Rotifers are a group of microscopic animals that are very common and often very pretty. It’s been recently discovered that they have prolifically incorporated genetic material from other organisms into their own DNA. The Not Exactly Rocket Science blog has a good article about it: link. Excerpt:
But among the DNA of the bdelloid Adineta vaga, he unexpectedly found traces of bacterial, fungal and even plant genes, many of which are incredibly rare. About half have no counterparts in animals and one gene is found in only 10 species of bacteria. Some genes appear to have been smuggled into the rotifer genome as a set, for they appear in the same order and orientation that they do in fungi or bacteria.
The genes are not passive hitchhikers either. Many appear to be fully functional; in their native species, they are involved in breaking down sugars and carbohydrates, or producing useful molecules like antibiotics and toxins. The chances are that the rotifers are putting them to similar uses.
And later:
It’s not clear why the bdelloids are so good at incorporating new genes, but their lifestyle may hold the answer. The freshwater ponds they call home frequently dry out and they cope with this by entering into a dry, dormant and extremely tough state. This drying process breaks their cell membranes and shatters their DNA. The bdelloids are very good at repairing these injuries, but it provides a temporary entrypoint for chunks of foreign DNA from species in the surrounding environment that have also succumbed to similar damage.
This newly discovered ability may help to explain the success of the bdelloids despite their rejection of sex. Compared to sex, asexual reproduction is often seen as a poor long-term strategy, for it lacks the chromosomal shuffling that brings about genetic diversity and is thought to gives species an adaptive edge in the face of new challenges. But bdelloids have contradicted this theory by being very successful; there are over 360 species alive today.
Gladyshev suggests that this success may be due to their ability to pick up new genes from their environment. If the main advantage of sex is that it promotes genetic diversity, why worry about it when you have the gene pools of entire kingdoms available to you?
No Comments Yet