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Author Topic:   Evolution Requires Reduction in Genetic Diversity
Faith 
Suspended Member (Idle past 1554 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 1 of 5 (691521)
02-22-2013 6:14 PM


I want to try to put together a spin-off from The Origin of Novelty thread because Bolder-dash is pursuing a different objective from mine there and it's getting too confusing to try to keep the arguments separate.
I'll try to pick out the posts from that thread I think best define where this thread should go:
I started my argument there with this brief statement in Message 235:
The fact that shows evolution to be wrong is that the development of varieties or breeds (otherwise known as MICROEVOLUTION) requires the reduction of genetic diversity. That's a FACT. To be true evolution would require the opposite, the increase in genetic diversity. But you can't get a true-breed Hereford if its DNA -- gene pool -- contains Black Angus alleles, you can't get a chihuahua if its DNA contains Great Dane alleles and so on and so forth. The farther out in a true-bred line the less genetic diversity you get. THAT's MICROEVOLUTION. Therefore MACROEVOLUTION couldn't possibly EVER occur. I've argued this many times here, it utterly utterly defeats evolution but forget anybody ever recognizing that fact. So there's your substance.
In Message 323 I said
I don't use the baramin terminology, simply never became familiar with it, but I get that it refers to the same class of things, also called Kinds, that microevolve within their own gene pools, which are considered to belong only to that class and are genetically unrelated to other baramins, Kinds or Species or whatever the terminology is that works best. (If the term "baramin' is useful to keep from this sort of confusion I should learn to use it I suppose.)
In any case I see that the usual question gets asked about this that all creationists encounter: Where is the dividing line between the baramins or Kinds, or where is the stopping point beyond which further evolution cannot occur.
My own argument is that because reduced genetic diversity MUST accompany the development of new varieties or breeds (within the Kind or baramin) there is a natural point beyond which further variation or "evolution" cannot occur and that is your stopping point or boundary that defines the Kind or baramin. I call this Evolution Defeats Evolution. That is, the very processes that bring about new phenotypes also yultimately lead to genetic depletion for a given line of true breed, which makes further evolution impossible when that point is reached.
In Message 356 I was responding to a post herebedragons made to Bolder but it was partly about my own posts:
I did not say that artificial breeding does not reduce genetic variability. It does and in that she was largely correct.
Hip hip hooray. I may have to copy that out, change the font to something formal like Olde English and put it in 72 point and hang it on my wall. Yikes, a tiny little concession. Means SO much.
But what she seemed to imply was that breeding is accomplished by eliminating genetic diversity alone.
Yes, that is indeed my argument. You do not get new breeds, new phenotypes, either in the wild or under domestication, or keep an established breed pure, without reducing the genetic diversity, or once the breed is established, by keeping the genetic understructure limited to ONLY what expresses the characteristics of that breed.
The implication is that all the characteristics we find in dog breeds were originally in the wolf; they were just so well mixed that the phenotype that is expressed is ... a wolf. It just can't be that simple. The alleles that originally existed in the wolf population must have changed sometime during the selection process.
This is somewhat of a tangent to the argument I'm making but my guess is that today's wolves have evolved as much as the dogs that bred from the original wolf so that their genetic diversity is also much reduced from that of whatever the original population was, which might have been very much like today's wolves or not as much as we suppose. My argument includes the observation that whenever you isolate a portion of a previous population you get the familiar formula "change in gene frequency" which is what creates the new varieties or breeds and this can affect both the "parent" population and the "daughter" population which in fact can in some cases be hard to differentiate from each other anyway, since the numbers are affected in both cases and the greater the reduction in numbers the more dramatic the remix of alleles and the phenotypes formed from them. The smaller the portion the greater the phenotypic change and the greater the decrease in its collective genetic diversity.
Your position is that these alleles did change but that all such changes were actually diseases that humans thought were neat so they breed for that disease. Is that accurate?
This doesn't apply to my own argument. In my argument alleles don't change, they just shuffle within the whole population from individual to individual, sometimes creating some interesting new phenotypes, but it is really only when a small number break off from the greater population that such new phenotypes become expressive to any noticeable extent.
The problem is that when you try to oversimplify a situation like this it just gets reduced to silliness. Greyhounds were bred for speed, they are the second fastest animal on earth. Do you consider that a loss of function as compared to the wolf?
I don't think in such terms myself and Bolder's frame of reference may be getting confused with mine here. I wasn't arguing for a "loss of function" at any point, my argument is that in order to get NEW functions or features, new phenotypes, new traits, you have to isolate the particular alleles for those traits from others that would interfere, and that is what happens when a portion of a population gets reproductively isolated, and the smaller its numbers the greater the phenotypic divergence you should get from the original ALONG WITH a great reduction in genetic diversity. Of course the speed of the greyhound involves no loss of function. What it DOES involve is the isolation or selection of whatever alleles for whatever genes are responsible for creating that speedy bodily structure, which of course means that genes/alleles that would interfere with it are eliminated from the breed, left behind in the "original" population from which it microevolved.
It is not. But while breeders are selecting for this gain in function (increased speed) they are inadvertently selecting for less desirable traits like lack of body fat and thin, fragile skin and long, thin bones. Breeders did not intentionally select specifically for these traits, they were by products of the desirable trait - speed.
Yes, of course that can happen.
The thing I wanted Faith to think about was that there is more going on that just allele frequency or eliminating Great Dane alleles to breed Chihuahuas.
The problem here is that I've been working on this for something like eight or ten years now and you aren't going to just casually get me to think about some other alternative until you've shown you understand what I'm arguing, which is far from the case at the moment.
Since the rest of this post is clearly responding to Bolder about something that doesn't impinge on my argument at all, I'll stop here.
The topic then took a turn as PaulK wanted me to account for the effect of mutations:
PaulK in message 359 writes:
If, after working for eight or more years, your argument that evolution must reduce genetic diversity still has no more support than "'cause I say so!" then I suggest that it is very likely that you are going down a blind alley.
At the least you ought to have some evidence that mutations do not occur sufficiently quickly to make up for lost diversity. But I've never seen any hint of that.
To which I responded in Messages 369 and 376:
(Message 369)
If mutations occurred the way you think they do, you could not establish a new breed or maintain a breed, and that I HAVE argued at some length. Mutations as a matter of fact INTERFERE with the normal processes of evolution.
(Message 376 in response to Taq who said mutations are found to be very necessary and gave some genetic information)
In the context of population genetics, you cannot have mutations constantly cropping up or you will never get a new variety let alone speciation. The development of new varieties does depend upon establishing an isolated gene pool, and once established keeping the gene pool isolated from new genetic material, otherwise known as gene flow, but mutation would have the same effect. Whatever you find in the laboratory about mutations is really another subject.
Message 380 in answer to PaulK
If mutations occurred the way you think they do, you could not establish a new breed or maintain a breed, and that I HAVE argued at some length. Mutations as a matter of fact INTERFERE with the normal processes of evolution.
No, that's absolutely false. Indeed it's not even true of selective breeding. If a mutation considered desirable should appear then breeders will incorporate it into their program, as they did with the Scottish Fold cat.
But then you would be CHANGING your breed for some other breed. What I'm talking about is maintaining an established breed where you do not want novelty, you want purity. You want a PERFECT Tonkinese cat or Friesian horse, you do not want imperfections and most mutations produce imperfections. It's very very rare that you get one that you want to incorporate.
And I also dispute that what are called mutations are really mutations anyway. I believe that most phenotypic occurrences that show up here and there within an established breed are nothing more than a new combination of a rare allele that has always been in the gene pool.
In fact mutations are the "fuel" of evolution and absolutely essential to the process.
This is only an assumption or an article of faith, and for the most part a matter of definition since what you call a mutation, if it IS desirable, is most likely not a mutation at all but a normally occurring allelic variant.
PaulK answer to above Message 384
quote:
But then you would be CHANGING your breed for some other breed.
So it would be evolution. That's supposed to be a problem ?
quote:
What I'm talking about is maintaining an established breed where you do not want novelty, you want purity.
That isn't evolution. Selection and gene flow can stabilise a population but there's no objective to keep a "pure" population in evolution.
quote:
You want a PERFECT Tonkinese cat or Friesian horse, you do not want imperfections and most mutations produce imperfections. It's very very rare that you get one that you want to incorporate.
Evolution isn't about maintaining some artificial idea of "PERFECT" breeds.
quote:
This is only an assumption or an article of faith, and for the most part a matter of definition since what you call a mutation, if it IS desirable, is most likely not a mutation at all but a normally occurring allelic variant.
No, it's what the theory SAYS happens. So it's what you've got to argue against. Arguing that the way that you think evolution ought to work wouldn't work is a bit pointless.
Taq answer to my last message387 saying the same thing PaulK was saying:
But then you would be CHANGING your breed for some other breed.
Exactly. You have novel changes arising from mutations that are then selected for. We call this evolution.
This is pretty unwieldy I guess but I'm going to post it as is and will probably come back to try to improve it.
(For reference as the thread proceeds, I want to keep the link to the Introduction to Genetics thread available. It was started but never finished though there was some good discussion there.
Edited by Faith, : No reason given.
Edited by Faith, : No reason given.
Edited by Faith, : No reason given.
Edited by Faith, : TO ELIMINATE SNARKY SENTENCE
Edited by Faith, : Add link to Intro to Genetics thread

Replies to this message:
 Message 2 by Faith, posted 02-23-2013 6:34 AM Faith has not replied
 Message 3 by Admin, posted 02-23-2013 9:51 AM Faith has replied

Faith 
Suspended Member (Idle past 1554 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 2 of 5 (691572)
02-23-2013 6:34 AM
Reply to: Message 1 by Faith
02-22-2013 6:14 PM


Bump?
Can this get promoted?

This message is a reply to:
 Message 1 by Faith, posted 02-22-2013 6:14 PM Faith has not replied

Admin
Director
Posts: 13084
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.5


Message 3 of 5 (691598)
02-23-2013 9:51 AM
Reply to: Message 1 by Faith
02-22-2013 6:14 PM


As you say, it is unwieldy. Would it be possible to compose a shorter opening post that is original (rather than cut-n-pastes) and doesn't contain lines like, "So there's your substance and now you can bring on your stupid answers as usual. Ho hum."
The part of your argument that I think is understood is that since sub-subspecies such as Herefords (of cattle) and chihuahuas (of wolves) have reduced genetic diversity, and since new species begin from isolated populations consisting of a subspecies or sub-subspecies, that therefore speciation can only occur from a reduction of genetic diversity. I don't think many would have a problem with a discussion based upon this style of speciation. It's fairly representative and it's unarguably true since by definition a subset is always an incomplete representation of the full set.
The part that isn't clear is your view of the role of mutations. You appear to be arguing that if mutations really had the effect that evolution claims then species would be inconstant and perpetually changing, which is precisely what evolution does claim based upon the available evidence. I think discussion would center around this and not around the initial reduction in genetic diversity that can be associated with speciation.
If the above is a sufficiently accurate representation of your views then I can just promote this now and you wouldn't have to attempt a rewrite of the opening post. I'll be checking back in in a few hours.

--Percy
EvC Forum Director

This message is a reply to:
 Message 1 by Faith, posted 02-22-2013 6:14 PM Faith has replied

Replies to this message:
 Message 4 by Faith, posted 02-23-2013 9:57 AM Admin has seen this message but not replied

Faith 
Suspended Member (Idle past 1554 days)
Posts: 35298
From: Nevada, USA
Joined: 10-06-2001


Message 4 of 5 (691600)
02-23-2013 9:57 AM
Reply to: Message 3 by Admin
02-23-2013 9:51 AM


I did want to have the whole basic argument on the table at least which i guess you are saying is possible. And I'm amazed that you agree with that much of it, even, since I don't recall that ever happening when I argued it many times before. But best not to look a gift horse in the mouth.
Yes that part can just be left as is and I'll go cut out that offending line if you want {ABE: Just did so}. I do think you stated my view pretty well, so the topic to be pursued at the moment is the questions about mutations raised by PaulK and Taq.
So I'm happy if you're willing to promote as is.
Edited by Faith, : No reason given.
Edited by Faith, : No reason given.

This message is a reply to:
 Message 3 by Admin, posted 02-23-2013 9:51 AM Admin has seen this message but not replied

Admin
Director
Posts: 13084
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.5


Message 5 of 5 (691637)
02-23-2013 1:37 PM


Thread Copied to Biological Evolution Forum
Thread copied to the Evolution Requires Reduction in Genetic Diversity thread in the Biological Evolution forum, this copy of the thread has been closed.

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