Taxonomic names and phylogenetic trees

Abstract

This paper addresses the issue of philosophy of names within the context of biological taxonomy, more specifically how names refer. By contrasting two philosophies of names, one that is based on the idea that names can be defined and one that they cannot be defined, I point out some advantages of the latter within phylogenetic systematics. Due to the changing nature of phylogenetic hypotheses, the former approach tends to rob taxonomy from its unique communicative value since a name that is defined refers to whatever fits the definition. This is particularly troublesome should the hypothesis of phylogenetic relationship change. I argue that, should we decide to accept a new phylogenetic hypothesis, it is also likely that our view of what to name may change. A system where names only refer acknowledge this, and accordingly leaves it open whether to keep a name (and accept the way it refers in the new hypothesis) or discard a name and introduce new names for the parts of the tree that we find scientifically interesting. One of the main differences between a phylogenetic system of definition (PSD) and a phylogenetic system of reference (PSR) is that the former is governed by laws of language while the latter by communicative needs of taxonomists. Thus, a PSR tends to give primacy to phylogenetic trees rather than phylogenetic definitions of names should our views of which phylogenetic hypothesis to accept change. © 1998 The Norwegian Academy of Sciences and Letters

Phylogenetic approaches to nomenclature: a comparison based on a nemertean case study

“…Basically, the results from this case study support the conclusions reached in the theoretical paper by HÌrlin (1998b). The di¡erence in practical outcome between these two approaches is minimized if uninomials are also used at the species level (see below) and such an approach is therefore encouraged.…”

“…Therefore, due to its historical fate there are no de¢ning properties and the problem of taxa is rather one of representation than of de¢nition (O'Hara 1993). Furthermore, the inferential nature of phylogenetics leads to the necessity of giving primacy to hypotheses rather than actual individuals when naming (HÌrlin 1998b).…”

“…Thus, if one wishes to keep the traditional Linnean approach to nomenclature or adopt a phylogenetic system of de¢nition sensu De Queiroz & Gauthier (1990, 1992, 1994, one is also forced to treat species and other clades as classes or natural kinds rather than individuals. If, on the other hand, one prefers to treat clades as historical individuals then we cannot de¢ne their names since no de¢ning properties are involved (HÌrlin 1998b). A few have tried to reconcile the view between classes and individuals (e.g.…”

“…There are several reasons for this (De Queiroz 1988;HÌrlin 1998aHÌrlin , 1999 but, during the last ten years or so, taxonomy has witnessed a revitalization in terms of phylogenetic theory (e.g. De Queiroz & Gauthier 1990, 1992, 1994De Queiroz 1992, 1994Sundberg & Pleijel 1994;Ghiselin 1995Ghiselin , 1997Schander & Thollesson 1995;Bryant 1996Bryant , 1997Lee 1996;HÌrlin 1998b;HÌrlin & Sundberg 1998;Sereno 1999). Although these new approaches to biological nomenclature emphasize the importance of incorporating phylogenetic theory, they also di¡er in interesting ways (HÌrlin 1998b).…”

“…De Queiroz & Gauthier 1992;Cantino et al 1997;De Queiroz 1997;Moore 1998;but see HÌrlin 1998b). This is the ¢rst study of the di¡erences between the phylogenetic system of de¢ni-tion (PSD) and the phylogenetic system of reference (PSR), as identi¢ed by HÌrlin (1998b), that is based on a real case study. I base my discussion on a case study from nemertean (Nemertea) phylogenetics, which includes two stages of phylogenetic nomenclature as well as one stage of Linnean nomenclature.…”