On the Phenetic Approach to Vertebrate Classification

Abstract

I consider the general subject of phenetic classification to possess two major subdivisions. The first is the matter of definition: what is meant by phenetic classification? The second is the matter of motivation: on what grounds do pheneticists advocate their particular methods for constructing classifications? The question of motivation can be looked at in two ways. First, what principles are involked by pheneticists in selecting the methods which they advocate; and second, what drawbacks do pheneticists ascribe to the methods of classification proposed by other schools of taxonomy? The definition of phenetic taxonomy is necessarily purely a matter of convention, and I shall therefore consider it only in enough detail to avoid ambiguity. The motivations of phenetic taxonomy are of much greater importance, for they touch on the long-standing debate among taxonomists of the phenetic, phylogenetic, and evolutionary schools concerning the proper basis upon which to select classificatory methods. This debate has been perpetuated at least in part by the tendency of some reviewers (for example, Mayr, 1974; Sokal, 1975) to criticize the principles of other schools of taxonomy on a superficial, terminological level. I shall devote most of my discussion to attempts to elucidate what appear to me to be the most fundamental principles of phenetic taxonomy and to obviate the purely terminological aspects of the debate through an evaluation of both phenetic and non-phenetic taxonomic methods on the basis of these principles.