Just a short update (hopefully a full post will follow soon), because I couldn’t ignore the news on the plant ‘barcode’ front. Of course, it’s not really a barcode, it’s a bit of a gene. Two genes, to be precise, or maybe even three—the final decision isn’t in yet.
A bit of background: identifying what species a plant is is not always easy. You may have met people who seem to recognise any plant at a casual glance, but it’s likely that if you tried, you’d soon find something that, without a book, they could only say what family it was in. And if you look at the tropics, there are far more species (and far fewer experts). We haven’t even described them all yet.
The usual way to definitively identify a species is with a key—a series of questions pointing to other questions, which eventually point to an answer. Keys are fairly resolutely paper-based, and where there are a lot of species, that means big books. Identification takes some time, and necessarily involves peering through hand lenses, trying to remember obscure jargon, wondering whether the leaf is more or less than twice as long as it is wide, and, if you’re unlucky, guessing the answers to questions about flowers or fruit that the plant hasn’t grown yet. This is what genetic barcodes aim to do away with.
The idea is straightforward: every living thing has DNA (the other week, I was showing people how you could extract it from kiwis), and it’s a bit different in every species. So, you can, in theory, use the code to identify the plant. The trick is finding a section of the DNA which changes quickly enough that (almost) all species are distinct, but slowly enough that the ‘barcode’ can always be recognised, while being short enough to conveniently ‘read’. This had already been decided for animals, but now there’s a general agreement on two bits of genes for the plant barcode.