Thoughts: How taxonomically binding is biological
by Nico Franz on April 20, 2015
Biological nomenclature and taxonomy are both different yet also somehow interconnected. It is sometimes stated that the two kinds of practices are largely independent of each other. Yet we also know that - to some degree - Code-compliant nomenclature must respond to taxonomic change. Pyle & Michel (2008) review the relationship of nomenclature and taxonomy in (what seem to me) often reiterated terms. They write (pages 41-42):
"Taxonomy and nomenclature are closely allied, but separate and complementary endeavors in developing the language of biodiversity. Discovering and delimiting species is the challenging job of alpha taxonomy; determining relationships and establishing higher taxa is referred to as beta taxonomy.
By contrast, the establishment of scientific names of animals is not a scientific process of testing alternatives; rather, it involves a bibliographic and quasi-legal process of presentation of a name with appropriate supporting documentation in a publication. Although a scientific name is generally established within the context of a published work on taxonomy, its link to actual organisms is through the primary type specimen (or specimens). This process of typification allows the name to be tied to a physical standard (and hence provides an objective basis for identifications), but leaves room for taxonomy to change; different names can be applied to taxa as is appropriate for their new boundaries.
We want to underscore that the work of nomenclature aims for stability in names, but is completely independent of the process of flexibility in taxonomic interpretation."
The authors go on to cite relevant sections of the Code. The notion that naming conventions refrain from infringing on taxonomic judgment is emphasized. Please refer to the links provided to get a more complete picture of their language, which I have no intention of misrepresenting.
Stressing the relative independence of nomenclature and taxonomy as an important point - for all to remember and adhere t0 - once seemed misplaced to me. That was some 12-15 years ago when the merits of Phylogenetic Nomenclature were hotly debated. One argument that presumably strengthened the case for the Linnaean system was - its superior responsiveness to taxonomic change! Nixon & Carpenter (2000) argued in essence that under the Phylogenetic Nomenclature paradigm the binding of name definitions and taxonomic content is too loose. On the other side, Cantino and Bryant (2002) appeared to concede that "many taxonomists also conceptualize taxa based on their content" - again implying that greater responsiveness to taxonomic content and content change is what may render the Linnaean system attractive to some. Two years ago, Vences et al. (2013) published detailed sets of recommendations that are deeply influenced by contemporary taxonomic theory. If nomenclature had no way of absorbing such theoretical commitments then I am not sure that their paper could have been written.
The stated adherence to the tenet of independence - refraining from infringing on taxonomic judgment - has its origins in a context different from that of the PhyloCode developments or phylogenetically informed naming regulations. I would like to better understand what these origins were. And I still tend to think that "independence" is not the most helpful term for understanding the relationship. More concretely:
- There are many nomenclatural emendations that require no immediately preceding taxonomic assessment of necessary change (e.g., a lapsus calami).
- There are also many taxonomic changes that require no immediately succeeding nomenclatural emendation (e.g., new placement of a non-Priority-carrying genus [names] from one tribe to another).
- Then there are some nomenclatural rules whose proper application may actually require new and immediately succeeding taxonomic research under certain conditions (e.g., neotypification when the original type is lost).
- And lastly, there are many new and immediately preceding taxonomic research insights that require nomenclatural emendations (e.g., inference of heterotypic synonymy).
Clearly, from (1) to (4) above it does not follow that nomenclatural conventions infringe upon the freedoms of taxonomic judgment. But it may follow that some nomenclatural rules sometimes force taxonomic action (3). And it does follow that, at any given time and under any particular taxonomic perspective, the rules of nomenclature actually force the corresponding sets of valid and invalid names and their parent/child/type relationships (in so far as they fall under the Codes' regulations) to be very significantly responsive to that taxonomic perspective. Alonso-Zarazaga and Lyal (1999) recognize some 5800 curculionoid genera, therein purported to entail more than 50,000 species. Arranging all corresponding type specimens for the latter entities in their particular system - thereby also accounting for a likely same or greater order-of-magnitude number of heterotypic type specimens anchoring junior synonyms - and then forming ~ 100,000+ valid and invalid binomials in strict accordance with that taxonomic perspective - is not an activity that evokes the term "independence" to my mind.
Instead, I think it is fine to say that the rules of nomenclature are designed in very significant ways so that the sets of valid and invalid names and name relationship must continuously respond to current and prevailing taxonomic inferences. To a large degree, the Codes force name making to follow taxonomy making. It could well be otherwise.
That the rules do not thereby dictate how (exactly) these inferences should be empirically grounded is perhaps not such a salient or unusual point? Do rules not guide processes rather frequently without dictating a particular outcome? Is that maybe a little like saying, the rules of voting do not dictate which party will win?
I like to think that the designers and refiners of Linnaean nomenclature purposefully relegated much semantic power and responsiveness to Code-compliant names and naming practices. By and large, the right sets of names should be reflective of the rights kinds of taxonomic inferences. The semantic contents of taxonomic names were designed to be quite narrow and deep when broader and shallower options are well conceivable. Accordingly, even though it is true to state that name making does not infringe on taxonomy making, I feel that the more salient feature of Code-compliant naming practice is actually its broad and deep commitment to be the binding force of strong taxonomic semantics.
Seeing it that way - i.e., biological nomenclature promotes deep taxonomic semantics - may also help situating our naming practices within emerging ontological solutions, but that is well beyond this blog post's scope.
The above graph is partly adopted (upper half redrawn) from Pyle & Michel (2008). Both models are effectively too simple.