A term that most of you in the sciences may have heard quite consistently in recent years is the term “DNA barcoding.” It sounds like science (DNA = science, am I right?) and a grocery store (all the bags of chips I buy have barcodes to scan) got together and just outputted that term after a fun night of partying. However, there’s a lot more to it and it has been dramatically changing how scientists perform scientific research.
So what is DNA barcoding? In a very simple form, it is the comparison of a short segment of DNA with a library of previously recorded DNA barcodes (other short segments of DNA). In other words, comparing unknown specimens to known specimens.
Now, why should we care about it? There are many uses for DNA barcoding, which include species identification for marketplace fraud (is it really salmon that’s in your sushi?), forensics (is that souvenir you bought in Thailand made of ivory? Let’s hope not!), environmental monitoring (quickly identifying insect species because there are way too many of those tiny small flies) and so much more! One of the most important reasons I believe that DNA barcoding is essential to our understanding, is that it allows us to work within a taxonomic impediment. With the various negative impacts associated with climate change, one of the most alarming results is the heightened rate of species extinction. Since we are constantly discovering new species of animals, especially insects, we are in a race with time to identify all of our planet’s species before they go extinct. Through DNA barcoding, we can identify species at a rate that is much faster than before.
In a little bit more detail, DNA barcoding can be divided into 4 main steps, and I will explain these steps with what I do at the Biodiversity Institute of Ontario (BIO) with insects. Yes guys, I’m a scientist:
- Specimen collection and processing -> involves me setting up a bunch of traps (Malaise traps, Pitfall traps, sweep netting, etc.) to collect insects in the field. After catching insects, I will take them back to BIO to sort them into orders (ex. Dipera : flies, Hymenoptera : wasps, bees, ants, Coleoptera : beetles). The specimens will then be tissue sampled, usually by pulling a single leg from the insect, or putting an entire tiny specimen into a microplate well.
- Laboratory analysis -> the tissue samples are applied a primer to locate a specific region of the DNA, usually 658 base pairs of the mitochondrial cytochrome oxidase 1 gene for insects. This is the “DNA barcode.”
- Data-basing the specimens -> once we have the barcode, we upload all of the information regarding that specimen into the Barcode of Life Data systems (BOLD). BOLD is an online reference library of barcodes. Some of the information includes where the specimen was caught (latitude, longitude, country, exact site), when it was caught, how it was caught, specimen image, sequence info, etc.
- The Data Analysis -> we will then compare the barcodes with barcodes we have previously acquired through field sampling, museums and other collaborators. So either the specimen will match at least one of the existing barcodes OR we consider it to be a new species in our database! Currently, as of March 19th, 2016, we have 4, 779, 816 barcode sequences, that fall into 444,161 Barcode Index Numbers (BINs) – a proxy for species.
Now after that information overload, I hope all of you guys have a better understanding of DNA barcoding and continue to support its many uses, so I can continue to have a job… Just kidding, but all of us in the sciences definitely need more funding for scientific research. *hint hint* @ Government of Canada.
Written by Thanushi Eagalle