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Author Topic:   What exactly is natural selection and precisely where does it occur?
Fosdick 
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Message 1 of 303 (389169)
03-11-2007 1:49 PM


This new thread topic arose from Message 65:

Quetzal wrote:
I DO understand that selection must, by definition, operate at the level of the individual organism. After all, it's the organism that reproduces (or not). Evolution, on the other hand, operates at the level of a population. I would have thought that would be obvious (and no, this is REALLY not the thread to get into the pros and cons of group selection theory).


HM replied:

Yes, perhaps a new thread is more appropriate, because “group selection” and “individual selection” need to be differentiated from “gene selection” and “kin selection.” It must be confusing to MartinV and his ilk that Darwinian biologists can’t agree on exactly what natural selection is and where it occurs. And, unless you invoke the selfish-gene theory, the same quandaries can be raised about evolution itself.

By definition, natural selection is the possible consequence of uneven reproductive success of individuals in a population. But this does not mean that natural selection necessarily operates on the individual or its population, even though the results may occasionally point in that direction. Looking closer, as did G. C. Williams, Wm. Hamilton, R. Dawkins, et al., the actual site of natural selection can often be seen at the level of genes and their alleles (i.e., genetic evidence of strategic altruism for kin survival). “Group selection” and “species selection” (i.e., 'for the good of the group or the species') are no longer regarded as credible by most biologists, although some still claim them to be true. Furthermore, natural selection is not the only cause of evolution. Non-selective agencies like genetic drift, gene flow, and preferential mating may also cause evolution to occur.

But who knows for sure exactly where natural selection occurs? And the same question can be raised about evolution. Any thoughts?

—HM


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AdminNem
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Message 2 of 303 (389174)
03-11-2007 2:39 PM


Thread moved here from the Proposed New Topics forum.

crashfrog
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Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 3 of 303 (389177)
03-11-2007 2:56 PM
Reply to: Message 1 by Fosdick
03-11-2007 1:49 PM


I'll repeat what I said over there.

Non-selective agencies like genetic drift, gene flow, and preferential mating may also cause evolution to occur.

Preferential mating is, by definition, selective. The mate's preference constitutes a selection. That's why they call it "sexual selection", after all.

And the same question can be raised about evolution.

You mean, where does evolution happen? Planet Earth. Next question.

No, seriously, though. Where doesn't evolution happen? It happens any time that living things are reproducing through descent via modification. I guess maybe you think you're asking an insightful question, but it sounds like a stupid one to me. Even in a population undergoing no appreciable selection, genetic drift is causing changes to the allele distribution of the population.


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MartinV 
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Message 4 of 303 (389178)
03-11-2007 3:34 PM


Natural selection
Another question is if Natural selection is capable of creating new species. In this case would darwinists put more stress on random mutation that makes possibilities from which natural selection can choose.

In thread discussing cospeciation they put more stress to natural selection - in other case cospeciation would lead to conclusion that it originated by "chance alone".

Darwinists minds are captured in the prison of "random mutation" and "natural selection" concepts which blind their reasoning completely. Once it is fit of "random mutation" then fit of "natural selection" combined with "sexual selection".

They try to explain all secrets of Nature using these concepts that were never observed to create new species. Belief in natural selection is so strong that they suppose it to be also there where we do not detect it by reason and experience - like in the case of white coloration of swans, or in many cases of curious mimicry discussed elsewhere. Having only phantasy they try to create stories how natural selection forms organs and coloration of species that helps them survive and also those that have no connection to survival. In that case they suppose that such connection existed once or we cannot detect it but it exist - we must only believe. To believe that natural selection combined with random mutation is allmighty evolutionary force that disclose all secret of Nature is only foundation that darwinism is resting upon.

Of course there are many scientists who deny Natural selection as evolutionary force - they consider it as only maintaing force that removes extremities. Eimer, Heikertinger, Suchantke and all great men mentioned in Davison's Manifesto.


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AZPaul3
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Message 5 of 303 (389181)
03-11-2007 3:36 PM


Not so Stupid
I understand the quandary a lot of people are in when they try to discuss Evolution and Natural Selection. As a science the discipline must of necessity use precise language to differentiate the mechanisms. This can often lead to confusion, as with MartinV, in thinking that Natural Selection and Sexual Selection are mutually exclusive phenomena. Then add concepts like point mutation, genetic drift, gene flow, insertion, copy error and add group selection, population selection, well, I can see where a newbie will scratch their heads and wonder.

With those just getting into the swing of things I always liked to define “mutation” as the all-inclusive process of changing the genome and leave the details to come as necessary. With Natural Selection, I define this as what effect those “mutations” have on the individual and leave groups, populations, etc. for a later time.

As for the Hooter’s question, Frog, it is not stupid. There are a lot of knowledge-seekers around these parts and such a discussion could be to their benfit.


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Fosdick 
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Message 6 of 303 (389182)
03-11-2007 3:39 PM
Reply to: Message 3 by crashfrog
03-11-2007 2:56 PM


Site of operation?
Non-selective agencies like genetic drift, gene flow, and preferential mating may also cause evolution to occur.

Preferential mating is, by definition, selective. The mate's preference constitutes a selection. That's why they call it "sexual selection", after all.

No, you're confusing that with natural selection. Preferential mating is well know as a non-selective agency of evolution.

Where does evolution happen? Planet Earth. Next question. No, seriously, though. Where doesn't evolution happen? It happens any time that living things are reproducing through descent via modification. I guess maybe you think you're asking an insightful question, but it sounds like a stupid one to me. Even in a population undergoing no appreciable selection, genetic drift is causing changes to the allele distribution of the population.

Then are you are saying that evolution happens homologically. I would agree that evolution couldn't happen without inheritance, but I don't think differential reproductive success (natural selection) is the only tool nature uses to stage an evolution event. Nevertheless, the question here concerns the exact meaning of natural selection and the precise location of its activity. In the case of differential reproductive success, which is a good definition of NS, at which of these leves would you say it operates?:

a. species
b. population
c. organism
d. kin
e. gene

We can go from there.

—HM


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Chiroptera
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Member Rating: 3.6


Message 7 of 303 (389183)
03-11-2007 3:56 PM
Reply to: Message 6 by Fosdick
03-11-2007 3:39 PM


Re: Site of operation?
quote:
Preferential mating is well know as a non-selective agency of evolution.

Huh? Peahens dig males with long tail feathers. Peacocks with long tail feathers therefore get to breed. Peacocks with short tail feathers don't get dates, and so don't reproduce.

How in the world is this not selection?


Actually, if their god makes better pancakes, I'm totally switching sides. -- Charley the Australopithecine

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Fosdick 
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From: Upper Slobovia
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Message 8 of 303 (389184)
03-11-2007 4:07 PM
Reply to: Message 4 by MartinV
03-11-2007 3:34 PM


Re: Natural selection
MartinV wrote:

Another question is if Natural selection is capable of creating new species. In this case would darwinists put more stress on random mutation that makes possibilities from which natural selection can choose.


Maybe if a random mutation constituted the critical difference for NS. But don't forget that there are other agencies of microevolution besides mutations that NS can eventually work on. Alleles can be imported into or exported from a population, and their frequencies can vary due to drift. These factors might also make a genome vulnerable to selective pressures.

Of course there are many scientists who deny Natural selection as evolutionary force - they consider it as only maintaing force that removes extremities. Eimer, Heikertinger, Suchantke and all great men mentioned in Davison's Manifesto.

In science there is a thing call the "peer review." You must understand that these "scientists" you mention above would have a very bad day if they tried to float their beliefs at one of those wire-brush scrubbings called a "peer review." It's sciences quality-control mechanism—usually harsh, sometimes bloody.

—HM


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MartinV 
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Message 9 of 303 (389185)
03-11-2007 4:08 PM
Reply to: Message 5 by AZPaul3
03-11-2007 3:36 PM


Re: Not so Stupid

This can often lead to confusion, as with MartinV, in thinking that Natural Selection and Sexual Selection are mutually exclusive phenomena.

Exclusive or inclusive phenomena who cares. Sexual selection is something darwinists use when they are clueless how to explain a phenomenon in Nature by Natural selection alone. When exclusive or inclusive combination of both principless can't lead to palusible explanation they invent somethig else - especially worth of notice is this one:

quote:

The polymorphic female form of P. phorcas is believed to have
originated as a male-mimicking 'transvestitism' from a primitively sexually dimorphic color pattern (Vane-Wright 1976; Clarke et al. 1985).

See the common darwinistic construct "is believed to have originated". And it is not all:

quote:

This suggests that the species may initially have
been sexually dimorphic (with brown/yellow females and
black/green males) and that a so-called transvestite evolutionary
step (Vane-Wright 1976; Clarke et al. 1985) produced
male-like females and was the origin of the female color

What a story-tellers some darwinists are having no plausible natural selection or sexual selection explanation at hand.


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Fosdick 
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Message 10 of 303 (389187)
03-11-2007 4:12 PM
Reply to: Message 7 by Chiroptera
03-11-2007 3:56 PM


Re: Site of operation?
Preferential mating is well know as a non-selective agency of evolution.

Huh? Peahens dig males with long tail feathers. Peacocks with long tail feathers therefore get to breed. Peacocks with short tail feathers don't get dates, and so don't reproduce.

How in the world is this not selection?


Well, it is a kind of selection, of course, but it is not natural selection. Instead it is regarded as a non-selective agency of evolution.

—HM


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Chiroptera
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Posts: 6914
From: Oklahoma
Joined: 09-28-2003
Member Rating: 3.6


Message 11 of 303 (389188)
03-11-2007 4:13 PM
Reply to: Message 9 by MartinV
03-11-2007 4:08 PM


Re: Not so Stupid
quote:
What a story-tellers some darwinists are having no plausible natural selection or sexual selection explanation at hand.

I don't know why you are accusing others of story telling, John. So far all you have ever done is invoke some sort of vague "spirit force" guiding evolution. You have never proposed a mechanism for this "spirit force", not presented any evidence in favor of such a force beyond your own inability to understand natural selection.


Actually, if their god makes better pancakes, I'm totally switching sides. -- Charley the Australopithecine

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Fosdick 
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Posts: 1793
From: Upper Slobovia
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Message 12 of 303 (389189)
03-11-2007 4:16 PM
Reply to: Message 5 by AZPaul3
03-11-2007 3:36 PM


Re: Not so Stupid
AZPaul3 wrote:

With those just getting into the swing of things I always liked to define “mutation” as the all-inclusive process of changing the genome and leave the details to come as necessary. With Natural Selection, I define this as what effect those “mutations” have on the individual and leave groups, populations, etc. for a later time.


Would you say then that NS operates at the gene/allele level of organization, or at the individual level?

—HM


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Chiroptera
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Posts: 6914
From: Oklahoma
Joined: 09-28-2003
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Message 13 of 303 (389190)
03-11-2007 4:19 PM
Reply to: Message 10 by Fosdick
03-11-2007 4:12 PM


Re: Site of operation?
Well, now this is starting to sound like a semantics issue.

Darwin spent a good chunk of Descent of Man discussing sexual selection, and it is clear that he didn't think it was so different from "ordinary" natural selection. I don't think any biologist really thinks of it as any different than natural selection, either. Why do you insist that there is a profound difference between the two?


Actually, if their god makes better pancakes, I'm totally switching sides. -- Charley the Australopithecine

This message is a reply to:
 Message 10 by Fosdick, posted 03-11-2007 4:12 PM Fosdick has not yet responded

crashfrog
Member
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 14 of 303 (389191)
03-11-2007 4:23 PM
Reply to: Message 6 by Fosdick
03-11-2007 3:39 PM


Re: Site of operation?
Preferential mating is well know as a non-selective agency of evolution.

Because you say so?

What's known is that preferential mating is selective. It's a kind of sexual selection. It's right there in the word "preference"! For instance

quote:
The success of an organism is not only measured by the number of offspring left behind, but by the quality or probable success of the offspring: reproductive fitness. Sexual selection is the expansion on the ability of organisms to differentiate each other at the species level, interspecies selection.

http://en.wikipedia.org/wiki/Sexual_selection

Clearly, preferential mating represents a selective force on a population - selection driven towards the preference in question. If females prefer males with bright plumage, males with bright plumage will be selected for and males without will be selected against.

I would agree that evolution couldn't happen without inheritance, but I don't think differential reproductive success (natural selection) is the only tool nature uses to stage an evolution event.

I don't know what an "evolutionary event" is, but clearly any influence that alters allele frequencies in a population over time is evolutionary. Things like HGT, or genetic drift, or mutation, alter those frequencies at random; forces such as natural selection and sexual selection alter those frequencies in response to environment (where "environment" includes other conspecifics).


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crashfrog
Member
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 15 of 303 (389192)
03-11-2007 4:27 PM
Reply to: Message 10 by Fosdick
03-11-2007 4:12 PM


Re: Site of operation?
Well, it is a kind of selection, of course, but it is not natural selection. Instead it is regarded as a non-selective agency of evolution.

A kind of selection is regarded as non-selective?

This isn't an issue of semantics, Chiroptera. This is ol' Jocko not knowing sense from nonsense, as usual.


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