One of the most vociferous debates in taxonomy is over a catchy-sounding concept called DNA barcoding. Since nearly all organisms carry a version of the COI gene in the mitochondrion, the idea is that the DNA sequence of the gene can serve as a standard identification marker. A barcode, of sorts. Of course, the practice only works if species have unique COI sequences. Which they do, much of the time, and the barcoders consequently have been successful in garnering research money and churning out publications.
So what’s the problem? There are two major objections. The first is largely philosophical. The intellectual backbone of DNA barcoding is conceptually the same as creationism- that species are unique entities that neither blend with nor give rise to other species- and about as vacuous.* A typological concept of species flies in the face of decades of empirical and theoretical research in population genetics documenting all sorts of situations- from hybridization to lineage sorting- where single genes do not reflect species boundaries. So the very notion of a unique genetic identifier is offensive to a great many biologists.
The second objection is more political and academic. DNA barcoding allows anyone with access to sequencers to identify just about anything. The horror! Without any knowledge of mycology, for instance, I can sequence a mushroom and put a name on it. Specialists in the taxonomy of particular groups are perceived as no longer needed, money and positions cease flowing to traditional taxonomists, and we lose a great deal of knowledge. I don’t think this is actually happening (positions ceased flowing to taxonomists long before DNA barcoding came along), but it’s understandable that systematists feel threatened.
Having said all that, though, most criticisms of DNA barcoding in practice fall flat. However vapid the barcode concept is, the fact remains that morphology-based identifications also have a signficant error rate, and it is normally substantially higher than that of mitochondrial DNA-based identification. Until critics come to grips with the foibles of traditional identifications, they are just shouting into the wind. What good is pointing out that the barcoding approach fails 5% of the time when the alternative fails 10% of the time?
Still, barcoding is monumentally stupid terminology when applied to biology. Species aren’t manufactered by make and model, even if implying that they are brings in research dollars. Can’t we figure out a way to incorporate DNA into taxonomy without resorting to marketeering?