Context dependency and metacommunity structuring in boreal headwater streams

We studied the relative importance of spatial and environmental factors as determinants of algal, bryophyte, and macroinvertebrate metacommunities in two boreal drainage basins differing in spatial extent. We used eigenfunction spatial analysis to model the spatial relationships among sites and distance‐based redundancy analysis to partition the variability in biotic communities between the spatial filters generated through spatial eigenfunction analysis and the environmental factors measured in the field. In the smaller study area, each metacommunity was structured mostly by environmental factors. This was evidenced by the fact that either the pure environmental effect was significant or environmental factors were strongly spatially structured. In the larger study area, only pure environmental effects were significant. These findings suggest that the environmental control prevails in boreal headwater streams. However, our findings also suggest that the specific details of the community‐environment and community–space relationships are dependent on the focal organism group and drainage basin.     

Environmental Risk Controllability and Management of VOCs during Remediation of Contaminated Sites

The environmental risk controllability assessment system and its method of controlling volatile organic compounds (VOCs) during remediation of contaminated sites are established in this article based on soil vapor extraction (SVE) technology. According to the properties of VOCs and the technical and operational characteristics of the site remediation process, the environmental risk controllability index system includes environmental risk identification, risk source analysis, and risk assessment. Environmental risk management during site remediation was focused on technical control methods and engineering control technologies. Specifically, acceptance based on risk management was suitable for low-risk levels such as RRI3 and RRI4. Furthermore, control methods for high-level risk (RRI1 or RRI2) could be developed along with transformation and control, combined with the necessary emergency risk plan.     

Environmental and spatial variables influence the composition of frog assemblages in sub-tropical eastern Australia

In community ecology, contrasting theories suggest that the distribution and abundance of species, and thus the composition of assemblages, are influenced by i) environmental gradients, or ii) contagious biotic processes such as predation, competition, dispersal and disease. In the former case, sites with similar environments would tend to support similar assemblages, while in the latter, geographically proximate sites would tend to support more similar assemblages than widely separated sites. I investigated the relative influence of environmental variables and spatial position on the composition of frog assemblages at forest streams in sub-tropical eastern Australia using redundancy analysis (RDA) and partial RDA. Data on the maximum abundance of the frog species at 65 survey sites were transformed such that RDA would yield the Hellinger distance between sites. The following analysis identified 11 environmental variables that explained 45% of the variation in the abundance of species at the survey sites (the species matrix), as a proportion of total variance. The geographic co-ordinates of the survey sites accounted for 12%, while the environmental and spatial variables combined accounted for 47% of the variation in the species matrix. Partial redundancy analysis indicated that of the explained variation, 74% was purely environmental, 5% was purely spatial and 21% was spatial environmental variation. This study is the first to quantify the relative influence of environmental and spatial variables on the composition of amphibian assemblages. It provides support for both the environmental control model and the biotic control model of species' distributions and assemblage composition, although environmental variables appear to have the greater effect at this scale of analysis.     

Metacommunity structuring in stream networks: roles of dispersal mode,distance type,and regional environmental context

Within a metacommunity, both environmental and spatial processes regulate variation in local community structure. The strength of these processes may vary depending on species traits (e.g., dispersal mode) or the characteristics of the regions studied (e.g., spatial extent, environmental heterogeneity). We studied the metacommunity structuring of three groups of stream macroinvertebrates differing in their overland dispersal mode (passive dispersers with aquatic adults; passive dispersers with terrestrial adults; active dispersers with terrestrial adults). We predicted that environmental structuring should be more important for active dispersers, because of their better ability to track environmental variability, and that spatial structuring should be more important for species with aquatic adults, because of stronger dispersal limitation. We sampled a total of 70 stream riffle sites in three drainage basins. Environmental heterogeneity was unrelated to spatial extent among our study regions, allowing us to examine the effects of these two factors on metacommunity structuring. We used partial redundancy analysis and Moran's eigenvector maps based on overland and watercourse distances to study the relative importance of environmental control and spatial structuring. We found that, compared with environmental control, spatial structuring was generally negligible, and it did not vary according to our predictions. In general, active dispersers with terrestrial adults showed stronger environmental control than the two passively dispersing groups, suggesting that the species dispersing actively are better able to track environmental variability. There were no clear differences in the results based on watercourse and overland distances. The variability in metacommunity structuring among basins was not related to the differences in the environmental heterogeneity and spatial extent. Our study emphasized that (1) environmental control is prevailing in stream metacommunities, (2) dispersal mode may have an important effect on metacommunity structuring, and (3) some factors other than spatial extent or environmental heterogeneity contributed to the differences among the basins.     

A new approach for environmental risk assessment

Environmental problems, such as global warming, the limited supply of sustainable energy, the depletion of natural resources, hazardous emissions released into the atmosphere and waste, are increasing global concerns. Therefore, individuals, communities, and businesses need to address environmental protection and sustainability. Environmental impact assessments are needed to identify, mitigate, and control aspects that affect the environment or a company's products, services, or activities. In this study, a general environmental aspect and impact assessment approach, which can be applied to any company that is involved in the production or service sector, is created. An environmental impact pattern that consists of 10 main and 32 sub-categories was formed based on the ISO 14001, environmental studies and field applications. The developed approach was applied to the dyeing units of a manufacturing firm. Sixteen environmental aspects were identified and assessed using the environmental impact template via the environmental failure mode and effect analysis (E-FMEA) method. The developed-approach can be applied to each sector, which will enable us to perform a detailed analysis of the environmental aspects in the environmental impact category. This approach provides a checklist for the environmental impact studies of businesses and has been pioneered as an effective method for company resources to improve their environmental performance.     

Integrated Environmental and Economic Assessment of Products and Processes

The eco-efficiency analysis method developed and used by the Öko-Institut analyzes different alternatives that fulfill a defined consumer need, from an environmental as well as an economic perspective.
Like life-cycle assessment (LCA), eco-efficiency analysis makes possible the setting of priorities in purchasing decisions or can be used to show optimization potentials in product development processes.
Eco-efficiency analysis builds upon two methods: LCA, according to ISO 14040 ff. (to assess the environmental aspects of products and processes), and life-cycle costing. Life-cycle costing results in a single figure—the total costs of ownership to one or several actors. The environmental impacts can be evaluated and aggregated as a single score or the impact category indicator results can be kept separate. In either case two single scores can be compared: the total environmental burden or the impact category indicator results, and the total costs of ownership of the alternatives under consideration.
The results can then be plotted in two-dimensional graphs that show the effectiveness of certain measures in environmental and economic terms. The efficiency is expressed as a numerical ratio of environmental savings to difference in costs.
Together with furnishing more detailed results and a discussion of additional benefits or potential barriers, eco-efficiency analysis broadens the basis for decision-making processes.     

Genome-wide identification and evaluation of novel internal control genes for Q-PCR based transcript normalization in wheat

To accurately quantify gene expression using quantitative PCR amplification, it is vital that one or more ideal internal control genes are used to normalize the samples to be compared. Ideally, the expression level of those internal control genes should vary as little as possible between tissues, developmental stages and environmental conditions. In this study, 32 candidate genes for internal control were obtained from the analysis of nine independent experiments which included 333 Affymetrix GeneChip Wheat Genome arrays. Expression levels of the selected genes were then evaluated by quantitative real-time PCR with cDNA samples from different tissues, stages of development and environmental conditions. Finally, fifteen novel internal control genes were selected and their respective expression profiles were compared using NormFinder, geNorm, Pearson correlation coefficients and the twofold-change method. The novel internal control genes from this study were compared with thirteen traditional ones for their expression stability. It was observed that seven of the novel internal control genes were better than the traditional ones in expression stability under all the tested cDNA samples. Among the traditional internal control genes, the elongation factor 1-alpha exhibited strong expression stability, whereas the 18S rRNA, Alpha-tubulin, Actin and GAPDH genes had very poor expression stability in the range of wheat samples tested. Therefore, the use of the novel internal control genes for normalization should improve the accuracy and validity of gene expression analysis.     

Control of body size of Lasius niger ant sexuals--worker interests, genes and environment

In most animals, the survival and reproductive success of males and females is linked to their size. The ability of individuals to control environmental influences on size will therefore have consequences for their fitness. In eusocial insects, individual males and reproductive females do not have to forage for themselves or control their local environment. Instead, they are reared by nonreproductive siblings (workers) inside colonies. Workers should benefit from controlling the size of sexuals because these sexuals are usually the only means for workers to transmit their genes to future generations. Nevertheless, considerable intraspecific variation exists around mean sexual size in social hymenopterans, even in species with monomorphic sexuals. This variation could result from genetic influences on sexual size, for instance sexuals may be selected to not agree to worker interests, or be due to strong, unpredictable environmental conditions constraining the efforts of workers to control sexual size. In a study that is the first of its kind I investigated genetic and environmental components of sexual body size variation in the ant Lasius niger, examining sexuals from wild colonies with one or several fathers (paternity levels established through microsatellite DNA offspring analysis). Evidence was found for a genetic component of size (broad-sense heritability of up to 42%) but strong common-colony effects (among-colony variation in food availability or in worker capacities to restrain sexual selfishness) also increased the size differences among colonies. Workers thus seem to only have partial-control over sexual size, but may be doing the best of a bad job.     

Study of spatial components of forest cover using partial Mantel tests and path analysis

Abstract. Plant species distributions are generally thought to be chiefly under environmental control, although they may be affected by disturbance events or dispersion properties of the species. The relative importance of these different factors is not easy to evaluate because they often share common spatial patterns, such that an inextricable network of relationships occurs between plant distributions, environmental conditions, disturbance events and endogenous factors such as propagule dispersion. In this paper we propose a method for untangling the common spatial component from the relationship between environmental conditions and the distribution of tree species. Using partial Mantel tests and path analysis, we test models of relationships between these data sets. Results show that in our study area, spatial patterns of species associated with hydric conditions remain largely correlated with environmental conditions. However, mesic sites show more complex forest covers, in which a significant spatial component persists when environmental variation is statistically controlled for. This remaining spatial variability suggests that other factors possessing spatial structure partly explain species distributions.     

The behaviour of Dutch fresh water ecologists in response to environmental concern

Due to the rise of environmental concern ecologists have been asked for advice more frequently since the late 1960s. This article discusses how the changing relationship between ecologists and society has affected the behaviour of one particular group of ecologists, namely Dutch fresh water ecologists, by focussing on their behaviour towards job market control and public interest activities. The analysis has been based on interviews with 65 Dutch fresh water ecologists together with an analysis of their publications.In contrast with American ecologists, Dutch fresh water ecologists have made little effort to control their job market by formal arrangements such as formulating a code of ethics and certification procedures. Secondly, Dutch fresh water ecologists generally conceive of their own role in contributing to the solution of environmental problems in relation to that of the environmentalists by doing good research and reliable advisory work. Although a significant number of researchers also address lay publics by writing popular articles and/or holding lectures, only a minority actively participates in environmental politics.     

Ecological control analysis: being(s) in control of mass flux and metabolite concentrations in anaerobic degradation processes

Identification of the functional groups of microorganisms that are predominantly in control of fluxes through, and concentrations in, microbial networks would benefit microbial ecology and environmental biotechnology: the properties of those controlling microorganisms could be studied or monitored specifically or their activity could be modulated in attempts to manipulate the behaviour of such networks. Herein we present ecological control analysis (ECA) as a versatile mathematical framework that allows for the quantification of the control of each functional group in a microbial network on its process rates and concentrations of intermediates. In contrast to current views, we show that rates of flow of matter are not always limited by a single functional group; rather flux control can be distributed over several groups. Also, control over intermediate concentrations is always shared. Because of indirect interactions, through other functional groups, the concentration of an intermediate can also be controlled by functional groups not producing or consuming it. Ecological control analysis is illustrated by a case study on the anaerobic degradation of organic matter, using experimental data obtained from the literature. During anaerobic degradation, fermenting microorganisms interact with terminal electron-accepting microorganisms (e.g. halorespirers, methanogens). The analysis indicates that flux control mainly resides with fermenting microorganisms, but can shift to the terminal electron-accepting microorganisms under less favourable redox conditions. Paradoxically, halorespiring microorganisms do not control the rate of perchloroethylene and trichloroethylene degradation even though they catalyse those processes themselves.     

Phenomics allows identification of genomic regions affecting maize stomatal conductance with conditional effects of water deficit and evaporative demand

Stomatal conductance is central for the trades‐off between hydraulics and photosynthesis. We aimed at deciphering its genetic control and that of its responses to evaporative demand and water deficit, a nearly impossible task with gas exchanges measurements. Whole‐plant stomatal conductance was estimated via inversion of the Penman–Monteith equation from data of transpiration and plant architecture collected in a phenotyping platform. We have analysed jointly 4 experiments with contrasting environmental conditions imposed to a panel of 254 maize hybrids. Estimated whole‐plant stomatal conductance closely correlated with gas‐exchange measurements and biomass accumulation rate. Sixteen robust quantitative trait loci (QTLs) were identified by genome wide association studies and co‐located with QTLs of transpiration and biomass. Light, vapour pressure deficit, or soil water potential largely accounted for the differences in allelic effects between experiments, thereby providing strong hypotheses for mechanisms of stomatal control and a way to select relevant candidate genes among the 1–19 genes harboured by QTLs. The combination of allelic effects, as affected by environmental conditions, accounted for the variability of stomatal conductance across a range of hybrids and environmental conditions. This approach may therefore contribute to genetic analysis and prediction of stomatal control in diverse environments.     

代谢物组学方法及其在植物学研究中的应用

代谢物是生物体受遗传控制和环境影响的最终表达产物,以全体代谢物(代谢物组)为研究对象的代谢物组学是继基因组学和蛋白质组学后必然出现的又一门"组学"技术。该文综述了代谢物组的检测、数据的处理和分析等以及这些技术在植物目标分析、基因功能、代谢途径和代谢工程、整合植物学、信号转导等研究中的应用和前景。     

Estimation of response to selection and utilization of control populations for additional information and accuracy

Problems associated with testing and estimation of response to selection are examined. An alternative procedure with increased power for testing hypotheses is given. The increased power results from a more precise method of estimating the variance about response. The new method is based on a Satterthwaite approximation which combines variance components estimated more precisely by other sources of variation in the analysis of variance. The expected variance about response and expected mean squares for the analysis of variance, used in the Satterthwaite procedure, are given. When intergeneration environmental trends cannot be ruled out, a control population must be used to estimate response to selection. However, if the experimental and control populations do not respond in the same direction and with the same magnitude to common environmental effects, then the usual method of estimating response by deviating the experimental values from the control will result in biased estimates. An alternative procedure, using the control as a covariate to adjust for environmental trends, gives relatively unbiased estimates of response in this situation. Some bias results from measurement error associated with the control. However, this bias is usually minimal.     

Frequency and intensity of facilitation reveal opposing patterns along a stress gradient

Disentangling the different processes structuring ecological communities is a long‐standing challenge. In species‐rich ecosystems, most emphasis has so far been given to environmental filtering and competition processes, while facilitative interactions between species remain insufficiently studied. Here, we propose an analysis framework that not only allows for identifying pairs of facilitating and facilitated species, but also estimates the strength of facilitation and its variation along environmental gradients. Our framework combines the analysis of both co‐occurrence and co‐abundance patterns using a moving window approach along environmental gradients to control for potentially confounding effects of environmental filtering in the co‐abundance analysis. We first validate our new approach against community assembly simulations, and exemplify its potential on a large 1,134 plant community plots dataset. Our results generally show that facilitation intensity was strongest under cold stress, whereas the proportion of facilitating and facilitated species was higher under drought stress. Moreover, the functional distance between individual facilitated species and their facilitating species significantly changed along the temperature–moisture gradient, and seemed to influence facilitation intensity, although no general positive or general negative trend was discernible among species. The main advantages of our robust framework are as follows: It enables detecting facilitating and facilitated species in species‐rich systems, and it allows identifying the directionality and intensity of facilitation in species pairs as well as its variation across long environmental gradients. It thus opens numerous opportunities for incorporating functional (and phylogenetic) information in the analysis of facilitation patterns. Our case study indicated high complexity in facilitative interactions across the stress gradient and revealed new evidence that facilitation, similarly to competition, can operate between functionally similar and dissimilar species. Extending the analyses to other taxa and ecosystems will foster our understanding how complex interspecific interactions promote biodiversity.     

Source metabolism dominates the control of source to sink carbon flux in tuberizing potato plants throughout the diurnal cycle and under a range of environmental conditions

The aim of this work was to investigate the effect of environmental conditions on the control of source to sink carbon flux in potato during tuberization. Top down metabolic control analysis was used to quantitatively determine the extent to which source and sink reactions control the flux from CO₂ to the tuber. Under all conditions investigated (beginning of the dark period, low nitrogen availability, variation in temperature) source metabolism accounts for at least 80% of the control. In plants grown with limiting nitrogen, or when measurements were made at low temperature the extent to which source metabolism controls flux increased to 90%.     

Quality assurance of biological monitoring in occupational and environmental medicine

Biological monitoring of chemical exposure in the workplace has become increasingly important in the assessment of health risk as an integral part of the overall occupational health and safety strategy. In environmental medicine biological monitoring plays also an important role in the assessment of excessive, acute or chronic exposure to chemical agents. To guarantee that the results obtained in biological monitoring are comparable with threshold limit values and results from other laboratories, the analysis must be carried out with tested and reliable analytical methods and accompanied by a quality assurance scheme. Confounding influences and interferences during the pre-analytical phase can be minimised by recommendations from experienced laboratories. For internal quality control commercially available control samples with an assigned concentration are used. External quality control programs for biological monitoring are offered by several institutions. The external quality control program of the German Society of Occupational and Environmental Medicine has been organised since 1982. In the meantime the 27th program has been carried out offering 96 analytes in urine, blood and plasma for 47 substances. This program covers most of the parameters relevant to occupational and environmental medicine. About 350 laboratories take part in these intercomparison programs. At present, ten German and 14 international laboratories are commissioned to determine the assigned values. The data evaluated from the results of the intercomparison programs give a good overview of the current quality of the determination of analytes assessed in occupational and environmental toxicological laboratories. For the analysis of inorganic substances in blood and urine the tolerable variation ranges from 7.5 to 43.5%. For organic substances in urine the tolerable variation ranges from 12 to 48%. The highest variations (36-60%) were found for the analysis of organochlorine compounds in plasma. The tolerable variations for the determination of solvents in blood by head space gas chromatography range from 26 to 57%. If the recommendations for the pre-analytical phase, the selection of reliable analytical methods by the laboratory and the carrying out of adequate quality control are observed, the pre-requisites for reliable findings during biological monitoring are fulfilled     

The nature of robustness in development

A trait is robust to a genetic or environmental variable if its variation is weakly correlated with variation in that variable. The source of robustness lies in the fact that the developmental processes that give rise to complex traits are nonlinear. A consequence of this nonlinearity is that not all genes are equally correlated with the trait whose ontogeny they control. Here we explore how developmental mechanisms determine and alter the correlation structure between genes and the traits that they control. A formula is developed by which the correlation of a gene or environmental variable with a trait can be calculated if the mechanism that gives rise to the trait is known. The nature of robustness and the ways in which robustness can evolve are discussed in the context of the problems that arise in the analysis of inherently nonlinear systems.