I did not see that so I need to take a fresh look. Thanks.
I’m sorry, I’m quite incredulous about this response. I’m a new member here, but you and I have both been members of Larry Moran’s Sandwalk page for quite some time. And you seriously do not understand how Lenski’s study demonstrated that adaptations arise thru non-Darwinian mechanisms? Are you really paying that little attention?
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Yes. And some roses can be white. Therefore red roses do not exist. You think?
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What do you consider are non Darwinian mechanisms?
Neutral mutations not subject to positive or negative selection.
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How do you think these can be functionally innovative?
Deliterious mutations are not subject to positive selection, and they are important too.
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No but they’re subject to purifying selection, and that’s Darwinian. If it’s subject to selection, it’s Darwinian.
Actually, not everyone understands it that way. Negative selection is different than positive selection. The “Darwinian mechanism” is positive selection, not negative selection.
I don’t really see how, it really just moves the emphasis of selection. When an allele is selected against, another is selected in favor of it. Negative selection can only exist if something else is being positively selected against it.
There is your misunderstanding. This is not true.
Elaborate please.
Imagine an embryonic lethal mutation that arises. It will cause a miscarriage no matter what. It doesn’t matter if there is positive selection taking place in the population at large or not. This also sometimes called “purifying” selection.
Compared to a lethal mutation, the allele that doesn’t have it is beneficial. But lethals are a bit unusual in that you can’t imagine a background of lethals in which a beneficial mutation arises, dead organisms don’t replicate.
But you started out saying deleterious (which isn’t lethal) mutations are important in response to me pointing out neutral mutations aren’t being subject to the Darwinian mechanism. “Merely” deleterious mutations being subject to “negative” selection are an unavoidable consequence of the Darwinian mechanism.
That is just an illustration. Purifying selection works on deliterious mutations, that might persist for a long time before being eliminated. This turns out to be an important fact, because the mutations can be along a pathway to greater fitness.
Read the article I posted above about Lenski’s experiment.
This is old news.
Disagree. It’s an arbitrary distinction based, apparently, on the initial frequency of the allele being discussed. If the rare allele is favored, it’s positive selection. If the common allele is favored, it’s negative selection. But in either case all we have are different alleles with different selection coefficients.
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Let’s just agree that the people touting that “Darwinism” is modern evolutionary science do not even adequately take this aspect of evolution into account.
I’m not sure I can agree. The only things they appear not to take into account are neutral and near-neutral evolution. “Darwinism” is, apparently, all about selection. But the type of selection is a quibble about which there seems no reason to argue.
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