Showing papers in "Trends in Ecology and Evolution in 2010"
TL;DR: The nature and extent of reported declines, and the potential drivers of pollinator loss are described, including habitat loss and fragmentation, agrochemicals, pathogens, alien species, climate change and the interactions between them are reviewed.
Abstract: Pollinators are a key component of global biodiversity, providing vital ecosystem services to crops and wild plants. There is clear evidence of recent declines in both wild and domesticated pollinators, and parallel declines in the plants that rely upon them. Here we describe the nature and extent of reported declines, and review the potential drivers of pollinator loss, including habitat loss and fragmentation, agrochemicals, pathogens, alien species, climate change and the interactions between them. Pollinator declines can result in loss of pollination services which have important negative ecological and economic impacts that could significantly affect the maintenance of wild plant diversity, wider ecosystem stability, crop production, food security and human welfare.
4,608 citations
TL;DR: Here, it is outlined how central ideas in behavioural ecology and quantitative genetics can be combined within a single framework based on the concept of 'behavioural reaction norms', facilitating analysis of phenomena usually studied separately in terms of personality and plasticity, thereby enhancing understanding of their adaptive nature.
Abstract: Recent studies in the field of behavioural ecology have revealed intriguing variation in behaviour within single populations. Increasing evidence suggests that individual animals differ in their average level of behaviour displayed across a range of contexts (animal 'personality'), and in their responsiveness to environmental variation (plasticity), and that these phenomena can be considered complementary aspects of the individual phenotype. How should this complex variation be studied? Here, we outline how central ideas in behavioural ecology and quantitative genetics can be combined within a single framework based on the concept of 'behavioural reaction norms'. This integrative approach facilitates analysis of phenomena usually studied separately in terms of personality and plasticity, thereby enhancing understanding of their adaptive nature.
1,287 citations
TL;DR: In this article, the authors suggest mechanisms for encouraging "wildlife-friendly" management of collections of gardens across scales from the neighbourhood to the city, where the individual garden is much smaller than the unit of management needed to retain viable populations.
Abstract: As urbanisation increases globally and the natural environment becomes increasingly fragmented, the importance of urban green spaces for biodiversity conservation grows. In many countries, private gardens are a major component of urban green space and can provide considerable biodiversity benefits. Gardens and adjacent habitats form interconnected networks and a landscape ecology framework is necessary to understand the relationship between the spatial configuration of garden patches and their constituent biodiversity. A scale-dependent tension is apparent in garden management, whereby the individual garden is much smaller than the unit of management needed to retain viable populations. To overcome this, here we suggest mechanisms for encouraging 'wildlife-friendly' management of collections of gardens across scales from the neighbourhood to the city.
1,234 citations
TL;DR: This work proposes a framework based on ideas from global-change biology, community ecology, and invasion biology that uses community modules to assess how species interactions shape responses to climate change.
Abstract: Predicting the impacts of climate change on species is one of the biggest challenges that ecologists face Predictions routinely focus on the direct effects of climate change on individual species, yet interactions between species can strongly influence how climate change affects organisms at every scale by altering their individual fitness, geographic ranges and the structure and dynamics of their community Failure to incorporate these interactions limits the ability to predict responses of species to climate change We propose a framework based on ideas from global-change biology, community ecology, and invasion biology that uses community modules to assess how species interactions shape responses to climate change
1,169 citations
TL;DR: It is argued that the use of ABC should incorporate all aspects of Bayesian data analysis: formulation, fitting, and improvement of a model if these principles are carefully applied.
Abstract: Understanding the forces that influence natural variation within and among populations has been a major objective of evolutionary biologists for decades. Motivated by the growth in computational power and data complexity, modern approaches to this question make intensive use of simulation methods. Approximate Bayesian Computation (ABC) is one of these methods. Here we review the foundations of ABC, its recent algorithmic developments, and its applications in evolutionary biology and ecology. We argue that the use of ABC should incorporate all aspects of Bayesian data analysis: formulation, fitting, and improvement of a model. ABC can be a powerful tool to make inferences with complex models if these principles are carefully applied.
1,154 citations
ETH Zurich1, Swiss Federal Institute of Aquatic Science and Technology2, University of Maryland, Baltimore3, University College Cork4, University of Le Havre5, Swedish University of Agricultural Sciences6, Lancaster University7, Colorado State University8, Centre national de la recherche scientifique9
TL;DR: It is suggested that changes in species diversity within and across trophic levels can significantly alter decomposition and this happens through various mechanisms that are broadly similar in forest floors and streams.
Abstract: Over 100 gigatons of terrestrial plant biomass are produced globally each year. Ninety percent of this biomass escapes herbivory and enters the dead organic matter pool, thus supporting complex detritus-based food webs that determine the critical balance between carbon mineralization and sequestration. How will changes in biodiversity affect this vital component of ecosystem functioning? Based on our analysis of concepts and experiments of leaf decomposition in forest floors and streams, we suggest that changes in species diversity within and across trophic levels can significantly alter decomposition. This happens through various mechanisms that are broadly similar in forest floors and streams. Differences in diversity effects between these systems relate to divergent habitat conditions and evolutionary trajectories of aquatic and terrestrial decomposers.
1,027 citations
TL;DR: Recent theory on how plasticity promotes: (i) the origin of novel phenotypes, (ii) divergence among populations and species, (iii) the formation of new species and (iv) adaptive radiation is reviewed.
Abstract: Phenotypic plasticity (the ability of a single genotype to produce multiple phenotypes in response to variation in the environment) is commonplace. Yet its evolutionary significance remains controversial, especially in regard to whether and how it impacts diversification and speciation. Here, we review recent theory on how plasticity promotes: (i) the origin of novel phenotypes, (ii) divergence among populations and species, (iii) the formation of new species and (iv) adaptive radiation. We also discuss the latest empirical support for each of these evolutionary pathways to diversification and identify potentially profitable areas for future research. Generally, phenotypic plasticity can play a largely underappreciated role in driving diversification and speciation.
998 citations
TL;DR: Learning how to avoid undesirable phase-shifts, and how to reverse them when they occur, requires an urgent reform of scientific approaches, policies, governance structures and coral reef management.
Abstract: Phase-shifts from one persistent assemblage of species to another have become increasingly commonplace on coral reefs and in many other ecosystems due to escalating human impacts. Coral reef science, monitoring and global assessments have focused mainly on producing detailed descriptions of reef decline, and continue to pay insufficient attention to the underlying processes causing degradation. A more productive way forward is to harness new theoretical insights and empirical information on why some reefs degrade and others do not. Learning how to avoid undesirable phase-shifts, and how to reverse them when they occur, requires an urgent reform of scientific approaches, policies, governance structures and coral reef management.
944 citations
University of Alaska Fairbanks1, University of Wisconsin-Madison2, Stockholm Resilience Centre3, Royal Swedish Academy of Sciences4, Commonwealth Scientific and Industrial Research Organisation5, Harvard University6, University of California, Santa Barbara7, University of Manitoba8, United States Forest Service9, Stanford University10, Simon Fraser University11, Australian National University12
TL;DR: All social-ecological systems are vulnerable to recent and projected changes but have sources of adaptive capacity and resilience that can sustain ecosystem services and human well-being through active ecosystem stewardship.
Abstract: Ecosystem stewardship is an action-oriented framework intended to foster the social-ecological sustainability of a rapidly changing planet. Recent developments identify three strategies that make optimal use of current understanding in an environment of inevitable uncertainty and abrupt change: reducing the magnitude of, and exposure and sensitivity to, known stresses; focusing on proactive policies that shape change; and avoiding or escaping unsustainable social-ecological traps. As we discuss here, all social-ecological systems are vulnerable to recent and projected changes but have sources of adaptive capacity and resilience that can sustain ecosystem services and human well-being through active ecosystem stewardship.
848 citations
TL;DR: A broad range of findings that indicate the potential severity of this threat to diverse taxa, and recent studies that document substantial changes in foraging and anti-predator behavior, reproductive success, density and community structure in response to noise are reviewed.
Abstract: Growth in transportation networks, resource extraction, motorized recreation and urban development is responsible for chronic noise exposure in most terrestrial areas, including remote wilderness sites. Increased noise levels reduce the distance and area over which acoustic signals can be perceived by animals. Here, we review a broad range of findings that indicate the potential severity of this threat to diverse taxa, and recent studies that document substantial changes in foraging and anti-predator behavior, reproductive success, density and community structure in response to noise. Effective management of protected areas must include noise assessment, and research is needed to further quantify the ecological consequences of chronic noise exposure in terrestrial environments.
805 citations
TL;DR: Attention is called on to the urgent need to study the role of sound in the lives of fish and to develop a better understanding of the ecological impact of anthropogenic noise.
Abstract: The underwater environment is filled with biotic and abiotic sounds, many of which can be important for the survival and reproduction of fish. Over the last century, human activities in and near the water have increasingly added artificial sounds to this environment. Very loud sounds of relatively short exposure, such as those produced during pile driving, can harm nearby fish. However, more moderate underwater noises of longer duration, such as those produced by vessels, could potentially impact much larger areas, and involve much larger numbers of fish. Here we call attention to the urgent need to study the role of sound in the lives of fish and to develop a better understanding of the ecological impact of anthropogenic noise.
TL;DR: This review emphasises the unusual opportunities and productivity of long-term, individual-based studies and documents the important role that they play in research on ecology and evolutionary biology as well as the difficulties they face.
Abstract: Many important questions in ecology and evolutionary biology can only be answered with data that extend over several decades and answering a substantial proportion of questions requires records of the life histories of recognisable individuals. We identify six advantages that long-term, individual based studies afford in ecology and evolution: (i) analysis of age structure; (ii) linkage between life history stages; (iii) quantification of social structure; (iv) derivation of lifetime fitness measures; (v) replication of estimates of selection; (vi) linkage between generations, and we review their impact on studies in six key areas of evolution and ecology. Our review emphasises the unusual opportunities and productivity of long-term, individual-based studies and documents the important role that they play in research on ecology and evolutionary biology as well as the difficulties they face.
TL;DR: Methods of evaluating change in biodiversity at the community level using long-term datasets are reviewed, and whole-community approaches with those that combine information from different species and habitats are contrasted.
Abstract: The growing need for baseline data against which efforts to reduce the rate of biodiversity loss can be judged highlights the importance of long-term datasets, some of which are as old as ecology itself. We review methods of evaluating change in biodiversity at the community level using these datasets, and contrast whole-community approaches with those that combine information from different species and habitats. As all communities experience temporal turnover, one of the biggest challenges is distinguishing change that can be attributed to external factors, such as anthropogenic activities, from underlying natural change. We also discuss methodological issues, such as false alerts and modifications in design, of which users of these data sets need to be aware.
TL;DR: Evidence for the hypothesis that CIDs in energy metabolism, as reflected by resting metabolic rate (RMR), promote CID in behavior patterns that either provide net energy and consume energy, and a framework for linking together RMR, behavior, and life-history productivity is provided.
Abstract: Consistent individual differences (CIDs) in behavior are a widespread phenomenon in animals, but the proximate reasons for them are unresolved. We discuss evidence for the hypothesis that CIDs in energy metabolism, as reflected by resting metabolic rate (RMR), promote CIDs in behavior patterns that either provide net energy (e.g. foraging activity), and/or consume energy (e.g. courtship activity). In doing so, we provide a framework for linking together RMR, behavior, and life-history productivity. Empirical studies suggest that RMR is (a) related to the capacity to generate energy, (b) repeatable, and (c) correlated with behavioral output (e.g. aggressiveness) and productivity (e.g. growth). We conclude by discussing future research directions to clarify linkages between behavior and energy metabolism in this emerging research area.
TL;DR: This work expands and integrates qualitative conceptual models of plant niche and feedback to explore implications of microbial interactions for understanding plant community ecology and applies this model to understanding plant coexistence, monodominance and invasion ecology.
Abstract: Predominant frameworks for understanding plant ecology have an aboveground bias that neglects soil micro-organisms. This is inconsistent with recent work illustrating the importance of soil microbes in terrestrial ecology. Microbial effects have been incorporated into plant community dynamics using ideas of niche modification and plant–soil community feedbacks. Here, we expand and integrate qualitative conceptual models of plant niche and feedback to explore implications of microbial interactions for understanding plant community ecology. At the same time we review the empirical evidence for these processes. We also consider common mycorrhizal networks, and propose that these are best interpreted within the feedback framework. Finally, we apply our integrated model of niche and feedback to understanding plant coexistence, monodominance and invasion ecology.
TL;DR: This miniature ocean can serve as a giant mesocosm of the world's oceans, with various sources of disturbances interacting synergistically and therefore providing an insight into a major unknown: how resilient are marine ecosystems, and how will their current functioning be modified.
Abstract: Little doubt is left that climate change is underway, strongly affecting the Earth's biodiversity. Some of the greatest challenges ahead concern the marine realm, but it is unclear to what extent changes will affect marine ecosystems. The Mediterranean Sea could give us some of the answers. Data recovered from its shores and depths have shown that sea temperatures are steadily increasing, extreme climatic events and related disease outbreaks are becoming more frequent, faunas are shifting, and invasive species are spreading. This miniature ocean can serve as a giant mesocosm of the world's oceans, with various sources of disturbances interacting synergistically and therefore providing an insight into a major unknown: how resilient are marine ecosystems, and how will their current functioning be modified?
TL;DR: How next generation sequencing (NGS) has transformed their ability to identify the genes underpinning adaptation is summarized to demonstrate how the application of these genomic tools to ecological model species means that the authors can start addressing some of the questions that have puzzled ecological geneticists for decades.
Abstract: Understanding the genetics of how organisms adapt to changing environments is a fundamental topic in modern evolutionary ecology. The field is currently progressing rapidly because of advances in genomics technologies, especially DNA sequencing. The aim of this review is to first briefly summarise how next generation sequencing (NGS) has transformed our ability to identify the genes underpinning adaptation. We then demonstrate how the application of these genomic tools to ecological model species means that we can start addressing some of the questions that have puzzled ecological geneticists for decades such as: How many genes are involved in adaptation? What types of genetic variation are responsible for adaptation? Does adaptation utilise pre-existing genetic variation or does it require new mutations to arise following an environmental change?
TL;DR: A conceptual framework for biodiversity dynamics following environmental change is outlined that incorporates lags in extinction and immigration, which lead to extinction debt and immigration credit, respectively, which enable a balanced consideration of changes in biodiversity following climate change, habitat fragmentation and other forcing events.
Abstract: Here, we outline a conceptual framework for biodiversity dynamics following environmental change. The model incorporates lags in extinction and immigration, which lead to extinction debt and immigration credit, respectively. Collectively, these concepts enable a balanced consideration of changes in biodiversity following climate change, habitat fragmentation and other forcing events. They also reveal transient phenomena, such as biodiversity surpluses and deficits, which have important ramifications for biological conservation and the preservation of ecosystem services. Predicting such transient dynamics poses a serious conservation challenge in a time of rapid environmental change.
TL;DR: In a recent TREE article, Sutherland and colleagues used horizon scanning to identify fifteen emerging issues in biodiversity conservation, including invasive species, synthetic meat, nanosilver and microplastic pollution, but feel they overlooked an emerging problem of great importance and urgency, namely light pollution.
Abstract: In a recent TREE article, Sutherland and colleagues [1] used horizon scanning to identify fifteen emerging issues in biodiversity conservation. They discussed both threats and opportunities for a broad range of issues, including invasive species, synthetic meat, nanosilver and microplastic pollution. We recognize that the article was not intended to be comprehensive, but feel they overlooked an emerging problem of great importance and urgency, namely that of light pollution. Although the widespread use of artificial light at night has enhanced the quality of human life and is positively associated with security, wealth and modernity, the rapid global increase of artificial light has fundamentally transformed nightscapes over the past six decades, both in quantity (6% increase per year, range: 0–20%) and quality (i.e.
University of Cambridge1, Fauna & Flora International2, International Union for Conservation of Nature and Natural Resources3, University of Auckland4, Natural Environment Research Council5, University of California, Davis6, Royal Society for the Protection of Birds7, Cranfield University8, Natural Resources Wales9, Joint Nature Conservation Committee10, University of Essex11, Stockholm University12, Venezuelan Institute for Scientific Research13, The Nature Conservancy14, Wetlands International15, University of East Anglia16
TL;DR: The authors in this article presented the output of the fifth annual horizon-scanning exercise, which aims to identify topics that increasingly may affect conservation of biological diversity, but have yet to be widely considered.
Abstract: This paper presents the output of our fifth annual horizon-scanning exercise, which aims to identify topics that increasingly may affect conservation of biological diversity, but have yet to be widely considered. A team of professional horizon scanners, researchers, practitioners, and a journalist identified 15 topics which were identified via an iterative, Delphi-like process. The 15 topics include a carbon market induced financial crash, rapid geographic expansion of macroalgal cultivation, genetic control of invasive species, probiotic therapy for amphibians, and an emerging snake fungal disease.
TL;DR: Current knowledge about relationships between plant invasion and global change is reviewed, research needed to improve forecasts of invasion risk is highlighted, and managers should be prepared for both expansion and contraction of invasive plants due to global change.
Abstract: The relationship between plant invasions and global change is complex. Whereas some components of global change, such as rising CO2, usually promote invasion, other components, such as changing temperature and precipitation, can help or hinder plant invasion. Additionally, experimental studies and models suggest that invasive plants often respond unpredictably to multiple components of global change acting in concert. Such variability adds uncertainty to existing risk assessments and other predictive tools. Here, we review current knowledge about relationships between plant invasion and global change, and highlight research needed to improve forecasts of invasion risk. Managers should be prepared for both expansion and contraction of invasive plants due to global change, leading to increased risk or unprecedented opportunities for restoration.
TL;DR: Four possible non-exclusive explanations involving the role of volatiles are discussed: in direct defense, as within-plant signals, as traits that synergistically interact with other defenses, and as cues among kin.
Abstract: In spite of initial doubts about the reality of ‘talking trees’, plant resistance expression mediated by volatile compounds that come from neighboring plants is now well described. Airborne signals usually improve the resistance of the receiver, but without obvious benefits for the emitter, thus making the evolutionary explanation of this phenomenon problematic. Here, we discuss four possible non-exclusive explanations involving the role of volatiles: in direct defense, as within-plant signals, as traits that synergistically interact with other defenses, and as cues among kin. Unfortunately, there is a lack of knowledge on the fitness consequences of plant communication for both emitter and receiver. This information is crucial to understanding the ecology and evolution of plant communication via airborne cues.
Queen's University1, University of Pittsburgh2, Cornell University3, University of Ottawa4, Simon Fraser University5, Centre national de la recherche scientifique6, East Carolina University7, Dalhousie University8, University of Kansas9, University of Georgia10, Field Museum of Natural History11, University of Stirling12, Florida State University13
TL;DR: A meta-analysis of 22 studies involving 27 plant species shows a significant reduction in the proportion of seeds outcrossed in response to anthropogenic habitat modifications, and whether reproductive assurance through selfing effectively compensates for reduced outcrossing is discussed.
Abstract: There is increasing evidence that human disturbance can negatively impact plant–pollinator interactions such as outcross pollination. We present a meta-analysis of 22 studies involving 27 plant species showing a significant reduction in the proportion of seeds outcrossed in response to anthropogenic habitat modifications. We discuss the evolutionary consequences of disturbance on plant mating systems, and in particular whether reproductive assurance through selfing effectively compensates for reduced outcrossing. The extent to which disturbance reduces pollinator versus mate availability could generate diverse selective forces on reproductive traits. Investigating how anthropogenic change influences plant mating will lead to new opportunities for better understanding of how mating systems evolve, as well as of the ecological and evolutionary consequences of human activities and how to mitigate them.
TL;DR: It is argued that the introduction of transposable elements by horizontal transfer in eukaryotic genomes has been a major force propelling genomic variation and biological innovation.
Abstract: Horizontal transfer is the passage of genetic material between genomes by means other than parent-to-offspring inheritance. Although the transfer of genes is thought to be crucial in prokaryotic evolution, few instances of horizontal gene transfer have been reported in multicellular eukaryotes; instead, most cases involve transposable elements. With over 200 cases now documented, it is possible to assess the importance of horizontal transfer for the evolution of transposable elements and their host genomes. We review criteria for detecting horizontal transfers and examine recent examples of the phenomenon, shedding light on its mechanistic underpinnings, including the role of host-parasite interactions. We argue that the introduction of transposable elements by horizontal transfer in eukaryotic genomes has been a major force propelling genomic variation and biological innovation.
TL;DR: This work outlines key features of programs to effectively monitor consequences of releases of translocated or captively raised individuals and their effects on natural populations.
Abstract: Large-scale exploitation of wild animals and plants through fishing, hunting and logging often depends on augmentation through releases of translocated or captively raised individuals. Such releases are performed worldwide in vast numbers. Augmentation can be demographically and economically beneficial but can also cause four types of adverse genetic change to wild populations: (1) loss of genetic variation, (2) loss of adaptations, (3) change of population composition, and (4) change of population structure. While adverse genetic impacts are recognized and documented in fisheries, little effort is devoted to actually monitoring them. In forestry and wildlife management, genetic risks associated with releases are largely neglected. We outline key features of programs to effectively monitor consequences of such releases on natural populations.
TL;DR: Chytridiomycosis is an archetypal emerging disease, with a broad host range and significant impacts on host populations and, as such, poses a crucial challenge for wildlife managers and an urgent conservation concern.
Abstract: Emerging infectious diseases are increasingly recognized as key threats to wildlife. Batrachochytrium dendrobatidis (Bd), the causative agent of chytridiomycosis, has been implicated in widespread amphibian declines and is currently the largest infectious disease threat to biodiversity. Here, we review the causes of Bd emergence, its impact on amphibian populations and the ecology of Bd transmission. We describe studies to answer outstanding issues, including the origin of the pathogen, the effect of Bd relative to other causes of population declines, the modes of Bd dispersal, and factors influencing the intensity of its transmission. Chytridiomycosis is an archetypal emerging disease, with a broad host range and significant impacts on host populations and, as such, poses a crucial challenge for wildlife managers and an urgent conservation concern.
TL;DR: The phylogenetic distribution of regeneration is reviewed and how the origin, maintenance and loss of regeneration can each be driven by distinct factors are discussed.
Abstract: Regeneration, the replacement of lost body parts, is widespread yet highly variable among animals. Explaining this variation remains a major challenge in biology. Great strides have been made in understanding the phylogenetic distribution, ecological context and developmental basis of regeneration, and these new data are yielding novel insights into why and how regeneration evolves. Here, we review the phylogenetic distribution of regeneration and discuss how the origin, maintenance and loss of regeneration can each be driven by distinct factors. As the complexity of factors affecting regeneration evolution is increasingly appreciated, and as explicitly evolutionary studies of regeneration become more common, the coming years promise exciting progress in revealing the underlying mechanisms that have shaped animal regeneration.
TL;DR: How animal personality research might benefit from insights into the study of alternative tactics and how selection can favour behavioural diversification and consistency due to fitness benefits resulting from conflict reduction among social partners are discussed.
Abstract: The existence of 'animal personality', i.e. consistent individual differences in behaviour across time and contexts, is an evolutionary puzzle that has recently generated considerable research interest. Although social factors are generally considered to be important, it is as yet unclear how they might select for personality. Drawing from ecological niche theory, we explore how social conflict and alternative social options can be key factors in the evolution and development of consistent individual differences in behaviour. We discuss how animal personality research might benefit from insights into the study of alternative tactics and illustrate how selection can favour behavioural diversification and consistency due to fitness benefits resulting from conflict reduction among social partners.
TL;DR: Here the various ways in which the concept of quality is currently applied are considered, and it is shown that subtle differences in intended meaning have very important consequences when the goal is to draw evolutionary inferences.
Abstract: In studies of population ecology, demography and life history evolution, among-individual differences in traits associated with survival and reproduction are often attributed to variation in 'individual quality' However, often intuitive quality is rarely defined explicitly, and we argue that this can result in ambiguity about what quality actually is Here we consider the various ways in which the concept of quality is currently applied, and show that subtle differences in intended meaning have very important consequences when the goal is to draw evolutionary inferences We also propose a novel approach that is consistent with all current ecological uses, but also allows the concept of quality to be integrated with existing evolutionary theory
TL;DR: A standard format for documenting models and their analyses is proposed: transparent and comprehensive ecological modeling (TRACE) documentation, which will disclose all parts of the modeling process to scrutiny and make modeling itself more efficient and coherent.
Abstract: Ecological models are important for environmental decision support because they allow the consequences of alternative policies and management scenarios to be explored. However, current modeling practice is unsatisfactory. A literature review shows that the elements of good modeling practice have long been identified but are widely ignored. The reasons for this might include lack of involvement of decision makers, lack of incentives for modelers to follow good practice, and the use of inconsistent terminologies. As a strategy for the future, we propose a standard format for documenting models and their analyses: transparent and comprehensive ecological modeling (TRACE) documentation. This standard format will disclose all parts of the modeling process to scrutiny and make modeling itself more efficient and coherent.