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Author Topic:   Definition of Evolution
Wounded King
Member (Idle past 2170 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 136 of 212 (419596)
09-03-2007 6:46 PM
Reply to: Message 133 by Fosdick
09-03-2007 1:25 PM


Re: So what is this evolution thing, anyway?
I have read Mary Jane West-Eberhard's entire "Developmental Plasticity and Evolution" (2003).

And I've worked in evolutionary and developmental biology for several years.

She is a leading evo-devo-ist, and she argues for the role of "homoplasy" as an alternative to homology (genetic inheritance) for explaining evolution.

Homology is not an equivalence term for genetic heritability. Two genetic sequences can as well be homplastic as any other trait. Either West-Eberhard has meade up her own definitions of some of those words or you are not accurately presenting her position.

you make it sound as if she is advocating some sort of vitalist form of intelligent design or process structuralism where similar environnments cause organisms to converge even on the gentic level. As it is none of West-Eberhard's writings that I can access fail to make much of the interplay of both the environmental and genetic factors in the evolution. For instance her 2005 paper Developmental plasticity and the origin of species differences. she says in the abstract...

Because selection acts on phenotypes, not directly on genotypes or genes, novel traits can originate by environmental induction as well as mutation, then undergo selection and genetic accommodation fueled by standing genetic variation or by subsequent mutation and genetic recombination.

This certainly doesn't suggest in the slightest evolution happening without the inheritance of genetic traits, it may perhaps suggest that you don't need the entirely de novo development of novel traits through gentic mutation.

Where she mentions homoplasy it is not as any sort of genetic context but simply in terms of similar traits developing in similar genetic backgrounds in response to similar environments, although these need not have exactly the same genetic basis.

but adaptation does not occur until the benefical alleles are fixed.

Balderdash, an entire population need not be adapted to a particular pressure for the trait to be adaptive, or are you using fixed in an unusual way here to merely mean genetic or heritable? If you are it seems obtuse since fixation in allelic terms is a pretty specific phenomenon.

Is there any doubt who he has in mind for this barb?

Whatthe heck does this have to do with saying that 'evolution can happen even without the inheritance of genetic traits.'

You have singularly failed to show either of your big 'evo-devo-ist' names saying anything like what you attribute to them.

I don't see evo-devo-ists talking about methylation or introns or other factors relavant to evolution.

Then you obviously don't actually read any research on evo-devo. I don't know why it is but recently people have been saying pretty whacky things about evo-devo and what evolutionary developmental biologists believe.

You were the one claiming 'evo-devo-ist's were saying evolution could happen without the inheritance of genetic traits, I had no idea what you were talking about so I suggested phenomena which many consider to not be strictly genetic. Now not only do I not really know what you are talking about, but I get the impression that you don't either.

TTFN,

WK


This message is a reply to:
 Message 133 by Fosdick, posted 09-03-2007 1:25 PM Fosdick has responded

Replies to this message:
 Message 137 by Fosdick, posted 09-03-2007 8:27 PM Wounded King has responded

    
Fosdick 
Suspended Member (Idle past 3575 days)
Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 137 of 212 (419616)
09-03-2007 8:27 PM
Reply to: Message 136 by Wounded King
09-03-2007 6:46 PM


Re: So what is this evolution thing, anyway?
WK wrote:

I've worked in evolutionary and developmental biology for several years. Homology is not an equivalence term for genetic heritability.

Yes, I do agree, it is not specifically about genetic heritability. But Gould is to blame for my reckless use of the term, as in his "deep homology." Consider what he says in "The Structure of Evolutuionary Theory" (2002, p. 82) he says:

quote:
Lankaster wanted to contrast homology of overt structure, or homology sensu stricto with homology of underlying generators (later called parallelism) building the same structure in two separate lineages (homoplasy, or homology sensu lato, in Lankaster's terms). Because parallelism could not be cashed out in operational terms (as science had no way, until our current revolution in evo-devo, to characterize, or even to recognize these underlying generators, proper conceptual distinctions between parallelism and convergence have generally not been made...
I'm not sold on convergence, but I can see Gould's deep homology, or parallelism, all right. Homoplasy, too, has legs, I quess, but I disagree with the evo-devo's nagging admonition that genes are not essentially and often selfishly in control of adaptation. That's all.

Two genetic sequences can as well be homplastic as any other trait. Either West-Eberhard has meade up her own definitions of some of those words or you are not accurately presenting her position. you make it sound as if she is advocating some sort of vitalist form of intelligent design or process structuralism where similar environnments cause organisms to converge ...

Read her. I can find issues with almost every page. Read Morris, too, and tell me he isn't grinding an ID axe.

Balderdash...

OK. Educated me. What is there in "development" that accomplishes the essentials of heritability? Because no embryo can escape its gametic origin (most of the time). It's a generational thing, isn't it? How do two gametes carry any more information into fertilization than genetic information (save whatever little information comes from their cytoplasm)? I've always wanted to know how "developmental information" evades or escapes its genetic limitations, as Lewontin argues in his "The Triple Helix." He's just spitting back at Dawkins for kicking his colleague's behind—Gould's, specifically.

Oh, btw, I come with no guarantee of satisfaction. I'm mostly just winging it, you know...and, boy, are my arms getting tired!

—HM


This message is a reply to:
 Message 136 by Wounded King, posted 09-03-2007 6:46 PM Wounded King has responded

Replies to this message:
 Message 141 by Wounded King, posted 09-04-2007 2:38 AM Fosdick has responded

    
Fosdick 
Suspended Member (Idle past 3575 days)
Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 138 of 212 (419622)
09-03-2007 8:39 PM
Reply to: Message 135 by Dr Adequate
09-03-2007 6:29 PM


Re: So what is this evolution thing, anyway?
Dr Adequate wrote:

No, but there might be considerable confusion as to what this has to do about "evolution without the inheritance of genetic traits".

Just curious, Dr A, do you know of any evolution going on without the inheriitance of genetic traits. Some people on this forum have claimed there are "traits" that are not heritable. I have agued that a "trait" must be heritable or it is not a "trait." Otherwise, you'd have to explain the three-legged-dog "trait."

—HM


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 Message 135 by Dr Adequate, posted 09-03-2007 6:29 PM Dr Adequate has not yet responded

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RAZD
Member
Posts: 19756
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 5.4


Message 139 of 212 (419627)
09-03-2007 9:26 PM
Reply to: Message 129 by Fosdick
09-03-2007 11:48 AM


Review time
"Change in a population's genetic traits across generations"

Is this acceptable?

Yes - it is acceptable. There are other acceptable definitions such as 'Evolution is the change in hereditary traits within populations of species over time'.

Works for me.


Yes, it works for me, too. But the evo-devo people say ...

Are you or are you not proposing a change to this definition?

If you are proposing a change what is it?

If not, is this discussion really on topic?

Enjoy.


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This message is a reply to:
 Message 129 by Fosdick, posted 09-03-2007 11:48 AM Fosdick has responded

Replies to this message:
 Message 142 by Fosdick, posted 09-04-2007 10:38 AM RAZD has responded

  
Rrhain
Member
Posts: 6349
From: San Diego, CA, USA
Joined: 05-03-2003


Message 140 of 212 (419656)
09-04-2007 1:27 AM
Reply to: Message 127 by Doddy
09-03-2007 12:12 AM


Doddy responds to me:

quote:
Firstly, the genome doesn't know what a kind is.

Then how can we say that the genome can't evolve beyond a kind? How is it supposed to know that it isn't allowed to go beyond the externally-defined boundary?

quote:
Just as evolutionists will point out that creatures do not know to evolve.

Well, no. Indeed, the genome doesn't evolve consciously, but it certainly does know how to evolve: Replication is a chemical process. No chemical process is ever perfect every single time. Therefore, there will necessarily be offspring genetically distinct from its parents. Because there is a differential between one generation and the next, there will necessarily be a differential in reproductive success among various offspring. Those with better reproductive success compared to the others will have a different genetic makeup than those who came before.

And that, by definition, is evolution.

quote:
Rather, it is just something that occurs due to physical laws.

But what is this physical law? How is it that each individual genetic change is allowable but the aggregation of them is prohibited? What is to prevent it?

quote:
Now, because the laws of the universe (as read by creationists) prohibit information increasing without intelligence (more information) instructing it to do so

Now, assuming that the chromosome is "information" (it isn't), why? Is it allowed to duplicate a gene? Is it allowed to alter a gene? Then how is it that duplication and alteration is not allowed?

If we go from "a" to "aa" to "ab," haven't we gained information?

quote:
A 'kind' simply refers to all those organisms that are commonly descended from this perfect created kind.

But what is it? How does one define this "kind" so that one can delineate one "kind" from another? If you can't actually use your definition to make a distinction, then it isn't a definition.

quote:
But just because we don't know, it doesn't mean the term 'kind' is meaningless

Acutally, it does. If you cannot use your definition to draw a distinction, then your definition is worthless. Surely using your definition, you can develop a process that will allow you to see if something satisfies the definition. What is a "kind" such that we can determine of a "fox" and a "dog" are of the same or differing "kinds"?

[Yes, I know you're trying to answer for a creationist.]


Rrhain

Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.
This message is a reply to:
 Message 127 by Doddy, posted 09-03-2007 12:12 AM Doddy has not yet responded

    
Wounded King
Member (Idle past 2170 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 141 of 212 (419663)
09-04-2007 2:38 AM
Reply to: Message 137 by Fosdick
09-03-2007 8:27 PM


Re: So what is this evolution thing, anyway?
Hoot, do you never get tired of 'winging it' which presumably means the way you just make up all sorts of shit and then use them to smear the people your talking to?

OK. Educated me. What is there in "development" that accomplishes the essentials of heritability?

What the hell? What on Earth has this got to do with my question 'an entire population need not be adapted to a particular pressure for the trait to be adaptive, or are you using fixed in an unusual way here to merely mean genetic or heritable?' in response to your contention that 'adaptation does not occur until the benefical alleles are fixed.'

Neither of these statements has a dickie bird to do specifically with development, they are purely questions of population genetics, unless as I suggest you are just making up a new meaning for the concept of 'fixation' of an allele.

But Gould is to blame for my reckless use of the term, as in his "deep homology."

What are you whining about now? Gould makes a very clear distinction between different types of convergencce and the way in which genetics has allowed us to make further distinctions. Is your point that you were just too confused so you decided all the terms were interchangeable or what? None of what Gould says supports your previous usage of the terms.

I disagree with the evo-devo's nagging admonition that genes are not essentially and often selfishly in control of adaptation.

Again you attribute a position with no evidence that anyone actually holds it. To argue that the environment holds as important a position in evolution hardly seems controversial, as you yourself admitted, so just what is your beef. You don't like them picking on Richard Dawkins? I'm sure he is more than capable of holding his own.

Read her.

I'm not going to read an entire book to see if you are right when the papers I have read strongly suggest you are wrong, why not read the developmnental plasticity paper I referenced and highlight for me where she makes the sorts of claims you ascribe to her.

Read Morris

I've read plenty of his original research.

and tell me he isn't grinding an ID axe.

Well that is harder to see from his actual research than his merely personal statements. Certainly he overemphasises the inevitable nature of evolution with his claims that something like a human was bound to come about. But I would only call this the weak sort of ID that any sort of theistic evolutionist must ascribe to no more Discovery Institute ID than the fact that a theistic evolutionist believes in a divine creator would make them a 6-day creationist.

I still don't understand how you can post so much and say so little substantively. You are like MartinV, your whole argument seems to be vague and elliptical inferences based on non-specific elements of other peoples work and the occasional complete misinterpretation of that work.

TTFN,

WK


This message is a reply to:
 Message 137 by Fosdick, posted 09-03-2007 8:27 PM Fosdick has responded

Replies to this message:
 Message 143 by Fosdick, posted 09-04-2007 10:51 AM Wounded King has responded

    
Fosdick 
Suspended Member (Idle past 3575 days)
Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 142 of 212 (419701)
09-04-2007 10:38 AM
Reply to: Message 139 by RAZD
09-03-2007 9:26 PM


Re: Review time
RAZD asks:

Are you or are you not proposing a change to this definition?

Yes, I am. If you will notice in Message 129 I wrote:

My own short definition of "this evolution thing" is simply: A population's success in fixing beneficial alleles. This definition goes a critical step beyond saying only that evolution is a "Change in a population's genetic traits across generations."

—HM


This message is a reply to:
 Message 139 by RAZD, posted 09-03-2007 9:26 PM RAZD has responded

Replies to this message:
 Message 144 by RAZD, posted 09-04-2007 11:51 AM Fosdick has responded

    
Fosdick 
Suspended Member (Idle past 3575 days)
Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 143 of 212 (419702)
09-04-2007 10:51 AM
Reply to: Message 141 by Wounded King
09-04-2007 2:38 AM


Re: So what is this evolution thing, anyway?
WK snorts:

Hoot, do you never get tired of 'winging it' which presumably means the way you just make up all sorts of shit and then use them to smear the people your talking to?

Smearing shit is not something I really care to do. But in your case...

But I would only call this the weak sort of ID that any sort of theistic evolutionist must ascribe to no more Discovery Institute ID than the fact that a theistic evolutionist believes in a divine creator would make them a 6-day creationist.

I still don't understand how you can post so much and say so little substantively.


How's that again?

—HM


This message is a reply to:
 Message 141 by Wounded King, posted 09-04-2007 2:38 AM Wounded King has responded

Replies to this message:
 Message 148 by Wounded King, posted 09-04-2007 5:24 PM Fosdick has responded

    
RAZD
Member
Posts: 19756
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 5.4


Message 144 of 212 (419713)
09-04-2007 11:51 AM
Reply to: Message 142 by Fosdick
09-04-2007 10:38 AM


Re: Review time
A population's success in fixing beneficial alleles.

Define beneficial so that it can be measured.

Does this evolution occur when the allele is fixed or when it becomes beneficial? If the later then fixing is irrelevant, if the former then it is no different than fixing a neutral allele.

Enjoy.


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


we are limited in our ability to understand
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RebelAAmericanOZen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 142 by Fosdick, posted 09-04-2007 10:38 AM Fosdick has responded

Replies to this message:
 Message 145 by Fosdick, posted 09-04-2007 12:47 PM RAZD has responded

  
Fosdick 
Suspended Member (Idle past 3575 days)
Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 145 of 212 (419717)
09-04-2007 12:47 PM
Reply to: Message 144 by RAZD
09-04-2007 11:51 AM


Re: Review time
RAZD, you wrote:

Define beneficial so that it can be measured.

Michael Whitlock and his colleagues at UBC have done this rather nicely in stochastic terms. I especially like these articles:

The Probability of Fixation in Populations of Changing Size and Fixation Probability of Time in Subdivided Populations.

Whitlock advances a stochastic model to define the probability of fixing new beneficial alleles:

2hs(1-FST)Ne / Ntot

“…where hs is the change in fitness of heterozygotes relative to the ancestral homozygote, FST is a weighted version of Wright’s measure of population subdivision, and Ne and Ntot are the effective and census sizes, respectively.”

So he uses this ratio to define and measure "beneficial."

—HM


This message is a reply to:
 Message 144 by RAZD, posted 09-04-2007 11:51 AM RAZD has responded

Replies to this message:
 Message 147 by RAZD, posted 09-04-2007 3:48 PM Fosdick has responded
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Taz
Member (Idle past 1366 days)
Posts: 5069
From: Zerus
Joined: 07-18-2006


Message 146 of 212 (419747)
09-04-2007 3:20 PM
Reply to: Message 138 by Fosdick
09-03-2007 8:39 PM


Re: So what is this evolution thing, anyway?
Hoot writes:

Just curious, Dr A, do you know of any evolution going on without the inheriitance of genetic traits.


The evolution of memes.

Some people on this forum have claimed there are "traits" that are not heritable.

Well, some traits are truly not heritable. For example, a trait caused by a specific mutation that renders an individual completely sterile will of course not be heritable.

I have agued that a "trait" must be heritable or it is not a "trait."

According to wikipedia, "A trait may be any single feature or quantifiable measurement of an organism."

But if we want to argue definition here, I guess you can define it whatever you want.


Disclaimer:

Occasionally, owing to the deficiency of the English language, I have used he/him/his meaning he or she/him or her/his or her in order to avoid awkwardness of style.

He, him, and his are not intended as exclusively masculine pronouns. They may refer to either sex or to both sexes!


This message is a reply to:
 Message 138 by Fosdick, posted 09-03-2007 8:39 PM Fosdick has not yet responded

  
RAZD
Member
Posts: 19756
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 5.4


Message 147 of 212 (419755)
09-04-2007 3:48 PM
Reply to: Message 145 by Fosdick
09-04-2007 12:47 PM


Re: Review time, qualified evolution
Whitlock advances a stochastic model to define the probability of fixing new beneficial alleles:

2hs(1-FST)Ne / Ntot

“…where hs is the change in fitness of heterozygotes relative to the ancestral homozygote,

So we're still stuck with defining fitness being beneficial or not to determine hs.

I note that Whitlock et al say:

quote:
The rate of adaptive evolution of a population ultimately depends on the rate of incorporation of beneficial mutations. ... The results developed in this paper can be used to estimate the fixation flux, defined as the rate at which beneficial alleles fix within a population. The fixation flux measures the rate of adaptive evolution of a population and, as we shall see, depends strongly on changes that occur in population size.

Which differs from your definition by the qualification of the evolution involved being adaptive evolution. In other words they do not make the distinction that you are making.

You also did not answer the rest of my questions on your definition:

Does this evolution occur when the allele is fixed or when it becomes beneficial? If the later then fixing is irrelevant, if the former then it is no different than fixing a neutral allele.

If deleterious mutations are fixed in the population, is that devolution - previous population more fit than current?

What happens if later those deleterious mutations turn out to be beneficial? At what point then does it become evolution?

Moving on ...

Personally I think that rather than focusing on relative benefit, that may change at any time, you should be focusing on new alleles becoming fixed in the population as the criteria, and let the beneficial\neutral\deleterious aspect sort itself out via selection etc. from generation to generation.

Thus you would have "evolution involves the introduction of new alleles and the subsequent change in frequency of alleles in a population from generation to generation"

By this definition the changes observed in populations for the Galapagos Finches and the Peppered Moths would not qualify as evolution per se as they did not involve new mutations\alleles but only existing ones.

In these instances it would take continued selection pressure and new mutations that become fixed in the populations during the period of stress to contribute to eventual evolution of those species.

Now we could use the qualification that Whitlock et al used above, and say that evolution was observed but that it did not reach the point of realizing "adaptive evolution" ... but I have trouble with that conceptualization, as the adaptation in both cases was clear and unambiguous. We need a different qualifier.

We need a qualifier for the "new and improved" set of alleles that includes the new mutations in the mix as opposed to only having a shifting balances of all previously existing alleles.

A logical qualifier for me would be "fixed" -- where evolution becomes fixed when the alleles in a population include fixed new alleles that did not exist in a previous populations set of alleles.

Thus we can say that the evolution of the Galapagos Finches and Peppered Moths was not fixed.

Thus I would say that "fixed evolution involves the introduction of new alleles and the subsequent change in frequency of alleles in a population from generation to generation"

We can also say that such a concept of fixed evolution is important for speciation to occur.

Enjoy.


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


we are limited in our ability to understand
by our ability to understand
RebelAAmericanOZen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

This message is a reply to:
 Message 145 by Fosdick, posted 09-04-2007 12:47 PM Fosdick has responded

Replies to this message:
 Message 150 by Fosdick, posted 09-04-2007 7:29 PM RAZD has responded

  
Wounded King
Member (Idle past 2170 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 148 of 212 (419773)
09-04-2007 5:24 PM
Reply to: Message 143 by Fosdick
09-04-2007 10:51 AM


Re: So what is this evolution thing, anyway?
Have you just totally given up on having your posts make any sort of sense?

You were moaning about Conway-Morris 'grinding an ID axe', I was simply pointing out that he was not neccessarily any more ID than any theistic evolutionist and certainly not a proponent of ID as it would be generally be understood on this site, i.e. the position espoused by Philip Johnson, Michael Behe, Will Dembski and promoted by the Discovery Institute.

I likened this to describing a theistic evolutionist as a creationist, since the believe in a creator, which would still be quite distinct from the common usage of creationist on this site either in the young earth or old earth context.

Are you actually going to address any of the points I made or just keep dodging and whining?

TTFN,

WK


This message is a reply to:
 Message 143 by Fosdick, posted 09-04-2007 10:51 AM Fosdick has responded

Replies to this message:
 Message 151 by Fosdick, posted 09-04-2007 7:40 PM Wounded King has responded

    
Brad McFall
Member (Idle past 3108 days)
Posts: 3428
From: Ithaca,NY, USA
Joined: 12-20-2001


Message 149 of 212 (419782)
09-04-2007 6:49 PM
Reply to: Message 145 by Fosdick
09-04-2007 12:47 PM


Re: Review time
I am more on Wright's side than the Fisher and Fords, I guess of the world, given a discussion from dividing the Evo Synthesis into phases and or claims about restrictions or constrictions etc. etc.

In Chapter 17 VOLUME 2 Evolution and Genetics of Populations, Conclusions of The Theory of Gene Frequencies(references BACK to volume appear as well as indications of what to expect in the sequal (volumes))Wright wrote fully; "At one time, natural populations were often thought of as being essentially bomalleic at all loci with qualification only because of the occassional occurrence of mutations, soon eliminated if, as usual, unfavorable. Favorable mutations appear very rarely and fixation o fone was considered a typical step in evolution. The basic viewpoint of population genetics is, on the contrary, that large populations tend to be heterallelic at all loci and strongly so at many. Mathematically, the species is thought of a as located at apoint in a gene frequency space with ∑(ki -1) dimensions, ki being the number of alleles at the ith locus ans ummation being over all loci. Evolution consists of movement in this space."

The entire volume 2 is necessary for one to visualize what this space "looks" like, but if one STARTS from the place of this space theoretically, rather than the difference of favorable or unfavorable mutations (Wright asserts that Fisher and others continued to misrealize, to say quickly, the algebra of the difference, while different rates of mutations are added to the usual perspective on the course of the changes in an environment that would otherwise soon have had it eliminated).

I did not realize that immigration and mutation are independent or orthogonal of the geometry of this space as to peaks and shifts which though overdetermining the relation of algebra and geometry in the theory is probable cause of most confusions over getting FROM the SPACE to the genetic accounts, whether reductionist or wholistic, regardless of if one thinks in terms of memes or irreducible epigentics etc.

There IS an issue here. Gould calls it a hardening. Provine a constriction. Wilson thinks biology can proceed a pace without strict reliance on fact contra Lewontin. Mayr wants the population put back in Punc Eq. etc etc etc.

I think Wright establishes what evolution is with this sentence, last, but since Provine who knows as much Wright as anyone, does not think nor promote it,(in fact by focusing on neutralism he suggests the theoretical outworking IS NOT occurring in nature (recently at Penn State)) shows that few are the people able to use it anyway. I can see my way through the theory and if Fisher is more correct than Wright than this will only be becuase Fisher's use of the heat equation actually unintentionally introduced thermodynamics into the evolution that is evolving that way no matter how much entropy is produced in the process. Instead, since, there is a discussion of static vs dynamic realisms the discussion can not get to where philosophy and creationism often intends to be sounding.


This message is a reply to:
 Message 145 by Fosdick, posted 09-04-2007 12:47 PM Fosdick has not yet responded

    
Fosdick 
Suspended Member (Idle past 3575 days)
Posts: 1793
From: Upper Slobovia
Joined: 12-11-2006


Message 150 of 212 (419784)
09-04-2007 7:29 PM
Reply to: Message 147 by RAZD
09-04-2007 3:48 PM


Re: Review time, qualified evolution
Which differs from your definition by the qualification of the evolution involved being adaptive evolution. In other words they do not make the distinction that you are making.

OK, good point. I was speaking of adaptive evolution. I also recognize drift, gene flow, and sexual selection as means of non-adaptive evolution. You are looking for a more generalized definition, I suppose.

You also did not answer the rest of my questions on your definition: Does this evolution occur when the allele is fixed or when it becomes beneficial? If the later then fixing is irrelevant, if the former then it is no different than fixing a neutral allele.

I see your point here. Good argument.

If deleterious mutations are fixed in the population, is that devolution - previous population more fit than current? What happens if later those deleterious mutations turn out to be beneficial? At what point then does it become evolution?

Then you don't have adaptation per se, you have exaptation, which is Gould's way of explaining how previously fixed alleles that were once neutral, or even deleterious, become usefully adaptive.

—HM


This message is a reply to:
 Message 147 by RAZD, posted 09-04-2007 3:48 PM RAZD has responded

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 Message 152 by RAZD, posted 09-04-2007 8:11 PM Fosdick has responded

    
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