排序方式: 共有8条查询结果,搜索用时 0 毫秒
1
1.
2.
Tina Heger Anna T. Pahl Zoltan Botta-Dukát Francesca Gherardi Christina Hoppe Ivan Hoste Kurt Jax Leena Lindström Pieter Boets Sylvia Haider Johannes Kollmann Meike J. Wittmann Jonathan M. Jeschke 《Ambio》2013,42(5):527-540
Invasion ecology has much advanced since its early beginnings. Nevertheless, explanation, prediction, and management of biological invasions remain difficult. We argue that progress in invasion research can be accelerated by, first, pointing out difficulties this field is currently facing and, second, looking for measures to overcome them. We see basic and applied research in invasion ecology confronted with difficulties arising from (A) societal issues, e.g., disparate perceptions of invasive species; (B) the peculiarity of the invasion process, e.g., its complexity and context dependency; and (C) the scientific methodology, e.g., imprecise hypotheses. To overcome these difficulties, we propose three key measures: (1) a checklist for definitions to encourage explicit definitions; (2) implementation of a hierarchy of hypotheses (HoH), where general hypotheses branch into specific and precisely testable hypotheses; and (3) platforms for improved communication. These measures may significantly increase conceptual clarity and enhance communication, thus advancing invasion ecology. 相似文献
3.
Meike Schmehl J. Müssig U. Schönfeld H.-B. Von Buttlar 《Journal of Polymers and the Environment》2008,16(1):51-60
The application of renewable raw materials in the automotive sector became more and more interesting in the last years. For the first time, a material system based on natural fibers and PTP®, a vegetable based thermoset resin, was produced and manufactured into a bus body component by Sheet-Moulding-Compound-technology. The Life Cycle Assessment on this component based on renewable raw materials shows advantages especially in the categories fossil resources and global warming. It can be expected that further concepts of development and optimization lead to a more efficient use of materials and so to an additional reduction of environmental impacts. 相似文献
4.
Joachim G. Frommen Meike Hiermes Theo C. M. Bakker 《Behavioral ecology and sociobiology》2009,63(8):1141-1148
Many animals live in groups most of their life. One function of this behaviour is an increased predator protection whereas
larger groups provide better protection than smaller ones. A causal explanation is that due to a higher number of shoal members
the individual risk of being predated will decrease (“dilution effect”). Additionally, shoaling leads to increased predator
confusion. This “confusion effect” can be strengthened by an increased group density, which often correlates with group size.
Many studies found that individuals prefer the larger of two groups. However, whether this preference is due to a larger group
size or because of an increased density of the larger group remained unclear. To disentangle these factors we gave three-spined
sticklebacks (Gasterosteus aculeatus) the choice between shoals of (1) different group size and density, (2) different group size, but equal density and (3) equal
group sizes, but different densities. As expected, test fish preferred the larger and denser shoal over the smaller, less
dense one. This preference was lost when shoal size differed but density was kept constant. When shoal size was equal but
density differed, test fish preferred the less dense shoal. However, this was only the case when test fish chose between two
relatively dense shoals. On the other hand, when overall density was low, test fish did not discriminate between shoals of
different densities. This result may be explained in terms of predator avoidance. The results show that shoaling preferences
might not always be influenced by a higher number of group members but also by the density and cohesiveness of the respective
groups.
An erratum to this article can be found at 相似文献
5.
Meike Janssen Manika Rödiger Ulrich Hamm 《Journal of Agricultural and Environmental Ethics》2016,29(6):1071-1100
Political decision-makers in the European Union (EU) are currently discussing the introduction of a mandatory uniform labelling scheme for meat and milk that provides information on husbandry systems similar to the already existent labelling scheme in the EU egg market. The objective of this paper was to assess whether such information is relevant to consumers when buying meat and milk. The paper was based on a systematic synthesis of 53 scientific journal articles on empirical consumer studies. The review revealed that consumers perceived the aspects of outdoor access, stocking density and floor type as important factors influencing animal welfare. On average, consumers not only had a positive attitude towards more animal welfare-friendly husbandry systems with outdoor access and space allowance but were also willing to pay a price premium for products from such systems. All studies on consumer segmentation identified at least one consumer segment that placed great importance on animal welfare-friendly husbandry systems. Interestingly, many studies identified one or more other segments who still had a significant preference for animal welfare-friendly products even though other product attributes were more important to them. Based on the findings, the paper presents conclusions regarding the labelling of husbandry systems for meat and milk. 相似文献
6.
Wiebke C. Holtmann Meike Stumpp Magdalena A. Gutowska Stephanie Syré Nina Himmerkus Frank Melzner Markus Bleich 《Marine Biology》2013,160(10):2631-2645
Experimental ocean acidification leads to a shift in resource allocation and to an increased [HCO3 ?] within the perivisceral coelomic fluid (PCF) in the Baltic green sea urchin Strongylocentrotus droebachiensis. We investigated putative mechanisms of this pH compensation reaction by evaluating epithelial barrier function and the magnitude of skeleton (stereom) dissolution. In addition, we measured ossicle growth and skeletal stability. Ussing chamber measurements revealed that the intestine formed a barrier for HCO3 ? and was selective for cation diffusion. In contrast, the peritoneal epithelium was leaky and only formed a barrier for macromolecules. The ossicles of 6 week high CO2-acclimatised sea urchins revealed minor carbonate dissolution, reduced growth but unchanged stability. On the other hand, spines dissolved more severely and were more fragile following acclimatisation to high CO2. Our results indicate that epithelia lining the PCF space contribute to its acid–base regulation. The intestine prevents HCO3 ? diffusion and thus buffer leakage. In contrast, the leaky peritoneal epithelium allows buffer generation via carbonate dissolution from the surrounding skeletal ossicles. Long-term extracellular acid–base balance must be mediated by active processes, as sea urchins can maintain relatively high extracellular [HCO3 ?]. The intestinal epithelia are good candidate tissues for this active net import of HCO3 ? into the PCF. Spines appear to be more vulnerable to ocean acidification which might significantly impact resistance to predation pressure and thus influence fitness of this keystone species. 相似文献
7.
8.
Meike Linnenschmidt Laura N. Kloepper Magnus Wahlberg Paul E. Nachtigall 《Die Naturwissenschaften》2012,99(9):767-771
Some odontocetes and bats vary both click intensity and receiver sensitivity during echolocation, depending on target range. It is not known how this so-called automatic gain control is regulated by the animal. The source level of consecutive echolocation clicks from a harbour porpoise was measured with a hydrophone array while the animal detected an aluminium cylinder at 2, 4 or 8?m distance in a go/no-go paradigm. On-axis clicks had source levels of 145–174?dB re 1?μPa peak-to-peak. During target-present trials the click trains reached comparable source levels independent of the range to the target after three clicks. After an additional click, the source level was reduced for the 2 and 4?m trials until it equalled the one-way transmission loss. During target-absent trials, the source level remained high throughout the entire click train. Given typical values of harbour porpoise inter-click intervals, the source level reduction commenced within a few 100?ms from the first click in the click train. This may indicate a sub-cortically regulated source level regulation in the harbour porpoise. 相似文献
1