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  • Comparing short DNA sequences from a standard gene is called DNA barcoding. This technique is being used to help discover, identify and distinguish species.


    Barcoding life

    A DNA barcode is a DNA sequence commonly used to identify a target molecule during DNA sequencing.

    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?

    Find out more in the article 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.

    Rights: © CaseyTucker, Wild Auk Photography

    DNA sequencing results

    The results from automatic DNA sequencing with the bases, guanine (G), adenosine (A), tryosine (T) and cytosine (C) shown in different colours.

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

    Find out more in the articles The ideal barcoding gene and 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. Initianlly the work was undertaken by two large international initiatives – CBOL and iBOL:

    • 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. Many of these projects have been completed.
    • 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.

    Barcoding sharks and Sequencing shark DNA looks at the work teacher Andrea Shaw undertook on sharks as part of the ambitious Fish-Bol project, an international effort to collect DNA barcodes for all fish species.

    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.

    Read the article Barcoding New Zealand swamp hens to find out more. New Zealand scientists have discovered that Lord Howe Island tree lobsters evolved from different ancestors, this is an example of convergent evolution.

    A controversial approach?

    …every naturalist knows vaguely what he means when he speaks of a species.

    Charles Darwin

    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?

    Find out more on why scientists name species and the modern system for classifying species.

    Useful link

    The New Zealand Inventory of Biodiversity is a comprehensive three-volume inventory that offers the first full review of New Zealand's entire known species of animals, plants, fungi and microorganisms, read the NIWA press release.

      Published 24 July 2009, Updated 22 May 2012 Referencing Hub articles
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