384 DIFFICULTIES AND IMPORTANCE OF THE CONCEPT 



such decisions, some of which by necessity will be incorrect, and 

 who prefer to classify all organisms into meaningless but com- 

 parable morphological species. It is quite evident that these 

 workers fight a losing battle because biologically trained tax- 

 onomists are unhappy to be degraded into pebble sorters. They 

 would much rather make an occasional mistake than be burdened 

 forever with a multitude of purely morphologically defined pi- 

 geon holes. 



Fossil Species. The need to evaluate fossil specimens in terms 

 of biological species has led and is leading to a new outlook in 

 paleontological classification (Sylvester-Bradley, 1956). It forces 

 the paleontologist to make clear decisions: Different specimens 

 found in the same exposure (the same sample) must be either 

 different species or intrapopulation variants, "for two geograph- 

 ical subspecies cannot come from the same locality, and two 

 chronological subspecies cannot come from the same horizon" 

 ( Sylvester-Bradley, op. cit. ) . The recognition of subspecies and 

 polytypic species in paleontology leads to the same simplification 

 and greater precision as it has in neontology. In all this work the 

 evidence is largely morphological, but the interpretation is based 

 on biological concepts. An occasional error of interpretation in 

 the synthesis of polytypic species in paleontology is vastly to be 

 preferred to the chaotic accumulation of morphologically defined 

 entities without biological meaning. 



Biological Races. The shift of emphasis from morphological 

 difference to reproductive isolation has necessitated a reanalysis 

 of the whole complex of phenomena loosely referred to as "bio- 

 logical races." These are of great practical importance since most 

 of these so-called biological races were found during the study 

 of disease vectors or of injurious animals. Here again the need 

 for a clear decision, species or not, has led to clarification and sim- 

 plification. The study of sibling species which has been the major 

 outcome of this analysis has been, in many cases, ol great prac- 

 tical importance in applied biology. 



The species is, however, of more than purely practical impor- 

 tance. It has a very distinct biological significance which has 



