DNA barcoding is a standardized genetic approach to species identification. In 2003, Paul Hebert, researcher at the University of Guelph in Ontario, Canada, proposed “DNA barcoding” as a new system of species identification and discovery using a short section of DNA from a standardized region of the genome. That DNA sequence can be used to identify different specimens, in a similar manner to how a supermarket scanner uses the black stripes of the UPC barcode to identify your purchases.
The gene region that has been chosen for most animal groups, a ~650 base-pair region in the mitochondrial cytochrome c oxidase 1 gene (“CO1”), is proving highly effective in identifying birds, butterflies, fish, flies and many other animal groups. The advantage of using CO1 is that it is short enough to be sequenced quickly and cheaply yet long enough to identify variations among species.
The CO1 barcode is not effective for identifying plants because it evolves too slowly, but two gene regions in the chloroplast, matK and rbcL, have been approved as the barcode regions for land plants. Furthermore, the nuclear ribosomal Internal Transcribed Spacer (ITS) region is effectively being used as the universal DNA barcode marker for fungi.
How does DNA barcoding work?
DNA barcoding provides an innovative solution to the challenges of morphology-based identification of organisms. In the laboratory, technicians extract DNA from a tiny piece of the specimen’s tissue. The barcode region is isolated, replicated using a process called PCR amplification and then sequenced. The sequence is made up of a series of letters: CATG, representing the nucleic acids cytosine, adenine, thymine and guanine. With the sequence derived from this tiny piece of tissue, biodiversity researchers and non-experts alike can identify an unknown specimen by comparing it to a DNA barcode reference library such as the Barcode of Life Data Systems (BOLD).This technique is effective for the rapid and accurate identification of specimens from many groups of living organisms (including animals, plants, and fungi) at different life stages (such as eggs and larvae), and in all forms (such as processed foods and partial remains).
Why does specimen identification matter?
The accurate identification of organisms, made possible through DNA barcoding, is paramount for many globally important issues including conservation, food security, and human health. Documenting and monitoring the world’s biodiversity has rapidly progressed by means of DNA barcoding, contributing to conservation efforts for a natural resource that is both valuable and vulnerable. Understanding the species present in our ecosystems will allow us to protect the planet’s biological diversity while continuing to benefit from it both economically and societally.
DNA barcoding provides a wealth of practical applications that have important implications for many economic sectors around the world. For one, DNA barcoding can detect market substitution in products such as seafood, meat, and herbal supplements and thereby aid in the protection of consumers from harmful contaminants and potential allergens. DNA barcoding has also given us the ability to easily and quickly track the spread of invasive species, including agricultural and forestry pests as well as vectors of human diseases, allowing for efficient responses to potentially major concerns.