According to the modern theory of evolution (the theory that scientists actually use), most differences between the genomes of complex eukaryotes are due to neutral drift, not natural selection.
“Not precisely predictable” is exactly what I mean by stochastic.
Does a beneficial allele replace all other alleles in a single generation in every single case?
It doesn’t. Mathematical models are tested against reality all of the time.
@glipsnort, @paleomalacologist, @pevaquark, @SkovandOfMitaze, @Daniel_Fisher
What is the scientific basis for this modern theory? What is the experiment that verifies this claim, or is this just speculation? Is there anything in writing other than this claim?
Is the Wikipedia and the Darwinian understanding of natural selection wrong? and if so why haven’t we been told about this until now?
This for me is a major change, if true, that needs serious discussion. We need to take science seriously.
According to this link it’s not suggesting that neutral drift is undermining, but elaborating on, a small part of the evolutionary theory. I don’t know enough about this aspect to have a real opinion. I’ll have to study it for a while.
This looks like a good article:
Neutral theory was first proposed by Motoo Kimura back in 1968. It’s been a part of the modern theory of evolution since the 1970’s. Biologists have been hearing about it for 50 years, so I can only guess as to why you have never heard of it until now.
Determining the relative role of neutral drift versus selection is not easy; a recent study showed that some popular analytical methods to try to get at this problem were not actually informative. Demonstrating that there is absolutely no selective influence is unsurprisingly difficult, as is proving that a particular past change was advantageous. Both certainly are operating in modern systems where we can test and function in simulations. Thus, it’s important to take into account; as Gould pointed out, we should not just assume that everything has a specific cause from natural selection. On the other hand, as Conway Morris has pointed out, the extensive occurrence of convergent evolution certainly indicates that selective pressures provide some strong constraints on evolution.
All good points. This is why I think it is helpful to frame neutral theory as the null hypothesis which leads to objective criteria for selection within a given model. Of course, this only leads to the question of how good the models are, but at least it gives us a scientific way to approach the data.
Becoming aware of neutral theory is a significant part of what allowed me to affirm evolutionary science and become an ‘evolutionary providentialist’.
Some points that I think most evolutionary geneticists agree upon:
What I think there is some disagreement is the relative importance of selection and drift on standing variation and the process of substitution. Even if a mutation is effectively neutral, that doesn’t necessarily mean that its fate is determined by genetic drift, since it is likely to be linked to other (potentially non-neutral) mutations on the same chromosome.
In that case, we have to consider things like the local rate of recombination, the rate of background selection and positive selection, etc.
My guess is that, like most of biology, there is no one-size-fits-all answer. The relative importance of drift and selection may differ greatly in different species, which is pretty fascinating if you ask me.
U want to think all those who responded to my question about natural selection. Please note that natural selection is not an option in terms of Darwin’s theory, it is the foundation and if it were to be changes or abandoned then our whole understanding of biology would need to be changed.
The information that Mi, @SkovandOfMitaze, posted was helpful to put neutral drift in proper perspective.
Nothing exists in a vacuum. Science, philosophy, and theology are all linked. That is why natural selection is very important, even through few people are interested in discussing it.
Thank you for sharing,
Even Darwin was ok with neutral theory:
A fluctuating element is neutral drift.
@T_aquaticus The statement that I questioned is clear. You said that according to the modern theory of evolution , which is the theory which most scientists actually use most differences between genomes is the result of neutral drift, not natural selection.
In the decades since its introduction, the neutral theory of evolution has become central to the study of evolution at the molecular level, in part because it provides a way to make strong predictions that can be tested against actual data. The neutral theory holds that most variation at the molecular level does not affect fitness and, therefore, the evolutionary fate of genetic variation is best explained by stochastic processes. This theory also presents a framework for ongoing exploration of two areas of research: biased gene conversion, and the impact of effective population size on the effective neutrality of genetic variants. from the paper on line that T cited.
However the paper you quoted to support this statement seems to say something else. It says that the neutral theory has become central to the study of evolution at the molecular level, which does not sound as if it is the only modern way to study evolution. However it does seem to be the field that you are engaged in. I would suggest that maybe you are saying that you way of looking at evolution in your field is not the only way, esp. when looking at the field as a whole.
I would suggest that they rest of this statement seems to confirm fact that neutral drift is an significant aspect of evolution, bit not determinative as natural selection. A;lso, that stochastic processes here refers to chemical processes which are not arbitrary or by chance, bit according to the rules of chemistry
As far as I am concerned the word stochastic is an unvented word that does not e3xpalin anything. It is used indicate that evolutionary processes are random or arbitrary when they are not.
I don’t see how you get from A to B. If you polled working molecular biologists and population geneticists I would be shocked if less than 99% listed neutral theory as an important part of the modern theory of evolution.
If you consider biology and emergent property of chemistry, then I guess so . . . in a very roundabout sense. You could say that the roll of the dice follows the laws of physics and chemistry in the same way.
Stochastic is a descriptive word, and it is not meant to be explanatory. It describes systems like the lottery, roll of the dice, and the fate of neutral mutations in populations.
I am not interested in what only "working molecular biologists and population geneticists " think, but what all ALL biologists in the field think, because this is what you claimed.
Please do not change the subject. You said that “most differences … are because of neutral drift,” which makes it more important than natural selection. No pone is saying that it is unimportant, just that it is less so than natural selection.
Where is your evidence that evolution is random in relationship to the ecology?
Description and explanation must be related. There is no way that the lottery, craps, and evolution are the same. To say that they can be reasonably described by the same word is wrong that no explanation can justify. It is a perfectly rational biological process guided by the ecology as most naturalist observers agree.
I apologize for my typos over the past weeks. This was before and after I had surgery for cataracts on both eyes this month. I underestimated the effect the cataracts had on my vision before and just after the surgery.
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