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The Unified Neutral Theory of Biodiversity and Biogeography (MPB-32)

The Unified Neutral Theory of Biodiversity and Biogeography (MPB-32)

Copyright Date: 2001
Pages: 448
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  • Book Info
    The Unified Neutral Theory of Biodiversity and Biogeography (MPB-32)
    Book Description:

    Despite its supreme importance and the threat of its global crash, biodiversity remains poorly understood both empirically and theoretically. This ambitious book presents a new, general neutral theory to explain the origin, maintenance, and loss of biodiversity in a biogeographic context.

    Until now biogeography (the study of the geographic distribution of species) and biodiversity (the study of species richness and relative species abundance) have had largely disjunct intellectual histories. In this book, Stephen Hubbell develops a formal mathematical theory that unifies these two fields. When a speciation process is incorporated into Robert H. MacArthur and Edward O. Wilson's now classical theory of island biogeography, the generalized theory predicts the existence of a universal, dimensionless biodiversity number. In the theory, this fundamental biodiversity number, together with the migration or dispersal rate, completely determines the steady-state distribution of species richness and relative species abundance on local to large geographic spatial scales and short-term to evolutionary time scales.

    Although neutral, Hubbell's theory is nevertheless able to generate many nonobvious, testable, and remarkably accurate quantitative predictions about biodiversity and biogeography. In many ways Hubbell's theory is the ecological analog to the neutral theory of genetic drift in genetics. The unified neutral theory of biogeography and biodiversity should stimulate research in new theoretical and empirical directions by ecologists, evolutionary biologists, and biogeographers.

    eISBN: 978-1-4008-3752-6
    Subjects: Biological Sciences

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
  3. Preface
    (pp. ix-2)
  4. CHAPTER ONE MacArthur and Wilson’s Radical Theory
    (pp. 3-29)

    This is a book about a new general theory of biodiversity in a geographical context. I definebiodiversityto be synonymous with species richness and relative species abundance in space and time.Species richnessis simply the total number of species in a defined space at a given time, andrelative species abundancerefers to their commonness or rarity. This is a less inclusive definition of biodiversity than is commonly used in policy circles, but more in keeping with the classical discipline of ecology as the scientific study of the distribution and abundance of species and their causes. Fragments of...

  5. CHAPTER TWO On Current Theories of Relative Species Abundance
    (pp. 30-47)

    No other general attribute of ecological communities besides species richness has commanded more theoretical and empirical attention than relative species abundance. Commonness, and especially rarity, have long fascinated ecologists (Rabinowitz et al. 1986, Hubbell and Foster 1986a, Gaston 1994), and species abundance is of central theoretical and practical importance in conservation biology (Soulé 1986). In particular, understanding the causes and consequences of rarity is a problem of profound significance because most species are uncommon to rare, and rare species are generally at greater risk to extinction.

    Given its central importance, it is surprising that relative species abundance is missing entirely...

  6. CHAPTER THREE Dynamical Models of the Relative Abundance of Species
    (pp. 48-75)

    In the previous chapter, I temporarily set aside a small and curious set of dynamical models of communities, most of which have not received the attention they deserve from mainstream theoretical community ecology. I have chosen to discuss them separately because I believe they are closer to the right track for developing a successful dynamical theory of biodiversity and relative species abundance. These models differ from the models discussed in the last chapter in that they explicitly incorporate the demographic processes of birth, death and dispersal.

    In the mid-1970s, when most eyes were still focused on the classical, niche-based theory...

  7. CHAPTER FOUR Local Community Dynamics under Ecological Drift
    (pp. 76-112)

    In previous chapters I examined current models of relative species abundance based on niche-assembly theories, and then a small class of dynamical models whose predictions derive from birth, death, and dispersal processes. I now discuss one of the latter models in greater detail, zero-sum ecological drift, the foundation for a unified theory of biodiversity and biogeography. It is useful to divide the problem into two spatio-temporal scales for analysis: local community dynamics, which are relatively rapid, and metacommunity dynamics, which are much slower and occur on large scales. In this chapter, I study local community dynamics from the perspective of...

  8. CHAPTER FIVE Metacommunity Dynamics and the Unified Theory
    (pp. 113-151)

    According to MacArthur and Wilson’s theory of island biogeography, a given local community or island achieves a steady-state species richness under a persistent rain of immigrants of already extant species inhabiting the much larger metacommunity source area. In the previous chapter I derived the probability density function for the abundance of theith species in an ergodic local community as a function ofPi, the metacommunity relative abundance of theith species. The ergodic community and MacArthur and Wilson’s theory both implicitly assume the permanence of theith species in the metacommunity. In reality, of course, communities are only ergodic...

  9. CHAPTER SIX The Unified Neutral Theory and Dynamical Species-Area Relationships
    (pp. 152-201)

    The rate at which species accumulate with increasing area surveyed—the species-area relationship—is perhaps the most basic and fundamental problem in biogeography. Yet on first consideration, a positive species-area relationship appears to be little more than a trivial corollary of the principle that Earth and its limiting resources are permanently and completely saturated with organisms. In an infinitely diverse world (θ= ∞), the number of species would equal the number of individuals, and the number of species would therefore increase linearly with area. Short of infinite diversity, however, the biotic saturation of landscapes dictates that the number of...

  10. CHAPTER SEVEN Metapopulations and Biodiversity on the Metacommunity Landscape
    (pp. 202-230)

    The theory of island biogeography has been criticized in recent years for failing to take into account the fragmented nature of populations and the habitats that they occupy (e.g., Hanski and Simberloff 1997). Perhaps this criticism has some validity when applied to the classical island-mainland problem posed in the original theory. But in fairness, MacArthur and Wilson did consider the more complex problem of the biogeography of archipelagos of islands or habitats. Since their monograph appeared more than 30 years ago, great strides have been made in understanding and mathematically characterizing complex landscapes (Mandelbrot 1982, Milne 1997, Ritchie 1997, Ritchie...

  11. CHAPTER EIGHT Speciation, Phylogeny, and the Evolution of Metacommunity Biodiversity
    (pp. 231-280)

    In the 142 years since publication ofThe Origin of Species(Darwin 1859), there has been remarkable progress in evolutionary biology and paleobiology in understanding natural selection, the genetical basis of evolutionary change, and the history of evolution. As a result of this progress, there remains today no credible scientific alternative to the conclusion that species did indeed evolve through a process of organic evolution. Ironically, however, much less progress has been made since Darwin on theoriginquestion itself—understanding the origin of species and characterizing the differences that, at a fundamental level, define and identify species. A recent...

  12. CHAPTER NINE Sampling, Parameter Estimation, and the Generality of the Unified Theory
    (pp. 281-318)

    I have deferred until now issues of sampling and parameter estimation in the unified theory, as well as a discussion of the theory’s generality. I first consider sampling, which might seem a prosaic and uninteresting subject. But one of the big questions about biodiversity that has captured considerable attention recently is a sampling question, namely: How many species are there on Earth—or on any part of it (Erwin 1982, May 1988, Wilsm 1995)? Because of the potentially fractal nature of biodiversity, there is an issue of how one identifies and tallies taxonomic units in the unified theory (chapter 8),...

  13. CHAPTER TEN Reconciling Dispersal-Assembly and Niche-Assembly Theories
    (pp. 319-346)

    The principal aim of this book has been to show that a powerful, formal neutral theory of biodiversity and biogeography can be constructed on the foundation of the original theory of island biogeography. This theory describes the dynamics of species richness and relative species abundance in local communities and metacommunities that are undergoing ecological drift, random dispersal, and random speciation. The theory’s key assumptions are, first, that the dynamics of ecological communities are a stochastic, zero-sum game, and second, that this game is neutral and played by individuals that are identical in their probabilities of giving birth, dying, and dispersing...

  14. Literature Cited
    (pp. 347-370)
  15. Index
    (pp. 371-375)