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Thread: Prokaryotic Evolution not a model for Eukaryotic Evolution

  1. #1 Prokaryotic Evolution not a model for Eukaryotic Evolution 
    Universal Mind John Galt's Avatar
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    The prevalence of horizontal gene transfer amongst prokaryotes makes it irrelevant as evidence for evolution amongst eukaryotes. Nevertheless evolutionists routinely use this on their debates with creationists. It is a weak flawed argument and should be abandoned forthwith.

    Discuss.


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  3. #2  
    Forum Ph.D. Darius's Avatar
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    Really? I have not heard of such an argument. Can you give me an example?

    Also, must you really use "evolutionist"? Evolution, the theory that genetic material of a population of organisms changes from one generation to the next, is very solid and used by geneticists every day. We don't call gravity believers gravitists, because that would be stupid.


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  4. #3 Re: Prokaryotic Evolution not a model for Eukaryotic Evoluti 
    Administrator KALSTER's Avatar
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    Quote Originally Posted by John Galt
    The prevalence of horizontal gene transfer amongst prokaryotes makes it irrelevant as evidence for evolution amongst eukaryotes. Nevertheless evolutionists routinely use this on their debates with creationists. It is a weak flawed argument and should be abandoned forthwith.

    Discuss.
    http://en.wikipedia.org/wiki/Horizon...fer#Eukaryotes

    Citations from the wiki article: ONE and TWO.

    The evidence seems to be mounting for inter-species gene transfer and even between organisms from different phylogenetic groups.

    Quote Originally Posted by Darius
    Also, must you really use "evolutionist"? Evolution, the theory that genetic material of a population of organisms changes from one generation to the next, is very solid and used by geneticists every day. We don't call gravity believers gravitists, because that would be stupid.
    Kind of like people that believe in genetics are called geneticists?
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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  5. #4 Re: Prokaryotic Evolution not a model for Eukaryotic Evoluti 
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by John Galt
    The prevalence of horizontal gene transfer amongst prokaryotes makes it irrelevant as evidence for evolution amongst eukaryotes. Nevertheless evolutionists routinely use this on their debates with creationists. It is a weak flawed argument and should be abandoned forthwith.

    Discuss.
    Only people I've ever heard hyping that one up are New Scientist and all the creationists who read the front cover of that issue and really thought "DARWIN WAS WRONG". It was a crap article that didn't live up to the headline. HGT is certainly a lot more common in prokaryotes, but it's also quite well-understood and is not the dominant means by which genes replicate in those species. They display conventional inheritance that roughly resembles that of eukaryotes.

    It's a model system. Like using mice to model asthma, it's not a perfect system because if it were, it wouldn't be a model. The key to using models effectively is to know their limitations and strengths and account for them. As long as parallels exist between model and the thing being modelled then it is valid to an extent. Since we don't possess more accurate models which can still give us a mean generation time comparable to prokaryotes, the model is very much valid.

    Quote Originally Posted by Darius
    Also, must you really use "evolutionist"? Evolution, the theory that genetic material of a population of organisms changes from one generation to the next, is very solid and used by geneticists every day. We don't call gravity believers gravitists, because that would be stupid.
    Seconded. "Evolutionist" is a term used by creationists to try and create the impression that the theory is dogma rather than science. A rhetorical tactic, as most of their main weapons are.
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  6. #5 Re: Prokaryotic Evolution not a model for Eukaryotic Evoluti 
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by KALSTER
    Kind of like people that believe in genetics are called geneticists?
    Except that the term evolutionist was hijacked by creationists to create a parallel with their own "ism" and is no longer used by anyone but them. It has become pejorative.
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  7. #6  
    Universal Mind John Galt's Avatar
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    Quote Originally Posted by Darius
    Really? I have not heard of such an argument. Can you give me an example?.
    Woese, Carl R. On the Evolution of Cells PNAS 2002

    Quote Originally Posted by Darius
    Also, must you really use "evolutionist"? .
    Yes. Because this thread is ultimately about using weak arguments to counter the claims of creationists. They routinely call biologists and other scientists involved with some aspect of biology 'evolutionists', so the term is appropraite in the context of this thread.

    Quote Originally Posted by Kalster
    The evidence seems to be mounting for inter-species gene transfer and even between organisms from different phylogenetic groups.
    Nevertheless, the scale of transfers for prokaryotes is much higher and one would anticipate the effects are much greater, so using evolution in a simple celled organism to justify the same process in complex, multi celled organisms, simply isn't going to cut it with your average evolutionist.
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  8. #7 Re: Prokaryotic Evolution not a model for Eukaryotic Evoluti 
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    Quote Originally Posted by TheBiologista
    Quote Originally Posted by KALSTER
    Kind of like people that believe in genetics are called geneticists?
    Except that the term evolutionist was hijacked by creationists to create a parallel with their own "ism" and is no longer used by anyone but them. It has become pejorative.
    At the risk of going too far off topic, I propose then that we "take back" the word evolutionist to be used in the proper context. If not, what alternative is there?
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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  9. #8  
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by JohnGalt
    Quote Originally Posted by Kalster
    The evidence seems to be mounting for inter-species gene transfer and even between organisms from different phylogenetic groups.
    Nevertheless, the scale of transfers for prokaryotes is much higher and one would anticipate the effects are much greater, so using evolution in a simple celled organism to justify the same process in complex, multi celled organisms, simply isn't going to cut it with your average evolutionist.
    It serves to counter some specific arguments, such as the assertion that beneficial mutations are not possible or that new genetic information cannot arise by mutation and selection. Prokaryotic models have been used to demonstrate this to be false. Horizontal gene transfer is not difficult spot in such a model, so it can be accounted for.
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  10. #9 Re: Prokaryotic Evolution not a model for Eukaryotic Evoluti 
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by KALSTER
    Quote Originally Posted by TheBiologista
    Quote Originally Posted by KALSTER
    Kind of like people that believe in genetics are called geneticists?
    Except that the term evolutionist was hijacked by creationists to create a parallel with their own "ism" and is no longer used by anyone but them. It has become pejorative.
    At the risk of going too far off topic, I propose then that we "take back" the word evolutionist to be used in the proper context. If not, what alternative is there?
    The words we already use. Evolutionary biologist, evolutionary scientist, evolutionary geneticist... the field is huge so there are many more specific titles that people take. Plus "evolutionist" was more traditionally a moniker for people like Huxley who were essentially activists promoting a new idea. We're well past that.
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  11. #10 Re: Prokaryotic Evolution not a model for Eukaryotic Evoluti 
    Forum Ph.D. Darius's Avatar
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    Quote Originally Posted by KALSTER
    Kind of like people that believe in genetics are called geneticists?
    They're called geneticists because that's their FIELD. There is no FIELD of evolution.

    Quote Originally Posted by John Galt
    Yes. Because this thread is ultimately about using weak arguments to counter the claims of creationists. They routinely call biologists and other scientists involved with some aspect of biology 'evolutionists', so the term is appropraite in the context of this thread.
    Does this not just spread misinformation? Don't stoop to their level. I'll try to see what I can dig up on "Woese, Carl R. On the Evolution of Cells PNAS 2002".
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  12. #11 Re: Prokaryotic Evolution not a model for Eukaryotic Evoluti 
    Universal Mind John Galt's Avatar
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    Quote Originally Posted by Darius
    I'll try to see what I can dig up on "Woese, Carl R. On the Evolution of Cells PNAS 2002".
    The full paper.
    http://www.pnas.org/content/99/13/8742.full.pdf+html
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  13. #12  
    Forum Ph.D. Darius's Avatar
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    Oh, well thanks. You're the helpful one today.
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  14. #13  
    Administrator KALSTER's Avatar
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    The words we already use. Evolutionary biologist, evolutionary scientist, evolutionary geneticist... the field is huge so there are many more specific titles that people take. Plus "evolutionist" was more traditionally a moniker for people like Huxley who were essentially activists promoting a new idea. We're well past that.
    Oh yeah...

    *faceplant* are you stupid? They're called geneticists because that's their FIELD. There is no FIELD of evolution.
    Refer to my red face above, although my response would be different if you were to talk to me like this face to face.

    Nevertheless, the scale of transfers for prokaryotes is much higher and one would anticipate the effects are much greater, so using evolution in a simple celled organism to justify the same process in complex, multi celled organisms, simply isn't going to cut it with your average evolutionist.
    Biologista makes a good point. In my experience of debating with creationists (which is entirely confined to this forum) and from other debates that I have seen, creationists don't go into details much, can't look at the whole picture or can't play out a scenario in their minds to a logical conclusion. They would typically say that the beetle is still a beetle and the slug is still a slug. So I am not sure whether arguments like these would make any difference, even if you were to be able to convince them of them.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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  15. #14  
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    Discussing, for example, the spread of a resistance plasmid throughout a bacterial population (an instance of HGT) can be useful to a creationist who's willing to learn. It illustrates some basic concepts that are critical to understanding evolution. The more stable parts of the bacterial genome are subject to many of the same mechanisms of evolution as germline cells in complex metazoans and are still dominated by neutral processes combined with purifying selection. So, I don't think that using prokaryotes is problematic at all.

    I do think that the idea of simple point mutations and a bit of natural selection or drift is what really gets creationists (or their debators) in to trouble. You take a simple organism and discuss one of the simplest evolutionary mechanisms going and then run in to trouble when you scale it up to large, slowly evolving animals with a long generation time.

    There's a whole bunch of stuff that should be being discussed more in such debates: the duplication of genes, parts of genomes or even of entire genomes; gene loss and loss of genome real estate; horizontal gene transfer; endosymbiosis; mobile element invasion and cooption etc etc.
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  16. #15 Re: Prokaryotic Evolution not a model for Eukaryotic Evoluti 
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    Quote Originally Posted by John Galt
    The prevalence of horizontal gene transfer amongst prokaryotes makes it irrelevant as evidence for evolution amongst eukaryotes. Nevertheless evolutionists routinely use this on their debates with creationists. It is a weak flawed argument and should be abandoned forthwith.

    Discuss.
    Horizontal gene transfer occurs amongst eucaryotes, via retro-viral infection (and other mecahnisms, it seems!).
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  17. #16  
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    Models are always not exactly the same as what they model.

    In that sense Prokaryotes are therefore the perfect model for Eukaryote evolution when contemplating the argument in the opening post.
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  18. #17 Re: Prokaryotic Evolution not a model for Eukaryotic Evoluti 
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by free radical
    Quote Originally Posted by John Galt
    The prevalence of horizontal gene transfer amongst prokaryotes makes it irrelevant as evidence for evolution amongst eukaryotes. Nevertheless evolutionists routinely use this on their debates with creationists. It is a weak flawed argument and should be abandoned forthwith.

    Discuss.
    Horizontal gene transfer occurs amongst eucaryotes, via retro-viral infection (and other mecahnisms, it seems!).
    It happens but is much less relevant. The relative frequency of successful HGT events is orders of magnitude lower for eukaryotes for many reasons. Nuclear membrane in single celled eukaryotes and for the multicellular eukaryotes, just being multicellular means that only transfection of germ cells or gametes results in something inheritable. Any other of the trillions of cells in the organism is a dead end.
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  19. #18  
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    Is this a reason to not use the argument "routinely" (whether that is an accurate characterisation in the opening post or not) when debating evolution?
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  20. #19  
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    Quote Originally Posted by free radical
    Is this a reason to not use the argument "routinely" (whether that is an accurate characterisation in the opening post or not) when debating evolution?
    Well not really. Prokaryotes make a good model for HGT but normal inheritance, mutation, natural selection and all the other fun evolutionary stuff are still relevant and more easily modelled in prokaryotes. Ease of culture and high mean generation time are big factors in that.
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  21. #20  
    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    Quote Originally Posted by TheBiologista
    Quote Originally Posted by free radical
    Is this a reason to not use the argument "routinely" (whether that is an accurate characterisation in the opening post or not) when debating evolution?
    Well not really. Prokaryotes make a good model for HGT but normal inheritance, mutation, natural selection and all the other fun evolutionary stuff are still relevant and more easily modelled in prokaryotes. Ease of culture and high mean generation time are big factors in that.
    Exactly, the prevalence of HGT requires us to look at the genomes of bacteria and archaea with a more attentive eye, but it does not make prokaryotic evolution irrelevant to eukaryotic evolution.

    Genes transferred by HGT are still subject to natural selection, some plasmids are almost viral in that they spread from bacterium to bacterium with no benefit to the transformed individual, most will either improve or harm the fitness of the transformed bacterium. New mutations still occur and they are subject to natural selection under a different context.

    Moreover, there are still conserved genes as well that are not subject to HGT.

    I love Woese by the way, 3 domains ftw.
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