Consumer-Resource Dynamics (MPB-36)

Consumer-Resource Dynamics (MPB-36)

Copyright Date: 2003
Pages: 456
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  • Book Info
    Consumer-Resource Dynamics (MPB-36)
    Book Description:

    Despite often violent fluctuations in nature, species extinction is rare. California red scale, a potentially devastating pest of citrus, has been suppressed for fifty years in California to extremely low yet stable densities by its controlling parasitoid. Some larch budmoth populations undergo extreme cycles; others never cycle. In Consumer-Resource Dynamics, William Murdoch, Cherie Briggs, and Roger Nisbet use these and numerous other biological examples to lay the groundwork for a unifying theory applicable to predator-prey, parasitoid-host, and other consumer-resource interactions. Throughout, the focus is on how the properties of real organisms affect population dynamics.

    The core of the book synthesizes and extends the authors' own models involving insect parasitoids and their hosts, and explores in depth how consumer species compete for a dynamic resource. The emerging general consumer-resource theory accounts for how consumers respond to differences among individuals in the resource population. From here the authors move to other models of consumer-resource dynamics and population dynamics in general. Consideration of empirical examples, key concepts, and a necessary review of simple models is followed by examination of spatial processes affecting dynamics, and of implications for biological control of pest organisms. The book establishes the coherence and broad applicability of consumer-resource theory and connects it to single-species dynamics. It closes by stressing the theory's value as a hierarchy of models that allows both generality and testability in the field.

    eISBN: 978-1-4008-4725-9
    Subjects: Biological Sciences

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-x)
  3. Preface
    (pp. xi-xvi)
  4. CHAPTER ONE Introduction
    (pp. 1-5)

    A central challenge, perhaps the central challenge, for population ecology is to explain the persistence of species. In the variable, uncertain, and sometimes catastrophic natural world, species extinction is rare—why? The broad answer is that most natural populations are regulated most of the time at some spatial scale. The study of population dynamics is therefore a search for regulatory mechanisms and their effects.

    Regulated populations can exhibit a range of dynamics. These include stability; instability, for example in the form of population cycles; local extinction but regional regulation; and local instability but regional stability (all discussed in more detail...

  5. CHAPTER TWO Population Dynamics: Observations and Basic Concepts
    (pp. 6-29)

    This chapter has two parts. The first discusses the various types of population dynamics observed in nature. The second looks at basic concepts that relate these observations to mathematical theory. A brief appendix introduces local stability analysis, illustrated by the logistic model.

    In this section we present a range of observed dynamics seen in populations. By “dynamics” we mainly mean temporal changes in density or abundance. Average density of a population, and the relative densities of different populations, are of course also of interest. For example, we care greatly about average density in pest control and in populations we harvest,...

  6. CHAPTER THREE Simple Models in Continuous Time
    (pp. 30-82)

    In this chapter we explore, in simple models, processes that tend to stabilize and those that tend to destabilize and cause cycles. Although more realistic and hence more complex models are the focus of much of the book, the simple models are central to our goal of a coherent set of theory. Many properties of simple models survive in complex models; simple models thus serve as a preliminary guide to the more complex. Indeed, complex models are often best understood in light of our necessarily more complete and deeper understanding of simple models. Finally, although the models in this chapter...

  7. CHAPTER FOUR Simple Models in Discrete Time
    (pp. 83-118)

    Most of the models in this book are framed in continuous time, which is a common framework for models of true predators and prey. Because they assume that dynamical processes such as births and deaths occur more or less all the time, however, they can mislead when applied to organisms in which reproduction occurs in a discrete pulse determined by season. Seasonal breeding can be incorporated into continuous-time models, for example by making the per-head birth rate a function of Julian day. The usual practice, though, is to turn to discrete-time models, i.e., difference equations.

    Discrete-time models describe changes in...

  8. CHAPTER FIVE An Introduction to Models with Stage Structure
    (pp. 119-178)

    One of our professors used to say that every biologist should visit the tropics if only to be appalled by the multiplicity of species. But one needn’t go to the tropics. Insects almost everywhere are appallingly diverse. And they exhibit a huge range of life histories and lifestyles. This variety increases enormously when we come to consider interactions between insect species, and in particular between insect hosts and their parasitoids. We look at this variation systematically in the next chapter. Here we content ourselves with stating the goals that motivate the models presented in the next four chapters, which together...

  9. CHAPTER SIX Dynamical Effects of Parasitoid Lifestyles
    (pp. 179-218)

    As noted in chapter 5, host life histories show enormous variation. Since parasitoid natural history is also highly variable, the diversity of forms of parasitoid-host interactions is great. Our task in chapters 6 and 7 is to bring order to this diversity and establish that we can encompass most of it in a general and relatively simple theory.

    The life histories of parasitoids, the ways they respond to the variety of host attributes, the “decisions” they make in allocating reproductive effort, etc., all show variation from one group of parasitoids to another. There is also variation in how any particular...

  10. CHAPTER SEVEN State-Dependent Decisions
    (pp. 219-244)

    In chapter 6 we discussed how the response of a female parasitoid to an encountered host depends on the host’s quality, especially its size or age. We noted that the overall pattern of responses is what we would expect based on evolutionary considerations. We showed that the range of responses, both within a parasitoid species and across parasitoids in general, exemplifies a single process: gain to the future female parasitoid population changes (usually increases) with host age. Finally, we showed that these responses have a consistent effect on the predicted population dynamics.

    In this chapter we look at the dynamical...

  11. CHAPTER EIGHT Competition between Consumer Species
    (pp. 245-317)

    In this chapter we examine interspecific competition between consumer species, with emphasis on competition between parasitoid species that attack the same host. Interspecific competition occurs between two species when individuals of each species have a negative effect on the population growth rate of the other species. The distinction is often made between exploitative and interference competition. In exploitative (or resource) competition, individuals interact only through suppression of their shared resource. In interference competition, individuals have a direct negative effect on each other through fighting, causing each other to waste searching time, or in the case of parasitoids, attacking and ovipositing...

  12. CHAPTER NINE Implications for Biological Control
    (pp. 318-340)

    Here we synthesize results, mainly from chapters 8 and 10, that relate to biological control, and where possible relate them to real systems. Mostly we consider “classical” biological control in which the pest is an alien species and the specialist natural enemies released to control it have typically been found in the pest’s region of origin. Such control has been most successful in long-lived crops such as forests and orchards, and this is where most of our models, with their long-term view, are relevant. But we also consider, briefly, temporary environments such as seasonal crops, where indigenous enemies are typically...

  13. CHAPTER TEN Dynamical Effects of Spatial Processes
    (pp. 341-393)

    Space has become a central focus in ecology over the past two decades, though 50 years ago Andrewartha and Birch (1954) recognized its general importance and Skellam (1951) wrote pioneering models. Throughout this chapter we concentrate on the effects of spatial processes, in particular spatial subdivision, spatial heterogeneity, and the movement of individuals, on the dynamics and stability of consumerresource interactions. It is useful to distinguish two scales at which spatial processes can occur, though they may overlap in real systems. At the among-subpopulation, or metapopulation, scale, the population is divided into subpopulations that typically persist longer than one generation....

  14. CHAPTER ELEVEN Synthesis and Integration across Systems
    (pp. 394-415)

    In chapters 5–8 we presented stage- and state-structured theory, formulated with mainly parasitoid-host interactions in mind. In chapters 6 and 7, especially, we showed how that theory is both more realistic than its predecessors and yet achieves generality. In this chapter we broaden our scope by showing how this theory is an integral part of a larger and coherent body of theory for population dynamics, including theory for single-species populations. We use this last connection to argue that it is often appropriate to use single-species models to describe the dynamics of generalist consumers in species-rich food webs.

    We begin...

  15. CHAPTER TWELVE Concluding Remarks
    (pp. 416-424)

    Here we summarize insights developed in earlier chapters. We also comment on some promising areas of future research.

    We began developing stage-structured models more than a decade ago because we were interested in how individual properties affect population dynamics. The models have uncovered new dynamic phenomena and hence provide new predictions, and explanations, for observed patterns not otherwise explicable.

    Among the phenomena emerging from stage-structured models are novel stabilizing mechanisms and three new types of cycles in consumer-resource systems: single-generation cycles whose periods are determined mainly by the resource development lag, and singlegeneration and delayed-feedback cycles, both of whose periods...

  16. Literature Cited
    (pp. 425-450)
  17. Index
    (pp. 451-460)
  18. Back Matter
    (pp. 461-462)