Originally posted by humy
-three different species of bacteria in this experiment evolved independently in exactly the same environment to diversify genetically and in survival strategy in almost exactly identical ways thus proving that evolution can, at least sometimes, be surprisingly very predictable.
At the start of the experiment, each population consisted of generalists competing for two different sources of dietary carbon (glucose and acetate), but after 1200 generations they had evolved into two coexisting types each with a specialized physiology adapted to one of the carbon sources.
Points of interest.
1,200 generations can be observed in the history of a population of bacteria within a very modest human timeframe but it is an awful lot of generations.
It is curious that the bacteria find an evolutionary advantage in becoming specialists rather than generalists, given access to both acetate and glucose, and that it is okay to specialise in either the one or the other, rather than either acetate or glucose being inherently preferable. Specialising would seem to me to make each population more vulnerable, generalising to make them more sustainable. On the other hand, I can envisage the notion that some bacteria prefer acetate and some prefer glucose for reasons that are trivial and just reflecting individual differences, which always exist in any population. So I would conclude we cannot just use commmon sense to assume how evolution will work. We do have to check what really happens.
With bacteria we are not dealing in sexual reproduction so once a difference exists between two groups in the population, there is no reason for it to be averaged out again by random mating. The difference will persist.
I'd like to know more about what is meant by referring to "mutations."
Any evolutionary process is some combination of predictable and unpredictable processes with random mutations,...
If random mutations were critical, then I would understand why there might be some surprise about the similarity of the changes in separate populations. However, if instead the basis for change is individual differences, then there is no process of mutation required and there is less reason to be surprised, if any reason at all. The differences might just become emphasised over generations to the point where there is a real gap between two groups of descendents. As a rule, mutation is far more likely to be harmful than helpful to adaptation and I think it gets too much emphasis. I think ( and lots of what I have read says the same) that most of evolution concerns the impact of individual differences, which are universal - no two creatures share totally identical genes with the exception of identical twins.