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The flagellum was an ancestor of the T3SS?

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  • The flagellum was an ancestor of the T3SS?

    For various reasons, it appears that the flagellum was an ancestor of the type-3 secretory system (T3SS), not the other way around.

    Source: Evolution News

    [I]t’s doubtful that the T3SS is useful at all in explaining the origin of the flagellum. The injectisome is found in a small subset of gram-negative bacteria that have a symbiotic or parasitic association with eukaryotes. Since eukaryotes evolved over a billion years after bacteria, this suggests that the injectisome arose after eukaryotes. However, flagella are found across the range of bacteria, and the need for chemotaxis and motility (i.e., using the flagellum to find food) precede the need for parasitism. In other words, we’d expect that the flagellum long predates the injectisome. And indeed, given the narrow distribution of injectisome-bearing bacteria, and the very wide distribution of bacteria with flagella, parsimony suggests the flagellum long predates injectisome rather than the reverse. As one paper observes:

    “Based on patchy taxonomic distribution of the T3SS compared to that of the flagellum, widespread in bacterial phyla, previous phylogenetic analyses proposed that T3SS derived from a flagellar ancestor and spread through lateral gene transfers.”

    (Sophie S. Abby and Eduardo P. C. Rocha, “An Evolutionary Analysis of the Type III Secretion System” (2012).)

    Likewise, New Scientist reported:

    “One fact in favour of the flagellum-first view is that bacteria would have needed propulsion before they needed T3SSs, which are used to attack cells that evolved later than bacteria. Also, flagella are found in a more diverse range of bacterial species than T3SSs. ‘The most parsimonious explanation is that the T3SS arose later,’ says biochemist Howard Ochman at the University of Arizona in Tucson.”

    Now under normal evolutionary reasoning, one would take this kind of phylogenetic evidence to indicate that the flagellum long predates the T3SS, and that the T3SS is in no way a precursor (or closely related to a precursor) of the flagellum.

    Source

    © Copyright Original Source


    In fact, a paper in "Cell" argues that the T3SS and the flagellum are not ancestral:

    Source: Cell, quoted in Evolution News

    Although the flagellum has been proposed to be the evolutionary ancestor of T3SSs, the structure of the flagellar motor is significantly different from that of the T3SS basal body.

    © Copyright Original Source



    Evolution News then goes on to quote an article in "Science" that proposes that the last common bacterial ancestor had a flagellum:

    Source: Science

    Using this information, the authors reconstructed the eubacterial ancestor, identifying that this organism likely had a double-membrane cell envelope, flagellum-mediated motility, antiphage defense mechanisms, and diverse metabolic pathways.

    Source

    © Copyright Original Source



    Blessings,
    Lee
    Last edited by lee_merrill; 05-15-2021, 03:21 PM.
    "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

  • #2
    Same old foolishness from a non-science reference.
    Glendower: I can call spirits from the vasty deep.
    Hotspur: Why, so can I, or so can any man;
    But will they come when you do call for them? Shakespeareís Henry IV, Part 1, Act III:

    go with the flow the river knows . . .

    Frank

    I do not know, therefore everything is in pencil.

    Comment


    • #3
      TL;DR: Scientists disagree on what some evidence indicates. Lee wants to believe that their disagreement is a sign that all of modern biology is false, and its falsity is evidence of God.

      Assuming that a the chronically unreliable source he's quoting is accurately relaying the details of the disagreement, which is far from guaranteed.


      Hey Lee, what's up with that shopping mall located inside the region once enclosed by Babylon's walls?
      "Any sufficiently advanced stupidity is indistinguishable from trolling."

      Comment


      • #4
        Originally posted by TheLurch View Post
        TL;DR: Scientists disagree on what some evidence indicates. Lee wants to believe that their disagreement is a sign that all of modern biology is false, and its falsity is evidence of God.

        Assuming that a the chronically unreliable source he's quoting is accurately relaying the details of the disagreement, which is far from guaranteed.


        Hey Lee, what's up with that shopping mall located inside the region once enclosed by Babylon's walls?
        And IIRC all that's necessary to demonstrate something isn't irreducibly complex is to provide a possible pathway for its evolution, not prove that was the pathway.

        I'm always still in trouble again

        "You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
        "Of course, human life begins at fertilization thatís not the argument." --Tassman

        Comment


        • #5
          Originally posted by rogue06 View Post
          And IIRC all that's necessary to demonstrate something isn't irreducibly complex is to provide a possible pathway for its evolution, not prove that was the pathway.
          Yeah, irreducible complexity was fundamentally a logical argument: things with these properties could not evolve, because they could not be selected for. Show a way that it's possible to select for them, and the whole thing falls apart logically - no need to demonstrate that this was the way any specific system evolved.

          I keep meaning to find time to write up a post that tracks the evolution of Behe's arguments over time. He never acknowledges that his critics have a point, but he keeps changing his arguments in response to criticisms all the same.
          "Any sufficiently advanced stupidity is indistinguishable from trolling."

          Comment


          • #6
            Originally posted by TheLurch View Post
            Yeah, irreducible complexity was fundamentally a logical argument: things with these properties could not evolve, because they could not be selected for. Show a way that it's possible to select for them, and the whole thing falls apart logically - no need to demonstrate that this was the way any specific system evolved.

            I keep meaning to find time to write up a post that tracks the evolution of Behe's arguments over time. He never acknowledges that his critics have a point, but he keeps changing his arguments in response to criticisms all the same.
            So, if I understand you correctly, what you are saying here is that over time Behe's arguments have themselves evolved.

            I'm always still in trouble again

            "You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
            "Of course, human life begins at fertilization thatís not the argument." --Tassman

            Comment


            • #7
              Originally posted by rogue06 View Post
              So, if I understand you correctly, what you are saying here is that over time Behe's arguments have themselves evolved.
              It seems to be a mixture of lethal selection and drift, yes.
              "Any sufficiently advanced stupidity is indistinguishable from trolling."

              Comment


              • #8
                Originally posted by TheLurch View Post
                TL;DR: Scientists disagree on what some evidence indicates. Lee wants to believe that their disagreement is a sign that all of modern biology is false, and its falsity is evidence of God.
                In all fairness, that seems to be somewhat 'biased'. Surely Lee can believe in the rest of the central tenets of modern biology aside from evolution itself? The old origins versus operational science issue.

                Comment


                • #9
                  Originally posted by Seeker View Post
                  In all fairness, that seems to be somewhat 'biased'. Surely Lee can believe in the rest of the central tenets of modern biology aside from evolution itself? The old origins versus operational science issue.
                  The "origins vs. operational science" thing is a non issue inflated to faux significance by people who don't have any better arguments to rely on.

                  And you think you can neatly separate out evolution from something practical like epidemiology? Tell that to the people tracking SARS variants.
                  "Any sufficiently advanced stupidity is indistinguishable from trolling."

                  Comment


                  • #10
                    Originally posted by Seeker View Post

                    In all fairness, that seems to be somewhat 'biased'. Surely Lee can believe in the rest of the central tenets of modern biology aside from evolution itself? The old origins versus operational science issue.
                    Not to sound trite, but nearly 50 years ago when the famous geneticists and biologist Theodosius Dobzhansky remarked that "nothing in biology makes sense except in the light of evolution" he was spot on, and that descriptor is even more true today as the evidence in support of it continues to amass literally on a daily basis. Without it we have nothing but a huge mound of data with little way of making sense of it all with biology back to the days of nothing but collecting and sorting.

                    Dobzhansky wrote an essay with that quote being its title that was published in 1973: "Nothing in Biology Makes Sense Except in the Light of Evolution
                    Last edited by rogue06; 05-17-2021, 07:51 PM.

                    I'm always still in trouble again

                    "You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
                    "Of course, human life begins at fertilization thatís not the argument." --Tassman

                    Comment


                    • #11
                      Originally posted by TheLurch View Post
                      TL;DR: Scientists disagree on what some evidence indicates. Lee wants to believe that their disagreement is a sign that all of modern biology is false, and its falsity is evidence of God.
                      Here I'm just disputing that the flagellum is derived from the T3SS.

                      Assuming that a the chronically unreliable source he's quoting is accurately relaying the details of the disagreement, which is far from guaranteed.
                      It's pretty clear that the T3SS came after flagella, though!

                      Hey Lee, what's up with that shopping mall located inside the region once enclosed by Babylon's walls?
                      I disagree with where you place the walls, but let's assume you are right! A few buildings would not be considered rebuilding Babylon, by any stretch of the imagination. That is not what Saddam Hussein set out to do.

                      Blessings,
                      Lee
                      "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

                      Comment


                      • #12
                        Originally posted by Seeker View Post
                        In all fairness, that seems to be somewhat 'biased'. Surely Lee can believe in the rest of the central tenets of modern biology aside from evolution itself? The old origins versus operational science issue.
                        I certainly don't believe all of modern biology is false! And I do believe (along with Behe) that evolution can do some things, the question is where is the limit of what evolution can be expected to do?

                        Blessings,
                        Lee
                        "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

                        Comment


                        • #13
                          Originally posted by lee_merrill View Post
                          Here I'm just disputing that the flagellum is derived from the T3SS.
                          Using a completely unreliable source, that's arguing about papers that are roughly a decade old.
                          "Any sufficiently advanced stupidity is indistinguishable from trolling."

                          Comment


                          • #14
                            Originally posted by TheLurch View Post
                            Using a completely unreliable source, that's arguing about papers that are roughly a decade old.
                            Do you disagree that the T3SS was and is attacking eukaryotes? That's one of the main points being made.

                            Blessings,
                            Lee
                            "What I pray of you is, to keep your eye upon Him, for that is everything. Do you say, 'How am I to keep my eye on Him?' I reply, keep your eye off everything else, and you will soon see Him. All depends on the eye of faith being kept on Him. How simple it is!" (J.B. Stoney)

                            Comment


                            • #15
                              Originally posted by lee_merrill View Post
                              Do you disagree that the T3SS was and is attacking eukaryotes? That's one of the main points being made.
                              Because the source is completely unreliable and the references it cites are so badly out of date, there's no way form me to make an informed judgement without doing the research myself, and that's just not worth the amount of time it would take.

                              What does strike me as interesting here is that, if the flagella were as important to intelligent design as its advocates make it out to be, you might think that some of the "scientists" at the Discovery Institute would do some research on the topic. Maybe publish a paper within the last decade or something. But nope, they're either incapable of performing actual research, or just can't be bothered.

                              What should we infer from that?
                              "Any sufficiently advanced stupidity is indistinguishable from trolling."

                              Comment

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