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1.
The evolution of the biotechnology industry in Germany 总被引:1,自引:0,他引:1
Müller C 《Trends in biotechnology》2002,20(7):287-290
In the past five years, the climate for commercial biotechnology in Germany has improved significantly and has resulted in an increase in the number of biotechnology companies. On examination of the underlying factors of the evolution of the biotechnology industry in Germany, and against the background of the current situation, it is predicted that many German biotech companies will have to change their business models to focus on product development rather than on platform technologies. 相似文献
2.
Ilan Eshel 《Theoretical population biology》1973,4(2):196-208
A statistical mechanism of long-run selection is formulated in order to explain the evolution of modifying features governing mutation, recombination, sexual behavior, demographic mobility, and other factors that do not directly increase the individual fitness of their carrier but which are, supposedly, essential for future evolution of a population. Survival probability of a clone, rather than that of the individual, is shown to play the main role in this mechanism. Changing environment proves to be the main factor affecting it.A theoretical possibility of a long-run adaptation to the dynamics of an environmental change—rather than to a static situation resulting from it—is demonstrated. 相似文献
3.
The potential for interactions between predation and habitat change to cause population declines of farmland birds 总被引:14,自引:8,他引:6
K. L. Evans 《Ibis》2004,146(1):1-13
Population declines are often attributed to either habitat change or increased predation rates, without a full consideration of the potential for these two factors to interact. This may lead to an inaccurate diagnosis of the causes of population decline and thus the selection of inappropriate management solutions. Here mechanisms through which habitat change and predation could interact are reviewed. Examples of how these may have contributed to population declines are provided, focusing on European farmland birds. However, very few appropriate studies have been conducted that allow the role of such interactions to be assessed accurately. To remedy this situation experimental designs that could detect the presence of interactive mechanisms are described. When habitat change and predation interact, conservation managers are provided with the opportunity to control predation impacts through habitat management rather than predator removal, which may provide a more cost-effective management strategy. 相似文献
4.
We review the evidence showing that the high turbidity levels of Lake Apopka are due primarily to resuspended sediments rather than phytoplankton, and that this situation is likely to persist unless there is a fundamental change in the lake. We discuss the reasons why reductions in phosphorus inputs, the gizzard shad removal program, and macrophyte plantings would not bring about such a change. Potentially the marsh flow-way could remove the flocculent sediments because of a unique combination of a very large surface area (125 km2), a mean depth of only 1.7 m, a layer of easily resuspended fluid mud, and a marsh flow-way that is designed to filter the lake volume about 2 times a year. Using several different estimates of the rate of sediment formation in the lake, our model calculates that it would take from 275 to 502 years to remove the sediments, so the lake could not attain clear water in a reasonable length of time. The model is mathematically correct but will give nonsense results if one tries to calculate removal times when the lake is accumulating sediments rather than losing them. 相似文献
5.
Using the satellite-derived NDVI to assess ecological responses to environmental change 总被引:41,自引:0,他引:41
Pettorelli N Vik JO Mysterud A Gaillard JM Tucker CJ Stenseth NC 《Trends in ecology & evolution》2005,20(9):503-510
Assessing how environmental changes affect the distribution and dynamics of vegetation and animal populations is becoming increasingly important for terrestrial ecologists to enable better predictions of the effects of global warming, biodiversity reduction or habitat degradation. The ability to predict ecological responses has often been hampered by our rather limited understanding of trophic interactions. Indeed, it has proven difficult to discern direct and indirect effects of environmental change on animal populations owing to limited information about vegetation at large temporal and spatial scales. The rapidly increasing use of the Normalized Difference Vegetation Index (NDVI) in ecological studies has recently changed this situation. Here, we review the use of the NDVI in recent ecological studies and outline its possible key role in future research of environmental change in an ecosystem context. 相似文献
6.
Lowe Börjeson 《African Journal of Ecology》2009,47(S1):185-191
Vegetation data in an early 20th century map from northern Tanzania are presented and discussed for its potential of expanding the analytical time-frame in studies of land-use and land-cover change. The starting point is that much research on land-use and land-cover change suffers from a time-frame bias, caused by limitations in remote sensing data. At the same time, the use of historical maps as a complementary data-set is rather insignificant. Can information in historical maps be used to extend the baseline in land-use and land-cover change studies? The historical context of the vegetation data is evaluated, and as an illustration of its potential for interdisciplinary research on land-cover and ecosystems change, a section of the map is juxtaposed with a recent pollen record specifically addressing the impact of a 'large infrequent disturbance' (LID) event at the end of the 19th century. It is concluded that the vegetation data in the map are not likely to be reflecting an extreme situation due to the LID event. Finally, the historical vegetation data were visually compared with a national 1995 land-cover data set, illustrating the possibility of using the map data as a baseline in land-cover change studies. 相似文献
7.
ANDRÉ A. DHONDT ROMAN EYCKERMAN JAN HUBLE 《Biological journal of the Linnean Society. Linnean Society of London》1979,11(3):289-294
The mean size of Great Tits Parus major in our study at Ghent shows a significant decreasing trend in the period 1962 to 1975. Since it has been shown that in the Great Tit the heritability of tarsus length, a measure for size, is rather high, we believe the observed trend to be a directional micro-evolutionary change. After investigating several possible causes for the size decrease, we suggest that the observed change is caused by a shift in the equilibrium between selective pressures favouring large and small individuals. Before our study, breeding numbers of Great Tits were limited through the lack of suitable nest-sites. We think that more of the large males could reproduce in mat situation. When we provided nestboxes in surplus this selective pressure was relaxed, and since small females must produce more surviving offspring, this further shifts the balance.
We argue that during the evolutionary history of the Great Tit there was no lack of suitable nest-sites in natural habitats, that by providing nest boxes we restore the natural situation, and diat therefore the decrease in size should level off. 相似文献
We argue that during the evolutionary history of the Great Tit there was no lack of suitable nest-sites in natural habitats, that by providing nest boxes we restore the natural situation, and diat therefore the decrease in size should level off. 相似文献
8.
Willy ⊘streng 《Ocean Development & International Law》2013,44(1-2):69-93
Abstract The Norwegian government has stated that creating a new international law of the sea is a foreign policy matter of the highest political priority in the period 1978–1981. A reasonable explanation might be the close correlation that normally exists between the political significance and the economic importance of issues and the area on which they impinge. As to Norway, it should suffice to point to the fact that the country ranks fifth among the merchant marine nations of the world, takes the fifth largest fish catch, and has sovereignty over the biggest continental shelf in Europe. Against this background, the author discusses the hypothesis that economic factors are the guiding hand in Norwegian ocean policy. However, the conclusion reached is that economic factors play a rather modest role in explaining this policy and that the reasons behind it are to be found at the intersection between economic interests, security policies, jurisdiction, the protection of resources and the environment as they are reflected in the rather peculiar situation of the North. 相似文献
9.
Jiménez-Alonso B 《Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences》2008,39(2):247-254
This study focuses on eugenics in Spain, and more specifically on the 'official' eugenics whose platform was the Primeras Jornadas Eugénicas Espa?olas (First Spanish Eugenic Days, FSED). The aim of this paper is to relate eugenics to 'governmentality' rather than to State politics alone and to 'Latin eugenics' rather than to 'mainline eugenics'. On the one hand, the FSED were largely centred on the development of a new sexual code which would set Catholic sexual morality aside. For this reason, sexual pedagogy was one of the most relevant topics during the FSED, personal responsibility becoming the first step to social change. The concern about making people play an active role in their own self-regulation is typical of governmentality. The latter refers to societies where power is decentered and where the objective is to structure the field of action of others (the conduct of conduct). On the other hand, the FSED emphasised preventive eugenics such as welfare programmes and health campaigns rather than negative eugenics such as the sterilisation of the unfit. The situation in Spain was mirrored in countries such as Brazil, Argentina and Mexico, which allows us to think about them in terms of 'Latin eugenics' rather than 'mainline eugenics' from countries such as Great Britain, Germany and the USA. 相似文献
10.
FITC-insulin binding and endogenous insulin content of Tetrahymena pyriformis, that had been 24 h or 30 min starved, continuously fed or re-fed after starvation was studied by flow cytometry and confocal microscopy. Long starvation elevated both insulin binding and endogenous insulin content of the cells. Short re-feeding after long starvation or short starvation after continuous feeding does not change the situation. Fixed cells also bind FITC-insulin, however, in this case long starvation reduces, and re-feeding after long starvation elevates, the binding, which means that hormone binding by receptors only differs from receptor binding and engulfment (in living cells). The increase of FITC-insulin content in living cells seems to be due to engulfment, rather than by receptor binding. The results point to the unicellular organism's requirement for insulin production and binding in a life-threatening stress situation. 相似文献
11.
《The Journal of general physiology》1976,68(6):653-669
In single muscle fibers from the giant barnacle, a small decrease in muscle length decreases both the calcium activation and the peak isometric tension produced by a constant current stimulus. The effect is most pronounced if the length change immediately precedes the stimulation. In some cases, the decrease in tension with shortening can be accounted for almost entirely by a decrease in calcium release rather than changes in mechanical factors such as filament geometry. During the constant current stimulation the muscle membrane becomes more depolarized at longer muscle lengths than at the shorter muscle lengths. Under voltage clamp conditions, when the membrane potential is kept constant during stimulation, there is little length dependence of calcium release. Thus, the effect of length on calcium release is mediated through a change in membrane properties, rather than an effect on a subsequent step in excitation-contraction coupling. Stretch causes the unstimulated fiber membrane to depolarize by about l mV while release causes the fiber membrane to hyperpolarize by about the same amount. The process causing this change in potential has an equilibrium potential nearly 10 mV hyperpolarized from the resting level. This change in resting membrane potential with length may account for the length dependence of calcium release. 相似文献
12.
In humans, hormonal responses to winning/losing and their relationships to mood and status change have mostly been examined in individual athletic competitions. In this study, the salivary testosterone (T) and cortisol (C) and mood responses to a real match between two professional basketball teams were investigated. Data about individuals' contributions to outcome, performance appraisal, and attribution of outcome to internal/external factors were also collected. Results did not show statistically significant different T and C responses depending on the outcome. Negative mood was significantly enhanced, especially in the losers, while winners showed a better appraisal of team performance and a more internal attribution. T response did not show a significant relationship with mood changes, but it correlated positively with the "score/time playing" ratio, an indicator of individual participation in the outcome. Furthermore, T response correlated negatively with external attribution in winners and positively in losers. These results indicate that in a real, highly competitive situation, T changes are not directly a response to the outcome, but rather to the contribution the individual makes to it and to the causes he attributes. 相似文献
13.
14.
Repression of In Vivo Synthesis of the Mitochondrial Elongation Factors T and G in Saccharomyces fragilis
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D. Richter 《Journal of bacteriology》1973,115(1):52-56
In vivo synthesis of the mitochondrial elongation factors T and G in the yeast Saccharomyces fragilis can be repressed. Enzymatic activity assays and immunochemical titration methods reveal that cells grown in the presence of 8% glucose or in the absence of oxygen contain relatively lower amounts of mitochondrial elongation factors than cells grown in the presence of lactate. In contrast, in vivo production of the cytoplasmic elongation factors 1 and 2 does not respond to such a change of extracellular conditions. The rate of growth does not affect the level of the mitochondrial elongation factors. Production of both enzymes is almost constant during logarithmic growth, but decreases when the stationary phase is reached. Chloramphenicol, an inhibitor of mitochondrial protein synthesis, does not block but, rather, seems to enhance the in vivo synthesis of mitochondrial T or G. 相似文献
15.
Forest responses to climate change will depend on demographic impacts in the context of competition. Current models used to predict species responses, termed climate envelope models (CEMs), are controversial, because (i) calibration and prediction are based on correlations in space (CIS) between species abundance and climate, rather than responses to climate change over time (COT), and (ii) they omit competition. To determine the relative importance of COT, CIS, and competition for light, we applied a longitudinal analysis of 27 000 individual trees over 6–18 years subjected to experimental and natural variation in risk factors. Sensitivities and climate and resource tracking identify which species are vulnerable to these risk factors and in what ways. Results show that responses to COT differ from those predicted based on CIS. The most important impact is the effect of spring temperature on fecundity, rather than any input variable on growth or survival. Of secondary importance is growing season moisture. Species in the genera Pinus, Ulmus, Magnolia, and Fagus are particularly vulnerable to climate variation. However, the effect of competition on growth and mortality risk exceeds the effects of climate variation in space or time for most species. Because sensitivities to COT and competition are larger than CIS, current models miss the most important effects. By directly comparing sensitivity to climate in time and space, together with competition, the approach identifies which species are sensitive to climate change and why, including the heretofore overlooked impact on fecundity. 相似文献
16.
Lluís Brotons 《PloS one》2014,9(11)
In this work, I evaluate the impact of species distribution models (SDMs) on the current status of environmental and ecological journals by asking the question to which degree development of SDMs in the literature is related to recent changes in the impact factors of ecological journals. The hypothesis evaluated states that research fronts are likely to attract research attention and potentially drive citation patterns, with journals concentrating papers related to the research front receiving more attention and benefiting from faster increases in their impact on the ecological literature. My results indicate a positive relationship between the number of SDM related articles published in a journal and its impact factor (IF) growth during the period 2000–09. However, the percentage of SDM related papers in a journal was strongly and positively associated with the percentage of papers on climate change and statistical issues. The results support the hypothesis that global change science has been critical in the development of SDMs and that interest in climate change research in particular, rather than the usage of SDM per se, appears as an important factor behind journal IF increases in ecology and environmental sciences. Finally, our results on SDM application in global change science support the view that scientific interest rather than methodological fashion appears to be the major driver of research attraction in the scientific literature. 相似文献
17.
The mechanism of excitation energy redistribution (state transition) in organisms containing phycobilins is reviewed. Recent measurements using time-resolved fluorescence spectroscopy in the picosecond range confirm that the state transition in cyanobacteria and red algae is controlled by changes in the kinetics of energy transfer from PS 2 to PS 1 (spillover) rather than by physical dislocation of the phycobilisome and reassociation between the two photosystems (mobile antenna model). Contrary to the analogous situation in higher plants, there is no compelling evidence for the involvement of a protein phosphorylation event in the rapid time range of the state transition, but a variety of data indicate that a membrane conformational change occurs that might change the relative distance between, and/or orientation of the two photosystems within the thylakoid. The state transition is most probably initiated by the redox state of the intersystem electron transport chain, and the conversion to state 1 is driven by coupled PS1 cyclic electron transport. The cryptomonads also undergo wavelength dependent changes in excitation energy distribution by a mechanism very similar to that observed in the red algae and cyanobacteria. However, the changes in energy distribution in this group are most likely related to a photoprotection mechanism for PS2 rather than to a state transition.Abbreviations APC
allophycocyanin
- EF
exoplasmic face
- PE
phycoerythrin
- PC
phycocyanin
- PF
protoplasmic face
- LHC
light harvesting chlorophyll a/b protein
- PBS
phycobilisome
- LD
linear dichroism
- RC
reaction center 相似文献
18.
Adaptive Dynamics is an approach to studying evolutionary change when fitness is density or frequency dependent. Modern papers identifying themselves as using this approach first appeared in the 1990s, and have greatly increased up to the present. However, because of the rather technical nature of many of the papers, the approach is not widely known or understood by evolutionary biologists. In this review we aim to remedy this situation by outlining the methodology and then examining its strengths and weaknesses. We carry this out by posing and answering 20 key questions on Adaptive Dynamics. We conclude that Adaptive Dynamics provides a set of useful approximations for studying various evolutionary questions. However, as with any approximate method, conclusions based on Adaptive Dynamics are valid only under some restrictions that we discuss. 相似文献
19.
Understanding the relative importance of factors driving savanna–forest dynamics is vital as changes in the extent of tropical forests can have major impacts on global climate and carbon balance, biodiversity, and human well-being. Comparison of aerial photographs for 50 rainforest patches in Kakadu National Park had previously revealed a landscape wide expansion of rainforest boundaries between 1964 and 2004. Here, we used generalized linear and mixed effects models to assess the role of fire, buffalo impact, and patch characteristics in determining the rate of boundary change. The analysis was conducted at both the patch scale, and within-patch (plot) scale, to capture the different processes operating. At the patch scale, the rate of change was best explained by rainforest type and historical buffalo impact. Fire activity, patch size, and fragmentation were not important predictors of the rate of change. At the plot scale, distance from rainforest edge was the most important predictor of the probability of change, while the fragmentation and aspect of the boundary were unimportant. Rainforest expansion has occurred through a process of margin extension rather than eruption of new patches. The rainforest expansion is consistent with having been driven primarily by shifts in global change phenomena, such as increased rainfall and atmospheric CO2 , rather than changes in disturbance regime. It appears that the current fire regimes are not sufficiently destructive to limit the overall expansion of the rainforest patches. Rainforest type and historical buffalo impact have mediated the rate of change at the patch scale. 相似文献
20.
Hans Georg Lindenberg Anabelle Auras 《Palaeogeography, Palaeoclimatology, Palaeoecology》1984,48(1):61-106
Recent to subrecent benthonic arenaceous foraminifera from two areas of the Southern Ocean have been investigated with regard to their depth distribution and agglutination patterns. Strong differences exist between the arenaceous faunas from (a) diatomaceous sediments west of the Kerguelen Plateau and (b) glacial marine sediments from the slope of the Antarctic continent. Major ecologic influences are seen in the effect of sedimentological factors (especially the clay content of the sediment), in the saturation level of calcium carbonate and in the nutrient condition of the biotope. Since these factors are a function of geographic position and related water masses, the main differences of deep-sea faunas are primarily induced by the overall situation of an oceanic area rather than by depth or oceanographic factors like temperature or salinity. Availability of colloidal iron compounds also seems to be a limiting factor for distinct arenaceous species. 相似文献