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A genetic interpretation of ecologically dependent isolation.

Hybrids may suffer a reduced fitness both because they fall between ecological niches (ecologically dependent isolation) and as a result of intrinsic genetic incompatibilities between the parental genomes (ecologically independent isolation). Whereas genetic incompatibilities are common to all theories of speciation, ecologically dependent isolation is a unique prediction of the ecological model of speciation. This prediction can be tested using reciprocal transplants in which the fitness of various genotypes is evaluated in both parental habitats. Here we expand a quantitative genetic model of Lynch (1991) to include two parental environments. We ask whether a sufficient experimental design exists for detecting ecologically dependent isolation. Analysis of the model reveals that by using both backcrosses in both parental environments, environment-specific additive genetic effects can be estimated while correcting for any intrinsic genetic isolation. Environment-specific dominance effects can also be estimated by including the F1 and F2 in the reciprocal transplant. In contrast, a reciprocal transplant comparing only F1s or F2s to the parental species cannot separate ecologically dependent from intrinsic genetic isolation. Thus, a reduced fitness of F1 or F2 hybrids relative to the parental species is not sufficient to demonstrate ecological speciation. The model highlights the importance of determining the contribution of genetic and ecological mechanisms to hybrid fitness if inferences concerning speciation mechanisms are to be made.

Adaptation, Physiological↗

Ecological effects in multi-level studies.

Multi-level research that attempts to describe ecological effects in themselves (for example, the effect on individual health from living in deprived communities), while also including individual level effects (for example, the effect of personal socioeconomic disadvantage), is now prominent in research on the socioeconomic determinants of health and disease. Such research often involves the application of advanced statistical multi-level methods. It is hypothesised that such research is at risk of reaching beyond an epidemiological understanding of what constitutes an ecological effect, and what sources of error may be influencing any observed ecological effect. This paper aims to present such an epidemiological understanding. Three basic types of ecological effect are described: a direct cross level effect (for example, living in a deprived community directly affects individual personal health), cross level effect modification (for example, living in a deprived community modifies the effect of individual socioeconomic status on individual health), and an indirect cross level effect (for example, living in a deprived community increases the risk of smoking, which in turn affects individual health). Sources of error and weaknesses in study design that may affect estimates of ecological effects include: a lack of variation in the ecological exposure (and health outcome) in the available data; not allowing for intraclass correlation; selection bias; confounding at both the ecological and individual level; misclassification of variables; misclassification of units of analysis and assignment of individuals to those units; model mis-specification; and multicollinearity. Identification of ecological effects requires the minimisation of these sources of error, and a study design that captures sufficient variation in the ecological exposure of interest.

Bias↗

Ecological risk assessment: implications of hormesis.

Hormesis is a widespread phenomenon across many taxa and chemicals, and, at the single species level, issues regarding the application of hormesis to human health and ecological risk assessment are similar. For example, convincing the public of a 'beneficial' effect of environmental chemicals may be problematic, and the design and analysis of laboratory studies may require modifications to detect hormesis. However, interpreting the significance of hormesis for even a single species in an ecological risk assessment can be complicated by considerations of competition with other species, predation effects, etc. Ecological risk assessments involve more than a single species; they may involve communities of hundreds or thousands of species as well as a range of ecological processes. Applying hormetic adjustments to threshold effect levels for chemicals derived from sensitivity distributions for a large number of species is impractical. For ecological risks, chemical stressors are frequently of lessor concern than physical stressors such as habitat alteration or biological stressors such as introduced species, but the relevance of hormesis to non-chemical stressors is unclear. Although ecological theories such as the intermediate disturbance hypothesis offer some intriguing similarities between chemical hormesis and hormetic-like responses resulting from physical disturbances, mechanistic explanations are lacking. Further exploration of the relevance of hormesis to ecological risk assessment is desirable. Aspects deserving additional attention include developing a better understanding of the hormetic effects of chemical mixtures, the relevance of hormesis to physical and biological stressors and the development of criteria for determining when hormesis is likely to be relevant to ecological risk assessments.

Adaptation, Physiological↗

Utilization of the psychiatric emergency service in Mannheim: ecological and distance-related aspects.

Ecologically oriented research of psychiatric service utilization has almost exclusively dealt with regular in- and out-patient services. There are hardly any results on the ecological distribution of utilization rates of psychiatric emergency services. This study aims at investigating the topographic distribution of utilization rates of the psychiatric emergency service out of office hours at the Central Institute of Mental Health (CIMH, Mannheim) from 1982 to 1993. Within this period of time 6463 patients with a total of 14,628 contacts were registered at the CIMH. In order to explain topographic differences in the utilization rates, ecological variables, the distance between patients' residence and service location, and diagnosis were taken into account. The study shows that ecological, distance-related and diagnostic factors all influence the utilization of the psychiatric emergency service in Mannheim. First contact and contact rates decrease from the city centre toward the outskirts. There was a strong general effect of ecological variables: the utilization rates were higher for districts with worse ecological conditions and specific for some diagnostic groups. The greatest difference in utilization rates between the city centre and the outskirts was found for schizophrenia and psychoactive substance use disorders, whereas there was no difference with regard to organic and symptomatic mental disorders. With increasing spatial and time-related distance between residence and service location, the utilization rate decreases. No relation was found between diagnosis and distance. The study also shows an interaction between time-related distance and the ecological variables. The influence of the ecological factors on service utilization is amplified with decreasing distance.

Ambulatory Care↗

An examination of ecological risk assessment and management practices.

Ecological risk assessment has grown and evolved since the 1980s, as have new challenges (e.g. global climate change, loss of habitat and biodiversity and the effects of multiple anthropogenic chemicals on ecological systems) that need to be factored into the risk assessment processes. There is also an on-going shift from evaluating adverse health impacts on particular, often small scale, environments to undertaking more complex ecological assessments of whole populations and communities across ecologically meaningful landscapes. These trends are generating an increased demand for much more complex ecological assessments, making it increasingly clear that to achieve its potential as a management tool, methods must be developed to apply ecological risk assessment to larger and more complex scales. This paper reviews the development of the ecological risk assessment paradigm in the United States, identifies ways it is being applied and adapted in other countries, explores future research needs and practice improvements, and examines current issues that need to be considered in taking forward the scientific development of ecological risk assessment as a useful environmental management tool.

Animals↗

Ecological and geographic characteristics predict nutritional status of communities: rapid assessment for poor villages.

The quality of poverty alleviation programmes relies heavily on appropriate targeting and priority setting. Major problems in assessing poverty include identification of the indicators of poverty and the methods used for its assessment. Nutritional status, expressed by anthropometric indices, has been proposed as a poverty indicator because of its validity, objectivity, reliability and feasibility. This study was conducted to explore the application of remote sensing to poverty mapping based on nutritional status at the community level. Relationships between the nutritional status within a community and the ecological characteristics of the community were investigated. Multiple linear regression tests were executed, and the resultant equations were tested for their validity in predicting communities with poor nutritional status. Among geographical and ecological indicators used, distance to the nearest market, main soil type, rice field area, and perennial cultivation area were found to be most useful predictors for the ranking of the communities by nutritional status. Among non-ecological determinants, food consumption, health service status and living conditions were also found as predictors. The highest correlation was found if total population was also taken into account in the regression model (R2 = 0.69; p < 0.0001). In the assessment of the sensitivity and specificity of the eight models studied, 'undernutrition' was defined as a condition where a community belongs in the first quartile for nutritional status (highest prevalence of undernutrition), and the baseline nutritional survey was considered as a standard method for final diagnosis. Most models which included only ecological factors in the equations had lower sensitivity and specificity than models which included all determinant factors in the equations. All models which took into account the total population had higher sensitivity and specificity than those that did not take total population into account. The best model of those that took into account only the geographical and ecological characteristics of the community's living environment had similar sensitivity and specificity (80% and 94.1%, respectively) as the models that considered non-geographical and non-ecological variables in addition to geographical and ecological variables. In the case of West Sumatra, only four ecological and geographic characteristics were sufficient to predict poverty in village. Since these characteristics could be surveyed by remote sensing, it may well be possible to use remote sensing for a rapid method for poverty mapping.

Data Collection↗

Microbial ecology in the age of genomics and metagenomics: concepts, tools, and recent advances.

Microbial ecology examines the diversity and activity of micro-organisms in Earth's biosphere. In the last 20 years, the application of genomics tools have revolutionized microbial ecological studies and drastically expanded our view on the previously underappreciated microbial world. This review first introduces the basic concepts in microbial ecology and the main genomics methods that have been used to examine natural microbial populations and communities. In the ensuing three specific sections, the applications of the genomics in microbial ecological research are highlighted. The first describes the widespread application of multilocus sequence typing and representational difference analysis in studying genetic variation within microbial species. Such investigations have identified that migration, horizontal gene transfer and recombination are common in natural microbial populations and that microbial strains can be highly variable in genome size and gene content. The second section highlights and summarizes the use of four specific genomics methods (phylogenetic analysis of ribosomal RNA, DNA-DNA re-association kinetics, metagenomics, and micro-arrays) in analysing the diversity and potential activity of microbial populations and communities from a variety of terrestrial and aquatic environments. Such analyses have identified many unexpected phylogenetic lineages in viruses, bacteria, archaea, and microbial eukaryotes. Functional analyses of environmental DNA also revealed highly prevalent, but previously unknown, metabolic processes in natural microbial communities. In the third section, the ecological implications of sequenced microbial genomes are briefly discussed. Comparative analyses of prokaryotic genomic sequences suggest the importance of ecology in determining microbial genome size and gene content. The significant variability in genome size and gene content among strains and species of prokaryotes indicate the highly fluid nature of prokaryotic genomes, a result consistent with those from multilocus sequence typing and representational difference analyses. The integration of various levels of ecological analyses coupled to the application and further development of high throughput technologies are accelerating the pace of discovery in microbial ecology.

DNA, Ribosomal↗

Ecological-economic modeling for biodiversity management: potential, pitfalls, and prospects.

Ecologists and economists both use models to help develop strategies for biodiversity management. The practical use of disciplinary models, however can be limited because ecological models tend not to address the socioeconomic dimension of biodiversity management, whereas economic models tend to neglect the ecological dimension. Given these shortcomings of disciplinary models, there is a necessity to combine ecological and economic knowledge into ecological-economic models. It is insufficient if scientists work separately in their own disciplines and combine their knowledge only when it comes to formulating management recommendations. Such an approach does not capture feedback loops between the ecological and the socioeconomic systems. Furthermore, each discipline poses the management problem in its own way and comes up with its own most appropriate solution. These disciplinary solutions, however, are likely to be so different that a combined solution considering aspects of both disciplines cannot be found. Preconditions for a successful model-based integration of ecology and economics include (1) an in-depth knowledge of the two disciplines, (2) the adequate identification and framing of the problem to be investigated, and (3) a common understanding between economists and ecologists of modeling and scale. To further advance ecological-economic modeling the development of common benchmarks, quality controls, and refereeing standards for ecological-economic models is desirable.

Biodiversity↗

Issues in ecological risk assessment: the CRAM perspective.

In 1989, a Committee on Risk Assessment Methodology (CRAM) was convened by the National Research Council (NRC) to identify and investigate important scientific issues in risk assessment. One of the first issues considered by the committee was the development of a conceptual framework for ecological risk assessment, defined as "the characterization of the adverse ecological effects of environmental exposures to hazards imposed by human activities." Adverse ecological effects include all biological and nonbiological environmental changes that society perceives as undesirable. The committee's opinion was that a general framework is needed to define the relationship of ecological risk assessment to environmental management and to facilitate the development of uniform technical guidelines. The framework for human health risk assessment proposed by the NRC in 1983 was adopted as a starting point for discussion. CRAM concluded that, although ecological risk assessment and human health risk assessment differ substantially in terms of scientific disciplines and technical problems, the underlying decision process is the same for both. Therefore, CRAM recommended that the 1983 risk assessment framework be modified to accommodate both human health and ecological risk assessment. CRAM defined an integrated health/ecological risk assessment framework consisting of the four components: Hazard Identification, Exposure Assessment, Exposure-Response Assessment, and Risk Characterization. CRAM further provided recommendations on the scope of issues to be addressed in ecological risk assessment, critical research needs, and mechanisms for providing more detailed guidance on the scientific content of ecological risk assessments.

Ecology↗

The semi-individual study in air pollution epidemiology: a valid design as compared to ecologic studies.

The assessment of long-term effects of air pollution in humans relies on epidemiologic studies. A widely used design consists of cross-sectional or cohort studies in which ecologic assignment of exposure, based on a fixed-site ambient monitor, is employed. Although health outcome and usually a large number of covariates are measured in individuals, these studies are often called ecological. We will introduce the term semi-individual design for these studies. We review the major properties and limitations with regard to causal inference of truly ecologic studies, in which outcome, exposure, and covariates are available on an aggregate level only. Misclassification problems and issues related to confounding and model specification in truly ecologic studies limit etiologic inference to individuals. In contrast, the semi-individual study shares its methodological and inferential properties with typical individual-level study designs. The major caveat relates to the case where too few study areas, e.g., two or three, are used, which render control of aggregate level confounding impossible. The issue of exposure misclassification is of general concern in epidemiology and not an exclusive problem of the semi-individual design. In a multicenter setting, the semi-individual study is a valuable tool to approach long-term effects of air pollution. Knowledge about the error structure of the ecologically assigned exposure allows consideration of the impact of ecologically assigned exposure on effect estimation. Semi-individual studies, i.e., individual level air pollution studies with ecologic exposure assignment, more readily permit valid inference to individuals and should not be labeled as ecologic studies.

Air Pollutants↗

A framework for understanding ecological traps and an evaluation of existing evidence.

When an animal settles preferentially in a habitat within which it does poorly relative to other available habitats, it is said to have been caught in an "ecological trap." Although the theoretical possibility that animals may be so trapped is widely recognized, the absence of a clear mechanistic understanding of what constitutes a trap means that much of the literature cited as support for the idea may be weak, at best. Here, we develop a conceptual model to explain how an ecological trap might work, outline the specific criteria that are necessary for demonstrating the existence of an ecological trap, and provide tools for researchers to use in detecting ecological traps. We then review the existing literature and summarize the state of empirical evidence for the existence of traps. Our conceptual model suggests that there are two basic kinds of ecological traps and three mechanisms by which traps may be created. To this point in time, there are still only a few solid empirical examples of ecological traps in the published literature (although those few examples suggest that both types of traps and all three of the predicted mechanisms do exist in nature). Therefore, ecological traps are either rare in nature, are difficult to detect, or both. An improved library of empirical studies will be essential if we are to develop a more synthetic understanding of the mechanisms that can trigger maladaptive behavior in general and the specific conditions under which ecological traps might occur.

Adaptation, Physiological↗

Sensitivity of ecological models to their climate drivers: statistical ensembles for forcing.

Global and regional numerical models for terrestrial ecosystem dynamics require fine spatial resolution and temporally complete historical climate fields as input variables. However, because climate observations are unevenly spaced and have incomplete records, such fields need to be estimated. In addition, uncertainty in these fields associated with their estimation are rarely assessed. Ecological models are usually driven with a geostatistical model's mean estimate (kriging) of these fields without accounting for this uncertainty, much less evaluating such errors in terms of their propagation in ecological simulations. We introduce a Bayesian statistical framework to model climate observations to create spatially uniform and temporally complete fields, taking into account correlation in time and space, spatial heterogeneity, lack of normality, and uncertainty about all these factors. A key benefit of the Bayesian model is that it generates uncertainty measures for the generated fields. To demonstrate this method, we reconstruct historical monthly precipitation fields (a driver for ecological models) on a fine resolution grid for a climatically heterogeneous region in the western United States. The main goal of this work is to evaluate the sensitivity of ecological models to the uncertainty associated with prediction of their climate drivers. To assess their numerical sensitivity to predicted input variables, we generate a set of ecological model simulations run using an ensemble of different versions of the reconstructed fields. We construct such an ensemble by sampling from the posterior predictive distribution of the climate field. We demonstrate that the estimated prediction error of the climate field can be very high. We evaluate the importance of such errors in ecological model experiments using an ensemble of historical precipitation time series in simulations of grassland biogeochemical dynamics with an ecological numerical model, Century. We show how uncertainty in predicted precipitation fields is propagated into ecological model results and that this propagation had different modes. Depending on output variable, the response of model dynamics to uncertainty in inputs ranged from uncertainty in outputs that matched that of inputs to those that were muted or that were biased, as well as uncertainty that was persistent in time after input errors dropped.

Animals↗

Industrial ecology: a new perspective on the future of the industrial system.

Industrial ecology? A surprising, intriguing expression that immediately draws our attention. The spontaneous reaction is that "industrial ecology" is a contradiction in terms, something of an oxymoron, like "obscure clarity" or "burning ice". Why this reflex? Probably because we are accustomed to considering the industrial system as isolated from the Biosphere, with factories and cities on one side and nature on the other, as well as the recurrent problem of trying to minimise th impact of the industrial system on what is "beyond" it: its surroundings, the "environment". As early as the 1950's, this end-of-pipe angle was the one adopted by ecologists, whose first serious studies focused on the consequences of the various forms of pollution on nature. In this perspective on the industrial system, human industrial activity as such remained outside the field of research. Industrial ecology explores the opposite assumption: The industrial system can be seen as a certain kind of ecosystem. After all, the industrial system, just as natural ecosystems, can be described as a particular distribution of materials, energy, and information flows. Furthermore, the entire industrial system relies on resources and services provided by the Biosphere, from which it cannot be dissociated. (It should be specified that "industrial", in the context of industrial ecology, refers to all human activities occurring within modern technological society. Thus, tourism, housing, medical services, transportation, agriculture, etc. are part of the industrial system.) Besides its rigorous scientific conceptual framework (scientific ecology), industrial ecology can also be seen as a practical approach to sustainability. It is an attempt to address the question, "How can the concept of sustainable development be made operational in an economically feasible way?" Industrial ecology represents precisely one of the paths that could provide concrete solutions. Governments have traditionally approached development and environmental issues in a fragmented and compartmentalised way. This is illustrated in the classical end-of-pipe strategy for the treatment of pollution, which has proven to be quite useful, but not adequate to make an efficient use of limited resources, in the context of a growing population with increasing economic aspirations. Thus, industrial ecology emerges at a time when it is becoming increasingly clear that the traditional pollution treatment approach (end-of-pipe) is not only insufficient to solve environmental problems, but also too costly in the long run.

Ecology↗

[Ecological water requirement of forests in Loess Plateau].

Converting degraded farmlands to forest or grass lands is the best approach to reduce the soil erosion, the Loess Plateau is faced with most serious ecological disaster. Loess Plateau located in the arid and semi-arid regions is a fragile region with the characteristics of little precipitation and intensive evapotranspiration. Therefore, water is the most important factor limiting the eco-restoration and construction of the vegetation in the region. According to the latest digital land use map and with GIS, the ecological water requirement for forests in Loess Plateau was estimated, and by the water balance of the forest ecosystem in their growing season, the ecological water shortage was calculated. The results revealed that the minimum and suitable ecological water requirement of the forests in Loess Plateau were approximately 262.49 x 10(8) m3 and 421.34 x 10(8) m3 respectively. Accordingly, if it is taken the minimum ecological water requirement as the quota, the area of forests suffered water shortage was about 7,639.09 km2, 9.1% of all, and the ecological water shortage was amounted to 4.77 x 10(8) m3; if it is taken the suitable ecological water requirement as the quota, the forest land area suffered water shortage was about 57.7% of all, and the ecological water shortage was roughly 58.55 x 10(8) m3.

Altitude↗

[Adaptation and ecological resistance].

The notion fitness, widely used in genetics usually serves to measure a relative rate of organism reproduction. Another important character of an organism is its ecological resistance which is basically the product of macroevolution. It can be determined as a probability of an organism survival and participation in reproduction of the species. Ecological resistance determines the level of the accidental death of organisms that are genetically valuable. For the comparison of ecological resistance in different organisms and species the negative meanings of the Malthusian parameter can be used. Ecological resistance depends on the presence in genomes of essential genes and fairly complete sets of nonessential, or adaptive, genes which can reside in genomes both as "plus" and "minus" alleles. The recovery of complete sets of adaptive genes lost as a result of mutations and, thus, of a high level of ecological resistance in organisms is provided by genetic exchange between them. With respect to mutations leading to the increase in fitness the effect of genetic exchange is negative since it leads to the formation of recombination load, i.e. a decrease in fitness of the offspring. In microevolutionary processes, the elevation in ecological resistance level does not take place since it requires a long time for the formation of new genes and new elements of organization in the process of positive selection. At the same time, a constant recovery of a high level of ecological resistance of the species decreased as a result of mutations takes place in some individuals due to genetic exchange. Mutations affecting ecological resistance of an organism, as a rule, cause a decrease in its viability and they are usually excluded from populations as a result of negative (stabilizing) selection.

Adaptation, Physiological↗

[Linear consociation equation set model of forest ecological benefits].

Based on the similar irrelative model of forest ecological benefits, the study analyzed the subordinate relations of numerous ecological benefits, and introduced end genetic variables Y1 and Y2 as the independent variables of another ecological equation to construct consociation equation set model. Leading from the forest's water absorption benefits, it deeply depicted the dependent and subordinate relations between the forest ecological benefits dependent variable set. Starting from the basic rule of forest ecological benefits, constructed the consociation equation set structure parameters matrix B and gamma restricted by parameter to get linear limit equation HA = L, which is the key to the forest ecological benefits consociation equation set. Especially, the study on the non-linear relation of forest ecological benefits dependent and independent variable was the foundation of forest ecological benefits consociation equation set. The model was excessiveness identified and error structure matrix, not cross matrix. The forest absorbing water and stabling soil and keeping fertilizer and defending sand benefits estimate equations were gotten through the three steps least square estimation method with Matlab program, and the average precision was more than 80%. From this method, the whole country forest absorbing water benefit was estimated as 4.7 x 10(8) t, forest fixing soil benefits was 39 x 10(8) t, forest keeping fertilizer benefit was 4.7 x 10(8) t and defending sand benefits was 22.8 x 10(8) t.

Conservation of Natural Resources↗

[Ecological niches of ectoparasites].

On mammals and birds communities of ectoparasites are present, which can include scores of ticks, mites and insects species. The parasitizing of arthropods terrestrial vertebrates appeared as far back a the Cretaceous period, and after 70-100 mil. years of the coevolution ectoparasites have assimilated all food resources and localities of the hosts' bodies. To the present only spatial and (to the less extent) trophic niches of parasitic insects, ticks and mites are studied completely enough. The main results these investigations are discussed in the present paper. A high abundance of the communities is reached because of their partition into the number of ecological niches. Host is complex of ecological niches for many ectoparasites species. These niches reiterate in the populations of a species closely related species of hosts and repeat from generation to generation. The each part of host (niche) being assimilated be certain parasite species is available potentially for other species. The partition of host into ecological niches is clearer than the structure of ecosystems including free-living organisms. A real extent of the ecological niches occupation by different species of ticks, mites and insects is considerably lower than a potential maximum. The degree of ecological niches saturation depends on the history of the coevolution of parasites community components, previous colonization be new ectoparasite species and many other ecological factors affecting host-parasite system. The use of the ecological niche conception in parasitology is proved to be rather promising. Ectoparasites communities because of their species diversity, different types of feeding and a number of habitats on host represent convenient models and study of them can contribute significantly to the developmeht of the general conception of ecological niche.

Animals↗

[Ecological functional regionalization of Changsha City based on RS and GIS].

A delineation method based on the idea of regarding urban-suburban-supporting area as a system was presented in this paper, with an ecological-social-economic database created. A total of five ecological suitability regions, four ecological sensitivity regions, four ecological service regions, and five economic development regions were plotted out, and the Changsha City ecosystem was divided into five ecological functional regions, according to the heterogeneity among ecological functional units and the similarity of interior units. The areas of the five functional regions accounted for 29.47%, 32.5%, 25.95%, 9.63% and 2.45% of the total area, respectively. This research method had some advantages over traditional methods. It was flexible and efficient, because it could accept any combination of parameters organized on a polygonal base map. The variables could be added, deleted, or updated to produce new thematic map products in a short period of time. Mapping procedures were quantitative and automated. With the incorporation of remote sensing data and global position system rapid positioning, the ecological and environmental changes could be detected by monitoring the changes of regional boundary patterns. Therefore, the ecological functional regionalization of Changsha City provided a fine way of integrating remote sensing data, global position system, and geographic information system.

China↗