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Species Concepts and Phylogenetic Theory

Species Concepts and Phylogenetic Theory: A Debate

Quentin D. Wheeler
Rudolf Meier
Copyright Date: 2000
Pages: 256
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  • Book Info
    Species Concepts and Phylogenetic Theory
    Book Description:

    No question in theoretical biology has been more perennially controversial or perplexing than "What is a species?" Recent advances in phylogenetic theory have called into question traditional views of species and spawned many concepts that are currently competing for general acceptance. Once the subject of esoteric intellectual exercises, the "species problem" has emerged as a critically important aspect of global environmental concerns. Completion of an inventory of biodiversity, success in conservation, predictive knowledge about life on earth, management of material resources, formulation of scientifically credible public policy and law, and more depend upon our adoption of the "right" species concept.

    Quentin D. Wheeler and Rudolf Meier present a debate among top systematic biology theorists to consider the strengths and weaknesses of five competing concepts. Debaters include (1) Ernst Mayr (Biological Species Concept), (2) Rudolf Meier and Rainer Willmann (Hennigian species concept), (3) Brent Mishler and Edward Theriot (one version of the Phylogenetic Species Concept), (4) Quentin Wheeler and Norman Platnick (a competing version of the Phylogenetic Species Concept), and (5) E. O. Wiley and Richard Mayden (the Evolutionary Species Concept).

    Each author or pair of authors contributes three essays to the debate: first, a position paper with an opening argument for their respective concept of species; second, a counterpoint view of the weakness of competing concepts; and, finally, a rebuttal of the attacks made by other authors. This unique and lively debate format makes the comparative advantages and disadvantages of competing species concepts clear and accessible in a single book for the first time, bringing to light numerous controversies in phylogenetic theory, taxonomy, and philosophy of science that are important to a wide audience. Species Concepts and Phylogenetic Theory will meet a need among scientists, conservationists, policy-makers, and students of biology for an explicit, critical evaluation of a large and complex literature on species. An important reference for professionals, the book will prove especially useful in classrooms and discussion groups where students may find a concise, lucid entrée to one of the most complex questions facing science and society.

    eISBN: 978-0-231-50662-5
    Subjects: Ecology & Evolutionary Biology, Biological Sciences

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-vi)
  3. List of Contributors
    (pp. vii-viii)
    (pp. ix-xiv)
    Quentin D. Wheeler and Rudolf Meier

    • 1 Species Concepts in Theoretical and Applied Biology: A Systematic Debate with Consequences
      (pp. 3-14)
      Joel Cracraft

      Biologists, especially systematists, had debated species concepts for a very long time, well into the nineteenth century. The debate intensified with the rise of the so-called New Synthesis in the 1930s and 1940s and then accelerated even more with the “systematics wars” of the 1960s to 1980s, particularly with the ascendancy of cladistics, or phylogenetic systematics.

      The debate itself has had many nuances. Some systematists have only been interested in discriminating all the discrete taxonomic variation they can in nature, without concern for the processes that might have produced this variation. Often called alpha taxonomists, they have been the workhorses...


    • 2 The Biological Species Concept
      (pp. 17-29)
      Ernst Mayr

      I define biological species as groups of interbreeding natural populations that are reproductively isolated from other such groups. Alternatively, one can say that a biological species is a reproductively cohesive assemblage of populations. The emphasis of this definition is no longer on the degree of morphological difference, but rather on genetic relationship. This species concept represents a complete change in the ontological status of species taxa. For those who adopt the Biological Species Concept, species are no longer considered to be classes (natural kinds) that can be defined, but rather concrete particulars in the view of the biologist that can...

    • 3 The Hennigian Species Concept
      (pp. 30-43)
      Rudolf Meier and Rainer Willmann

      Hardly any concept in biology is as important or as controversial as the species concept. Yet, there is hardly a scientific paper in biology that does not at least implicitly use a species concept by generalizing the results of studies on individuals to the species level (Osche 1984:164; Sudhaus 1984:183). We will argue that a modified version of Hennig’s species concept (Hennig 1950,1966) is not only compatible with phylogenetic systematics, but suits the needs of biologists in other fields as well. We shall not enter the species-as-individuals discussion but offer our viewpoint that species as described by the modified Hennigian...

    • 4 The Phylogenetic Species Concept (sensu Mishler and Theriot): Monophyly, Apomorphy, and Phylogenetic Species Concepts
      (pp. 44-54)
      Brent D. Mishler and Edward C. Theriot

      Various attempts have been made at forging a species concept compatible with phylogenetic systematics or cladistics. Several such concepts have been called the Phylogenetic Species Concept, thus leading to considerable confusion in the literature. We support one version of the Phylogenetic Species Concept, one that, we will argue, can serve as a synthesis of all versions, but for historical clarity we will distinguish among different versions, their origins, and motivations (see also discussion by Baum 1992).

      Hennig himself apparently held a view on species close to the Biological Species Concept. He defined species as “a complex of spatially distributed reproductive...

    • 5 The Phylogenetic Species Concept (sensu Wheeler and Platnick)
      (pp. 55-69)
      Quentin D. Wheeler and Norman I. Platnick

      Our Phylogenetic Species Concept has its origin in the writings ofWilli Hennig (1966) and subsequent transformations of phylogenetic theory. Hennig recognized that the Biological Species Concept (Mayr 1942, 1963, 1969) was problematic relative to the chronological history of species and proposed modifications designed to fix this species concept (Hennig 1966; Ridley 1989). As phylogeneticists divorced the discovery of historical patterns of cladistic relationships from unnecessary assumptions about evolutionary processes (Platnick 1979), it became apparent that modes of speciation need not be confounded with criteria used to distinguish among species. This recognition and increased awareness of problems associated with the Biological...

    • 6 The Evolutionary Species Concept
      (pp. 70-90)
      E. O. Wiley and Richard L. Mayden

      We view the Evolutionary Species Concept as identical to the species-as-lineages concept that is a central part of Hennig’s (1966) philosophical development of phylogenetic systematics. We assert that competing concepts, including the Biological Species Concept, the several versions of the Phylogenetic Species Concept, and the concept that species are the same kind of taxa as supraspecific taxa, among others, do not serve to satisfy the basic objective in studies of biodiversity (accurate estimates of the number of species present) or the general needs of the phylogenetic system as Hennig (1966) conceived that system and as it is used by phylogeneticists...


    • 7 A Critique from the Biological Species Concept Perspective: What Is a Species, and What Is Not?
      (pp. 93-100)
      Ernst Mayr

      For someone who has published books and papers on the biological species for more than 50 years, and who has revised and studied in detail more than 500 species of birds and many species of other groups of organisms, the reading of some recent papers on species has been a rather troubling experience. There is only one term that fits some of these authors: armchair taxonomists. Because many authors have never personally analyzed any species populations or studied species in nature, they lack any feeling for what species actually are. Darwin already knew this when, in September 1845, he wrote...

    • 8 A Critique from the Hennigian Species Concept Perspective
      (pp. 101-118)
      Rainer Willmann and Rudolf Meier

      The search for a species concept that is applicable to all of life and acceptable to all biologists has a long history. Over the years, the species discussion has probably spawned more publications than any other conceptual issue in systematics and evolutionary biology. After a period of relative tranquility following the introduction of the Biological Species Concept, the number of conflicting species ideas is again increasing, and species definitions are again being vigorously debated. The position chapters reflect this development.

      We have already briefly discussed some aspects of the competing species concepts in our first chapter in this volume and...

    • 9 A Critique from the Mishler and Theriot Phylogenetic Species Concept Perspective: Monophyly, Apomorphy, and Phylogenetic Species Concepts
      (pp. 119-132)
      Brent D. Mishler and Edward C. Theriot

      The set of position papers in this volume clearly shows the diversity of positions that can be taken on issues surrounding species concepts, even by a group of scientists who presumably share a common evolutionary paradigm. To respond to the other papers effectively, and hopefully to clarie where the differences lie, we will first summarize the major basic issues and see how each of the authors seems to stand on these and where we differ from them (table 9.1). Then, we will go through each paper in turn and respond to it in more detail.

      As has been pointed out...

    • 10 A Critique from the Wheeler and Platnick Phylogenetic Species Concept Perspective: Problems with Alternative Concepts of Species
      (pp. 133-145)
      Quentin D. Wheeler and Norman I. Platnick

      The goal for developing a Phylogenetic Species Concept is to support the aims of phylogenetic systematics: to discover elements for reconstruction of phylogenetic history, distinguish among kinds of organisms, describe and predictively classify the earth’s biological diversity, and permit the study of evolution and comparison of clades. In order for a species concept to be phylogenetic, it need only accurately identify those elements among which evidence of shared history may be unambiguously retrieved; cladistic analyses of subdivisions of phylogenetic species need not, and indeed should not, be possible.

      We will discuss alternatives to our Phylogenetic Species Concept presented in preceding...

    • 11 A Critique from the Evolutionary Species Concept Perspective
      (pp. 146-158)
      E. O. Wiley and Richard L. Mayden

      Perhaps some of the differences among systematists regarding their views of the nature of species are due to their different views of how concepts function in the phylogenetic system and science in general. To Wheeler and Platnick, a concept seems to function as an operational device allowing one to discover something. To Mayr, a concept seems to function as a biological description of how entities should behave if they are distinct things. To Mishler and Theriot, the world is too complicated to allow for a monistic concept sensu Kluge (1990).

      We believe that concepts should serve as bridges between pattern...


    • 12 A Defense of the Biological Species Concept
      (pp. 161-166)
      Ernst Mayr

      Every naturalist and every evolutionist is awed by the diversity of living nature. One cannot help asking oneself why there are so many species. Indeed, why are there species at all? Why is not the organic world a single continuity? Why has nature, and more precisely natural selection, favored the discontinuities among the species? What is the meaning of species? The answer the evolutionist gives to these questions is the Biological Species Concept.

      Reading through the proposals of various phylogenetic, evolutionary, and other species concepts, I am disappointed that these putative concepts do not give answers to these questions. Rather,...

    • 13 A Defense of the Hennigian Species Concept
      (pp. 167-178)
      Rudolf Meier and Rainer Willmann

      “The species concept is crucial to the study of biodiversity. It is the grail of systematic biology. Not to have a natural unit such as the species would be to abandon a large part of biology into free fall, all the way from the ecosystem down to the organism. It would be to concede the idea of amorphous variation and arbitrary limits for . . . intuitively obvious entities . . .” (Wilson 1992:38).

      The Hennigian Species Concept describes species as natural entities, that is, as entities that are individual-like products of evolution. The question is, which species criterion is...

    • 14 A Defense of the Phylogenetic Species Concept (sensu Mishler and Theriot): Monophyly, Apomorphy, and Phylogenetic Species Concepts
      (pp. 179-184)
      Brent D. Mishler and Edward C. Theriot

      We find little of substance in most of the criticisms directed our way in the previous section of the book (although, of course, we enjoyed all the criticisms directed elsewhere!), but a few criticisms do come close to the mark. The former we will address quickly, and then will explore the latter more caremy, as they are instructive about the differences among us and the possible solutions.

      Although we applaud their specific, logical deconstruction of the Phylogenetic Species Concept of Wheeler and Platnick, Willmann and Meier simply criticize our violations of Hennigian orthodoxy, restate their original opinions without further evidence,...

    • 15 A Defense of the Phylogenetic Species Concept (sensu Wheeler and Platnick)
      (pp. 185-197)
      Norman I. Platnick and Quentin D. Wheeler

      The phylogenetic species concept, as we have presented it, represents a logical next step in the development of phylogenetic theory. Hennig (1966) corrected certain problems associated with the Biological Species Concept (see Meier and Willmann papers, this volume) but, regrettably, other equally severe problems remained. With the general adoption of phylogenetic theory in taxonomy, it became obvious that a concept of species was necessary that was consistent with phylogenetic thinking yet independent of cladistic analysis so that the elements for such studies might be assessed beforehand. At the same time, the emerging biodiversity crisis has made it imperative that we...

    • 16 A Defense of the Evolutionary Species Concept
      (pp. 198-208)
      E. O. Wiley and Richard L. Mayden

      We have organized our responses first on an author-by-author basis. In some cases, a single topic is discussed in more than one section so that we can respond directly to particular criticisms. We present a summary after dealing with each of the critiques of the Evolutionary Species Concept.

      We are not sure if Mayr is criticizing us for not making the distinction between taxa and categories. Fundulus lineolatus is a taxon. Because it is hypothesized to be a lineage and not a monophyletic group of lineages, it is given a binorninal according to the rules of naming taxa of the...

    (pp. 209-224)
  10. INDEX
    (pp. 225-230)