首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
A thorough and quantified method for classifying seabird diving behaviour   总被引:1,自引:0,他引:1  
Time-depth recorders are commonly deployed on diving animals to obtain information on their aquatic behaviour. The recorded data provide a 2D profile of diving activity. As analyses of diving behaviour from such profiles have become more complex, these analyses have often suffered from a lack of consistency and rigour. There is a growing need for a simple, comparative method to classify diving behaviour thoroughly and quantitatively. Here, a new approach to the classification of the dive profiles of penguins is described, which probably has applicability for many other diving predators as well. This simple approach uses a small, coherent set of criteria to classify behaviours in a detailed and quantified manner, and with relative objectivity. Classification of diving behaviour is possible from the temporal scale of a wiggle within a dive to the scale of a bout of dives. The new method will make comparisons between species easier and clearer because these comparisons will be undertaken within a consistent, more objective framework.  相似文献   

3.
气候变化背景下野生动物脆弱性评估方法研究进展   总被引:2,自引:2,他引:0  
李佳  刘芳  张宇  薛亚东  李迪强 《生态学报》2017,37(20):6656-6667
脆弱性评估是研究气候变化影响野生动物的重要内容,识别野生动物脆弱性,是适应和减缓气候变化影响的关键和基础。开展气候变化背景下野生动物的脆弱性评估工作,目的是为了确定易受气候变化影响的物种和明确导致物种脆弱性的因素,其评估结果有助于人类认识气候变化对野生动物的影响,为野生动物适应气候变化保护对策的制定提供科学依据。对野生动物而言(物种),脆弱性是物种受气候变化影响的程度,包括暴露度、敏感性和适应能力三大要素。其中,暴露度是由气候变化引起的外在因素,如温度、降雨量、极值天气等;敏感性是受物种自身因素影响,如种间关系、耐受性等;适应能力是物种通过自身调整来减小气候变化带来的影响,如迁移或扩散到适宜生境的能力、塑性反应和进化反应等。对近期有关气候变化背景下野生动物脆弱性评估方法予以综述,比较每种评估方法所选取指标的差异,总结在脆弱性评估中遇到的不确定性指标的处理方法,以及脆弱性评估结果在野生动物适应气候变化对策中的应用。通过总结野生动物脆弱性评估方法,以期为气候变化背景下评估我国野生动物资源的脆弱性提供参考方法。  相似文献   

4.
The doubly labeled water (DLW) method has been essential for understanding animal energetics of free-ranging individuals. The first published studies on free-ranging seabirds were conducted on penguins in the early 1980s. Since then, nearly 50 seabird species with representatives from each major taxonomic order have been studied using DLW. Although the basic methodology has not changed, there are at least nine different equations, varying with respect to assumptions on fractionation and the total body water pool, to estimate field metabolic rate (FMR) from isotopic water turnover. In this review, I show that FMR can vary by as much as 45% depending on the equation used to calculate CO2 production in five albatross species. Energy budgets derived from DLW measurements are critical tools for understanding patterns of energy use and allocation in seabirds. However, they depend on accurate and representative measurements of FMR, so analyses that include greater partitioning of activity specific FMR yield more realistic cost estimates. I also show how the combined use of DLW and biologging methods can 1) provide greater clarity for explaining observed variation in FMR measurements within a species and 2) allow FMRs to be viewed in a wider physiological, behavioral, or ecological context. Finally, I update existing allometric equations with new FMR data. These updates reaffirm that albatrosses have the lowest at-sea FMRs per equivalent body mass and that individuals of other seabird orders have FMRs ranging between 1.39 and 2.24 times higher than albatrosses.  相似文献   

5.
Environmental changes are driving rapid geographic shifts of suitable environmental conditions for species. These might survive by tracking those shifts, however successful responses will depend on the spatial distribution of suitable habitats (current and future) and on their connectivity. Most herptiles (i.e., amphibians and reptiles) have low dispersal abilities, and therefore herptiles are among the most vulnerable groups to environmental changes. Here we assessed the vulnerability of herptile species to future climate and land use changes in fragmented landscapes. We developed and tested a methodological approach combining the strengths of Species Distribution Models (SDMs) and of functional connectivity analysis. First, using SDMs we forecasted current and future distributions of potential suitable areas as well as range dynamics for four herptile species in Portugal. SDM forecasts for 2050 were obtained under two contrasting emission scenarios, translated into moderate (low-emissions scenario) or large (high-emissions scenario) changes in climate and land use conditions. Then, we calculated and analysed functional connectivity from areas projected to lose environmental suitability towards areas keeping suitable conditions. Landscape matrix resistance and barrier effects of the national motorway network were incorporated as the main sources of fragmentation. Potential suitable area was projected to decrease under future conditions for most test species, with the high-emissions scenario amplifying the losses or gains. Spatiotemporal patterns of connectivity between potentially suitable areas signalled the most important locations for maintaining linkages and migration corridors, as well as potential conflicts due to overlaps with the current motorway network. By integrating SDM projections with functional connectivity analysis, we were able to assess and map the vulnerability of distinct herptile species to isolation or extinction under environmental change scenarios. Our framework provides valuable information, with fairly low data requirements, for optimizing biodiversity management and mitigation efforts, aiming to reduce the complex and often synergistic negative impacts of multiple environmental change drivers. Implications for conservation planning and management are discussed from a global change adaptation perspective.  相似文献   

6.
7.
Recent studies have shown that the detrimental effects of anthropogenic pollutants may be worse if organisms are exposed to natural stress. In this study, we examined whether negative effects of organochlorines (OCs) could be influenced by parasites. In two breeding seasons, we administered an anti-helminthic drug to groups of breeding glaucous gulls (Larus hyperboreus), whereas control groups were placebo treated. In all birds, blood residues of the most important OCs in the study population (hexachlorobenzene, oxychlordane, p,p'-dichlorodiphenyldichloroethylene and polychlorinated biphenyl), were measured. The relationships between OCs and fitness components (i.e. nesting success and return rate between breeding seasons) were then compared between the birds receiving anti-parasite treatment and the controls. Among untreated males, higher blood residues of OCs were associated with lowered nesting success, while in males receiving anti-parasite treatment, there was no detrimental effect of OCs on fitness. Return rate was not affected by treatment or OCs. Our findings suggest that parasites may be an important factor in triggering reproductive effects of such pollutants, and that relatively low levels of OCs may have serious reproductive consequences in natural populations when stress from other sources is high.  相似文献   

8.
A rapid soil burial method for assessing the susceptibility of polyurethanes to biodeterioration was developed. The time of the test was reduced by prestressing the polyurethanes. The degree of deterioration was measured by following changes in the appearance of the polyurethanes and in selected physical properties. It was found that pre-stressing produced significant reductions in the tensile strength of a known susceptible polyurethane after burial in soil for 2 weeks. The reduction was greater than that found with unstressed polyurethanes buried for 26 weeks in active soil. Changes in tensile strength were less after burial for 4 weeks in sterile soil than after burial in active soil for the same period. The results suggest that deterioration of polyurethane during soil burial is a result of both chemical and microbial action.  相似文献   

9.
10.
A laboratory method for assessing the toxicity of stomach poisons to slugs   总被引:1,自引:0,他引:1  
A method is described that allows the toxicity of stomach poisons to the grey field slug, Agriolimax reticulatus (Muller), to be measured in the laboratory. The relative toxicities of three commonly used molluscicides, as expressed by the median lethal dose values, were: sodium pentachlorophenate most toxic with a median value of 22·9 ± 2·5 μg/slug, metaldehyde next with one of 85·2 ± 4·0 μg/slug, and copper sulphate least toxic with one of 129·2 ± 5·9 to 131·6 ± 5·6 μg/slug. The technique allows a given dose of any poison, however repellent, to be administered, but does not measure the repellency or attractiveness.  相似文献   

11.
Rotational core training is said to be beneficial for rotational power athletes. Currently, there has been no method proposed for the reliable assessment of rotational power. Therefore, our purpose was to determine the test-retest reliability of kinetic and kinematic rotational characteristics of a pulley system when performing a rotational exercise of the axial skeleton in the transverse plane to find out if this would be a reliable tool for evaluating rotational power. Healthy, college-aged men (n = 8) and women (n = 15) reported for 3 testing sessions. The participants were seated on a box, and they held the handle with both arms extended in front of their body, starting their motion with their torso rotated toward the machine. All the participants rotated their torso forcefully until they reached 180° of rotation, and they then slowly returned to the starting position, 3 times per trial, with 3 loads: 9% body weight (BW), 12% BW, and 15% BW. The repetition with the greatest power for each trial for each load was analyzed. The mean peak power repetition (watts) for all the subjects was 20.09 ± 7.16 (9% BW), 26.17 ± 8.6 (12% BW), and 30.74 ± 11.022 (15% BW) in the first training session and 22.3 ± 8.087 (9% BW), 28.7 ± 11.295 (12% BW), and 33.52 ± 12.965 (15% BW) in the second training session with intraclass correlation coefficients of 0.97 (9%BW), 0.94 (12%BW), and 0.95 (15%BW). When the participants were separated by sex, there were no significant differences between groups. Based on these results, it was found that a pulley system and an external dynamometer can be used together as a reliable research tool to assess rotational power.  相似文献   

12.
农业生态系统脆弱性评价方法   总被引:14,自引:0,他引:14  
开展农业生态系统脆弱性评价是减缓气候、环境变化带来不利影响的重要环节.虽然近10年对不同的生态系统已经开展了一些脆弱性的评估研究,但尚未形成统一和公认的方法.本文以典型的农业生态脆弱区北方农牧交错带为研究对象,在分析影响其农业生态系统脆弱性主要因素基础上,选取了4类共17项指标构建了农业生态系统气候脆弱性评价指标体系.通过层次分析法确定了指标权重,并采用模糊评判原理,得出农业生态系统的气候脆弱性的综合定量评价方法.  相似文献   

13.
Cystic fibrosis: a disease of vulnerability to airway surface dehydration   总被引:2,自引:0,他引:2  
Cystic fibrosis (CF) lung disease involves chronic bacterial infection of retained airway secretions (mucus). Recent data suggest that CF lung disease pathogenesis reflects the vulnerability of airway surfaces to dehydration and collapse of mucus clearance. This predisposition is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, resulting in (i) the absence of CFTR-mediated Cl- secretion and regulation of epithelial Na+ channel (ENaC) function; and (ii) the sole dependence on extracellular ATP to rebalance these ion transport processes through P2 purinoceptor signaling. Recent clinical studies indicate that inhalation of hypertonic saline osmotically draws sufficient water onto CF airway surfaces to provide clinical benefit.  相似文献   

14.
Kong M  Lee JJ 《Biometrics》2008,64(2):396-405
Summary .   When multiple drugs are administered simultaneously, investigators are often interested in assessing whether the drug combinations are synergistic, additive, or antagonistic. Existing response surface models are not adequate to capture the complex patterns of drug interactions. We propose a two-component semiparametric response surface model with a parametric function to describe the additive effect of a combination dose and a nonparametric function to capture the departure from the additive effect. The nonparametric function is estimated using the technique developed in thin plate splines, and the pointwise bootstrap confidence interval for this function is constructed. The proposed semiparametric model offers an effective way of formulating the additive effect while allowing the flexibility of modeling a departure from additivity. Example and simulations are given to illustrate that the proposed model provides an excellent estimation for different patterns of interactions between two drugs.  相似文献   

15.
Frameworks that provide a system for assessing species according to their vulnerability to climate change can offer considerable guidance to conservation managers who need to allocate limited resources among a large number of taxa. To date, climate change vulnerability assessments have largely been based on projected changes in range size derived from the output of species distribution models (SDMs). A criticism of risk assessments based solely on these models is that information on species ecological and life history traits is lacking. Accordingly, we developed a points-based framework for assessing species vulnerability to climate change that considered species traits together with the projections of SDMs. Applying this method to the Australian elapid snakes (family Elapidae), we determined which species may be particularly susceptible in the future and assessed broad-scale biogeographic patterns in species vulnerability. By offering a more comprehensive and rigorous method for assessing vulnerability than those based solely on SDMs, this framework provides greater justification for resource allocation, and can help guide decisions regarding the most appropriate adaptation strategies.  相似文献   

16.
17.
湖泊生态系统健康定量评价方法   总被引:43,自引:2,他引:43  
提出了湖泊生态系统健康定量评价的一种新方法生态系统健康指数法。该方法首先设计了一个0~100的生态系统健康指数作为定量尺度,然后通过评价指标选择、各指标生态系统健康分指数计算、各指标权重计算、生态系统健康综合指数计算等基本步骤,评价湖泊生态系统健康状态。以实用实例对意大利西西里湖泊群及单个湖泊进行了生态系统健康评价。结果表明,该方法原理简单,计算简便,结果可靠、直观,既可用于同一湖泊又可用于不同湖泊生态系统健康状态的定量评价与比较,是一种值得推广的定量评价方法。  相似文献   

18.
19.
A field cage method was evaluated as an alternative to field trials for identifying sources of resistance to turnip root fly in brassicas. This involved the controlled release of adult flies and the use of egg traps to quantify egg-laying on potted plants. Overall levels of resistance to Delia floralis, and its components, were assessed for 15 swede genotypes. Significant levels of antixenosis and antibiosis type resistance were identified in several cultivars and breeding lines. There was a close agreement between the field cage results and those from previous field trials, using comparable susceptible and resistance control cultivars. Compared with field selection, the field cage method reduced by c. 40% the time required to quantify resistance and each of its components.  相似文献   

20.
We propose a simple and inexpensive method to determine the rate and pattern of surface sediment reworking by benthic organisms. Unlike many existing methods commonly used in bioturbation studies, which usually require sediment sampling, our approach is fully non-destructive and is well suited for investigating non-cohesive fine sediments in streams and rivers. Optical tracer (e.g. luminophores or coloured sand) disappearance or appearance is assessed through time based on optical quantification of surfaces occupied by tracers. Data are used to calculate surface sediment reworking (SSR) coefficients depicting bioturbation intensities. Using this method, we evaluated reworking activity of stream organisms (three benthic invertebrates and a fish) in laboratory microcosms mimicking pool habitats or directly in the field within arenas set in depositional zones. Our method was sensitive enough to measure SSR as low as 0.2 cm2 day?1, such as triggered by intermediate density (774 m?2) of Gammarus fossarum (Amphipoda) in microcosms. In contrast, complex invertebrate community in the field and a fish (Barbatula barabatula) in laboratory microcosms were found to yield to excessively high SSR (>60 cm2 day?1). Lastly, we suggest that images acquired during experiments can be used for qualitative evaluation of species-specific effects on sediment distribution.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号