On the Relationship Between Species Concepts and Speciation Processes

Abstract

-Although many biologists acknowledge a fundamental relationship between species concepts and the processes thought to give rise to species, there is less agreement on the extent and desirability of this relationship. While some advocate species concepts explicitly linked to particular mechanisms of speciation, others believe that concepts will function best when they are independent of particular notions of process. The existence of a diversity of interpretations of has hampered a clear view of the concept-process link. Although there are general reciprocal constraints between concepts and processes, we suggest that it is profitable to maintain species concepts logically distinct from particular mechanisms of speciation. We analyze an example (from the work of Hugh Paterson) in which such a logical distinction between concept and process has not been maintained. Paterson makes the validity of the biological species concept contingent upon a particular process of speciation (reinforcement). However, such a link occurs only if biologists impose the requirement that a species criterion be a functional trait. We argue that what qualifies the members or parts of evolving populations as different species is not a function of the particular mechanism that drives the divergence. [Species concepts; speciation; mate recognition.] Two of the most fundamental problems in evolutionary biology are the proper definition of species (species concepts) and the origin of species (speciation). Because the voluminous literature devoted to these topics has tended to treat these problems separately, there has been relatively little explicit attention to the logical nexus between a species concept and possible processes of speciation. Nevertheless, those who have discussed the concept-process relationship (e.g,. Sokal, 1973; Wiley, 1978; Cracraft, 1983, 1987; Rosenberg, 1985; Templeton, 1989) suggest that an explicit analysis of this relationship may be crucial to further progress in both areas. The purpose of this paper is to provide an overview of the issues and discussions surrounding the link between concept and process and to analyze a specific example from the recent literature. We suggest that biologists hold differing (sometimes implicit) views of this relationship, that some ambiguity remains concerning the nature of the relationship, and that species concepts which are not linked to particular theories of speciation will be most fruitful. We do not attempt to provide an exhaustive review or a definitive solution to the issues raised, but rather to bring the questions into sharper focus.