Biology without species: A solution to the species problem.

摘要

This dissertation develops an argument for the elimination of the concept species from most of its uses in biology. The argument is based upon the contradictory nature of the roles assigned to the concept, both as a classificatory unit and as the unit of evolution.;The opening chapter describes what is commonly called The Species Problem and demonstrates that it is in fact four separate questions. The following chapters elaborate these problems and show how, once disentangled, they may ultimately be solved. However, these solutions entail the dysfunctional nature of the concept species.;Chapter 2 addresses the first Species Problem, that of defining species taxa. After surveying the different delineation criteria and approaches, it shows that each approach is limited in its scope and that they do not converge. The proliferation of species definitions, coupled with their failure to converge, lays the foundation for the next Species Problem.;Chapter 3 takes up Species Problem II which addresses the unity of the species category and of the classificatory rank of species. After discussing the aims of classification, the chapter defends the thesis that the best-justified position regarding the species rank is a multi-concept pluralism, and that this position in fact leads to the elimination of the species rank in classification. The chapter makes a further claim that multi-concept pluralism entails multiple monisms which expose the competing goals of classification, as both a unifying taxonomy with uniquely designated entities and a system representing different evolutionary processes. Thus, with multi-concept pluralism, not only is the species rank eliminated, but the whole classificatory system is broken down into separate contextual systems.;Chapter 4 discusses Species Problem III, the ontological status of species taxa as classes or individuals, and Species Problem IV, the role of species as a concept in biological theory. This chapter demonstrates that species cannot be regarded unproblematically either as kinds or as individuals. In view of that and of the conclusions derived in chapter 3, the dissertation concludes by arguing that species is not a useful concept in biological theory.