barcoding

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…