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Author Topic:   What prevents micro evolution from becoming macro evolution
frako
Member (Idle past 306 days)
Posts: 2932
From: slovenija
Joined: 09-04-2010


Message 1 of 25 (590298)
11-07-2010 1:16 PM


What is the fine line that separates micro evolution from macro evolution. What is the biological or logical barrier that prevents micro evolution from becoming macro evolution.
In science the terms are used for descriptive purposes though macro evolution is only the combination of lots of micro evolutions.
While creationists use the terms to describe 2 totally different processes.
So what is that fine magic line that micro evolution cannot cross, why cant it cross it, and what evidence supports that.

Replies to this message:
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Message 2 of 25 (590320)
11-07-2010 4:36 PM


Thread Copied from Proposed New Topics Forum
Thread copied here from the What prevents micro evolution from becoming macro evolution thread in the Proposed New Topics forum.

  
slevesque
Member (Idle past 4641 days)
Posts: 1456
Joined: 05-14-2009


Message 3 of 25 (590328)
11-07-2010 5:06 PM
Reply to: Message 1 by frako
11-07-2010 1:16 PM


I'll put it in the most basic form I can think of.
Both groups observe Mutations happening. Both group realize that these muations are copying errors during the replication of DNA.
Both groups will observe that some of these mutations will become fixed in a population. This is what both will call micro-evolution
Both group will observe that therefore, these copying errors will accumulate in a population, driven sometimes by factors such as natural selection, but also sometimes simply through genetic drift.
But each group has a different opinion on the eventual outcome of all this accumulation of mutations:
- Neo-Darwinian evolutionists will say that these will accumulate to the point that new features, organs, etc. will appear in the population, showing an ever evolving and changing trend in biological populations. This is what they will cal macro-evolution.
- Creationists will say that these will accumulate to the point that the mutational burden will become much too high, and this will lead the population down a spiralling path to genetic meltdown. Macro-evolution will therefore never happen.
Creationist will often complain when evolutionist use examples of micro-evolution to prove that macro-evolution will happen, because it simply does not discard the possibility that accumulating mutations could lead to genetic meltdown.
Edited by slevesque, : Tried reformulating that opening line, thanks WK, my biology classes are getting a bit buried underneath my university courses.

This message is a reply to:
 Message 1 by frako, posted 11-07-2010 1:16 PM frako has replied

Replies to this message:
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Panda
Member (Idle past 3713 days)
Posts: 2688
From: UK
Joined: 10-04-2010


Message 4 of 25 (590337)
11-07-2010 5:49 PM
Reply to: Message 3 by slevesque
11-07-2010 5:06 PM


slevesque writes:
- Creationists will say that these will accumulate to the point that the mutational burden will become much too high, and this will lead the population down a spiralling path to genetic meltdown. Macro-evolution will therefore never happen.
Creationist will often complain when evolutionist use examples of micro-evolution to prove that macro-evolution will happen, because it simply does not discard the possibility that accumulating mutations could lead to genetic meltdown.
Fantastic.
Now we need an OP that addresses that opinion.
Oh look!
frako writes:
So what is that fine magic line that micro evolution cannot cross, why cant it cross it, and what evidence supports that.
Now we need to find someone willing to answer the OP...
Edited by Panda, : No reason given.
Edited by Panda, : No reason given.

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Percy
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Posts: 22394
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 5 of 25 (590342)
11-07-2010 6:23 PM
Reply to: Message 3 by slevesque
11-07-2010 5:06 PM


slevesque writes:
- Neo-Darwinian evolutionists will say that these will accumulate to the point that new features, organs, etc. will appear in the population, showing an ever evolving and changing trend in biological populations. This is what they will cal macro-evolution.
This isn't an accurate characterization of what evolutionary biologists say. Through natural selection, deleterious mutations are removed and advantageous mutations retained. It is advantageous mutations (and to be more complete, also mostly neutral mutations) that accumulate, not all mutations.
- Creationists will say that these will accumulate to the point that the mutational burden will become much too high, and this will lead the population down a spiralling path to genetic meltdown. Macro-evolution will therefore never happen.
Because your characterization of the position of evolutionary biologists was incomplete, this characterization of the position of creationists fails to address the fact that deleterious mutations are removed from populations by natural selection and are not included among the mutations that accumulate.
--Percy

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Dr Adequate
Member (Idle past 285 days)
Posts: 16113
Joined: 07-20-2006


Message 6 of 25 (590355)
11-07-2010 7:07 PM
Reply to: Message 3 by slevesque
11-07-2010 5:06 PM


- Neo-Darwinian evolutionists will say that these will accumulate to the point that new features, organs, etc. will appear in the population, showing an ever evolving and changing trend in biological populations. This is what they will cal macro-evolution.
- Creationists will say that these will accumulate to the point that the mutational burden will become much too high, and this will lead the population down a spiralling path to genetic meltdown. Macro-evolution will therefore never happen.
And when we look at what actually happens, genetic meltdown does not occur unless researchers deliberately and repeatedly force populations through artificially small bottlenecks.
So apparently the neo-Darwinians win.
I'm glad we sorted that out. What do we do now?
Creationist will often complain when evolutionist use examples of micro-evolution to prove that macro-evolution will happen, because it simply does not discard the possibility that accumulating mutations could lead to genetic meltdown.
But they don't. We can watch what happens.
Imaginary genetic meltdown doesn't happen.

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 7 of 25 (590357)
11-07-2010 7:10 PM
Reply to: Message 5 by Percy
11-07-2010 6:23 PM


Because your characterization of the position of evolutionary biologists was incomplete, this characterization of the position of creationists fails to address the fact that deleterious mutations are removed from populations by natural selection and are not included among the mutations that accumulate.
I'm not sure why you think this. There is plenty of pop. gen. and comparative genetic evidence for fixation of deleterious mutations. Certainly the trends for beneficial and deleterious mutations are as you desribe, but in the real world there is plenty of evidence of deleterious mutations accumulating.
The real question is, as Slevesque posits, whether such mutations are balanced by compensating beneficial mutations or conversely whether organismal fitness is in an irreversible decline, for which there is no evidence except in some organisms with drastically reduced population sizes.
TTFN,
WK

This message is a reply to:
 Message 5 by Percy, posted 11-07-2010 6:23 PM Percy has replied

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 8 of 25 (590359)
11-07-2010 7:20 PM
Reply to: Message 3 by slevesque
11-07-2010 5:06 PM


Truly schoolboy errors
Both group realize that these muations are copying errors during the transcription of the genetic code.
When you want to try and frame an opening post about science it would probably be good not to get half of it wrong.
Transcription is the process whereby a DNA strand template is used to produce mRNA, when DNA is copied it is called replication. The genetic code also specifically refers to the complementarity of certain codons for certain amino acids. What is copied during replication, and transcribed in transcription, are genetic sequences.
Terms like 'transcription' and 'Genetic code' have specific well defined meanings in molecular genetics, couldn't you try and adhere to them?
TTFN,
WK

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Percy
Member
Posts: 22394
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 9 of 25 (590361)
11-07-2010 7:26 PM
Reply to: Message 7 by Wounded King
11-07-2010 7:10 PM


Hi WK,
I made clear I was aware of the neutral and nearly neutral theories when I parenthetically said, "and to be more complete, also mostly neutral mutations." If you don't like the level of detail I've chosen then make your own arguments at your own chosen level of detail to Slevesque.
--Percy

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Coyote
Member (Idle past 2106 days)
Posts: 6117
Joined: 01-12-2008


Message 10 of 25 (590362)
11-07-2010 7:27 PM
Reply to: Message 3 by slevesque
11-07-2010 5:06 PM


Creationists meltdown?
Creationist will often complain when evolutionist use examples of micro-evolution to prove that macro-evolution will happen, because it simply does not discard the possibility that accumulating mutations could lead to genetic meltdown.
Creationists seem to have focused on "genetic meltdown" and "genetic entropy" lately.
Is there any evidence that these actually occur in normal populations?
I know that Sanford believes in this, but then he believes in a young earth. The fact that the earth is old completely changes the dynamics of his argument, and not for the better.
None of the other explanations creationists have put forth over the years have withstood the tests of science, and I suspect this one is no different.
Given that, there seems to be no barrier to a lot of micro-evolutionary events adding up over time to a macro.

Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.

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Replies to this message:
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Rrhain
Member
Posts: 6351
From: San Diego, CA, USA
Joined: 05-03-2003


(2)
Message 11 of 25 (590372)
11-07-2010 8:07 PM
Reply to: Message 1 by frako
11-07-2010 1:16 PM


frako writes:
quote:
What is the fine line that separates micro evolution from macro evolution.
That depends upon if you are asking a biologist or a creationist.
That is, the idea of "microevolution" and "macroevolution" is a creationist construct. It came about because observations of populations showed that the flat out denial of mutations arising and becoming fixed in populations could no longer be denied while retaining any sense of intellectual integrity.
As an example, there is a common experiment that is done in high schools that proves the point:
Take a single E. coli bacterium of K-type. This means the bacterium is susceptible to T4 phage. Let this bacterium reproduce until it forms a lawn. Then, infect the lawn with T4 phage.
What do we expect to happen? That's right, plaques should start to form and, eventually, the entire lawn will die. After all, every single bacterium in the lawn is descended from a single ancestor, so if the ancestor is susceptible, then all the offspring should be susceptible, too.
But what we actually see is that some colonies of bacteria in the lawn are not affected by the phage.
How can this be? Again, the entire lawn is descended from a single ancestor. They should all behave identically. If one is susceptible, then they're all susceptible. If one is immune, then they're all immune. This can't be an example of "adaptation" because if one could do it, they all could do it.
But since there is a discrepancy, we are left with only one conclusion: The bacteria evolved. There must be a genetic difference between the bacteria that are surviving and those that died.
Indeed, we call the new bacteria K-4 because they are immune to T4 phage.
But we're not done. Take a single K-4 bacterium and repeat the process: Let it reproduce to form a lawn and then infect the lawn with T4 phage.
What do we expect to happen? That's right: Absolutely nothing. All of the bacteria are descended from a single ancestor that is immune to T4 phage. Therefore, they all should survive and we shouldn't see any plaques form.
But we do. Plaques do, indeed start to form. How can this be? Again, all the bacteria in the lawn are descended from a single ancestor that was immune to T4 phage, so they should all behave identically. If one is immune, then all are immune. There must be something else going on.
Something evolved, but the question is what. What evolved? Could it be the bacteria experiencing a reversion mutation back to K-type? No, that can't be it. Suppose any given bacteria did revert back to wild. It is surrounded by K-4 type who are immune to T4 phage. As soon as the lawn is infected, those few bacteria will die and immediately be replaced by the offspring of the immune K-4 bacteria. We would never see any plaques forming because the immune bacteria keep filling in any holes that appear.
So if it isn't the bacteria that evolved, it must be the phage. And, indeed, we call the new phage T4h as it has evolved a new host specificity.
There is a similar experiment where you take bacteria that have had their lactose operons removed and they evolve to be able to digest lactose again.
This sort of thing cannot be denied since we can reproduce the effect at will.
So creationinsts came up with the argument of, "But it's still a bacterium!" ignoring that the whole point of the experiment was not to produce a new species in the course of a week but rather to show proof of concept: The genome does not reproduce perfectly from generation to generation, that some of these mutations are beneficial, and that these beneficial mutations can become fixed in a population through a process of selection.
Unable to argue the fundamental claim that the genome never changes because god made it perfect, that all mutations are bad, and thus evolution is impossible as a concept on a primary level, they shifted the argument to say that, "OK, so you showed that change to the genome can happen, but it's impossible to have large-scale change."
"Microevolution" and "macroevolution" are creationist terms. Now, biologists have been known to use such terms, but they usually make reference to evolutionary changes below the species level as "microevolution" and evolutionary changes above the species level as "macroevolution."
But notice, there is no distinction in the mechanisms involved when biologists refer to such things. That is, there is no "microevolutionary" process and some different "macroevolutionary" process that is distinct and different. Instead, there are simply "evolutionary processes." If the changes created by those processes don't result in speciation-level events, then a biologist might (and mind you, I said, "might") refer to it as "microevolution." But if those processes result in speciation-level events or even higher, then it might (again, mind you, I said, "might") be referred to as "macroevolution."
In essence, as far as biology is concerned, "macroevolution" is nothing more than a whole lot of "microevolution." If 1 + 1 = 2, why on earth is there anything to stop 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 = 10?
And, indeed, we have seen speciation happen right in front of our eyes both in the lab and in the field. The problem, of course, is the denial of the creationists to this evidence. It's essentially taking it to the next level. You see, speciation rarely results in gross morphological change. You simply don't get ostriches hatching from alligator eggs. Yet that seems to be the expectation of the creationists: They want huge morphological changes in incredibly short periods of time.
Now, evolution can happen quite rapidly. We have seen reproductive isolation happen in only 13 generations. But you aren't going to see Hyracotherium turn into Equus in our lifetimes.
But in the end, you have to remember, "microevolution" and "macroevolution" are creationist terms developed as a way to keep their claims in spite of evidence against them.

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.

Minds are like parachutes. Just because you've lost yours doesn't mean you can use mine.

This message is a reply to:
 Message 1 by frako, posted 11-07-2010 1:16 PM frako has replied

Replies to this message:
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Percy
Member
Posts: 22394
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 12 of 25 (590378)
11-07-2010 8:45 PM
Reply to: Message 3 by slevesque
11-07-2010 5:06 PM


slevesque in his edit reason writes:
Tried reformulating that opening line, thanks WK, my biology classes are getting a bit buried underneath my university courses.
I wouldn't sweat it too much. When you said "transcription" instead of "replication," I think your meaning was pretty clear from context anyway.
--Percy

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frako
Member (Idle past 306 days)
Posts: 2932
From: slovenija
Joined: 09-04-2010


Message 13 of 25 (590412)
11-08-2010 4:58 AM
Reply to: Message 3 by slevesque
11-07-2010 5:06 PM


Creationist will often complain when evolutionist use examples of micro-evolution to prove that macro-evolution will happen, because it simply does not discard the possibility that accumulating mutations could lead to genetic meltdown.
That is bullshit, because anything that might hinder the fitness of the species gets "filtered" out by natural selection.
Well in almost any species that is there is one exception human ever since our advances in medicine we kinda went around natural selection. If you have bad gens that might lead to Diabetis you do not die young you get insulin and they tell you what you can eat, and if you get bad geens for something else you can get treated for it so we are able to pass on the bad mutations more easely than any other animal.

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frako
Member (Idle past 306 days)
Posts: 2932
From: slovenija
Joined: 09-04-2010


Message 14 of 25 (590413)
11-08-2010 4:59 AM
Reply to: Message 11 by Rrhain
11-07-2010 8:07 PM


My point exactly.

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Dr Jack
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Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


Message 15 of 25 (590414)
11-08-2010 5:14 AM
Reply to: Message 11 by Rrhain
11-07-2010 8:07 PM


"Microevolution" and "macroevolution" are creationist terms. Now, biologists have been known to use such terms, but they usually make reference to evolutionary changes below the species level as "microevolution" and evolutionary changes above the species level as "macroevolution."
This is not really true. Or, at the very least, it's an open question in Evolutionary theory.
It's generally accepted that there are some processes important at the macroevolutionary level which are not explicable at the microevolutionary level and some theorists argue for a large role for these processes. For example, mass extinctions, geographical shifts, clade level selection for generalism, sexual reproduction, etc.
So, while the changes within each lineage can be described as incremental microevolutionary steps; there is good reason to think that the description of macroevolutionary patterns of evolution needs additional mechanisms.

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