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This chapter examines how the process of ecological niche evolution and diversification helps us better understand ecology, biogeography, and biodiversity. It first considers how species respond to changes in the environmental substrate on which the niches are manifested before discussing the concept of niche conservatism as well as tests of conservatism in areas such as species invasions and comparison of the ecological niche requirements of sister–species pairs. It then explores how temporal change in niche dimensions occurs, how it can be studied, and what can be learned. It also describes some of the challenges associated with applications of ecological niche modeling in the realm of evolution and concludes by outlining future directions for research.

This chapter proposes a formal and operational definition of a particular niche concept, introduces approaches for characterizing and measuring it, and uses it as a conceptual and terminological basis for describing and understanding much of the related practices of ecological niche modeling and species distribution modeling. It begins with a discussion of the themes that are most important in understanding niche concepts, focusing on three interrelated points: the meaning of “exist indefinitely”; what kinds of variables constitute the hypervolume; and the nature of feedback loops between a species and the variables composing the hypervolume. The chapter then considers the Grinnellian and Eltonian niches as well as the practicalities of estimating Grinnellian niches. It also considers two important interpretations of the niche concept, one of which is concerned with geographic and environmental spaces, and the other emphasizes the Eltonian niche.

This chapter explains how environmental data can be used to create models that characterize species’ ecological niches in environmental space. It introduces a model, which is a function constructed by means of data analysis for the purpose of approximating the true relationship (that is, the niche) in the form of the function f linking the environment and species occurrences. The chapter first considers the “meaning” of the function f that is being estimated by the algorithms before discussing the modeling algorithms, the approaches used to implement ecological niche modeling, model calibration, model complexity and overfitting, and model extrapolation and transferability. The chapter concludes with an overview of differences among methods and selection of “best” models, along with strategies for characterizing ecological niches in ways that allow visualization, comparisons, definition of quantitative measures, snf more.

This chapter considers a concept of niche that emphasizes multidimensional spaces of scenopoetic variables and provides a natural connection to the study of geographic distributions of species. It first explains the relations between environmental and geographic spaces before discussing the use of equations to link spatially explicit population growth patterns to variation in the ecological characteristics of species. It then describes the BAM diagram, a Venn diagram that displays the joint fulfillment in geographic space of three sets of conditions that together determine species distribution: biotic conditions, abiotic conditions, and movement of the species. The chapter also explores the spatial resolution of scenopoetic variables, estimation of the fundamental and existing fundamental niches, the biotically reduced niche, and caveats about reducing Grinnellian niches and the Eltonian Noise Hypothesis. Finally, it shows how distributional areas and ecological niches can be estimated.

This chapter discusses the conceptual basis of using ecological niche modeling for discovering new elements of biodiversity. More specifically, it examines the use of ecological niche models to guide searches for and discovery of unknown populations of species as well as species limits. It also explains how niche conservatism provides some degree of predictability across related taxa and makes the use of niche models for discovering biodiversity possible. For applications focused on discovery of unknown species, the chapter shows that niche conservatism is necessary if predictions of likely distributional areas are to prove realistic. Finally, it reviews practical considerations that must be taken into account in applications of ecological niche models oriented at discovering biodiversity, along with the caveats and limitations of such applications.

This chapter discusses various applications of ecological niche modeling in the study of the geography and ecology of disease transmission. Niche modeling approaches have many applications in the field of public health and epidemiology. Among the most common spatial epidemiological applications are mapping geographic patterns of disease transmission risk, identification of risk factors, and assessment of populations at risk of infection. The chapter describes a number of applications of ecological niche modeling in the realm of disease transmission, such as characterizing disease ecology, disease distributions and risk mapping, and potential distributions of pathogens or other individual component species in transmission systems, as well as forecasting disease transmission patterns in the face of ongoing global climate change. It also reviews practical considerations to keep in mind when exploring such applications and outlines some caveats, limitations, and challenges involved. Finally, it suggests future directions for research.

This chapter focuses on the conceptual and applied aspects of environmental data in the context of building and interpreting ecological niche models. It first examines how different suites of environmental factors may affect species distributions across a range of spatial scales before discussing which and how many variables are needed for ecological niche modeling. It then reviews the diverse sources of environmental datasets that are of potential utility in ecological niche modeling and concludes by considering a number of challenges involved in designing and choosing environmental data for ecological niche modeling. These challenges include data preparation, data quality, spatial extent, resolution in space and time, types of environmental data, and ancillary data.

This chapter discusses the use of ecological niche modeling to study species invasions, and more specifically to identify and understand genuine exceptions to ecological niche equivalency between native and introduced ranges of species. In addition, it examines the degree to which the geographic course of species’ invasions can be anticipated based on scenopoetic variables and biotic interactions. The chapter also reviews practical considerations that must be taken into account when exploring the utility of ecological niche models in understanding species’ invasions, such as using niche conservatism to predict likely changes in the distributional potential of invasive species under scenarios of changing environmental conditions. Finally, it describes caveats and limitations of the approach and outlines future research directions and challenges involved in the application of niche modeling ideas in species invasions.

This book has described a comprehensive framework for thinking about the geography and ecology of species distributions, arguing that such a framework is critical to further progress in the field of ecological niches and distributions. To develop this framework, traditional concepts in ecology have been radically reworked. In this conclusion, some of the challenges for future work regarding ecological niche modeling are discussed, such as fully integrating the BAM diagram with central concepts of population biology and statistical theory; clarifying the notion of niche conservatism versus niche evolution as regards scenopoetic versus bionomic environmental dimensions; and improving the link between correlational and mechanistic approaches to estimating and understanding ecological niches. The book argues that careful conceptual thinking must be combined with detailed empirical exploration in order to address each of these challenges.

This chapter considers the practice of modeling ecological niches and estimating geographic distributions. It first introduces the general principles and definitions underlying ecological niche modeling and species distribution modeling, focusing on model calibration and evaluation, before discussing the principal steps to be followed in building niche models. The first task in building a niche model is to collate, process, error-check, and format the data that are necessary as input. Two types of data are required: primary occurrence data documenting known presences (and sometimes absences) of the species, and environmental predictors in the form of raster-format GIS layers summarizing scenopoetic variables that may (or may not) be involved in delineating the ecological requirements of the species. The next step is to use a modeling algorithm to characterize the species’ ecological niche as a function of the environmental variables, followed by model projection and evaluation and finally, model transferability.

This book deals with ecological niche modeling and species distribution modeling, two emerging fields that address the ecological, geographic, and evolutionary dimensions of geographic distributions of species. It provides a conceptual overview of the complex relationships between ecological niches and geographic distributions of species, both across space and (perhaps to a lesser degree) through time. The emphasis is on how that conceptual framework relates to ecological niche modeling and species distribution modeling, which the book argues are complementary and are most broadly applicable to diverse questions regarding the ecology and geography of biodiversity phenomena. Part I of the book introduces the conceptual framework for thinking about and discussing the distributional ecology of species, Part II is concerned with the data and tools that have been used in the early development of the field, and Part III focuses on real-world situations to which these tools have been applied.

This chapter discusses the use of niche models to help address the “what” and “where” questions in conservation biology as well as climate change effects. It first reviews the conceptual aspects of the “what” and “where” questions in conservation planning, focusing on topics such as inferences about extinction risk, identification of regions for species reintroductions, conservation reserve network planning, and considerations of how climate change may affect species distributions. Each of these conservation applications is then examined with respect to the conceptual framework laid out for ecological niche modeling. The chapter concludes by offering practical recommendations regarding calibration and evaluation of niche models.

This chapter explores the conceptual bases for the discrepancy between species’ potential geographic distributional areas and their occupied distributional areas, focusing on the case of conditions when the Eltonian Noise Hypothesis is true as well as the necessary modifications when it is not. It first considers the meaning of the potential distributional area and the reasons why an ecological niche model may not estimate it correctly. It then explains why a species may not be at equilibrium with its potential distributional area, but rather inhabits only some subset of areas suitable for it. It also discusses nonequilibrium distributions that may arise in terms of the BAM diagram before concluding with an analysis of procedures for further processing of a niche model, which expresses potential geographic distributional area, to yield an estimate of occupied distributional area.

This chapter argues that parasite-induced changes in host phenotypes can have a dramatic impact on the community structure of their free-living hosts. It begins with a review of host-manipulation literature, illustrating how parasites can modify their host phenotypes in dramatic ways. It then considers two generic examples of host manipulation: parasite-induced susceptibility to predation (PISP) and parasite-induced castration (PIC), and develops simple population-dynamical models of the consequences of PISP and PIC on communities (host plus two predators for PISP, host plus competitor for PIC). Finally, the chapter highlights how the simple model results are likely to have parallels in a range of empirical systems, offering an agenda for future theoretical and empirical research.

Ecological specificity describes the affinity of an organism for a subset of every axis forming its ecological niche. It is a powerful concept that integrates concepts in evolutionary biology, such as local adaptation, with those in ecology, such as dispersal and biotic interactions. This chapter reviews the current perspective on the concept, and highlights areas where refinements of conceptual definitions are needed. In particular, it focuses on the potential of improving our understanding of ecological specificity as a way to gain more predictive ability on the evolution of ecological niches, species interactions, and species distributions.

This chapter provides an introduction to various applications of correlative approaches used in ecological niche modeling, along with the theoretical principles on which the applications are based. It demonstrates how the methods can be applied to interesting challenges to yield highly useful results, provided that the researcher understands exactly what is being estimated based on which data. It also gives examples of types of model predictions that can yield useful information. Each of the following chapters describes key questions that the niche models address, for example, where unknown populations are likely to be present, or which areas are most susceptible to nonnative species invasions. Practical considerations for implementing each application are also taken into account, and future directions and challenges are discussed.

This chapter considers some of the ways in which the conditions for existence can serve as a unifying concept in evolutionary biology. It examines some of the areas in which recognition of the principle of the conditions for existence can highlight interconnections that are not often made, both within evolutionary biology and between evolutionary biology and other fields. These fields include quantitative genetics, the levels of selection, evo-devo, the ecological niche, physiology, and conservation biology.

This introductory chapter first sets out the book's primary objectives: (i) to develop a framework around the niche concept that better accommodates several recent insights about niche relations in ecology; (ii) to use this updated niche framework to point the way to new questions, conclusions, and syntheses; and (iii) to link this interpretation to some of the insights developed using alternative approaches and identify those areas where the greatest challenges for the field of ecology in relation to the niche concept lie. It then presents a brief history of the ecological niche concept, and discusses the concept's downfall and revision.