November 28, 2021

I, Science

The science magazine of Imperial College

Posthumously, Lonesome George has become a very famous tortoise. Believed to be the last of his subspecies, and often billed as the rarest creature on Earth, he has served as something of a poster boy for endangered species all over the world.

We still know relatively little about the effects that the environment has on species change. In part this is due to the laborious and inaccurate affair of species identification. Usually, a professional taxonomist is needed in order to identify and isolate the species a specimen belongs to using features such as the shape, size and colours of the specimen’s body parts. Thus, there is a need to make species identification a foolproof process that any lab can perform quickly and with certainty. This is where the DNA barcode comes in.

Using a technique first proposed by Paul Herbert of the University of Guelph, Ontario, scientists have been able to identify species using a standard section of DNA found within all animal genomes. The makeup of this section of DNA differs slightly between animal species, similar to the way that the eleven digits comprising a barcode differ between items on a supermarket shelf. In a lab this ‘barcode’ section of the genome can be determined and sequenced from even the smallest sample of specimen. The theory being that this sequence can then be compared against a library of known sequences and the species to which the specimen belongs can be determined.

The barcode system of species identification has real relevance within the field of conservation, especially now that the need to identify and monitor the possible effect that environmental pressures, such as climate change, has become that much greater. The system will also allow for the speedy and more accurate identification of endangered species such as the Chelonoidis abingdoni to which George belonged.

The barcode system is also playing an active role in limiting the potential harm that climate change is inflicting on humans. Mosquito-borne diseases already kill over a million people every year and as global warming allows different species of mosquitoes to spread to Europe this number is only set to increase. Specific species of mosquitoes are responsible for carrying with them diseases such as dengue fever, West Nile fever, yellow fever and encephalitis. The Mosquito Barcoding Initiative (MBI) is a project which has been set up with the aim of collating a database of mosquito barcodes. The initiative hopes that such a library will make identification and control of the key species of mosquitoes that transmit certain diseases infinitely easier, thus potentially saving countless lives.

The barcode of life is certainly set to become a valuable tool. And with groups now having been set up to sequence the barcode of everything from bees to sharks we are more than likely set to discover a few more Georges along the way.

Image from Galapagos Tortoise from