Have you ever stumbled upon an interesting plant, animal, or insect and wondered what it was? Traditionally, we could consult a field guide or taxonomic key to help us attempt to identify the specimen. But there are still some problems. Scientists estimate that there exist over 8.7 million different species on earth, yet only about 1.25 million have been described and catalogued. That field guide you’re referencing is only going to have the most common species listed. And even if your specimen of interest is a common species, often multiple species can look so similar that even experts have trouble telling them apart. For example Astraptes fulgerator is a common type of skipper butterfly that was first described in 1775. Not until 2004, however, did scientists learn what was thought to be a single species of butterfly was actually a species complex consisting of at least 10 different species. With this much complexity, how can non-experts ever hope to get a handle on species identification?

Enter DNA Barcoding. Like a barcode found on a box of cereal allows point-of-sale systems to automatically identify a product, DNA barcodes use a short section of DNA to uniquely identify organisms to the species level. This technique was first proposed by a scientist named Paul Hebert in his landmark paper Biological Identification through DNA Barcodes. In the paper, Hebert described the use of short, highly variable regions of DNA, that he called barcodes, as a means to identify species. And since it’s publication, the protocol for DNA barcoding has been robustly developed by a team of scientists out of Cold Spring Harbor Laboratory (CSH).

Once DNA is extracted and isolated, the barcode region needs to be isolated and amplified. To do this, we use a technique called PCR or polymerase chain reaction. PCR is an important molecular biology technique used to create lots of copies of certain regions of DNA– think of it as a molecular photocopier. PCR will use primer sequences, short pieces of DNA that match genomic regions ahead of and behind our barcode, to isolate just the region we’re interested in. After PCR we should be left with lots of copies of our barcode that can then be sequenced.