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Evolution of carnivorous plants

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  • Evolution of carnivorous plants

    A nice rather detailed article on how carnivory evolved in plants (several times in fact) through adapting what already exists (cooption): How plants turned predator

    One bit that the article missed, some plants have evolved to trap and digest worms underground: Hungry plant traps worms underground

    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)
    "Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
    "Of course, human life begins at fertilization that’s not the argument." --Tassman

  • #2
    Thanks for the reference.

    I believe that I read before that some carnivory plants may have evolved in nutrient poor environments where they are found like the Venus Fly Trap of the sandy nutrient soils of of the Coastal Plains in North Carolina
    Last edited by shunyadragon; 03-14-2022, 08:42 PM.
    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? Shakespeare’s Henry IV, Part 1, Act III:

    go with the flow the river knows . . .

    Frank

    I do not know, therefore everything is in pencil.

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    • #3
      Originally posted by shunyadragon View Post
      Thanks for the reference.

      I believe that I read before that some carnivory plants may have evolved in nutrient poor environments where they are found like the Venus Fly Trap of the sandy nutrient soils of of the Coastal Plains in North Carolina
      FWIU all carnivorous plants seem to have evolved in nutrient-poor environments. And in the 12 separate times it did evolve it was by co-opting and repurposing the same genes.

      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)
      "Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
      "Of course, human life begins at fertilization that’s not the argument." --Tassman

      Comment


      • #4
        Originally posted by rogue06 View Post
        A nice rather detailed article on how carnivory evolved in plants (several times in fact) through adapting what already exists (cooption): How plants turned predator

        One bit that the article missed, some plants have evolved to trap and digest worms underground: Hungry plant traps worms underground
        Well, there are problems here, the first being the number of times this has supposedly evolved!

        Source: KnowableMagazine

        Quirky though it is, carnivory has evolved repeatedly over the 140 million-plus years that flowering plants have been around. The adaptation arose independently at least 12 times, says Tanya Renner, an evolutionary biologist at Penn State.

        © Copyright Original Source



        Let's say the probability of carnivory evolving is 10%, then it's less than 1% probable that this happened a dozen times.

        Then there is an overstatement here: "how carnivory evolved in plants". I note the following quote:

        Source: KnowableMagazine

        Many features of the carnivorous lifestyle have yet to give up their genetic secrets.

        © Copyright Original Source


        So we don't know how carnivory evolved, we only think we know about 2 features.

        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


        • #5
          Originally posted by lee_merrill View Post
          Well, there are problems here, the first being the number of times this has supposedly evolved!

          Source: KnowableMagazine

          Quirky though it is, carnivory has evolved repeatedly over the 140 million-plus years that flowering plants have been around. The adaptation arose independently at least 12 times, says Tanya Renner, an evolutionary biologist at Penn State.

          © Copyright Original Source



          Let's say the probability of carnivory evolving is 10%, then it's less than 1% probable that this happened a dozen times.
          So, since it evolved at least 12 times, that would suggest that the probability of carnivory evolving over 140 million years is somewhat greater than 10%.

          Isn't math wonderful?

          Comment


          • #6
            Originally posted by lee_merrill View Post
            Well, there are problems here, the first being the number of times this has supposedly evolved!

            Source: KnowableMagazine

            Quirky though it is, carnivory has evolved repeatedly over the 140 million-plus years that flowering plants have been around. The adaptation arose independently at least 12 times, says Tanya Renner, an evolutionary biologist at Penn State.

            © Copyright Original Source



            Let's say the probability of carnivory evolving is 10%, then it's less than 1% probable that this happened a dozen times.

            Then there is an overstatement here: "how carnivory evolved in plants". I note the following quote:

            Source: KnowableMagazine

            Many features of the carnivorous lifestyle have yet to give up their genetic secrets.

            © Copyright Original Source


            So we don't know how carnivory evolved, we only think we know about 2 features.

            Blessings,
            Lee
            More interesting than how many times is in how many different ways that plants developed carnivory. For instance

            ...drown prey in fluid-filled pitchers, immobilize them with adhesive “flypaper” leaves or imprison them in snap-traps and underwater suction traps.

            [...]

            Some, like pitcher plants and many sundews, are passive receivers of prey — albeit with ingenious adaptations such as slippery rims and gluey-tipped hairs that help to secure a meal. Others are more active: Some sundews curl inward, nudging prey into the trap’s stickier center, while a few have an outer ring of fast-moving tentacles that hurl victims to their doom. Most sophisticated of all is the Venus flytrap, Dionaea muscipula, with its sensitive trigger hairs and snap-traps that can distinguish the touch of an insect from a falling raindrop or dead leaf and can judge the size of prey and respond accordingly.


            And yet, despite all these different methods, they all had one thing in common -- a genetic alteration of the enzymes that combat bacteria, allowing them to breakdown and digest insects.

            And the number of times it evolves hardly matters. Eyes -- from simple light receptors to complex ones -- are thought to have evolved up to 40 times in metazoan development, which you, I'm sure, would dismiss as statistically impossible.

            But is it really?

            In 1994, Dan-Erik Nilsson and Susanne Pelger looked into working out a mathematical model on the time needed for a patch of light sensitive cells or photoreceptors covered by a layer of transparent tissue to evolve into a lensed eye resembling those commonly seen in many fish was reached. They found that it would only take roughly 364,000 generations -- which equates to less than half a million years.

            It took roughly 400 steps for the photoreceptor layer and pigment layer to form a retinal pit which continued to deepen until after approximately 1000 steps until it formed into a pin-hole camera eye. After this the lens shape continued evolving and the iris flattened, allowing better focusing, thereby providing improved optical properties.

            In the end, they found that the complete evolution of an eye like those found in a vertebrate or octopus took less than 2000 steps.

            Moreover, Nilsson and Pelger took great pains to deliberately choose very conservative (low), pessimistic assumptions concerning variation, heritability, and selection intensity in their calculations, so in reality it probably would have taken much less time to take place. For instance, they assumed that for every 101 organisms that got a certain mutation which provided them improved vision, 100 without this improvement also survived. This assumes that you are essentially as well off without the improvement in vision as you are with it, which, in the real world, is extremely unlikely.

            For those actually interested the paper can be found here: A pessimistic estimate of the time required for an eye to evolve

            While I'm at it, for an over overview of the fossil evidence for early eye evolution, although from 2008: Early Evolution of the Vertebrate Eye—Fossil Evidence

            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)
            "Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
            "Of course, human life begins at fertilization that’s not the argument." --Tassman

            Comment


            • #7
              Originally posted by Stoic View Post
              So, since it evolved at least 12 times, that would suggest that the probability of carnivory evolving over 140 million years is somewhat greater than 10%.
              Well, that's circular reasoning! Assuming it evolved, it's probable it evolved.

              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


              • #8
                Originally posted by lee_merrill View Post
                Well, that's circular reasoning! Assuming it evolved, it's probable it evolved.
                No, it's not circular, because probability isn't the reason scientists concluded it evolved.

                Comment


                • #9
                  Originally posted by Stoic View Post
                  No, it's not circular, because probability isn't the reason scientists concluded it evolved.
                  Well, I didn't mean a probability calculation, necessarily, maybe use the word "likely" instead of "probably".

                  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


                  • #10
                    Originally posted by rogue06 View Post
                    In the end, they found that the complete evolution of an eye like those found in a vertebrate or octopus took less than 2000 steps.
                    But if the steps are independent, it is indeed remotely unlikely to develop just once! 99%2000 is 1.86 x 10-9.

                    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


                    • #11
                      Originally posted by lee_merrill View Post
                      Well, I didn't mean a probability calculation, necessarily, maybe use the word "likely" instead of "probably".
                      My point is that no one is "assuming" it evolved.

                      Comment


                      • #12
                        Originally posted by lee_merrill View Post
                        But if the steps are independent, it is indeed remotely unlikely to develop just once! 99%2000 is 1.86 x 10-9.

                        Blessings,
                        Lee
                        For whatever reason you left out this part

                        Moreover, Nilsson and Pelger took great pains to deliberately choose very conservative (low), pessimistic assumptions concerning variation, heritability, and selection intensity in their calculations


                        meaning that they made it far more difficult to develop than what we would expect in nature.

                        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)
                        "Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
                        "Of course, human life begins at fertilization that’s not the argument." --Tassman

                        Comment


                        • #13
                          Originally posted by Stoic View Post
                          My point is that no one is "assuming" it evolved.
                          Oh, but I think you are: "since it evolved at least 12 times" (Stoic).

                          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


                          • #14
                            Originally posted by rogue06 View Post

                            For whatever reason you left out this part

                            Moreover, Nilsson and Pelger took great pains to deliberately choose very conservative (low), pessimistic assumptions concerning variation, heritability, and selection intensity in their calculations


                            meaning that they made it far more difficult to develop than what we would expect in nature.
                            Well, I'm saying that a back-of-the-envelope seems to contradict their conclusions. The paper is restricted, so I can't read it for myself.

                            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
                              Oh, but I think you are: "since it evolved at least 12 times" (Stoic).
                              The fact that I said it doesn't make it an assumption. You might as well say that I "assume" that the earth is about 4 1/2 billion years old.

                              If you are curious as to why scientists believe that carnivory in plants has evolved at least 12 times, you can start with this source. (It only says at least ten times, but it's a little out of date.)

                              The eleventh is described here (though the authors were only aware of nine previous examples at the time of writing).

                              The twelfth is described here.

                              If I was a betting man, I'd put my money on them eventually finding more.

                              Comment

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