Quote:
Originally Posted by Neapolitan
I think the evolving part is just as interesting as in the result of multi-cellularity.
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The reason the evolving part is not as interesting is that it's been proven many times before and would show nothing new. Many times, micro organisms have adapted to artificially induced selection pressures
Quote:
Originally Posted by Neapolitan
I guess the page I was coming from was like: Was multi-cellularity already a forgotten part of this organanism pre-historic past? Was there some environmental change that forced this multi-cell yeast of the past to evolved in singlular cellularity of today. But still even after the evolutionary step it kept those multi-cellular codes in it's DNA but they remained dormant, it never reach multi-cellularity form because whatever environment that organonsim once live no longer exist, and in the new environment singular-cellularity was more advantageous for survival. Then along came a scientist and he did an experiment by shaking vials, in reality he didn't forced evolution on the yeast but unwittingly unlocked a pre-existing code that was already there - the multi-cellularity code. I think that is more my point than the validity of evolution or how much I know about evolution.
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This is pretty much the plasticity scenario I mentioned in my earlier post. I'm sure they're trying to keep up with the genetic changes of the organisms and will document proof.
I should perhaps mention that an example of evolution does not necessarily require new mutations. We call it evolution even when the allelic frequencies differ from one generation to the next. That means that if there is two versions of a clumping gene, one which creates a unicellular yeast and another which makes a multicellular type yeast and in the generation you're looking at there is 9 unicellular genes for every 1 multicellular gene .. if the multicellular type yeast have more reproductive success, in the next generation you could have 7 unicellular gene versions for every 3 multicellular genes.
We call versions of genes alleles. In this case, even though both alleles were present at the start, the ratio between two alleles has changed from one generation to the next. As a result, the genetic makeup of the yeast population has changed somewhat. That's also called evolution.
edit :
The good old Hardy Weinberg principles demonstrate what conditions you'd have to meet in order
not to evolve.
- Population size has to be huge (infinite size basically)
- Mating has to be random (no sexual selection)
- There can also be no non-sexual selection pressures
- There can be no mutations
- There can be no gene flow (gene migration from other populations)
These criterias are used as a reference to see how fast a population of animals evolve by looking at specific alleles and monitoring how they change in frequencies from one generation to the next.
If you understand the concept of evolution and these principles, you'll see that life can't not evolve.
edit 2 :
For the record, I don't believe that what we're seeing in the study is merely a change in the frequency of old alleles. I'm just saying that you could call it evolution even if that was the case. As it's a novel trait which the yeast seem to have adapted over time (gradually changing the way they work/look/behave), I'm still sure they will document changing DNA and not just changing allele frequencies.