the measured data with calculations. In addition, the high photon flux predicted will enable a sensitive search for new physics beyond the Standard Model. The initial phase of the experiment will employ an existing 40 TW laser, whereas the second phase will utilise an upgraded laser power of 350 TW. All expectations regarding the performance of the experimental set-up as well as the expected physics results are based on detailed numerical simulations throughout.
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| 2. |
- Albrecht, Matthias, et al.
(författare)
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The effectiveness of flower strips and hedgerows on pest control, pollination services and crop yield : a quantitative synthesis
- 2020
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 23:10, s. 1488-1498
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Tidskriftsartikel (refereegranskat)abstract
- Floral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control (18 studies) and pollination services (17 studies) in adjacent crops in North America, Europe and New Zealand. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimise floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future.
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| 3. |
- Kennedy, Christina M., et al.
(författare)
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A global quantitative synthesis of local and landscape effects on wild bee pollinators in agroecosystems
- 2013
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 16:5, s. 584-599
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Bees provide essential pollination services that are potentially affected both by local farm management and the surrounding landscape. To better understand these different factors, we modelled the relative effects of landscape composition (nesting and floral resources within foraging distances), landscape configuration (patch shape, interpatch connectivity and habitat aggregation) and farm management (organic vs. conventional and local-scale field diversity), and their interactions, on wild bee abundance and richness for 39 crop systems globally. Bee abundance and richness were higher in diversified and organic fields and in landscapes comprising more high-quality habitats; bee richness on conventional fields with low diversity benefited most from high-quality surrounding land cover. Landscape configuration effects were weak. Bee responses varied slightly by biome. Our synthesis reveals that pollinator persistence will depend on both the maintenance of high-quality habitats around farms and on local management practices that may offset impacts of intensive monoculture agriculture.
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| 4. |
- Lichtenberg, Elinor M., et al.
(författare)
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A global synthesis of the effects of diversified farming systems on arthropod diversity within fields and across agricultural landscapes
- 2017
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 23:11, s. 4946-4957
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural intensification is a leading cause of global biodiversity loss, which can reduce the provisioning of ecosystem services in managed ecosystems. Organic farming and plant diversification are farm management schemes that may mitigate potential ecological harm by increasing species richness and boosting related ecosystem services to agroecosystems. What remains unclear is the extent to which farm management schemes affect biodiversity components other than species richness, and whether impacts differ across spatial scales and landscape contexts. Using a global metadataset, we quantified the effects of organic farming and plant diversification on abundance, local diversity (communities within fields), and regional diversity (communities across fields) of arthropod pollinators, predators, herbivores, and detritivores. Both organic farming and higher in-field plant diversity enhanced arthropod abundance, particularly for rare taxa. This resulted in increased richness but decreased evenness. While these responses were stronger at local relative to regional scales, richness and abundance increased at both scales, and richness on farms embedded in complex relative to simple landscapes. Overall, both organic farming and in-field plant diversification exerted the strongest effects on pollinators and predators, suggesting these management schemes can facilitate ecosystem service providers without augmenting herbivore (pest) populations. Our results suggest that organic farming and plant diversification promote diverse arthropod metacommunities that may provide temporal and spatial stability of ecosystem service provisioning. Conserving diverse plant and arthropod communities in farming systems therefore requires sustainable practices that operate both within fields and across landscapes.
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| 5. |
- Morandin, C., et al.
(författare)
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Caste-biases in gene expression are specific to developmental stage in the ant Formica exsecta
- 2015
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 28:9, s. 1705-1718
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Tidskriftsartikel (refereegranskat)abstract
- Understanding how a single genome creates and maintains distinct phenotypes is a central goal in evolutionary biology. Social insects are a striking example of co-opted genetic backgrounds giving rise to dramatically different phenotypes, such as queen and worker castes. A conserved set of molecular pathways, previously envisioned as a set of 'toolkit' genes, has been hypothesized to underlie queen and worker phenotypes in independently evolved social insect lineages. Here, we investigated the toolkit from a developmental point of view, using RNA-Seq to compare caste-biased gene expression patterns across three life stages (pupae, emerging adult and old adult) and two female castes (queens and workers) in the ant Formica exsecta. We found that the number of genes with caste-biased expression increases dramatically from pupal to old adult stages. This result suggests that phenotypic differences between queens and workers at the pupal stage may derive from a relatively low number of caste-biased genes, compared to higher number of genes required to maintain caste differences at the adult stage. Gene expression patterns were more similar among castes within developmental stages than within castes despite the extensive phenotypic differences between queens and workers. Caste-biased expression was highly variable among life stages at the level of single genes, but more consistent when gene functions (gene ontology terms) were investigated. Finally, we found that a large part of putative toolkit genes were caste-biased at least in some life stages in F. exsecta, and the caste-biases, but not their direction, were more often shared between F. exsecta and other ant species than between F. exsecta and bees. Our results indicate that gene expression should be examined across several developmental stages to fully reveal the genetic basis of polyphenisms.
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| 6. |
- Morandin, C., et al.
(författare)
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Gene flow and immigration : genetic diversity and population structure of lions (Panthera leo) in Hwange National Park, Zimbabwe
- 2014
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Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 15:3, s. 697-706
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Tidskriftsartikel (refereegranskat)abstract
- The genetic diversity and population structure of a population of African lions in Hwange National Park, Zimbabwe, was studied using 17 microsatellite loci. Spatial genetic analysis using Bayesian methods suggested a weak genetic structure within the population and high levels of gene flow across the study area. We were able to identify a few individuals with aberrant or admixed ancestry, which we interpreted as either immigrants or as descendants thereof. This, together with relatively high genetic diversity, suggests that immigrants from beyond the study area have influenced the genetic structure within the park. We suggest that the levels of genetic diversity and the observed weak structure are indicative of the large and viable Okavango-Hwange population of which our study population is a part. Genetic patterns can also be attributed to still existing high levels of habitat connectivity between protected areas. Given expected increases in human populations and anthropogenic impacts, efforts to identify and maintain existing movement corridors between regional lion populations will be important in retaining the high genetic diversity status of this population. Our results show that understanding existing levels of genetic diversity and genetic connectivity has implications, not only for this lion population, but also for managing large wild populations of carnivores.
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| 7. |
- Woodcock, B. A., et al.
(författare)
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Meta-analysis reveals that pollinator functional diversity and abundance enhance crop pollination and yield
- 2019
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- How insects promote crop pollination remains poorly understood in terms of the contribution of functional trait differences between species. We used meta-analyses to test for correlations between community abundance, species richness and functional trait metrics with oilseed rape yield, a globally important crop. While overall abundance is consistently important in predicting yield, functional divergence between species traits also showed a positive correlation. This result supports the complementarity hypothesis that pollination function is maintained by non-overlapping trait distributions. In artificially constructed communities (mesocosms), species richness is positively correlated with yield, although this effect is not seen under field conditions. As traits of the dominant species do not predict yield above that attributed to the effect of abundance alone, we find no evidence in support of the mass ratio hypothesis. Management practices increasing not just pollinator abundance, but also functional divergence, could benefit oilseed rape agriculture.
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