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Author | Topic: the phylogeographic challenge to creationism | |||||||||||||||||||||||
Faith  Suspended Member (Idle past 1472 days) Posts: 35298 From: Nevada, USA Joined: |
Sorry, yes you were answering the OP.
However, one sentence later you mention "variation" which as you know is the result of mutation -- or what you would call the "additive process." No, variation is the result of normal reproduction which shuffles alleles into new combinations, at least in the case of sexual reproduction. Mutation does not have to enter into it. (I started calling these processes subtractive and additive to make my basic point about them clear). This message has been edited by Faith, 12-08-2005 02:39 PM
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TimChase Inactive Member |
Faith writes: Sorry, yes you were answering the OP.
TimChase writes: However, one sentence later you mention "variation" which as you know is the result of mutation -- or what you would call the "additive process." No, variation is the result of normal reproduction which shuffles alleles into new combinations, at least in the case of sexual reproduction. Mutation does not have to enter into it. (I started calling these processes subtractive and additive to make my basic point about them clear). With regard to my responding to the OP, no problem. With regard to the variation, what creates the alleles themselves and maintains their diversity is mutation. In any case, I learned a bit more by responding to you, and hopefully my response will provide a clearer picture for some other people. At the same time, I am looking forward to seeing the responses of some others -- haven't had the time to as of yet, but I am sure I will learn even more. Time to go feed the crows...
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Faith  Suspended Member (Idle past 1472 days) Posts: 35298 From: Nevada, USA Joined: |
With regard to the variation, what creates the alleles themselves and maintains their diversity is mutation. Yes, so I understand, but when I am using the term I'm not thinking of mutation, merely the usual Mendelian process of variation.
In any case, I learned a bit more by responding to you, and hopefully my response will provide a clearer picture for some other people. At the same time, I am looking forward to seeing the responses of some others -- haven't had the time to as of yet, but I am sure I will learn even more. I hope to have time to answer your post more fully later. Just wanted to make that one correction as I saw it.
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TimChase Inactive Member |
Faith writes: I hope to have time to answer your post more fully later. Just wanted to make that one correction as I saw it. No problem. However, one point I would like to emphasize (before it gets lost in the allele shuffle) is the fact that there has been an overemphasis upon the role of genes in evolutionary theory up until the past few years. Mutations in genes are important, of course, but it is the regulatory DNA which appears to be most important. The proteins and genes we use aren't really that much different from those of any other eukaryote -- it is how the proteins are put together into a living organism which seems to matter most. From: Message 226, (Point #9)
TimChase writes: "... it is important to realize that much of the change which occurs due to evolution occurs not in the genes themselves, but in the regulatory DNA -- which contains more than double the amount of DNA found in the genes (3.5% regulatory, 1.5% in the genes). Regulatory DNA results in low fidelity, high redundancy networks of proteins with a great deal of plasticity." This message has been edited by TimChase, 12-08-2005 09:03 PM
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crashfrog Member (Idle past 1495 days) Posts: 19762 From: Silver Spring, MD Joined: |
Yes, so I understand, but when I am using the term I'm not thinking of mutation, merely the usual Mendelian process of variation. Mendelian sexual recombination doesn't actually constitute a source of variation, though - it's only an explanation for patterns of variation. For instance, Mendel's models explain how much of a population of pea plants will be tall, and how many will be short. They do nothing to explain where the "tall" and "short" traits actually come from. For that, mutation is required. It really doesn't make any sense to examine variation in the absence of mutation, although I understand that you're tenaciously attempting to do so because the very existence of mutation completely undermines your argument.
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TimChase Inactive Member |
Faith writes: I guess if ten offspring is fecundity, fine, I had in mind rather more than that. The question is still whether the mutations offset the subtractions, it can't merely be asserted that they provide a "massive increase" even with the aid of fecundity, considering that beneficial mutations are very few and far between and I could say in return that the selecting and reducing factors produce a "massive decrease" over time. Crashfrog claims he provided evidence for this a long way back and if you didn't comment on his evidence, would you please? Just going to point out that this was addressed in point #6 in post 240: Message 240 (which deals with Kimura's neutral theory of molecular evolution).
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TimChase Inactive Member |
mark24 writes: Hall (Hall 1982) removed the ability for a single bacteria to metabolise lactose. He removed the genes that coded for the enzyme, the permease, & the expression control. As far as your scenario is concerned the situation could not reduce the populations diversity more, it was first reduced to a single organism, then even more was removed. All three functions re-evolved in the susequent grown culture.
quote: In other words, reduction of diversity to a single individual did not prevent evolution. Wow -- I hadn't ever heard of this... [looked it up, editing this in within the box directly below -- consider this a case of lateral transfer]
In Times of Stress, Mutate Early and Often DOI: 10.1371/journal.pbio.0020438 Published: November 23, 2004 http://biology.plosjournals.org/perlserv/?request=get-doc... Reminds me of what they discovered with the hothead plant. Scientists bread a version of hothead which was missing a given allele, and the following generation the allele turned up again. Some thought that an RNA transcription of the missing allele might be hanging around, but it turned out that the gene was hypermutative. Of course, the example involving the bacteria reaquiring removed functions is even more dramatic in some ways -- although no doubt it had a larger population and more generations to play with. For an article on the hothead, see one of my favorite nonfiction authors: Stay Right There, Mendelby Carl Zimmer November 3, 2005 http://www.corante.com/.../11/03/stay_right_there_mendel.php Oh, and I have mentioned another couple of examples of hypermutation -- two that hit particularly close to home for our species:
TimChase writes:
Message 240, point #6 Similarly, if one were looking for the rate of production of either beneficial alleles (where the benefit was judged relative to other alleles for the same gene and one neglected the effects of alleles for other genes), this would be a mistake, as some alleles and genes are hypermutative, or may become hypermutative when exposed to certain proteins. For a very important example of this, there is the phenomena of hypermutation by which our B cells (part of the immune system) adapt to new pathogens. See: Researchers Uncover Secrets of Immune System’s Munitions FactoryAugust 26, 2004 Researchers Uncover Secrets of Immune Systems Munitions Factory | HHMI Selection and hypermutation seems to work rather well in the immune system, wouldn't you agree? Of course, when faced with a hypermutative pathogen such as HIV, things do turn out differently. This message has been edited by TimChase, 12-08-2005 10:21 PM
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TimChase Inactive Member |
pink sasquatch writes: Strictly speaking, a "mutation" is any genetic sequence (or lack thereof) in an offspring that does not match the portion of genome inherited from its parent(s). A "copy error" simply means that the polymerase made a mistake during replication - what you are describing (a mutation that results in two copies of some DNA sequence) is a duplication mutation. Subclassifying is definitely useful, but it is all still mutation. Even whole chromosome rearrangments/translocations are mutations. I remember a while back looking at some old conversation between genetics students at this site regarding lateral gene transfer -- and I believe origin of endogenous retroviruses (RNA viruses which reverse transcribe themselves into a host's genome as proviruses, get stuck, and then passed from generation to generation). One viewpoint I was rather sympathetic towards was that the insertion counted as a form of heredity -- where the ancestor was the original, infectious exogenous retrovirus. But technically, from the perspective of genetics, it is interpretted not as a form of heredity, but as a mutation in the host genome.
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pink sasquatch Member (Idle past 6050 days) Posts: 1567 Joined: |
But technically, from the perspective of genetics, it is interpretted not as a form of heredity, but as a mutation in the host genome. Right. Of course, if the host reproduces and passes along the retroviral insertion to its progeny, that is heredity. It is my understanding that even movement of a transpositional element already present in the genome is considered mutation.
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TimChase Inactive Member |
AdminNosy writes: (emphasis added) I think that says it all. As long as everyone understands what it is that they are dealing with this sort of thing can continue for the enjoyment of some. "Enjoyment" is really the key. There are a great many games being played on the internet. I believe Faith's is a zero-sum -- like the good majority of them. However, the most interesting games are positive-sum....
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NosyNed Member Posts: 9004 From: Canada Joined: |
LOL, so I am more closely related to any number of viri than I am to a chimp. In fact, it is possible I have 3 or more parents.
I like that thought. It is almost as good at the factino that I am 90% not me but rather bacteria.
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Iblis Member (Idle past 3923 days) Posts: 663 Joined: |
Wow, what if we aren't chimps at all then? What if we were originally some sort of super-intelligent velociraptor types who got a bunch of uh, retroviruses from chimps, by you know Doin It with them, thinking it would be Safe ("No eggs in this one," said ZZaxx, slapping her hairy thigh)and so now 50 million years later, we have a rule about that stuff but it's way too late, we're chimps, wages of sin and all that.
Just a theory
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pink sasquatch Member (Idle past 6050 days) Posts: 1567 Joined: |
"No eggs in this one," said ZZaxx, slapping her hairy thigh. Oh. My. God. (welcome, by the way.)
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Omnivorous Member Posts: 3990 From: Adirondackia Joined: Member Rating: 6.9 |
What if we were originally some sort of super-intelligent velociraptor types who got a bunch of uh, retroviruses from chimps, by you know Doin It with them, thinking it would be Safe ("No eggs in this one," said ZZaxx, slapping her hairy thigh) Shouldn't that be "feathered thigh"? (Or maybe not...after...) I know that sounds like a quibble, but I really just wanted to see that passage in print again. Welcome.
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Wounded King Member Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
Some thought that an RNA transcription of the missing allele might be hanging around, but it turned out that the gene was hypermutative. Do you have a reference? I know that there have been a couple of alternative hypotheses put forward (Comai and Cartwright, 2005; Chaudhury, 2005), but I was unaware that there was definitive research on the subject. TTFN, WK
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