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排序方式: 共有2566条查询结果,搜索用时 31 毫秒
831.
832.
Lee Hannah Patrick R. Roehrdanz Pablo A. Marquet Brian J. Enquist Guy Midgley Wendy Foden Jon C. Lovett Richard T. Corlett Derek Corcoran Stuart H. M. Butchart Brad Boyle Xiao Feng Brian Maitner Javier Fajardo Brian J. McGill Cory Merow Naia Morueta-Holme Erica A. Newman Daniel S. Park Niels Raes Jens-Christian Svenning 《Ecography》2020,43(7):943-953
Limiting climate change to less than 2°C is the focus of international policy under the climate convention (UNFCCC), and is essential to preventing extinctions, a focus of the Convention on Biological Diversity (CBD). The post-2020 biodiversity framework drafted by the CBD proposes conserving 30% of both land and oceans by 2030. However, the combined impact on extinction risk of species from limiting climate change and increasing the extent of protected and conserved areas has not been assessed. Here we create conservation spatial plans to minimize extinction risk in the tropics using data on 289 219 species and modeling two future greenhouse gas concentration pathways (RCP2.6 and 8.5) while varying the extent of terrestrial protected land and conserved areas from <17% to 50%. We find that limiting climate change to 2°C and conserving 30% of terrestrial area could more than halve aggregate extinction risk compared with uncontrolled climate change and no increase in conserved area. 相似文献
833.
Nerea Abrego Tomas Roslin Tea Huotari Ayco J. M. Tack Bjrn D. Lindahl Gleb Tikhonov Panu Somervuo Niels Martin Schmidt Otso Ovaskainen 《Molecular ecology》2020,29(14):2736-2746
Understanding the role of interspecific interactions in shaping ecological communities is one of the central goals in community ecology. In fungal communities, measuring interspecific interactions directly is challenging because these communities are composed of large numbers of species, many of which are unculturable. An indirect way of assessing the role of interspecific interactions in determining community structure is to identify the species co‐occurrences that are not constrained by environmental conditions. In this study, we investigated co‐occurrences among root‐associated fungi, asking whether fungi co‐occur more or less strongly than expected based on the environmental conditions and the host plant species examined. We generated molecular data on root‐associated fungi of five plant species evenly sampled along an elevational gradient at a high arctic site. We analysed the data using a joint species distribution modelling approach that allowed us to identify those co‐occurrences that could be explained by the environmental conditions and the host plant species, as well as those co‐occurrences that remained unexplained and thus more probably reflect interactive associations. Our results indicate that not only negative but also positive interactions play an important role in shaping microbial communities in arctic plant roots. In particular, we found that mycorrhizal fungi are especially prone to positively co‐occur with other fungal species. Our results bring new understanding to the structure of arctic interaction networks by suggesting that interactions among root‐associated fungi are predominantly positive. 相似文献
834.
Nerea Abrego Tea Huotari Ayco J. M. Tack Bjrn D. Lindahl Gleb Tikhonov Panu Somervuo Niels Martin Schmidt Otso Ovaskainen Tomas Roslin 《Ecology and evolution》2020,10(16):8989-9002
How community‐level specialization differs among groups of organisms, and changes along environmental gradients, is fundamental to understanding the mechanisms influencing ecological communities. In this paper, we investigate the specialization of root‐associated fungi for plant species, asking whether the level of specialization varies with elevation. For this, we applied DNA barcoding based on the ITS region to root samples of five plant species equivalently sampled along an elevational gradient at a high arctic site. To assess whether the level of specialization changed with elevation and whether the observed patterns varied between mycorrhizal and endophytic fungi, we applied a joint species distribution modeling approach. Our results show that host plant specialization is not environmentally constrained in arctic root‐associated fungal communities, since there was no evidence for changing specialization with elevation, even if the composition of root‐associated fungal communities changed substantially. However, the level of specialization for particular plant species differed among fungal groups, root‐associated endophytic fungal communities being highly specialized on particular host species, and mycorrhizal fungi showing almost no signs of specialization. Our results suggest that plant identity affects associated mycorrhizal and endophytic fungi differently, highlighting the need of considering both endophytic and mycorrhizal fungi when studying specialization in root‐associated fungal communities. 相似文献
835.
Jarid1b targets genes regulating development and is involved in neural differentiation 总被引:1,自引:0,他引:1
Schmitz SU Albert M Malatesta M Morey L Johansen JV Bak M Tommerup N Abarrategui I Helin K 《The EMBO journal》2011,30(22):4586-4600
836.
837.
Niels Blaum Eva Mosner Monika Schwager Florian Jeltsch 《Biodiversity and Conservation》2011,20(11):2333-2345
Understanding mechanisms to predict changes in plant and animal communities is a key challenge in ecology. The need to transfer
knowledge gained from single species to a more generalized approach has led to the development of categorization systems where
species’ similarities in life strategies and traits are classified into ecological groups (EGs) like functional groups/types
or guilds. While approaches in plant ecology undergo a steady improvement and refinement of methodologies, progression in
animal ecology is lagging behind. With this review, we aim to initiate a further development of functional classification
systems in animal ecology, comparable to recent developments in plant ecology. We here (i) give an overview of terms and definitions
of EGs in animal ecology, (ii) discuss existing classification systems, methods and application areas of EGs (focusing on
terrestrial vertebrates), and (iii) provide a “roadmap towards an animal functional type approach” for improving the application
of EGs and classifications in animal ecology. We found that an animal functional type approach requires: (i) the identification of core traits describing species’ dependency on their habitat and life history traits, (ii) an optimization of trait selection by clustering traits into hierarchies, (iii) the assessment of “soft traits” as substitute for hardly measurable traits, e.g. body size for dispersal ability, and (iv) testing of delineated groups for validation including experiments. 相似文献
838.
Pedersen JT Østergaard J Rozlosnik N Gammelgaard B Heegaard NH 《The Journal of biological chemistry》2011,286(30):26952-26963
Cu(II) ions are implicated in the pathogenesis of Alzheimer disease by influencing the aggregation of the amyloid-β (Aβ) peptide. Elucidating the underlying Cu(II)-induced Aβ aggregation is paramount for understanding the role of Cu(II) in the pathology of Alzheimer disease. The aim of this study was to characterize the qualitative and quantitative influence of Cu(II) on the extracellular aggregation mechanism and aggregate morphology of Aβ(1-40) using spectroscopic, microelectrophoretic, mass spectrometric, and ultrastructural techniques. We found that the Cu(II):Aβ ratio in solution has a major influence on (i) the aggregation kinetics/mechanism of Aβ, because three different kinetic scenarios were observed depending on the Cu(II):Aβ ratio, (ii) the metal:peptide stoichiometry in the aggregates, which increased to 1.4 at supra-equimolar Cu(II):Aβ ratio; and (iii) the morphology of the aggregates, which shifted from fibrillar to non-fibrillar at increasing Cu(II):Aβ ratios. We observed dynamic morphological changes of the aggregates, and that the formation of spherical aggregates appeared to be a common morphological end point independent on the Cu(II) concentration. Experiments with Aβ(1-42) were compatible with the conclusions for Aβ(1-40) even though the low solubility of Aβ(1-42) precluded examination under the same conditions as for the Aβ(1-40). Experiments with Aβ(1-16) and Aβ(1-28) showed that other parts than the Cu(II)-binding His residues were important for Cu(II)-induced Aβ aggregation. Based on this study we propose three mechanistic models for the Cu(II)-induced aggregation of Aβ(1-40) depending on the Cu(II):Aβ ratio, and identify key reaction steps that may be feasible targets for preventing Cu(II)-associated aggregation or toxicity in Alzheimer disease. 相似文献
839.
Weber M Prodöhl A Dreher C Becker C Underhaug J Svane AS Malmendal A Nielsen NC Otzen D Schneider D 《Journal of molecular biology》2011,407(4):594-10230
The folding and stabilization of α-helical transmembrane proteins are still not well understood. Following cofactor binding to a membrane protein provides a convenient method to monitor the formation of appropriate native structures. We have analyzed the assembly and stability of the transmembrane cytochrome b559′, which can be efficiently assembled in vitro from a heme-binding PsbF homo-dimer by combining free heme with the apo-cytochrome b559′. Unfolding of the protein dissolved in the mild detergent dodecyl maltoside may be induced by addition of SDS, which at high concentrations leads to dimer dissociation. Surprisingly, absorption spectroscopy reveals that heme binding and cytochrome formation at pH 8.0 are optimal at intermediate SDS concentrations. Stopped-flow kinetics revealed that genuine conformational changes are involved in heme binding at these SDS concentrations. GPS (Global Protein folding State mapping) NMR measurements showed that optimal heme binding is intimately related to a change in the degree of histidine protonation. In the absence of SDS, the pH curve for heme binding is bell-shaped with an optimum at around pH 6-7. At alkaline pH values, the negative electrostatic potential of SDS lowers the local pH sufficiently to restore efficient heme binding, provided the amount of SDS needed for this does not denature the protein. Accordingly, the higher the pH value above 6-7, the more SDS is needed to improve heme binding, and this competes with the inherent tendency of SDS to dissociate cytochrome b559′. Our work highlights that, in addition to its denaturing properties, SDS can affect protein functions by lowering the local pH. 相似文献
840.
Soil water content, maize yield and its stability as affected by tillage and crop residue management in rainfed semi-arid highlands 总被引:3,自引:0,他引:3
Nele Verhulst Victoria Nelissen Niels Jespers Heleen Haven Ken D. Sayre Dirk Raes Jozef Deckers Bram Govaerts 《Plant and Soil》2011,344(1-2):73-85
Rainfed crop management systems need to be optimized to provide more resilient options to cope with projected climatic scenarios forecasting a decrease in mean precipitation and more frequent extreme drought periods in Mexico. Soil water content (0?C60 cm) was measured during three crop cycles in maize plots with different agronomic management practices in a long-term rainfed experiment (established in 1991) in the highlands of Mexico. Maize yields of 1997?C2009 were reported. Crop management practices varied in (1) tillage (conventional [CT] vs. zero tillage [ZT]) and (2) residue management (full or partial retention and removal). ZT with residue retention had higher soil water content than management practices involving CT and ZT with residue removal which provided a buffer for drought periods during the growing seasons. In 2009, a cycle with a prolonged drought during vegetative growth, this resulted in yield differences of up to 4.7 Mg ha?1 between ZT with (partial) residue retention and the other practices. Averaged over 1997?C2009, these practices had a yield advantage of approximately 1.5 Mg ha?1 over practices involving CT and ZT with residue removal. ZT with (partial) residue retention used rainfall more efficiently and resulted in a more resilient agronomic system than practices involving either CT or ZT with residue removal. 相似文献