ABSTRACT
Introduction
Understanding biological diversity by means of classifications requires that we translate our observations into characters. Characters are the units of language through which we communicate our ideas of homology, relationship, diagnosis and identity. Although most biologists would agree with this as a general statement, it is equally true that different workers would partition their observations into different units or characters (Smith, 1994). Sometimes these differences are purely practical, commensurate with a particular method of systematic analysis. For example, a pheneticist would accept a ratio (e.g. 0.5) or a simple length measurement (e.g. 6.2 mm) as a character. In contrast, a cladist, because of the demands of the method, needs to translate observations to discrete variables (Archie, 1985; Thiele, 1993). Different workers may also choose to describe shape, or mutual relationships of bones or insect wing venation, in different ways. These relatively trivial differences are usually transparent. But beneath this veneer of variation there is a more fundamental core of differences as to what we mean by a character and this often implicitly determines how we code our observations in any cladistic analysis. Furthermore, because the coding method that we use is the prime determinant of the systematic outcome, particular attention to this aspect of cladistic analysis is necessary (Pimentel and Riggins, 1987; Bryant, 1989; Pogue and Mickevich, 1990; Hawkins et al., 1997).
