Historically taxonomy has been an art. People have looked at stuff and said “well, that LOOKS like that other animal, so it is probably the same thing”. In the 1800s, it was a popular hobby – so if you had enough free time (and you had to be rich, too), you could wander out into the woods, pick up a bug, take it home, compare it to other bugs that people had already looked at, and tell people that you think that this bug is this other one.
Is this good enough? Is it? I think we all agree that this isn’t not science, and it is not good enough. Enter: barcodes. Barcoding species involves sequencing regions of DNA – the molecule of heredity. This molecule is inherited, it’s passed down from parents to offspring, it tells each species which species it is. DNA=species, it’s a direct correlation. Hence, it sounds like a good idea to look at this to figure out what a species is, no? Am I wrong? Tell me I’m wrong, go on – I dare ya!
Some individuals of the same species look very different. That fish species where the male looks like a tiny leech attached to the female, male and female humans, seaweeds from below the low tide line vs the same species from the intertidal zone. They all look really different and are very hard to declare as the same species from morphology. Their DNA is the same, though. Example: moa are a family of extinct birds from New Zealand. Many skeletons found were believed to be different species until ancient DNA studies were performed on these bones – showing that many different species were male/female pair. The females were just bigger.
So what is this barcoding stuff? Well every species has a lot of DNA in its genome. In the ballpark of billions of bases. You can’t look at billions of As, Cs, Gs and Ts – you just look at a little bit of it. You pick a bit that evolves slowly (for distantly related species) or quickly (for closely related species). Amplify this using PCR, sequence your PCR product, and look in a database to see what animal you just sequenced it from! It couldn’t be simpler!
The process to barcode all species on Earth has started, and when it’s finished taxonomy will never look the same again.
