Multicellular Life Evolves In Months, In a Lab 285
ananyo writes "The origin of multicellular life, one of the most important developments in Earth's history, could have occurred with surprising speed, U.S. researchers have shown. In the lab, a single-celled yeast (Saccharomyces cerevisiae) took less than 60 days to evolve into many-celled clusters that behaved as individuals. The clusters even developed a primitive division of labor, with some cells dying so that others could grow and reproduce. Multicellular life has evolved independently at least 25 times, but these transitions are so ancient that they have been hard to study. The researchers wanted to see if they could evolve multicellularity in a single-celled organism, using gravity as the selective pressure. In a tube of liquid, clusters of yeast cells settle at the bottom more quickly than single cells. By culturing only the cells that sank, they selected for those that stick together. After many rounds of selection over 60 days, the yeast had evolved into 'snowflakes' comprising dozens of cells."
Not so sure about this. (Score:5, Informative)
Here's the actual article (Score:5, Informative)
And PNAS has it listed as open access, which means you should be able to download the full text regardless of your subscriber (or non-subscriber) status. Just click the Full Text link.
Re:Not so sure about this. (Score:5, Informative)
Also mentioned in tfa. The scientist says that he plans to do an experiment with organisms without multicellular ancestors.
Re:I've always wondered... (Score:5, Informative)
Flocculation (Score:3, Informative)
Actually I thought Eukaryotes were the big jump (Score:5, Informative)
Not to diminish the importance of multi-cellularity (and of this discovery) but wasn't the development of Eukaryotes (cells with Nuclei and other differentiated organelles) the big step needed for complex life? I mean with chloroplasts you get plants and mitochondria (or mitoklorines for you Star Wars fans) you get animals.
With multi-cellularity and prokaryotes you get strombolites (algal mats).
That said, it shows that evolution can happen quite quickly and can overcome some serious obstacles in a short amount of time in a very limited scope (a laboratory workbench). When multiplied by geologic ages and oceans of room is it any wonder that life has evolved in so many fascinating ways?
Re:Actually I thought Eukaryotes were the big jump (Score:5, Informative)
Re:I've always wondered... (Score:5, Informative)
Re:Not so sure about this. (Score:5, Informative)
This was on RichardDawkins.net back in June, and in the version of the article linked there, there were these telling paragraphs:
Sceptics, however, point out that many yeast strains naturally form colonies, and that their ancestors were multicellular tens or hundreds of millions of years ago. As a result, they may have retained some evolved mechanisms for cell adhesion and programmed cell death, effectively stacking the deck in favour of Ratcliff's experiment.
"I bet that yeast, having once been multicellular, never lost it completely," says Neil Blackstone, an evolutionary biologist at Northern Illinois University in DeKalb. "I don't think if you took something that had never been multicellular you would get it so quickly."
Re:Yes - sounds like "grant time" (Score:5, Informative)
Bzzt. Please review the difference between mass and density and the relationship between density and buoyancy.
Re:Yes - sounds like "grant time" (Score:5, Informative)
The summary is true, but ultimately misleading.
This is evolution, and it did happen in months. What it doesn't account for is getting the clumping gene in the first place, and that the likelihood of getting selection pressures as extreme as the ones in the lab is fairly low.
They've proven that yeast has the capacity to evolve in this way given the right selection pressures, which is interesting. With additional research they may be able to prove that many other single celled life forms have the same capacity, from which we may extrapolate that the gene responsible for this behavior either occurred very early or is a relatively minor mutation.
The "more quickly than we believed" part is probably bogus. They applied extreme selection pressures to this particular colony of yeast and so they got an extreme time scale result the same would happen in any species if you extrapolated for the length of a given generation. You could do the same thing to humans for some arbitrary characteristic.
Re:Yes - sounds like "grant time" (Score:5, Informative)
IIRC from the times when I used yeast in my PhD research, wild type (that means: not mutated) S. cerevisiae clumps in advanced stationary phase (end of growth curve, nutritional deprivation). Such circumstances happen more often that not in the real life of S. cerevisae: just imagine that in nature it cannot walk to the nearest grapevine and say 'hey lets do some sugar fermentation here'... no it depends on being able to survive in times of drought. ne way it does that is through forming spores, another way of temporarily surviving could be this kind of 'clumping'. So, the 'clumping gene' is already there, it is just expressed in certain circumstances, circumstances easily simulated in a lab situation.
In my mind the argument would revolve around self-organisation versus (old, dormant) organisational information still present in the S. cerevisae genome. I'm bummed I cannot access the original article at the PNAS site, else I could comment on that in a bit more detail.
Re:I've always wondered... (Score:5, Informative)
Re:Yes - sounds like "grant time" (Score:4, Informative)