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A. Cole Burton 《Biodiversity and Conservation》2012,21(12):3079-3094
Effective monitoring programs are required to understand and mitigate biodiversity declines, particularly in tropical ecosystems where conservation conflicts are severe yet ecological data are scarce. “Locally-based” monitoring has been advanced as an approach to improve biodiversity monitoring in developing countries, but the accuracy of data from many such programs has not been adequately assessed. I evaluated a long-term, patrol-based wildlife monitoring system in Mole National Park, Ghana, through comparison with camera trapping and an assessment of sampling error. I found that patrol observations underrepresented the park’s mammal community, recording only two-thirds as many species as camera traps over a common sampling period (2006–2008). Agreement between methods was reasonable for larger, diurnal and social species (e.g., larger ungulates and primates), but camera traps were more effective at detecting smaller, solitary and nocturnal species (particularly carnivores). Data from patrols and cameras corresponded for some spatial patterns of management interest (e.g., community turnover, edge effect on abundance) but differed for others (e.g., richness, edge effect on diversity). Long-term patrol observations were influenced by uneven sampling effort and considerable variation in replicate counts. Despite potential benefits of locally-based monitoring, these results suggest that data from this and similar programs may be subject to biases that complicate interpretation of wildlife population and community dynamics. Careful attention to monitoring objectives, methodological design and robust analysis is required if locally-based approaches are to satisfy an aim of reliable biodiversity monitoring, and there is a need for greater international support in the creation and maintenance of local monitoring capacity. 相似文献
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Rolf Sattler 《Acta biotheoretica》1990,38(3-4):303-315
From the point of view of a dynamic morphology, form is not only the result of process(es) — it is process. This process may be analyzed in terms of two pairs of fundamental processes: growth and decay, differentiation and dedifferentiation. Each of these processes can be analyzed in terms of various modalities (parameters) and submodalities. This paper deals with those of growth (see Table 1). For the purpose of systematits and phylogenetic reconstruction the modalities and submodalities can be considered dynamic characters that have “states”. Each “state” of such a dynamic character is a more detailed process, hence not static. For example, determinate growth represents a “state” of the dynamic character (or modality) of growth duration. The processes of Table 1 can be applied to the whole plant kingdom (although in certain cases only some processes of the whole set may be applicable). Thus, the diversity of plant form is seen as a diversity of process combinations. From this point of view, change in form implies change in the process combination(s). Questions that arise are, for example, the following: Which process combinations actually occur? Which of these are the most frequent? How and why have process combinations changed during ontogeny and phylogeny? In comparative morphogenesis, process combinations are compared within an ontogeny or between ontogenies. The combinations may be repeated (i.e., conserved) or changed. Since repetition is limited, regularity that is the basis for structural categories is also limited or relative. With regard to change in process combinations, sequential change within an ontogeny and phylogenetic change between ontogenies can be distinguished. A large number of additional processes, such as heterochrony, that have been investigated by many zoologists and botanists, refer to these sequential and phylogenetic changes. General implications and consequences of the proposed approach are pointed out. As well, its limits, which are related to the language and concepts used, are discussed. The importance of a dynamic language is emphasized. 相似文献
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Direct in vivo visualization, in full atomic detail, of the microbial cell wall and its stress-bearing structural architecture remains one of the prime challenges in microbiology. In the meantime, molecular modeling can provide a framework for explaining and predicting mechanisms involved in morphogenesis, bacterial cell growth and cell division, during which the wall and its major structural component--murein--have to protect the cell from osmotic pressure and multiple tensile forces. Here, we illustrate why the scaffold concept of murein architecture provides a more comprehensive representation of bacterial cell wall physiology than previous models. 相似文献
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Towards a more plant physiological perspective on soil ecology 总被引:8,自引:0,他引:8
Soil respiration almost balances carbon fixation by terrestrial photosynthesis and exceeds all anthropogenic carbon emissions by an order of magnitude, yet we lack precise knowledge of the sources of, and controls upon, the release of carbon dioxide from soils. Here, we discuss the increasing evidence that half of this carbon release is from living plant roots, their mycorrhizal fungi and other root-associated microbes, and that this release is driven directly by recent photosynthesis. The new studies challenge the widespread view that soil activity is dominated by decomposer organisms using older detrital material and that root litter inputs equal those of aboveground litter. The new observations emphasize the physiological continuity and dynamic interdependence of the plant-microbe-soil system and highlight the need for closer cooperation between plant and soil scientists. 相似文献
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Martelli AM Falcieri E Zweyer M Bortul R Tabellini G Cappellini A Cocco L Manzoli L 《Histology and histopathology》2002,17(4):1193-1205
The nuclear matrix is defined as the residual framework after the removal of the nuclear envelope, chromatin, and soluble components by sequential extractions. According to several investigators the nuclear matrix provides the structural basis for intranuclear order. However, the existence itself and the nature of this structure is still uncertain. Although the techniques used for the visualization of the nuclear matrix have improved over the years, it is still unclear to what extent the isolated nuclear matrix corresponds to an in vivo existing structure. Therefore, considerable skepticism continues to surround the nuclear matrix fraction as an accurate representation of the situation in living cells. Here, we summarize the experimental evidence in favor of, or against, the presence of a diffuse nucleoskeleton as a facilitating organizational nonchromatin structure of the nucleus. 相似文献
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X-ray crystallography was used to solve the atomic structure of the ligand binding domain of the metabotropic glutamate receptor type1 homo-dimer, making it possible to show the conformational change of this domain upon glutamate binding. Studies of dimeric metabotropic receptors thereafter have focused on the respective roles and interaction of the two subunits, on the activation mechanisms following the structural rearrangements of the ligand-binding domain, and on the functional significance of polyvalent cations, the binding of which was identified in the crystal. The direct interaction between the GABA(B) receptor and the metabotropic glutamate receptor (mGluR1) has also attracted attention. Recently, attention has focused on incorporating these structural features into a functional view of the receptors. 相似文献
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Starch is an important storage polysaccharide in many plants. It is composed of densely packed alpha-glucans, consisting of 1,4- and 1,4,6-linked glucose residues. The starch polymers are used in many industrial applications. The biosynthetic machinery for assembling the granule has been manipulated in many different ways to gain insight into the process of starch biosynthesis and to engineer starches with improved functionalities. With respect to the latter, two generic technologies with great potential have been developed: (i) introduction of new linkage types in starch polymers (1,3- and 1,6-linkages), and (ii) engineering granule-boundness. The toolbox to engineer this new generation of starch polymers is discussed. 相似文献
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Swartz KJ 《Nature reviews. Neuroscience》2004,5(12):905-916
Voltage-activated cation channels have pores that are selective for K(+), Na(+) or Ca(2+). Neurons use these channels to generate and propagate action potentials, release neurotransmitters at synaptic terminals and integrate incoming signals in dendrites. Recent X-ray and electron microscopy studies of an archaebacterial voltage-activated K(+) (Kv) channel have provided the first atomic resolution images of the voltage-sensing domains in Kv channels. Although these structures are consistent with previous biophysical analyses of eukaryotic channels, they also contain surprises, which have provoked new ideas about the structure and movements of these proteins during gating. This review summarizes our current understanding of these intriguing membrane proteins and highlights the open questions. 相似文献
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We present a systematic study of B-DNA flexibility in aqueous solution using long-scale molecular dynamics simulations with the two more recent versions of nucleic acids force fields (CHARMM27 and parmbsc0) using four long duplexes designed to contain several copies of each individual base pair step. Our study highlights some differences between pambsc0 and CHARMM27 families of simulations, but also extensive agreement in the representation of DNA flexibility. We also performed additional simulations with the older AMBER force fields parm94 and parm99, corrected for non-canonical backbone flips. Taken together, the results allow us to draw for the first time a consensus molecular dynamics picture of B-DNA flexibility. 相似文献
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Beloin-Saint-Pierre Didier Hischier Roland 《The International Journal of Life Cycle Assessment》2021,26(2):327-343
The International Journal of Life Cycle Assessment - This study compares prior life cycle assessment (LCA) studies on graphene-based materials (GBMs) with new results from original data on ball... 相似文献
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The Convention on Biological Diversity's strategic plan lays out five goals: “(A) address the underlying causes of biodiversity loss by mainstreaming biodiversity across government and society; (B) reduce the direct pressures on biodiversity and promote sustainable use; (C) improve the status of biodiversity by safeguarding ecosystems, species and genetic diversity; (D) enhance the benefits to all from biodiversity and ecosystem services; (E) enhance implementation through participatory planning, knowledge management and capacity building.” To meet and inform on the progress towards these goals, a globally coordinated approach is needed for biodiversity monitoring that is linked to environmental data and covers all biogeographic regions. During a series of workshops and expert discussions, we identified nine requirements that we believe are necessary for developing and implementing such a global terrestrial species monitoring program. The program needs to design and implement an integrated information chain from monitoring to policy reporting, to create and implement minimal data standards and common monitoring protocols to be able to inform Essential Biodiversity Variables (EBVs), and to develop and optimize semantics and ontologies for data interoperability and modelling. In order to achieve this, the program needs to coordinate diverse but complementary local nodes and partnerships. In addition, capacities need to be built for technical tasks, and new monitoring technologies need to be integrated. Finally, a global monitoring program needs to facilitate and secure funding for the collection of long-term data and to detect and fill gaps in under-observed regions and taxa. The accomplishment of these nine requirements is essential in order to ensure data is comprehensive, to develop robust models, and to monitor biodiversity trends over large scales. A global terrestrial species monitoring program will enable researchers and policymakers to better understand the status and trends of biodiversity. 相似文献
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M J Cassidy G Gaskin J Savill C D Pusey A J Rees 《BMJ (Clinical research ed.)》1990,301(6747):329-331
An attempt was made to provide simple practical guidelines to alert general practitioners to the diagnosis of rapidly progressive glomerulonephritis and lead to early referral to hospital. The duration of illness before referral to this hospital and its effect on outcome in patients with crescentic nephritis were assessed retrospectively from the case notes of 24 patients referred over two years. Four patients had Goodpasture''s syndrome, 11 Wegener''s granulomatosis, seven microscopic polyarteritis, and two idiopathic progressive glomerulonephritis. The duration of symptoms before referral to the local hospital was similar in the four groups of patients and varied from one week to 28 months (mean 10 months). The duration of stay in the local hospital was two, nine, 11, and 180 days in the patients with Goodpasture''s syndrome and a mean of four days (range one to eight) in those with Wegener''s granulomatosis and 10 days (one to 18 days) in those with microscopic polyarteritis. In the local hospital the diagnosis was based on the results of renal biopsy and detection of antibodies to glomerular basement membrane in two patients with Goodpasture''s syndrome and on the results of renal biopsy in seven of the other patients aided by the detection of antibodies to the cytoplasm of neutrophils (ANCA) in 10. Three of the 24 patients died and four required maintenance haemodialysis. Patients who present to their general practitioners with persistent non-specific symptoms should have a urine dipstick test and then blood tests and emergency referral to hospital if necessary. Hospital physicians should be aware of the speed and accuracy with which current assays can confirm a diagnosis of rapidly progressive glomerulonephritis. 相似文献
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A balanced view of scale in spatial statistical analysis 总被引:25,自引:0,他引:25
J. L. Dungan J. N. Perry M. R. T. Dale P. Legendre S. Citron‐Pousty M.‐J. Fortin A. Jakomulska M. Miriti M. S. Rosenberg 《Ecography》2002,25(5):626-640
Concepts of spatial scale, such as extent, grain, resolution, range, footprint, support and cartographic ratio are not interchangeable. Because of the potential confusion among the definitions of these terms, we suggest that authors avoid the term "scale" and instead refer to specific concepts. In particular, we are careful to discriminate between observation scales, scales of ecological phenomena and scales used in spatial statistical analysis . When scales of observation or analysis change, that is, when the unit size, shape, spacing or extent are altered, statistical results are expected to change. The kinds of results that may change include estimates of the population mean and variance, the strength and character of spatial autocorrelation and spatial anisotropy, patch and gap sizes and multivariate relationships. The first three of these results (precision of the mean, variance and spatial autocorrelation) can sometimes be estimated using geostatistical support-effect models. We present four case studies of organism abundance and cover illustrating some of these changes and how conclusions about ecological phenomena (process and structure) may be affected. We identify the influence of observational scale on statistical results as a subset of what geographers call the Modifiable Area Unit Problem (MAUP). The way to avoid the MAUP is by careful construction of sampling design and analysis. We recommend a set of considerations for sampling design to allow useful tests for specific scales of a phenomenon under study. We further recommend that ecological studies completely report all components of observation and analysis scales to increase the possibility of cross-study comparisons. 相似文献
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Regulatory decision-making over the use of products of new technology aims to be based on science-based risk assessment. In some jurisdictions, decision-making about the cultivation of genetically modified (GM) plants is blocked supposedly because of scientific uncertainty about risks to the environment. However, disagreement about the acceptability of risks is primarily a dispute over normative values, which is not resolvable through natural sciences. Natural sciences may improve the quality and relevance of the scientific information used to support environmental risk assessments and make scientific uncertainties explicit, but offer little to resolve differences about values. Decisions about cultivating GM plants will thus not necessarily be eased by performing more research to reduce scientific uncertainty in environmental risk assessments, but by clarifying the debate over values. We suggest several approaches to reveal values in decision-making: (1) clarifying policy objectives; (2) determining what constitutes environmental harm; (3) making explicit the factual and normative premises on which risk assessments are based; (4) better demarcating environmental risk assessment studies from ecological research; (5) weighing the potential for environmental benefits (i.e., opportunities) as well as the potential for environmental harms (i.e., risks); and (6) expanding participation in the risk governance of GM plants. Recognising and openly debating differences about values will not remove controversy about the cultivation of GM plants. However, by revealing what is truly in dispute, debates about values will clarify decision-making criteria. 相似文献