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Evolutionary Ecology of Parasites

Evolutionary Ecology of Parasites: (Second Edition)

Robert Poulin
Copyright Date: 2007
Pages: 342
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  • Book Info
    Evolutionary Ecology of Parasites
    Book Description:

    Parasites have evolved independently in numerous animal lineages, and they now make up a considerable proportion of the biodiversity of life. Not only do they impact humans and other animals in fundamental ways, but in recent years they have become a powerful model system for the study of ecology and evolution, with practical applications in disease prevention. Here, in a thoroughly revised and updated edition of his influential earlier work, Robert Poulin provides an evolutionary ecologist's view of the biology of parasites. He sets forth a comprehensive synthesis of parasite evolutionary ecology, integrating information across scales from the features of individual parasites to the dynamics of parasite populations and the structuring of parasite communities.

    Evolutionary Ecology of Parasitespresents an evolutionary framework for the study of parasite biology, combining theory with empirical examples for a broader understanding of why parasites are as they are and do what they do. An up-to-date synthesis of the field, the book is an ideal teaching tool for advanced courses on the subject. Pointing toward promising directions and setting a research agenda, it will also be an invaluable reference for researchers who seek to extend our knowledge of parasite ecology and evolution.

    eISBN: 978-1-4008-4080-9
    Subjects: Ecology & Evolutionary Biology

Table of Contents

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  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-viii)
  3. Preface
    (pp. ix-x)
  4. 1 Introduction
    (pp. 1-7)

    Ecology is the scientific study of interactions between organisms of the same or different species, and between organisms and their nonliving environment. One of the main goals of ecologists is to explain the abundance and distribution of organisms over space and time. The scope of ecology includes all sorts of interactions, from the most intimate, permanent associations to the briefest of encounters. Although parasitism qualifies as the sort of interaction of interest to ecologists, it has somehow become the focus for another branch of science, parasitology, which uses a multidisciplinary approach to investigate host-parasite interactions. Because of the intimate and...

  5. 2 Origins of Parasitism and Complex Life Cycles
    (pp. 8-40)

    Parasites have obviously evolved from free-living ancestors—there first had to be animals around for parasites to exploit. Parasitism has originated independently in several animal taxa, and has sometimes arisen more than once in a given taxon. The origins of parasites typically go back several million years, as indicated by the classical fossil evidence (Conway Morris 1981) supplemented lately by the discovery of well-preserved specimens fossilized in amber (e.g., Poinar 1999; Klompen and Grimaldi 2001). Since these early days parasites have diversified greatly (Poulin and Morand 2000a, 2004), and modern species now display a wide variety of life cycles and...

  6. 3 Host Specificity
    (pp. 41-69)

    Over evolutionary time, parasites have added hosts to their life cycles by adding steps to the cycle and thus increasing its complexity. Hosts can also be added to the life cycle in parallel rather than in series (Combes 1991b, 1995, 2001). The spectrum of potential hosts that can be used at any step in the cycle can be broadened without an increase in the number of steps. Instead, selection simply adds alternative pathways through the cycle. A complex life cycle allows parasites to specialize on two or more hosts by partitioning specialization to different times during the cycle (Thompson 1994);...

  7. 4 Evolution of Parasite Life-History Strategies
    (pp. 70-95)

    Parasites must complete difficult journeys through several hosts as well as through the external environment. Evolution has sometimes favored longer and more complex journeys. Sometimes it has opened up alternative paths through the same cycle by relaxing host specificity. The length, complexity, and flexibility of the life cycle are the outcome of selection acting on the cycle as a unit of selection. But evolution has also shaped the organism itself, and this chapter now focuses on the parasite as an organism rather than as a life cycle.

    Throughout the history of parasitology, several laws or rules have been proposed to...

  8. 5 Strategies of Host Exploitation
    (pp. 96-133)

    Most if not all definitions ofparasitisminvolve the concept of harm, and restrict the use of the termparasitesto symbionts that have a negative impact on the fitness of their host. In fact, the level of harm done to the host is often the main criterion used to categorize symbioses in which the host does not benefit. Symbioses fall along a continuum, from commensalism in which the host incurs no harm, to highly virulent parasitism in which host fitness is greatly reduced. This wide range of effects among contemporary symbioses has long been viewed as a series of...

  9. 6 Parasite Aggregation: Causes and Consequences
    (pp. 134-159)

    The previous chapters have focused on properties of individual parasites, somewhat variable among members of the same species but shared by all. The next level of organization is the population, consisting of conspecific parasites interacting and coexisting in time and space. This and the next chapter step up to the parasite population level, in particular the distribution of parasite individuals, their dynamics and their persistence. Because of their complex life cycles, different members of parasite populations occupy completely distinct habitats. For instance, infective larval stages may be in the external environment, immature stages in intermediate hosts, and adults in definitive...

  10. 7 Parasite Population Dynamics and Genetics
    (pp. 160-187)

    Parasite populations vary in size over both short and long time scales and are affected by both biotic and abiotic factors. Some of these factors produce changes in parasite numbers, whereas others act to reduce the amplitude of fluctuations around an equilibrium population size. The study of parasite population dynamics has been tightly linked with epidemiology, which is concerned with the spread of disease in host populations (Anderson and May 1991; Anderson 1993). The theoretical framework developed in epidemiology is proving useful for the interpretation of field and experimental observations and has played a key role in motivating parasitologists to...

  11. 8 Interactions between Species and the Parasite Niche
    (pp. 188-208)

    Previous chapters have addressed several aspects of parasite ecology as though parasites of one species were alone in their host. This is rarely the case as most free-living animals, especially vertebrates, are used as host simultaneously by several species of parasites. Various pairs of these different parasite species, though sharing a host, will not always co-occur on a finer scale: an intestinal worm and an ectoparasitic arthropod on the same vertebrate host will not interact directly and can probably be treated as entirely independent of one another. Often, however, hosts harbor several parasite species belonging to the same guild, which...

  12. 9 Parasite Infracommunity Structure
    (pp. 209-232)

    The assemblage consisting of all parasites of different species in the same host individual, whether they actually interact or not, forms an infracommunity (Holmes and Price 1986; Bush et al. 1997). Infracommunities are subsets of the component community, which consists of all parasite species exploiting the host population. The composition of infracommunities, in terms of the number and identity of species and the relative numbers of individuals of each species, will depend on many factors. In theory, infracommunities can range from highly structured and predictable sets of species, to purely stochastic assemblages of species coming together entirely at random. Interactions...

  13. 10 Component Communities and Parasite Faunas
    (pp. 233-261)

    The infracommunities of parasites discussed in the previous chapters are subsets of a larger assemblage of species known as the component community, or the ensemble of populations of all parasite species exploiting the host population at one point in time. Component communities are longer-lived assemblages than any of their infracommunities; they last at least a few host generations and usually much longer, as long as the host population persists in time. This creates an important distinction between the structure and dynamics of infracommunities and component communities. Whereas infracommunities are assembled over ecological time scales by infection and demographic processes, component...

  14. 11 Conclusion
    (pp. 262-270)

    Completed in 1997, the first edition of this book left the reader with many unanswered questions. This was not meant only as a reflection of the state of our knowledge of parasite evolutionary ecology at that point in time, but also as a call to arms, an appeal to parasitologists to tackle unsolved problems. Much was already known about parasites at the time. The parasitology literature of the twentieth century contains a wealth of information on the diverse taxa of parasites and on their relationship with their hosts. There are tens of thousands of pages devoted to descriptive studies, laboratory...

  15. References
    (pp. 271-324)
  16. Index
    (pp. 325-332)