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Author Topic:   Directly Observed Mutation
crashfrog
Member (Idle past 1547 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 3 of 50 (153972)
10-29-2004 12:04 AM
Reply to: Message 1 by markoo
10-28-2004 10:36 PM


IOW, are there any instances that do not have to necessarily infer that a mutated event gave rise to NS, but that we have directly observed the gene sequence itself and can conclude without a doubt it was mutation?
Probably, but why would we have to?
The only inheritable change is that that occurs genetically, at least as far as bacteria go. (I think there's some epigenetic inheritance at work in metazoans but I'm not sure about that.)
Hypothetical situation - we observe that a bacillus population declines precipitously in response to a disadvantageous environment (or a new predator), but then rebounds. We know that a change must have happened, or else the original population would have survived. We know the change must be heritable, or else the new members of the population would have had it.
The only conclusion is that a mutation occured. There's no other kind of heritable change that can occur in a bacterium.
But, yes. It's fairly often, in bacteria at least, that we can sequence the genetics before and after the mutation, and see what locus mutated, and in what way.

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 Message 1 by markoo, posted 10-28-2004 10:36 PM markoo has replied

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 Message 7 by markoo, posted 10-29-2004 11:21 AM crashfrog has replied

  
crashfrog
Member (Idle past 1547 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 9 of 50 (154133)
10-29-2004 12:06 PM
Reply to: Message 7 by markoo
10-29-2004 11:21 AM


A person I am discussing this issue with simply does not believe a mutation is the answer without verifiable, empirical evidence that the DNA (or in some cases, I suppose RNA) has been altered.
That's stupid. I mean, we've never directly oberved matter exchanging carrier particles for gravity, but it would be idiotic for someone to assert that, unless he saw direct observation of gravity and not just it's effects, he'd have to believe that it was invisible angels that pushed him down into his chair and not the same force that does that for the rest of us.
And anyway, even if he saw the mutation happen (assuming we had techniques that could peer inside the genetics of a cell without destroying it), whats to say that it isn't still "divine intervention"? How does he know what divine intervention looks like?

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 Message 7 by markoo, posted 10-29-2004 11:21 AM markoo has replied

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crashfrog
Member (Idle past 1547 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 14 of 50 (154379)
10-30-2004 6:16 AM
Reply to: Message 12 by RustyShackelford
10-30-2004 2:27 AM


Bacteria surviving environmental changes is evidence of natural selection, because there's clearly something hartier about the bacteria that survive than the bacteria that don't, but it'snot evidence for evolution....
Ok, well, we have natural selection, which you admit.
We must have mutation, because that's the only heritable difference between individual bacteria. They are, after all, asexual.
So we have mutation and natural selection. We have those processes changing the frequency of alleles in the population.
So we've proved we have evolution in that population. Case closed. it really is just that simple, unless something other than science compels you to reject any conclusion that supports evolution.

This message is a reply to:
 Message 12 by RustyShackelford, posted 10-30-2004 2:27 AM RustyShackelford has replied

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 Message 15 by RustyShackelford, posted 11-01-2004 1:10 AM crashfrog has replied

  
crashfrog
Member (Idle past 1547 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 21 of 50 (154760)
11-01-2004 2:44 AM
Reply to: Message 15 by RustyShackelford
11-01-2004 1:10 AM


how is that evidence for macroevolution?
Because there's no such thing as "macro" or "microevolution"; there's just evolution.
It's all the same thing - natural selection and random mutation changing allele frequencies.

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crashfrog
Member (Idle past 1547 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 22 of 50 (154761)
11-01-2004 2:45 AM
Reply to: Message 19 by RustyShackelford
11-01-2004 1:53 AM


I've heard that a lot of changes that life goes through to adapt to environment aren't really new mutations but activations of recessive genes........
Recessive genes don't get "activated." They're already activated; they're just not expressed if their counterposing allele is dominant.

This message is a reply to:
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crashfrog
Member (Idle past 1547 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 37 of 50 (154920)
11-01-2004 2:42 PM
Reply to: Message 26 by RustyShackelford
11-01-2004 2:26 PM


But is there any evidence for it occuring?
Loads. Happens all the time:
Observed Instances of Speciation
It's called "speciation." It happens when you separate a population into two subpopulations that no longer have the opportunity to interbreed. As muations accumulate, the two populations lose any ability to interbreed, so even if you tried to merge them again, they wouldn't be able to breed.
Contrary to this (and despite Crash and Lam playing dumb), micro-evolution is no evidence for the unlimited variablity of living things.
Well, yeah, actually, it is. If there's a barrier to variability on that level, how come we've never run into it, or into any mechanism that might cause it?
If you assert that there is one, it's up to you to substantiate that claim.

This message is a reply to:
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crashfrog
Member (Idle past 1547 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 38 of 50 (154921)
11-01-2004 2:44 PM
Reply to: Message 31 by RustyShackelford
11-01-2004 2:31 PM


Loudmouth, but if the people haven't mutated, then they haven't evolved, right?
Not so. Evolution is simply a change in allele frequencies. That change can occur via selection, or mutation, or by reproductive isolation (which, like death, takes some number of genes out of the gene pool.)

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crashfrog
Member (Idle past 1547 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 42 of 50 (154962)
11-01-2004 3:33 PM
Reply to: Message 41 by coffee_addict
11-01-2004 3:29 PM


You're Selling Yourself Short
Well, there's no such thing as proving whether something is as a result of evolution or not.
No, you just did prove it:
However, the examples I gave clearly show the rise of new species due to mutation and natural selection.
See? That's all there is to it.

This message is a reply to:
 Message 41 by coffee_addict, posted 11-01-2004 3:29 PM coffee_addict has replied

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crashfrog
Member (Idle past 1547 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 45 of 50 (154965)
11-01-2004 3:35 PM
Reply to: Message 43 by coffee_addict
11-01-2004 3:33 PM


What about sickel cell that we find in people of African origin? If you are a heterozygous then you are immune to malaria. If you are a homozygous then you have sickel cell disease.
How about the new one, where if you have it, you have the malarial resistance without the anemia?

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