Ecological units: definitions and application

Concepts of ecological units, such as population, community, and ecosystem, are at the basis of ecological theory and research and have increasingly become the focus of conservation strategies. Concepts of these units still suffer from inconsistencies and confusions over terminology. The different concepts are treated here together as a common "conceptual cluster," with similar ecological functions (roles) and similar problems in their definition and use. An analysis of the multitude of existing terms and concepts that have been developed for these units reveals that they differ with respect to at least four basic criteria: (i) the questions as to whether they are defined statistically or via a network of interactions; (ii) if their boundaries are drawn by topographical or process-related criteria; (iii) how high the required internal relationships are; and (iv) if they are perceived as "real" entities or abstractions by an observer The various definitions cannot be easily sorted into just a few types, but they can be characterized by several independent criteria. I argue that serious problems arise if the different possibilities of defining ecological units are not recognized and if the concepts are perceived as self-evident. The different concepts of ecological units should be defined and used in a philosophically informed manner I propose a dual approach to the use of ecological units. Generic meanings of the main concepts (especially population, community, and ecosystem) should be retained only as heuristically useful perspectives, while specific and "operational" definitions of the concepts as units should be developed, depending on specific purposes of their use. Some thoughts on the basic requirements for such definitions and the domains of their uses are briefly explained.     

What is cyclomorphosis?

1. The history of the term cyclomorphosis and of research investigating the phenomenon it describes are reviewed briefly.
2. Several distinct definitions of this term appear in the limnological literature. Some of these definitions are consistent with earlier studies; others are not and are very restrictive and reliant upon extensive laboratory analysis.
3. We argue for the adoption of a broad definition of cyclomorphosis that is consistent with the majority of previous studies and practical to apply to the field populations it attempts to describe.
4. We also urge all researchers investigating this phenomenon to provide their working definition of this term in their reports in order to avoid terminological confusion.     

Coming to Terms with the Concept of Moving Species Threatened by Climate Change – A Systematic Review of the Terminology and Definitions

Intentional moving of species threatened by climate change is actively being discussed as a conservation approach. The debate, empirical studies, and policy development, however, are impeded by an inconsistent articulation of the idea. The discrepancy is demonstrated by the varying use of terms, such as assisted migration, assisted colonisation, or managed relocation, and their multiple definitions. Since this conservation approach is novel, and may for instance lead to legislative changes, it is important to aim for terminological consistency. The objective of this study is to analyse the suitability of terms and definitions used when discussing the moving of organisms as a response to climate change. An extensive literature search and review of the material (868 scientific publications) was conducted for finding hitherto used terms (N = 40) and definitions (N = 75), and these were analysed for their suitability. Based on the findings, it is argued that an appropriate term for a conservation approach relating to aiding the movement of organisms harmed by climate change is assisted migration defined as follows: Assisted migration means safeguarding biological diversity through the translocation of representatives of a species or population harmed by climate change to an area outside the indigenous range of that unit where it would be predicted to move as climate changes, were it not for anthropogenic dispersal barriers or lack of time. The differences between assisted migration and other conservation translocations are also discussed. A wide adoption of the clear and distinctive term and definition provided would allow more focused research on the topic and enable consistent implementation as practitioners could have the same understanding of the concept.     

流域生态学的发展困境——来自河流景观的启示

随着中国生态环境问题越来越多地呈现出流域特性,流域生态研究的重要性和紧迫性也日渐凸显。整合流域生态研究,形成一个有效的研究体系,流域生态学迄今未能予以实现。通过对"流域生态学"和"河流景观"这两个相近概念提出过程的比较研究,探讨流域生态学发展困境产生的原因,为流域生态研究体系的构建提供思路。分析结果显示流域生态学目前主要存在两个不足:1)因为提出流域生态学概念的关键现实需求不明确,导致难以确定其核心科学问题;2)因为没有相应的流域生态系统概念模型,进而也就难以带动相关研究落实跟进。要推进流域生态学的发展,第一步要做的就是明确流域生态研究体系构建的核心现实需求,并对流域生态系统进行一个概念模型上的相应设计。     

The conceptualisation of health and disease in veterinary medicine

Background  

The concept of health, as well as the concept of disease, is central in veterinary medicine. However, the definitions "health" and "disease" are not generally acknowledged by veterinarians. The aim of this study was to examine how the concepts "health" and "disease" are defined in veterinary textbooks.     

On the revised concept of linear energy transfer

The quantities linear energy transfer or restricted linear energy transfer are utilized in calculations that link absorbed dose to the fluence distribution of a radiation field. The computations provide approximations to absorbed dose in terms of the intermediate quantity cema or reduced cema. With the definition of the restricted linear energy transfer,L , given in ICRU Report 33, the approximation remains imperfect. This study deals with the resulting need for a modified definition ofL , as proposed in a draft report of ICRU. Essential differences between the old and the new definitions are demonstrated. The changed definition permits a rigorous formulation of the dependence between fluence and absorbed dose.     

Terminology of a computer network: notes of a non-epidemiologist

In the development of discussion on epidemiological terms containing definitions "epidemic" and "epidemiological" variants of these terms as used in electronic documents placed on Internet sites are considered. Both most common combinations and contradictions in the use of some terminological constructions are presented.     

On microrefugia and cryptic refugia

The existence of microrefugia and/or cryptic refugia has been proposed to explain the colonization patterns of temperate continents after the Last Glacial Maximum, as well as to gain an understanding of the present genetic structure of species and their populations. The concepts ‘microrefugia’ and ‘cryptic refugia’ largely overlap but do not fully coincide, which may lead to terminological duplication and eventual semantic misconceptions. Here, after a terminological and conceptual analysis, it is proposed that most situations currently characterized as cryptic refugia can be accommodated within the definition of microrefugia, with one single exception, for which some alternative terms are suggested. Moreover, the concept and definition of cryptic refugia are considered to be more imprecise, perishable and subjective than those of microrefugia, which is the preferred term in the current context.     

What biological invasions ‘are’ is a matter of perspective

Invasion research today integrates active fields like biogeography, nature conservation, ecology, and evolutionary biology, and each of these fields contributes its own conceptual and terminological background. In this essay we advance the view that this is the reason why discussions on terminology keep flaring up time and time again. Our basic argument is that biological invasions cannot be perceived and defined independent of the specific research motivation. There are different, but equally valuable perspectives on biological invasions, each entailing a specific opinion about what the peculiarity of invasions is. We argue that a uniform usage of terms is not feasible, and even not desirable for invasion research, and suggest that the existing plurality of terms and concepts should be taken as an incentive to discuss the implications of different definitions. A stronger awareness and acknowledgement of the concepts underlying the terms used in interrelated research fields will enhance communication and promote progress in invasion research towards integrative, problem-oriented transdisciplinarity.     

Mapping data elements to terminological resources for integrating biomedical data sources

Background

Data integration is a crucial task in the biomedical domain and integrating data sources is one approach to integrating data. Data elements (DEs) in particular play an important role in data integration. We combine schema- and instance-based approaches to mapping DEs to terminological resources in order to facilitate data sources integration.

Methods

We extracted DEs from eleven disparate biomedical sources. We compared these DEs to concepts and/or terms in biomedical controlled vocabularies and to reference DEs. We also exploited DE values to disambiguate underspecified DEs and to identify additional mappings.

Results

82.5% of the 474 DEs studied are mapped to entries of a terminological resource and 74.7% of the whole set can be associated with reference DEs. Only 6.6% of the DEs had values that could be semantically typed.

Conclusion

Our study suggests that the integration of biomedical sources can be achieved automatically with limited precision and largely facilitated by mapping DEs to terminological resources.

     

Assessment of Heat-Related Health Impacts in Brisbane,Australia: Comparison of Different Heatwave Definitions

Background

There is no global definition of a heatwave because local acclimatisation and adaptation influence the impact of extreme heat. Even at a local level there can be multiple heatwave definitions, based on varying temperature levels or time periods. We investigated the relationship between heatwaves and health outcomes using ten different heatwave definitions in Brisbane, Australia.

Methodology/Principal Findings

We used daily data on climate, air pollution, and emergency hospital admissions in Brisbane between January 1996 and December 2005; and mortality between January 1996 and November 2004. Case-crossover analyses were used to assess the relationship between each of the ten heatwave definitions and health outcomes. During heatwaves there was a statistically significant increase in emergency hospital admissions for all ten definitions, with odds ratios ranging from 1.03 to 1.18. A statistically significant increase in the odds ratios of mortality was also found for eight definitions. The size of the heat-related impact varied between definitions.

Conclusions/Significance

Even a small change in the heatwave definition had an appreciable effect on the estimated health impact. It is important to identify an appropriate definition of heatwave locally and to understand its health effects in order to develop appropriate public health intervention strategies to prevent and mitigate the impact of heatwaves.     

A Complex-Systems Approach to Pastoral Commons

In recent years a new approach has begun to emerge in commons scholarship that draws on complex systems thinking and that makes use of concepts such as fit, scale, and the adaptive renewal cycle. This paper explores what complex systems thinking has to offer for commons scholarship by applying these concepts to the pastoral commons of the Gabra ethnic group of north-central Kenya. The concepts of fit and scale can help us to understand why some features of the institutional regime of the Gabra do not conform to mainstream principles such as clearly defined boundaries, clearly defined membership rules, and subsidiarity. The notion of the adaptive renewal cycle can help us to describe and understand some aspects of dynamics of Gabra institutions, especially those related to the management of shallow wells. Applying the adaptive renewal cycle to larger and longer scales highlights the possibility that the Gabra social–ecological system is becoming increasingly brittle, with evolving institutional arrangements putting more and more constraints on adaptation and especially on nomadic mobility. An examination of the distinctive nature of dryland pastoral commons, and in particular a complex systems approach to this examination, suggests a number of issues that relief and development organizations should consider, including how to foster novelty and innovation through all the phases of the adaptive cycle.

Philopatry in the alpine grasshopper, Podisma pedestris: a novel experimental and analytical method

Abstract.

• 1 Local dispersal and philopatric behaviour of the alpine grasshopper, Podisma pedestris, were studied at two sites in the Alpes Maritimes using a new mark—release—resight technique featuring marking in situ, and multiple resighting without handling. The time-consuming nature of the design was justified by the quantity and quality of the data yielded.
• 2 Philopatry is defined independently of any concept of home range as a phenomenon by which movements over longer periods are less than would be expected by extrapolation of measures over shorter periods.
• 3 By this definition, the grasshoppers are shown to exhibit philopatry. Nymphs comprise two heterogenous classes of those which move little and those which move considerable distances.
• 4 Daily dispersal estimates were obtained from movements of 1055 nymphs and adults at one site, and of 593 adults at another.
• 5 Differences are demonstrated in daily dispersal distances for age, sex and site combinations.
• 6 Some differences in microhabitat preference were observed.
• 7 The findings are compared with previous measurements of dispersal in this species, and the merits of the new technique are discussed.

     

Toward consistent definitions for preload and afterload

Significant differences exist among textbook definitions for the terms preload and afterload, leading to confusion and frustration among students and faculty alike. Many faculty also chose to use in their teaching simple terms such as "end-diastolic volume" or "aortic pressure" as common-usage approximations of preload and afterload, respectively, but these are only partial representations of these important concepts. Straightforward definitions both of preload and afterload that are concise yet still comprehensive can be developed using the Law of LaPlace to describe the relationships among chamber pressure, chamber radius, and wall thickness. Within this context, the term "preload" can be defined as all of the factors that contribute to passive ventricular wall stress (or tension) at the end of diastole, and the term "afterload" can be defined as all of the factors that contribute to total myocardial wall stress (or tension) during systolic ejection. The inclusion of "wall stress" in both definitions helps the student appreciate both the complexities of cardiac pathophysiology and the rationale for therapeutic intervention.     

Evolution,reproduction and definition of life

Synthetic theory of evolution is a superior integrative biological theory. Therefore, there is nothing surprising about the fact that multiple attempts of defining life are based on this theory. One of them even has a status of NASA’s working definition. According to this definition, ‘life is a self-sustained chemical system capable of undergoing Darwinian evolution’ Luisi (Orig Life Evol Bios 28:613–622, 1998); Cleland, Chyba (Orig Life Evol Bios 32:387–393, 2002). This definition is often considered as one of the more theoretically mature definitions of life. This Darwinian definition has nonetheless provoked a lot of criticism. One of the major arguments claims that this definition is wrong due to ‘mule’s problem’. Mules (and other infertile hybrids), despite being obviously living organisms, in the light of this definition are considered inanimate objects. It is strongly counterintuitive. The aim of this article was to demonstrate that this reasoning is false. In the later part of the text, I also discuss some other arguments against the Darwinian approach to defining life.     

Toward a Practical Ontology for Socioeconomic Metabolism

The complexity of data and methods in industrial ecology (IE) keeps growing, and the demand for comprehensive and interdisciplinary assessments increases. To keep up with this development, the field needs a data infrastructure that allows researchers to annotate, store, retrieve, combine, and exchange data at low cost, without loss of information, and across disciplines and model frameworks. A consensus‐building debate about how to describe the common object of study, socioeconomic metabolism (SEM), is necessary for the development of practical data structures and databases. We review the definitions of basic concepts to describe SEM in IE and related fields such as integrated assessment modeling. We find that many definitions are not compatible, are implicit, and are sometimes lacking. To resolve the conflicts and inconsistencies within the current definitions, we propose a hierarchical system of terms and definitions, a practical ontology, for describing objects, their properties, and events in SEM. We propose a typology of object properties and use sets to group objects into a hierarchical, mutually exclusive, and collectively exhaustive (H‐MECE) classification. This grouping leads to a general definition of stocks. We show that a MECE representation of events necessarily requires two complementary concepts: processes and flows, for which we propose general definitions based on sets. Using these definitions, we show that the system structure of any interdisciplinary model of SEM can be formulated as a directed graph. We propose guidelines for semantic data annotation and database design, which can help to turn the vision of a powerful data infrastructure for SEM research into reality.     

Phylogenetic definitions and taxonomic philosophy

An examination of the post-Darwinian history of biological taxonomy reveals an implicit assumption that the definitions of taxon names consist of lists of organismal traits. That assumption represents a failure to grant the concept of evolution a central role in taxonomy, and it causes conflicts between traditional methods of defining taxon names and evolutionary concepts of taxa. Phylogenetic definitions of taxon names (de Queiroz and Gauthier 1990) grant the concept of common ancestry a central role in the definitions of taxon names and thus constitute an important step in the development of phylogenetic taxonomy. By treating phylogenetic relationships rather than organismal traits as necessary and sufficient properties, phylogenetic definitions remove conflicts between the definitions of taxon names and evolutionary concepts of taxa. The general method of definition represented by phylogenetic definitions of clade names can be applied to the names of other kinds of composite wholes, including populations and biological species. That the names of individuals (composite wholes) can be defined in terms of necessary and sufficient properties provides the foundation for a synthesis of seemingly incompatible positions held by contemporary individualists and essentialists concerning the nature of taxa and the definitions of taxon names.