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Friday, April 07, 2006

Say No to Taxonomy

I was thinking about the old Linnean vs. Cladistic taxonomy debate again, and not for the first time, when a new thought struck me, why is it necessary to have a formal taxonomic system at all?

Linnean taxonomy sought to emphasise correlates of morphology as well as phylogeny, and in doing so over-formalised these correlations to the extent that it becomes almost anti-evolutionary, creating false dilemmas and the dreaded typological thinking that has been so criticised. But it was the formality that led it to such an undesirable outcome. Rather than being defined in paper for utility, taxa became objects of communication; static and difficult to criticise.

Cladistic taxonomy, of course, corrects many of these shortcomings; but I would argue that it does so at a price. The price is content - cladistic taxonomy in itself holds absolutely no information about the external world.

I'm not saying that we need abandon concepts such as clades, stems, nodes, and all the conceptual framework of phylogenetics, but I do question the utility in the institutionalised formality this branch of biology has taken on.

Clade names may be useful in the written discussion of phylogenetic hypothesis, and in discussions in involving phylogenetic bracketing. However, I don't see why these discussions warrant the formality not afforded to (or it seems needed in) other branches or biology.

Indeed, the formality of phylogenetic taxonomic groups make discussion of subjects not directly related to phylogeny cumbersome and difficult, because nothing can be said of a clade apart from phylogenetic inference. The feeling - generated by their formal institutionalisation - that they should be used above other possible groupings is unhelpful.

Phylogenetic units (clades in this case) are not THE units of biology, they are one of numerous possible units. Nothing should prevent us from erecting paraphyletic or polyphyletic groups based on other biological correlations such as functional morphology or ecology; as the context demands. Institutionalising any of them would be a poor choice however.

Perhaps it would be a good thing if the biological groups used in papers was based purely on utility to the subject, rather than and a formal classification system of marginal utility and perhaps hindrance.