14 CONCEPTS AND DEFINITIONS 



large intercommunicating gene pool whereas each individual 

 is only a temporary vessel holding a small portion of this gene 



ol for a short period of time. These three properties make the 

 species transcend a purely typological interpretation or the con- 

 cept of a "class of objects." 



The very fact that a species is a gene pool, with numerous 

 devices facilitating genie intercommunication within and genie 

 separation from without, is responsible for the morphological 

 distinctness of species as a byproduct of their biological unique- 

 ness. The empirical observation that a certain amount of mor- 

 phological difference between two populations is normally corre- 

 lated with a given amount of genetic difference is undoubtedly 

 correct. Yet, it must be kept in mind at all times that the biolog- 

 ical distinctness is primary and the morphological difference sec- 

 ondary. As long as this is clearly understood, it is legitimate and 

 indeed very helpful to utilize morphological criteria. This caution 

 has been exercised, consciously or unconsciously, by nearly all 

 proponents of the morphological species concept. As pointed out 

 by Simpson (1951) and Meglitsch (1954), they invariably 

 abandon the morphological concept when it comes in conflict 

 with biological data. This was true for Linnaeus himself and for 

 his followers to the present day. 



The typological species concept has a certain amount of opera- 

 tional usefulness when applied to inanimate objects. Ignoring 

 the population structure of species, however, and incapable of 

 coping with the facts of biological variation, it has proved 

 singularly inadequate as a conceptual basis in taxonomy. Much 

 of the criticism directed against the taxonomic method was pro- 

 voked by the application of the typological concept by taxono- 

 ii lists themselves or by other biologists who mistakenly con- 

 sidered it the basis of taxonomy. 



The Second Species Concept. This is sometimes called the 

 aondimensional species concept and has no generally accepted 

 designation. The essence of this concept is the relationship of 

 two coexisting natural populations in a nondiinensional system, 

 that is, at a single locality at the same time (sympatric and syn- 

 chronous). This is the species concept of the local naturalist. It 



