What has become increasingly clear in the past 10 years is that this liberal genetic exchange is definitely not limited to the DNA of the microscopic world. It likewise happens to genes that belong to animals, fungi and plants, collectively known as eukaryotes because they boast nuclei in their cells. The ancient communion between ferns and hornworts is the latest in a series of newly discovered examples of horizontal gene transfer: when DNA passes from one organism to another generally unrelated one, rather than moving ‘vertically’ from parent to child. In fact, horizontal gene transfer has happened between all kinds of living things throughout the history of life on the planet – not just between species, but also between different kingdoms of life. Bacterial genes end up in plants; fungal genes wind up in animals; snake and frog genes find their way into cows and bats. It seems that the genome of just about every modern species is something of a mosaic constructed with genes borrowed from many different forms of life.
Shake any branch on the tree of life and another astonishing case of interspecies gene transfer will fall at your feet. Bdelloid rotifers – tiny translucent animals that look something like sea slugs – have constructed a whopping eight per cent of their genome using genes from bacteria, fungi and plants. Fish living in icy seawater have traded genes coding for antifreeze proteins. Gargantuan-blossomed rafflesia have exchanged genes with the plants they parasitise. And in Japan, some people’s gut bacteria have stolen seaweed-digesting genes from ocean bacteria lingering on raw seaweed salads.
The fact that horizontal gene transfer happens among eukaryotes does not require a complete overhaul of standard evolutionary theory, but it does compel us to make some important adjustments. …
No. It really IS a big overhaul.
Having finally faced up to the astonishing reality, we are unfortunately asked by author Ferris Jabr to personify the gene, by way of explanation:
We did not invent gene transfer; DNA did. Genes are concerned with one thing above all else: self-perpetuation. If such preservation requires a particular gene to adapt to a genome it has never encountered before – if riding a parasite from one species to another turns out to be an extremely successful way of guaranteeing perpetuity – so be it. Species barriers might protect the integrity of a genome as a whole, but when an individual gene has a chance to advance itself by breaching those boundaries, it will not hesitate.
No. Genes have a capacity to travel but they have no brains, no minds, no desires. The Dawkinsian metaphysic of the vertical “selfish gene” becomes not only questionable but ridiculous when applied to horizontal gene transfer. Too bad Jabr felt he had to take refuge in anthropomorphism of the gene at the last minute.
That was, at one time, regarded as a primitive way of thinking (lucky pennies, evil trees, selfish genes).
Follow UD News at Twitter!