Why do we need DNA barcodes?

The earth is home to a staggering number of species. Estimates for the number of eukaryote species range from 10 million to 100 million. Traditionally, taxonomy has been used to classify organisms. However, less than 2 million species have been classified since taxonomy began 250 years ago.

In 2003, the idea was proposed that scientists could tell species apart by comparing a short gene sequence from a standard gene. So, could DNA sequencing technology provide a quicker approach for species identification?

Get information sheet: DNA barcoding

Which gene to sequence?

The first thing scientists had to do was choose a gene to sequence. They wanted one that was common to all living things. It needed to show enough variation to be able to tell species apart, but not so much as to distinguish individuals of the same species.

DNA sequencing results

The 648 base-pair mitochondrial encoded cytochrome c oxidase subunit 1 (CO1) was chosen as the gene.

Get information sheet: The ideal barcoding gene

Get information sheet: More about mitochondria

Collaborative work

There’s an enormous amount of work involved in determining a barcode for every one of more than 10 million living species on Earth.

Much of this work is being done collaboratively. Two large international initiatives – CBOL and iBOL – have emerged:

• CBOL (Consortium for the Barcode of Life) – Established in 2004, the consortium promotes DNA barcoding as a new scientific standard. A range of barcoding projects, including ABBI (All Birds Barcoding Initiative), FISH-BOL (the Fish Barcode of Life Campaign) and Bee-BOL (the Bee Barcode of Life Initiative), are part of this consortium.
• iBOL (International Barcode of Life) – The iBOL project, which began in 2007, aims to analyse 5 million specimens representing 500,000 species over 5 years. Their goal is to assemble a library of DNA barcodes and develop technology that can identify species rapidly and inexpensively.

Species identification is important

Species identification is important in a wide range of scientific and technological fields. These include basic research in taxonomy, evolutionary biology, conservation biology and biodiversity studies, as well as more practical matters such as protecting endangered species, monitoring environmental quality, stopping disease vectors, controlling agricultural pests, identifying birds involved in bird strike and identifying foods.

Get information sheet: Barcoding New Zealand swamp hens

A controversial approach?

Charles Darwin wrote: “…every naturalist knows vaguely what he means when he speaks of a species”. Despite scientific advances since Darwin’s time, this vagueness still exists. The question at this time is: Will DNA barcoding fulfil its early promise and develop into a ubiquitous, user-friendly tool for species identification?

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