Yes, technically it is selective pressures that act on variation, and selective pressures are but one component of the larger process of natural selection.
I think what may be going on here is this all started with the language on the Evolution 101 page. It's important to keep in mind that the site is just giving a simplistic overview for laypeople, whereas what we're getting into now (the difference between natural selection and selective pressure, and how selective pressures are but one component of natural selection) is more detailed.
It's like if you went to a web page that described how cars work, but was designed for people with little to no understanding of cars. The page might say something like "the engine is what makes the car go". But if you started talking about that in more detail with a mechanic, you would quickly get into how actually, the engine is but one component that makes the car go.
So just as "the engine is what makes the car go" isn't
technically correct, "natural selection acts of variation" isn't
technically correct either. But if a layperson said the former to a mechanic and the latter to a biologist, both would most likely respond "Yeah, that's right" because both are true enough in a broad, general sense.
Thanks. You too.
I don't agree.
The fact that you can't say true, when the answer is obviously true, seems to indicates what I think to be the case.
I think people use broad terms for convenience - in order to "take a little here, and a little there", and still be in the game.
It's like playing a baseball game, where the touch base is five times the regular size.
I see it, not only in this case, but in other terms, including the use of the term evolution.
It's easy to say something, but when it comes to explaining it, one begins to see that the terms are just used loosely, because "it really doesn't matter as long as it works for the proposed idea"... imv.
I think natural selection
needs to act, because it is proposed as the driver for evolution, and we can't have a mindless driver that doesn't just drive randomly.
Can you imagine a driver-less car with no AI? It's path would be random, not guided.
However, I am not really interested in what people say, if they can't explain it. That's like asking me to believe in what others believe, without understanding why they believe it.
Note though, that Evolution 101 is not the only site that says "natural selection acts on variation".
A
quick google will reveal that.
We will also see from
this source...
* Natural selection acts on the phenotype, the characteristics of the organism which actually interact with the environment...
* Natural selection can act on any heritable phenotypic trait...
* Natural selection acts on an organism's phenotype, or physical characteristics
* Natural selection is here understood to act on embryonic development to change the morphology of the adult body.
* Natural selection acts on individuals...
So natural selection acts on almost everything, apparently.
I can certainly understand a few of those expressions, since they indicate an effect on - not what makes it happen, but something else.... like the example I gave of the weather. It produces an effect.
So I can understand the conditions that form natural selection, and what drives it in one direction or other.
It may be, I don't fully understand it, but if it is not simple to explain, then perhaps it's not simple to understand, as some claim.
In my opinion, Evolution 101 explains things in a very simple way. I understand how it explains natural selection
here, but it also makes statements I don't agree with, and there are valid reasons not to agree. It's not a case of my not wanting to agree.
It's okay to not agree with something. That's fair, isn't it?