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Author Topic:   Population Genetics
RAZD
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Message 31 of 90 (385810)
02-17-2007 9:27 AM
Reply to: Message 30 by Allopatrik
02-17-2007 3:49 AM


Welcome to the fray young frankenstein Allopatrik,

... it was a problem for a population needing to fix beneficial mutations in a rapidly deteriorating environment.

In other words it explains extinctions, but not survival.

The dilemma is, populations of organisms with long generation times cannot fix the mutations needed to adapt to drastic ecological changes fast enough

But it is not restrictive on other populations. It does not affect short generation populations, nor does it affect the survival of long generation populations outside the area of stress, which can then later radiate back into an extinction evacuated niche.

Given that this is the pattern of evolution that we actually see following extinction events, this is no surprise either.

The bottom line is that a mathematical calculation cannot possibly force reality to behave according to the calculations, all it can do is model what happens: the better the model the better the relationship to reality, but if the model fails to represent reality it is the model that is in error.

Enjoy.


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This message is a reply to:
 Message 30 by Allopatrik, posted 02-17-2007 3:49 AM Allopatrik has responded

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Allopatrik
Member (Idle past 4357 days)
Posts: 59
Joined: 02-07-2007


Message 32 of 90 (385832)
02-17-2007 12:59 PM
Reply to: Message 31 by RAZD
02-17-2007 9:27 AM


In other words it explains extinctions, but not survival

Well, the literal dilemma refers to the problem for the population, not individual survival, yes. People have--mistakenly--come to think of "Haldane's Dilemma' as a dilemma for evolutionary theory, which it definitely is not.

But it is not restrictive on other populations. It does not affect short generation populations, nor does it affect the survival of long generation populations outside the area of stress, which can then later radiate back into an extinction evacuated niche.

Given that this is the pattern of evolution that we actually see following extinction events, this is no surprise either.

No, it isn't. However, it is important to keep in mind that there is a cost associated with any gene substitution, so Haldane's work can be applied generally, even though it's true that the basic assumptions of his model in the original papers were somewhat restrictive. Let's take a look at each:

1. Large, randomly mating population. This should not be controversial-- it's very common in population genetics models. Haldane was interested in the effects of selection, so he assumes a large population to eliminate any stochastic effects of genetic drift on the analysis. Of course (and Haldane was very aware of this) in any finite population genetic drift does play a role.

2. Constant population size. Again, this shouldn't be controversial. What was interesting to Haldane (and other population geneticists such as Crow and Kimura) was the common observation that substitutions could go on and populations would not change much in size.

3. The allele starts in the population at a very low frequency. Haldane had in mind an allele that was originally harmful, and kept in the population purely by mutation pressure, but which became beneficial when the environment suddenly and drastically changed for the worse. Nothing particularly unusual with that, though (as we will see later) the higher the initial frequency of a beneficial allele, the lower the cost of substitution. If it sounds odd that a beneficial allele could begin at a high frequency, consider an allele that is originally neutral, rising to a high initial frequency due to drift, then becoming selected for when the environment changes, and I think you can see one way such a thing can come to pass.

Haldane also made a couple of other minor assumptions in the initial paper (such as constant selective value throughout the substitution), but we won't get into those since they don't have much to do with the "controversy".

Haldane's key insight here wasn't that, on average, a population could only endure 1 substitution per 300 generations, as many seem to think. Instead, what made Haldane's paper so interesting was his revelation that, as long as selection wasn't intense, the cost of substitution was independent of selective value. Instead, the cost was entirely dependent on the allele's frequency in the population when selection for it began. This makes sense if one thinks carefully about what is happening with the substitution of one allele for another: the beneficial allele must have some kind of reproductive advantage over its rival. In some way it must be making more copies of itself at the expense of the other. Natural selection can favor an allele by simply enabling it to have greater reproductive capacity over another—it doesn’t have to be a case of killing off individuals who carry the rival allele (that would be the case of intense selection that Haldane pointed out was an exception to his model). But, ultimately, it comes down to one allele having enough reproductive excess over the other to eventually replace it. With this in mind, it should now be very clear why the initial frequency is so important: it determines what frequency of the population must be replaced with individuals carrying the new allele, and therefore how long that will take.

Haldane originally used genetic death (juvenile mortality or its equivalent in reduced fertility) as the currency to measure the cost of substitution. Remine prefers to use pure reproductive excess in his book and paper, but in reality they are ways of measuring the same thing. Many authors on the subject (Warren Ewens, Joe Felsenstein, James Crow, Motoo Kimura, and Masatoshi Nei) clearly understood that reproductive excess is the heart of the discussion, and said so clearly in their papers in the late 60’s and early 70’s. I know Remine thinks his approach is cleaner, and I agree, from what I’ve seen of his work. But I disagree with his insistence that the others were confused or that his approach is so radically different. It must have been galling when both Ewens and Crow, who reviewed his paper when he submitted it to The Journal of Theoretical Biology, said he wasn’t really saying anything that they hadn’t already been saying since the 60’s, but it’s true. So it should come as no surprise that neither of them recommended publication in that particular journal, since it does not contribute significantly new theory. Remine likes to complain that he is being suppressed, but Crow has publicly made it clear he thinks Remine’s paper could be published in another journal. I think so as well, though I must say, after reading it, that Remine clearly has no idea how to write a scientific paper. Its style is so poor it is surprising that Remine spent such a long time wrangling with editors and reviewers not only with the The Journal of Theoretical Biology but with Heredity as well. One would have thought he could have taken their input or at the very least look at some articles in them and modified his manuscript. Looking at what he eventually published online, it’s obvious he did neither.

A


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zcoder
Member (Idle past 4379 days)
Posts: 66
Joined: 03-19-2007


Message 33 of 90 (390452)
03-20-2007 1:37 PM
Reply to: Message 32 by Allopatrik
02-17-2007 12:59 PM


Is this true?
quote:

we do know that evolution has occurred, the evidence overwhelmingly shows that all known species share a common ancestal species.

couse I was really wondering about that, really and so I did some
fact finding to see for my self the overwhelming evidence in detail
couse if I adope the theroy of evolution I must have all answers to
be fact not assumptions. But I ran into a brick wall.

here is what I have a problem with.
I found out that at a certain level (rocks corresponding to the “Pre Cambrian Era”) the geologic layers
contain almost no fossils. The few that exist are those from cellular and multicellular creatures such as algae or
bacteria. Suddenly, in the next higher layer (corresponding to the “Cambrian Period”) many sophisticated, fully formed
fossils appear. These varied creatures include Trilobites, brachiopods, gastropods, bivalves, crinoids, graptolites,
sponges, and segmented worms. This sudden appearance of so many fully developed life forms can not be explained using
the theory of evolution and the slow-working microevolution model.
Too many different creatures appear fully developed, too suddenly.

Scientists also discovered “living fossils” like the coelacanth that have not changed in form for “millions of years.
This is a genuine embarrassment for scientists who believe in evolution, who had to scramble for ideas that explained
why these animals did not evolve while others did. (They had to find some explanation, or admit that the theory of evolution
was wrong.) A popular example of such an explanation uses the concept of “stabilizing selection,” which would be worded like this:
“Natural selection prevented change by eliminating all the innovations, sometimes for periods of millions of years.
” Notice that this statement is the exact opposite of normal evolutionary thought. If that is really the case, I wonder why some
“renegade” species chose to follow stabilizing selection while others chose to evolve. The reality is that the theory of evolution
has no valid explanation for living fossils.

This is an example of the concept of stasis—standing in one spot. It may help you to know that stasis is not limited to “living fossils.”
Stephen Jay Gould (an evolutionist) stated, “Most species exhibit no directional change during their tenure on earth. They appear in the
fossil record looking pretty much the same as when they disappear; morphological change is usually limited and directionless.”
Therefore, both living fossils and the fossil record itself are in conflict with the theory of evolution, which normally teaches that we
should see constant change in species—not stasis. Actually, the concept of stasis fits the Bible’s creation model perfectly. We would expect
created plants and animals to remain in stasis—the way God created them.

And when I searched more I found a tree of life, I observe something surprising—no species on one branch changes
into a species on another branch. In each case the species is distinct. There are no links where one species
changes into another. Yes, you can line up a dog and a cat and a person, but where is the transitional form
that split into the two species? You are only shown a gap where the change was to have taken place.
It does not take a Ph.D. to realize that no true transitional forms have been found, and the tree is trying
to illustrate a principle that does not actually exist.

But they had to change their theory of that tree for a cladogram:
http://www.clarifyingchristianity.com/p_tree.shtml#cladogram

So I hope you can understand my delima about facts of evolution.

Zcoder....


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ringo
Member
Posts: 16671
From: frozen wasteland
Joined: 03-23-2005
Member Rating: 2.9


Message 34 of 90 (390456)
03-20-2007 1:52 PM
Reply to: Message 33 by zcoder
03-20-2007 1:37 PM


zcoder writes:

So I hope you can understand my delima about facts of evolution.

Your dilemna seems to be caused by swallowing the crap from creationist websites hook, line and sinker.


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zcoder
Member (Idle past 4379 days)
Posts: 66
Joined: 03-19-2007


Message 35 of 90 (390460)
03-20-2007 2:15 PM
Reply to: Message 34 by ringo
03-20-2007 1:52 PM


oh, but I searched universities who teach this crap to verify it.
and then took a walk to the university just down the block from me.
"Westlen University and Nebraska University."
I got books and university websites to do my comparison with.

All is still theories and you swallowing the crap from evolisonists
hook, line and sinker.

Now Show Me proof that evolution was proven before it was adopted.
and please do not show me those theories, becouse I am searching
for facts only, and I will just reject a theory.

Zcoder...


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Replies to this message:
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NosyNed
Member
Posts: 8842
From: Canada
Joined: 04-04-2003


Message 36 of 90 (390461)
03-20-2007 2:20 PM
Reply to: Message 35 by zcoder
03-20-2007 2:15 PM


Meaning of Theory
Now Show Me proof that evolution was proven before it was adopted.
and please do not show me those theories, becouse I am searching
for facts only, and I will just reject a theory.

You don't have a clue what theory, in this context, means. Not an iota!


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ringo
Member
Posts: 16671
From: frozen wasteland
Joined: 03-23-2005
Member Rating: 2.9


Message 37 of 90 (390463)
03-20-2007 2:29 PM
Reply to: Message 35 by zcoder
03-20-2007 2:15 PM


zcoder writes:

oh, but I searched universities who teach this crap to verify it.

No you didn't.

Everything you mentioned is PRATTs (Points Refuted A Thousand Times). It has all been refuted right here on this very site. If you take the time to read some posts, you'll see that nothing you have said is any challenge to evolution.

But this thread is not the place to discuss that.


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zcoder
Member (Idle past 4379 days)
Posts: 66
Joined: 03-19-2007


Message 38 of 90 (390465)
03-20-2007 2:39 PM
Reply to: Message 36 by NosyNed
03-20-2007 2:20 PM


Re: Meaning of Theory
Theory, methodologies, discussion.
In science, a theory is a mathematical description, a logical explanation,
conjecture, an opinion, or a speculation. In this usage, a theory is not
necessarily based on facts; in other words, it is not required to be consistent
with true descriptions of reality.

for instance the theory Albert Einstein had about gravitational deflection of starlight
by a large mass was just theory untill 1919, when a team led by British astronomer Arthur Eddington
claimed to have confirmed Einstein's prediction of gravitational deflection of starlight by
the Sun while photographing a solar eclipse in Brazil and Principe.

Now that part is confirmed to my standard, and is now fact not a theory.
But my close friend at westlen Univerity Dr. Michael Baden
would say you will try to say theory is also fact. but it can't
be both. so drop the theory word and with his help I will
tell you if it's fact or not. that should cut through the bull.

Now I still would like the facts on the above evolution delima I have.

Zcoder....


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Chiroptera
Member
Posts: 6638
From: Oklahoma
Joined: 09-28-2003
Member Rating: 4.9


Message 39 of 90 (390467)
03-20-2007 2:43 PM
Reply to: Message 33 by zcoder
03-20-2007 1:37 PM


quote:
So I hope you can understand my delima about facts of evolution.

Yes, I can. Your dilemma stems from your "facts" being untrue.

-

quote:
I found out that at a certain level (rocks corresponding to the \u201cPre Cambrian Era\u201d) the geologic layers
contain almost no fossils. The few that exist are those from cellular and multicellular creatures such as algae or
bacteria

This is untrue. There are plenty of Precambrian fossils, with plenty of candidates for precursors of Cambrian fauna. What is more, genetic and molecular evidence shows the seperate lineages of extant phyla extending well before the Cambrian, rendering this point moot.

-

quote:
This sudden appearance of so many fully developed life forms can not be explained using
the theory of evolution and the slow-working microevolution model.

Actually, the precursors of many of the so-called "fully developed" Cambrian fauna can be found in Precambrian deposits. And the transition seems to have taken on the order of tens of millions of years -- plenty of time for evolution to have taken place.

-

quote:
Scientists also discovered \u201cliving fossils\u201d like the coelacanth that have not changed in form for \u201cmillions of years.

This is not true. There are no fossil precursors of the modern coelacanth, so it is unknown how much it has changed or over how long.

Furthermore, it is sufficiently different from related Mesozoic species that modern species are placed in their own family.

-

quote:
Stephen Jay Gould

Taken out of context. I have read a lot of Gould, and I have a little familiarity with his ideas.

-

quote:
And when I searched more I found a tree of life, I observe something surprising\u2014no species on one branch changes
into a species on another branch

The important thing is that the tree exists. It is hard to reconcile a tree with a separate creation of the different species.

-

quote:
It does not take a Ph.D. to realize that no true transitional forms have been found

It also doesn't take a PhD to realize that true transitional species have been found. Lots of them, too.


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zcoder
Member (Idle past 4379 days)
Posts: 66
Joined: 03-19-2007


Message 40 of 90 (390468)
03-20-2007 2:45 PM
Reply to: Message 38 by zcoder
03-20-2007 2:39 PM


Re: Meaning of Theory
I can't find it, I don't use forums for facts I use the internet
for leads, then I use Universities for the facts from there libarys.

Zcoder....


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ringo
Member
Posts: 16671
From: frozen wasteland
Joined: 03-23-2005
Member Rating: 2.9


Message 41 of 90 (390470)
03-20-2007 2:46 PM
Reply to: Message 38 by zcoder
03-20-2007 2:39 PM


Re: Meaning of Theory
If you're going to copy and paste from Wikipedia, you should provide a reference.


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zcoder
Member (Idle past 4379 days)
Posts: 66
Joined: 03-19-2007


Message 42 of 90 (390474)
03-20-2007 3:00 PM
Reply to: Message 41 by ringo
03-20-2007 2:46 PM


Re: Meaning of Theory

This is untrue. There are plenty of Precambrian fossils, with plenty of
candidates for precursors of Cambrian fauna. What is more, genetic and
molecular evidence shows the seperate lineages of extant phyla extending
well before the Cambrian, rendering this point moot.

Point me to where you got this information, so I can go find it in
the Universities libarys. just a lead.


Actually, the precursors of many of the so-called "fully developed" Cambrian
fauna can be found in Precambrian deposits. And the transition seems to have
taken on the order of tens of millions of years -- plenty of time for evolution
to have taken place.

same here I would like to search on what fact you got that from too.


The important thing is that the tree exists. It is hard to reconcile a tree
with a separate creation of the different species.

You lost me there, you can't show me the fossils of different species inbetween
their changes? yet you adopt the theory as fact?


It also doesn't take a PhD to realize that true transitional species have been found.
Lots of them, too

I will need you to tell me where these species are today, who found them ect.
ok?

Zcoder....

Edited by zcoder, : post needs quote fixing to look right.


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zcoder
Member (Idle past 4379 days)
Posts: 66
Joined: 03-19-2007


Message 43 of 90 (390475)
03-20-2007 3:07 PM
Reply to: Message 42 by zcoder
03-20-2007 3:00 PM


Re: Meaning of Theory
ok
http://www.alberteinstein.info/
http://en.wikipedia.org/wiki/Theory

Zcoder....

Edited by zcoder, : No reason given.


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Chiroptera
Member
Posts: 6638
From: Oklahoma
Joined: 09-28-2003
Member Rating: 4.9


Message 44 of 90 (390476)
03-20-2007 3:18 PM
Reply to: Message 42 by zcoder
03-20-2007 3:00 PM


Re: Meaning of Theory
quote:
Point me to where you got this information, so I can go find it in
the Universities libarys. just a lead.

Glad to oblige. Palaeos is a pretty good resource. Here is their description of the Ediacaran fauna. It also includes references from the scientific literature that you can look up. The Ediacaran fauna have been known for a long time -- I'm surprised that you never read about it in all your trips to the university library.

-

quote:
You lost me there, you can't show me the fossils of different species inbetween
their changes?

I'm saying that the nested hierarchical classification of species (the so-called Linnaean classification system) is by itself pretty good evidence for common descent. In fact, Douglas Theobald does a pretty good job at describing some of the evidence in favor of common descent and exactly why it is considered good evidence.

-

quote:
I will need you to tell me where these species are today, who found them ect.

The abbreviation for et cetera is etc., not ect.

Anyway, Palaeos once again lists lots of transitional fossils, as well as descriptions, the reason that they are considered transitionals, and scientific references that you can look up yourself at the university library. Also, Kathleen Hunt has list (unfortunately out of date and incomplete) of quite a few transitionals important in vertebrate evolutionary history.


Actually, if their god makes better pancakes, I'm totally switching sides. -- Charley the Australopithecine
This message is a reply to:
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ringo
Member
Posts: 16671
From: frozen wasteland
Joined: 03-23-2005
Member Rating: 2.9


Message 45 of 90 (390477)
03-20-2007 3:23 PM
Reply to: Message 43 by zcoder
03-20-2007 3:07 PM


Re: Meaning of Theory
Thanks for the link, but what I meant was: in your earlier post, you quoted Wikipedia verbatim but you never said you were quoting Wikipedia or even that Wikipedia was your source. That makes it look like plagiarism (even if it was unintentional). It's dishonest and it's contrary to the Forum Guidelines.


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