Mitochondria, the cell’s energy producers, are descended from free-living bacteria that took up residence within other cells some 2 billion years ago. They have a modest genetic size being only 37 genes in vertebrates, compared with more than 20,000 in a nucleus.
Yet within this little genome, researchers have identified a 64S-nucleotide stretch as the ultimate identifier of species, dubbed the DNA bar code. The sequence can distinguish between closely related species such as humans and chimps and even classify new species from identical-looking ones, such as the blue-flasher butterfly (Astraptes fulgerator), which has since been divided into ten separate species, verified by the habitats, lifestyles and diets of their caterpillars. ,
The DNA bar code has been both praised and attacked for its simplicity.
Lane 2009 On the origins of bar codes Nature vol 462 pp272-3
- Martin Eastwood