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Author Topic:   WTF is wrong with people
Faith
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Posts: 24406
Joined: 10-06-2001
Member Rating: 1.0


Message 376 of 457 (708658)
10-11-2013 6:14 PM
Reply to: Message 374 by AZPaul3
10-11-2013 5:01 PM


Re: Environment-driven evolution
No, Faith, an individual with a reproductive advantage does not constitute a "subpopulation" of the species any more than a woman with stronger leg muscles than the average constitutes a "subpopulation" of the human species.

No, Arizona Paul, I'm not talking about an individual, I'm talking about the proliferation of the adaptive alleles throughout the population in many individuals, which gradually displace all the nonadaptive alleles BECAUSE of their reproductive advantage. This constitutes a subpopulation within the original population that might even grow from generation to generation until it completely displaces the original.

Edited by Faith, : No reason given.


This message is a reply to:
 Message 374 by AZPaul3, posted 10-11-2013 5:01 PM AZPaul3 has acknowledged this reply

    
Percy
Member
Posts: 15561
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.3


Message 377 of 457 (708668)
10-12-2013 7:55 AM
Reply to: Message 362 by NoNukes
10-11-2013 12:22 PM


Re: Environment-driven evolution
NoNukes writes:

I may have been unclear about that. A breed is not necessarily a dead end, but the process of breeding as practiced by say collie breeders is indeed a dead end. The process is designed to create a specific phenotype and to reject the breeder's idea of unacceptable diversity. A mutation that generates more powerful legs on a collie would get kicked out ot the gene pool by breeders even if such a thing would produce a survival advantage out in the wild.

Right, but again, the only meaningful difference is in the criteria of selection. In nature survival to reproduce is the criteria. In breeding programs pleasing the breeder is the criteria. Both approaches produce greater adaptation to the criteria, which is all that's important.

Yes, but that turns out to make a huge difference...

The huge difference being the resulting phenotypes? How is the difference in phenotypes produced by natural versus artificial selection any more significant than the differences produced by placing a population in the desert versus the rain forest? The specifics of the resultant phenotypes are irrelevant to the central point: selection produces adaptation.

--Percy


This message is a reply to:
 Message 362 by NoNukes, posted 10-11-2013 12:22 PM NoNukes has responded

Replies to this message:
 Message 382 by NoNukes, posted 10-12-2013 11:56 AM Percy has responded

    
Percy
Member
Posts: 15561
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.3


Message 378 of 457 (708669)
10-12-2013 8:08 AM
Reply to: Message 366 by Tangle
10-11-2013 1:32 PM


Re: Environment-driven evolution
How is it that the role played by regulatory genes (Hox related or not) in "large evolutionary changes in body morphology...contradicts the neo-Darwinian synthesis?" I don't see it. Sounds like someone trying to puff up the importance of their particular sub-discipline of interest.

--Percy


This message is a reply to:
 Message 366 by Tangle, posted 10-11-2013 1:32 PM Tangle has responded

Replies to this message:
 Message 379 by Tangle, posted 10-12-2013 10:22 AM Percy has acknowledged this reply
 Message 380 by herebedragons, posted 10-12-2013 10:46 AM Percy has responded

    
Tangle
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Posts: 4537
From: UK
Joined: 10-07-2011
Member Rating: 3.2


Message 379 of 457 (708677)
10-12-2013 10:22 AM
Reply to: Message 378 by Percy
10-12-2013 8:08 AM


Re: Environment-driven evolution
Percy writes:

How is it that the role played by regulatory genes (Hox related or not) in "large evolutionary changes in body morphology...contradicts the neo-Darwinian synthesis?"

Seems like it simply adds to it to me - and makes it a little easier to understand how major changes can be made.

If organisms have a box of parts that are common across phyla that can be plugged in, or not, dependant on swiching on or off regulatory genes, it makes big changes to morphology easier to do - or understand.

Selection would carry on as usual.


Life, don't talk to me about life - Marvin the Paranoid Android

This message is a reply to:
 Message 378 by Percy, posted 10-12-2013 8:08 AM Percy has acknowledged this reply

  
herebedragons
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Posts: 1298
From: Michigan
Joined: 11-22-2009
Member Rating: 4.7


Message 380 of 457 (708679)
10-12-2013 10:46 AM
Reply to: Message 378 by Percy
10-12-2013 8:08 AM


Re: Environment-driven evolution
The way I understand it is that Neo-Darwinism suggests that the accumulation of small changes over long periods of time is sufficient to explain all evolutionary processes. I, like Tangle, feel that is a vast over-simplification that leaves much to be desired and, I feel makes for "just-so" stories. When we simply talk about random mutations + natural selection + time = evolution, it just leaves so many holes in our understanding of the processes involved. We are finding that the reality of evolution is much more complicated than we had previously imagined.

Tangle writes:

I only wish I'd kept studying it - now it's all so advanced that I'd have to devote far too much of my life to understand it.

It seems to me this was more his point than evo-devo contradicting the neo-darwinian synthesis. Its my point too, that the modern understanding of evolutionary processes are way beyond RS + NS.

I was recently introduced to the term Meta-Darwinism by this book (which I have not read, just glanced through). The concept of Meta(beyond)-Darwinism was intriguing though. I don't think this is a universally recognized school of thought yet, but seems to be growing.

An interesting article here

quote:
These new biologists are perhaps best called "meta-Darwinists," as they encompass Darwinian and neo-Darwinian evolutionary insights yet also refuse to ignore the broad evidence for what is often called "convergent evolution" seen in life's evolutionary developmental record. Examples of convergence can be found at all scales, from biochemistry to plant and animal forms to life cycles to human culture ...

quote:
In other words, the emergence of "homoplasy" (convergent function via independent evolutionary pathways) is best seen as a process of not simply evolution but evolutionary development, occurring multilocally throughout the universe.

quote:
Putting together the insights of modern evo-devo and meta-Darwinian biologists like those described above, and positing that the same process of evo-devo is going on at universal scales (the most parsimonious assumption, if the universe is just another complex adaptive system)

It seems to me to tie together all the evolutionary concepts and frame them in the context of development, which is where the critical evolutionary processes actually occur.

So ... say good bye to neo-darwinism??? :shrug:

HBD


Whoever calls me ignorant shares my own opinion. Sorrowfully and tacitly I recognize my ignorance, when I consider how much I lack of what my mind in its craving for knowledge is sighing for. But until the end of the present exile has come and terminated this our imperfection by which "we know in part," I console myself with the consideration that this belongs to our common nature. - Francesco Petrarca

"Nothing is easier than to persuade people who want to be persuaded and already believe." - another Petrarca gem.


This message is a reply to:
 Message 378 by Percy, posted 10-12-2013 8:08 AM Percy has responded

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ringo
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Posts: 12915
From: frozen wasteland
Joined: 03-23-2005
Member Rating: 2.6


Message 381 of 457 (708688)
10-12-2013 11:53 AM
Reply to: Message 375 by Faith
10-11-2013 6:12 PM


Re: Environment-driven evolution
Faith writes:

There is no point in referring me to a technical paper full of terminological mystifications.


As my father used to say to people like you, "Don't confuse you will facts."
This message is a reply to:
 Message 375 by Faith, posted 10-11-2013 6:12 PM Faith has not yet responded

  
NoNukes
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Posts: 9434
From: Central NC USA
Joined: 08-13-2010
Member Rating: 2.8


Message 382 of 457 (708690)
10-12-2013 11:56 AM
Reply to: Message 377 by Percy
10-12-2013 7:55 AM


Re: Environment-driven evolution
Both approaches produce greater adaptation to the criteria, which is all that's important.

No Percy, that is not all that is important for this discussion. The selection criterion for natural selection is simply the competitive survival to reproduce successful offspring. Period. Unlike the case for breeding, no specific trait is necessarily advantageous in isolation from any other trait. A gazelle can escape lions by being faster, or having great senses, or by being able to predict where and when lions are going o show up, or by being just smart enough to hang around gazelles that have sensory advantages in escaping lions.

Also, breeding requires enforced isolation while natural selection does not.

And accordingly the population dynamics are completely different under those completely different selection criteria. Breeding might well lead to a loss of diversity while natural selection does not require any such thing.


Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.
Richard P. Feynman

If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass


This message is a reply to:
 Message 377 by Percy, posted 10-12-2013 7:55 AM Percy has responded

Replies to this message:
 Message 383 by Faith, posted 10-12-2013 2:25 PM NoNukes has not yet responded
 Message 388 by Percy, posted 10-13-2013 8:53 AM NoNukes has responded

    
Faith
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Posts: 24406
Joined: 10-06-2001
Member Rating: 1.0


Message 383 of 457 (708707)
10-12-2013 2:25 PM
Reply to: Message 382 by NoNukes
10-12-2013 11:56 AM


Selection does lead to reduced genetic diversity
Breeding might well lead to a loss of diversity while natural selection does not require any such thing.

I've been trying to argue why it does and must require a loss of diversity -- meaning GENETIC DIVERSITY -- In the long run at least.

Also why I've been arguing that it is merely one of the ways that lead to evolution (meaning of course microevolution) BY CHANGING ALLELE FREQUENCIES, including migration, bottleneck, founder effect, probably Drift too, and how all these share with domestic breeding the basic fact of increasing the frequency of some alleles and reducing or eliminating others, and that despite their differences it all amounts to the same thing in the end as far as getting new varieties and reducing genetic diversity goes. Allele frequencies change randomly in some of these processes, but due to particular selection in NS and domestic breeding, but the allele frequencies alone are enough to make big changes and bring about a new variety whatever the cause.

Natural selection to one degree or another eliminates alleles that are not adaptive according to what is being selected for. It doesn't matter if a breeder is doing the selecting or the environment is, whether the gazelle is selected for speed or sensory advantage and so on, WHATEVER is being selected is going to spread through the population down the generations, displacing the genetic substrate for the less adaptive traits, the slower gazelle, the less acutely sensitive gazelle. This in a sense forms a subpopulation of those better adapted, even within the original population, while those less adapted with their reproductive disadvantage become less numerous and their alleles lower frequency in the overall population. The preponderance of a particular type of allele among the reproductively advantaged forms a subpopulation that is less genetically diverse than the former population because it has ONLY those alleles that promote the adaptive trait or traits.

ALSO, there is likely to be an inadvertent effect on other genes as well, changing THEIR frequencies, just because only certain individuals are being favored with whatever their alleles happen to be for whatever traits they happen to be for. (This is very much the same situation as in a migration where alleles for all kinds of traits change frequencies, only there is a different REASON for it and it occurs within the original population instead of outside it.)

Finally if the adaptation is crucially important to the creature ALL the nonadapted individuals will have no offspring or even die out before reproductive age and all you will have left is a population of the adapted with their high frequency alleles for the adaptive traits and LOSS of the alleles for the nonadaptive traits along with the loss of alleles for whatever other traits happen to become low frequency inadvertently. If merely an advantage is conferred but it's not dire you will still have the adaptive alleles proliferating and forming this subpopulation over the generations, and that subpopulation MUST have reduced genetic diversity as compared with the mother population because its alleles for the adaptive traits are very high frequency over those for nonadaptive traits.

And in the case of Natural Selection it ought to be easy to see why all those who keep wanting to increase the inevitable reduction in genetic diversity by insisting that mutations will come in and increase it, as if that were a good thing, are really promoting a bad thing, and what I've meant about how mutations that alter the new adaptive picture only "blur" it and lose the new variety that's been developed. Losing the adaptive alleles has to be a step backward, an overall loss for the creature as well as a loss for the whole idea of evolution in the end. Do you want your adapted creature or not? Meaning does evolution depend on getting established adaptive new varieties of creatures or not?

ABE: OK, the mutations could occur at other locations for other traits but then you've got your increased genetic diversity to what purpose? NS has done its job of bringing out an adapted creature. It works, what's the point of altering it except to convince yourself that there doesn't have to be an inevitable trend to reduced genetic diversity?

I have yet to go through many posts prior to this one but this one caught my eye.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.


This message is a reply to:
 Message 382 by NoNukes, posted 10-12-2013 11:56 AM NoNukes has not yet responded

Replies to this message:
 Message 384 by PaulK, posted 10-12-2013 2:57 PM Faith has responded
 Message 390 by Percy, posted 10-13-2013 2:15 PM Faith has responded

    
PaulK
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Posts: 12565
Joined: 01-10-2003
Member Rating: 2.3


(2)
Message 384 of 457 (708708)
10-12-2013 2:57 PM
Reply to: Message 383 by Faith
10-12-2013 2:25 PM


Re: Selection does lead to reduced genetic diversity
quote:

And in the case of Natural Selection it ought to be easy to see why mutations that alter the new adaptive picture only "blur" it and lose the new variety that's been developed. Losing the adaptive alleles has to be a step backward, an overall loss for the creature as well as a loss for the whole idea of evolution in the end. Do you want your adapted creature or not?

It should also be easy to see that mutations don't need to alter that adaptive picture at all, and don't have to alter it in a way that seriously disadvantages the traits already being selected for. They certainly don't have to cause any adaptive alleles to be lost from the population entirely - in fact that would be very, very unlikely (it wouldn't be common even for single individuals to lose an adaptive allele and it wouldn't matter much if it did happen). And besides evolution expects failures as well as successes, so even if it did happen on very rare occasions it wouldn't be a problem.

So you,re really going to have to stop being vague explain what you mean, because I can't come up with any interpretation that would be a plausible problem for evolution at all.


This message is a reply to:
 Message 383 by Faith, posted 10-12-2013 2:25 PM Faith has responded

Replies to this message:
 Message 385 by Faith, posted 10-12-2013 3:25 PM PaulK has responded

    
Faith
Member
Posts: 24406
Joined: 10-06-2001
Member Rating: 1.0


Message 385 of 457 (708710)
10-12-2013 3:25 PM
Reply to: Message 384 by PaulK
10-12-2013 2:57 PM


Re: Selection does lead to reduced genetic diversity
It should also be easy to see that mutations don't need to alter that adaptive picture at all, and don't have to alter it in a way that seriously disadvantages the traits already being selected for. They certainly don't have to cause any adaptive alleles to be lost from the population entirely - in fact that would be very, very unlikely (it wouldn't be common even for single individuals to lose an adaptive allele and it wouldn't matter much if it did happen). And besides evolution expects failures as well as successes, so even if it did happen on very rare occasions it wouldn't be a problem.

{I was apparently adding something to this effect while you were wring this post).

HOWEVER, evolution supposedly builds on established new "species" does it not? Isn't that the whole point of Natural Selection, that it supposedly can ultimately bring about a new species that can be a stepping stone to further speciation? And on and on and on out to something entirely NOT that same species at all but something new? We have to get that entire evolutionary genealogical tree into the picture here don't we?

So if you're constantly starting and stopping the process that produces these varieties -- starting with new varieties built on less genetic diversity, stopping with mutations that increase the genetic diversity -- where is evolution finally?

And keep in mind that you all want to answer Creationists who insist that microevolution occurs but not macroevolution, by saying that there is nothing to stop the one from going on to the other, as if its all a matter of addition, so if you are now acknowledging that the evolutionary processes that bring about new varieties do in fact overall reduce genetic diversity that OUGHT to be a BIG DEAL, and not something to just run on past as if it's meaningless. It effectively answers the constant refrain about there being no barrier to macroevolution.

If NS and all the other natural processes that bring about new varieties or species by changing allele frequencies actually in the long run bring about sufficiently reduced genetic diversity to interfere with further variation or speciation, then you've got less rather than more ability to evolve.

ABE: and let me add that I mean less ability to evolve down whatever line of evolution is occurring, not in the overall genome of any particular species. I keep trying to remember to say this but sometimes don't get it said. While you are breeding Dachshunds all the other dogs in the overall dog genome are not necessarily evolving (although many are). I'm talking ONLY about what happens in the line of Dachshunds. Or the third population in a ring species, or the second or fifth, or in fact any species in the wild that has formed from an isolated subpopulation off a former population.

So of course again now you want to bring in mutations to save the day. I've been struggling to say how they can't although it's intuitively obvious to me that they can't.

So you,re really going to have to stop being vague explain what you mean, because I can't come up with any interpretation that would be a plausible problem for evolution at all.

I certainly don't mean to be vague, I'm trying very hard to be as precise and specific as I can.

But I'd start here again with reminding you that IF you see what I mean about how phenotypic variation, at least if brought about through a relatively small subpopulation, MUST be built upon reduced genetic diversity and if further subdivisions should occur the effect will only increase until you have no ability to vary further, THAT should be acknowledged here. I've been working hard to get that much across.

You'd also have to consider the huge probability that these changes do NOT take "deep time" to accomplish. Let that video of Dawkins about the lizards on Pod Mrcaru be the evidence for that. If lizards can do it in 37 years there is no reason any given population in a ring species needs to take any longer, or any new "species" whatever, except those developed from much larger founding populations, and that is only going to add hundreds of years at the most for all the new allele frequencies to work through it generation by generation.

And IF you take that seriously then you also have to consider that mutations are not going to occur frequently enough anyway to make the changes you are hoping they might make.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.

Edited by Faith, : No reason given.


This message is a reply to:
 Message 384 by PaulK, posted 10-12-2013 2:57 PM PaulK has responded

Replies to this message:
 Message 386 by PaulK, posted 10-12-2013 3:58 PM Faith has not yet responded

    
PaulK
Member
Posts: 12565
Joined: 01-10-2003
Member Rating: 2.3


(1)
Message 386 of 457 (708711)
10-12-2013 3:58 PM
Reply to: Message 385 by Faith
10-12-2013 3:25 PM


Re: Selection does lead to reduced genetic diversity
quote:

HOWEVER, evolution supposedly builds on established new "species" does it not? Isn't that the whole point of Natural Selection, that it supposedly can ultimately bring about a new species that can be a stepping stone to further speciation? And on and on and on out to something entirely NOT that same species at all but something new? We have to get that entire evolutionary genealogical tree into the picture here don't we?

And that's why evolution needs a source of new variations.

quote:

So if you're constantly starting and stopping the process that produces these varieties -- starting with new varieties built on less genetic diversity, stopping with mutations that increase the genetic diversity -- where is evolution finally?

There is no "stopping and starting". Your question makes no sense at all. I've told you that adaptive evolution is the interaction of mutation and selection - what you are describing as an absence of evolution IS evolution.

quote:

And keep in mind that you all want to answer Creationists who insist that microevolution occurs but not macroevolution, by saying that there is nothing to stop the one from going on to the other, as if its all a matter of addition, so if you are now acknowledging that the evolutionary processes that bring about new varieties do in fact overall reduce genetic diversity that OUGHT to be a BIG DEAL, and not something to just run on past as if it's meaningless. It effectively answers the constant refrain about there being no barrier to macroevolution.

But it isn't a big deal because it DOESN'T even address the issue. Now remember you are talking about a scientific debate using the scientific terms and many YECs gave no problem with the scientific form of macroevolution anyway - in fact they INSIST that it has happened. And it isn't even a big deal for your argument either. Reality isn't the way that you think it "SHOULD" be.

quote:

If NS and all the other natural processes that bring about new varieties or species by changing allele frequencies actually in the long run bring about sufficiently reduced genetic diversity to interfere with further variation or speciation, then you've got less rather than more ability to evolve.

Which is why a process that adds new variations is NOT a problem for evolution. It is NECESSARY for ongoing evolution. Your own argument SAYS so!

quote:

So of course again now you want to bring in mutations to save the day. I've been struggling to say how they can't although it's intuitively obvious to me that they can't.

I have no idea how it can be obvious to you. It is intuitively obvious that increases in diversity can offset decreases and I believe that is obvious to you, to. So you need a reason specific to this case and quite frankly you haven't offered anything that cones close to explaining such a reason.

quote:

But I'd start here again with reminding you that IF you see what I mean about how phenotypic variation, at least if brought about through a relatively small subpopulation, MUST be built upon reduced genetic diversity and if further subdivisions should occur the effect will only increase until you have no ability to vary further, THAT should be acknowledged here. I've been working hard to get that much across.

Only if you have no source of new variations. As I've been pointing out for years now.

quote:

You'd also have to consider the huge probability that these changes do NOT take "deep time" to accomplish. Let that video of Dawkins about the lizards on Pod Mrcaru be the evidence for that. If lizards can do it in 37 years there is no reason any given population in a ring species needs to take any longer, or any new "species" whatever, except those developed from much larger founding populations, and that is only going to add hundreds of years at the most for all the new allele frequencies to work through it generation by generation.

If the lizards did it your way which is far from proven. But the evidence for deep time hardly relies in the time required for speciation. Even Darwin noted that species were stable for a very large proportion of their existence.

quote:

And IF you take that seriously then you also have to consider that mutations are not going to occur frequently enough anyway to make the changes you are hoping they might make.

No, I don't since the large majority of the mutations will occur in the long period where the species is not undergoing speciation - as I have said earlier in this thread. Both the time factor and the factor of population size make this inevitable. Shrink the time required for speciation all you like, it makes no difference to this issue.

ABE: Because of this the vast majority of the mutations we are talking about cannot interfere with speciation - because they do not enter the population until speciation has occurred. There's a lot more to be said against the idea of mutations interfering with soeciation in any way that would cause a problem for evolution, but this is so obvious I don't see how it can be denied.

Edited by PaulK, : No reason given.


This message is a reply to:
 Message 385 by Faith, posted 10-12-2013 3:25 PM Faith has not yet responded

    
Percy
Member
Posts: 15561
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.3


Message 387 of 457 (708726)
10-13-2013 8:23 AM
Reply to: Message 380 by herebedragons
10-12-2013 10:46 AM


Re: Environment-driven evolution
herebedragons writes:

The way I understand it is that Neo-Darwinism suggests that the accumulation of small changes over long periods of time is sufficient to explain all evolutionary processes.

I don't think the synthesis of Darwin's conception of evolution with genetics is so constraining. It's only a framework for interpreting the evidence, not a set of rules. There's no neo-Darwinian rule that change can only come about through the accumulation of small genetic changes.

So though we do know that offspring in sexual species will be very little changed morphologically from their parents (otherwise they will find no mates), we also know that at the genetic level changes can be massive, such as duplication of entire chromosome sets in some flowering plants, or the incorporation of one cell into another at the beginning of the eukaryotic line.

We are finding that the reality of evolution is much more complicated than we had previously imagined.

In my view there are two forces at work here here. My experience has been that trying to boil down science into simple explanations understandable by laypeople lends an impression that any given science is simpler than the actual scientists themselves believe. And also in all branches of science there is always a large subset who believes the universe is far simpler than it really is, though I think one tends to grow out of this as one grows older.

The pace of scientific discovery has not slowed. Obviously there is much we don't know. It should therefore come as no surprise each time we discover something we do not know, no matter how much the popular press reports on scientific amazement and surprise. In the whole history of science there are few discoveries that actually deserve those adjectives. The Big Bang is one. That continents move is another. That the expansion of the universe is accelerating is yet another. But evo-devo? No.

Its my point too, that the modern understanding of evolutionary processes are way beyond RS + NS.

Again, sounds like puffery to me.

--Percy


This message is a reply to:
 Message 380 by herebedragons, posted 10-12-2013 10:46 AM herebedragons has not yet responded

    
Percy
Member
Posts: 15561
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.3


Message 388 of 457 (708727)
10-13-2013 8:53 AM
Reply to: Message 382 by NoNukes
10-12-2013 11:56 AM


Re: Environment-driven evolution
NoNukes writes:

Percy writes:

Both approaches [artificial versus natural selection] produce greater adaptation to the criteria, which is all that's important.

No Percy, that is not all that is important for this discussion.

But Faith responded to you like this:

Faith in Message 383 writes:

It doesn't matter if a breeder is doing the selecting or the environment is...

Precisely!

Does it make my position more clear if I add that when I think of "breeding" I don't think of just actual breeders of pets and cattle? I think of all types of artificial selection (I did use that term earlier), which means only that the selection choices are made by human beings. The kind of breeding you have in mind where the goal is to maintain the breed is a subset of artificial selection, and it's even just a subset of what breeders do, since sometimes they're creating new breeds, and sometimes they're increasing diversity.

I'm not arguing that there aren't distinctions, simply that they aren't relevant to this discussion, and in fact may be confusing the discussion. One of the errors in Faith's understanding is believing that selection plays at best a minor role in producing new phenotypes, and that simply reducing diversity is sufficient. The evidence from breeding says this is wrong and that selection has primacy.

--Percy


This message is a reply to:
 Message 382 by NoNukes, posted 10-12-2013 11:56 AM NoNukes has responded

Replies to this message:
 Message 389 by NoNukes, posted 10-13-2013 10:40 AM Percy has acknowledged this reply

    
NoNukes
Member
Posts: 9434
From: Central NC USA
Joined: 08-13-2010
Member Rating: 2.8


Message 389 of 457 (708728)
10-13-2013 10:40 AM
Reply to: Message 388 by Percy
10-13-2013 8:53 AM


Re: Environment-driven evolution
NoNukes writes:

No Percy, that is not all that is important for this discussion.

Does it make my position more clear if I add that when I think of "breeding" I don't think of just actual breeders of pets and cattle?

If you can convince me that Faith is talking about the type of breeding that increases diversity, then yes we can ignore the "important for this discussion qualifier" I added to my remarks. I've already acknowledged your position. That's why the only thing I took issue was your claim to have covered everything of importance.

I'm not arguing that there aren't distinctions, simply that they aren't relevant to this discussion, and in fact may be confusing the discussion.

Well you are wrong. The distinctions are relevant. I don't doubt that the discussion has produced confusion, but some of that confusion is years in the making.

Edited by NoNukes, : No reason given.

Edited by NoNukes, : No reason given.


Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.
Richard P. Feynman

If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass


This message is a reply to:
 Message 388 by Percy, posted 10-13-2013 8:53 AM Percy has acknowledged this reply

    
Percy
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Message 390 of 457 (708735)
10-13-2013 2:15 PM
Reply to: Message 383 by Faith
10-12-2013 2:25 PM


Re: Selection does lead to reduced genetic diversity
Faith writes:

Allele frequencies change randomly in some of these processes, but due to particular selection in NS and domestic breeding, but the allele frequencies alone are enough to make big changes and bring about a new variety whatever the cause.

You keep saying this, and it is as false as ever. The allelic frequencies of the very common alleles that define a species are going to be pretty much the same when one first creates a randomly chosen subpopulation. The only allelic frequencies different in the subpopulation would be those that were uncommon in the parent population. Many of the frequencies of these uncommon alleles will drop from some low percentage like 5% or 3% or 1% all the way down to 0%. This is what accounts for the drop in genetic diversity in a subpopulation.

A change in allelic frequency is necessary to bringing about a phenotypic change in a subpopulation. Without different selection pressures the allelic frequencies will remain about the same as the parent population. Only different selection pressures will cause the allelic frequencies to change.

What are you imagining could cause allelic frequencies to change in the absence of selection pressures? In answering this question, consider a main population that becomes split right down the middle when a river changes course, and assume that the environment remains the same on both sides of the river. Let's say that one of the alleles had a frequency of 95% in the original main population, and that it begins at that level in both subpopulations. What cause of change to allelic frequency could there be that would affect one subpopulation but not the other?

If the selection pressures remain the same then the main contributor to change (aside from drift, which is random and slow) is mutation. The paper AZPaul3 cited was about a chain of lizard subpopulations distributed around the perimeter of a mountain, here's the link:

Predictors for reproductive isolation in a ring species complex following genetic and ecological divergence.

AZPaul3 already quoted one portion about the arise of new DNA sequences, and here's another portion about the cause of reproductive isolation:

Experimental studies strongly favor this view, showing that mutations in coevolving gene complexes can rapidly cause hybrid incompatibilities in closely related species.

In other words, mutations play a key role in producing reproductive incompatibility, and reproductive incompatibility must be considered the foremost of phenotypic differences in speciation processes.

And if selection pressures on the two populations do become different, then the divergent selection pressures will result in divergent allelic frequencies.

But just removing genetic interflow between two populations in the same environment will do little to produce phenotypic differences, and certainly not in a mere 37 years.

--Percy


This message is a reply to:
 Message 383 by Faith, posted 10-12-2013 2:25 PM Faith has responded

Replies to this message:
 Message 392 by Faith, posted 10-13-2013 4:41 PM Percy has not yet responded

    
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