‘Evolutionary scandal’ of sexless bug solved - October 12, 2007
Reproducing asexually means losing much of the ability to adapt to environmental changes that comes from combining the genes of two parents. So it had been thought that asexual animals would be disadvantaged over serious timescales. However the hard-to pronounce bdelloid rotifer has been around for 80 million years and Cambridge scientists say that its sex-free life is part of its robustness (BBC, Telegraph, The Scientist, and Reuters – which says 40 not 80m years).
The water-dwelling invertebrate has the neat trick of drying out when there is a lack of liquid and surviving in this desiccated state for years, until the rains or some other sort of water comes along. Dr Alan Tunnacliffe, from University of Cambridge, discovered that the beasties have a gene where the two copies can do totally different jobs: one prevents proteins from clumping together and the other helps to maintain cell membranes. This differs from organisms that reproduce sexually where the two copies have the same job.
“Evolution of gene function in this way can’t happen in sexual organisms, which means there could be some benefit to millions of years without sex after all,” he said (press release). He expanded on this point to Reuters: “It is like having a bigger tool kit. You can do the same job but better.”
The Telegraph thinks Tunnacliffe has solved one of evolutionary science’s biggest problems. “[T]his pond life has been the one ugly fact undermining the beauty of sex: the translucent organisms abandoned sex such a long time ago that they were once denounced as an ‘evolutionary scandal’ by the late and great biologist Prof John Maynard Smith.”
The research is published in Science.
Image: Bdelloid rotifer by N. N. Pouchkina-Stantcheva
