Are DNA Barcodes Really Reliable?

DNA barcoding is a technique for characterizing species of an organism using short genetic tags. These tags are from a standard and agreed-upon position in the genome, usually from the mitochondria. It is possible to catalog all life on earth using these genetic markers, similar to products in stores labeled with unique barcodes. Scientists foresee a future hand-held device, akin to a supermarket scanner, that would sequence the DNA tag of an organism, compare it with a library of barcode sequences and spit-out the species’ name.

But are DNA barcodes always accurate? Scientists from the Brigham Young University don’t think so. In a study published by the journal Proceedings of the National Academy of Sciences (PNAS), the scientists found out that current barcoding approaches churn out results as erroneously as a “supermarket checker scanning an apple and ringing it up as an orange”. Current techniques can mistakenly record the non-functional copy of the tag present in the nucleus instead of the standard barcode gene in the mitochondria. The non-functional copy can be similar enough for the barcoding technique to capture, but different enough to call it a unique species, which would be a mistake.

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