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Author | Topic: Evolution of Nepenthes pitcher plants. | |||||||||||||||||||||||
Tupinambis Junior Member (Idle past 4655 days) Posts: 18 Joined: |
The evolution of carnivorous plants is one topic in particular which befuddles me. Modern genetic evidence indicates that the Venus Fly Trap and all of the Old-World pitcher plants (except Cephalotus, which is a completely separate lineage) share a common ancestor with the Sundews and probably originated from ancestors which would be considered sundews by modern definition.
I can see how a Venus Flytrap may have evolved from a sundew; they look very similar at first glance too. I have my own ideas on how exactly the "bear trap" first appeared, but that's not the topic. I just honestly cannot imagine what kind of processes would have been needed to go from a flypaper trap to a pitcher. Does anyone here have any better insight than I do? This one has been giving me a hard time.
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Admin Director Posts: 12995 From: EvC Forum Joined: Member Rating: 2.3 |
Thread copied here from the Evolution of Nepenthes pitcher plants. thread in the Proposed New Topics forum.
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Dr Adequate Member (Idle past 284 days) Posts: 16113 Joined: |
I just honestly cannot imagine what kind of processes would have been needed to go from a flypaper trap to a pitcher. Does anyone here have any better insight than I do? This one has been giving me a hard time. Well, the gross morphology of plants is very flexible. These, for example, are all the same species.
Could you go into more detail as to what is giving you a hard time?
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Tupinambis Junior Member (Idle past 4655 days) Posts: 18 Joined: |
Yes. The transformation from a flypaper trap to a pitcher trap looks to me as if it were an example of a "complete hardware rewiring" (or something like that) that Dr. Dawkins says does not happen in Evolution; the argument used to explain the recurrent laryngeal nerve.
What I'm having trouble seeing is how the intermediate species between a Sundew and a Pitcher plant could not have been considerably worse off than its ancestor and, thus have been eliminated by natural selection before their evolution progressed any further. Under what conditions was it favorable to develop an intermediate form and what would this intermediate form have even looked like? Edited by Tupinambis, : No reason given.
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Dr Adequate Member (Idle past 284 days) Posts: 16113 Joined: |
What I'm having trouble seeing is how the intermediate species between a Sundew and a Pitcher plant could not have been considerably worse off than its ancestor and, thus have been eliminated by natural selection before their evolution progressed any further. Under what conditions was it favorable to develop an intermediate form and what would this intermediate form have even looked like? I'm guessing that you know more about sundews and pitcher plants than I do. I'd stop posting on this thread, except that you've got me kind of interested. Could you supply some pictures and/or diagrams, along the lines of "this is a basal sundew, this is a pitcher plant, this is what an intermediate form would look like and you can see why it wouldn't work"? I looked it up on WP and it says that some pitcher plants are derived from fly-traps rather than directly from basal sundews. I don't know if this is of any use to you because at this point I don't know what would be.
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jar Member (Idle past 394 days) Posts: 34026 From: Texas!! Joined: |
It also seems that the pitcher plant mechanism is found in several different genus. In addition, there are also closing trap plants and just plain sticky dissolve it where it lands plants. The area of carnivorous plants is also one where we don't have a very complete historical record yet but since several different methods (and combination of methods) seem to cross genus I would guess that the differences go back quite a ways.
AbE: If you get a chance, look at Bladderworts. They seem to incorporate many of the transitional features, a hair like trigger that causes a physical reaction in the plant and a fluid container where the actual dissolving and absorption happens. Just remember I am old and the little I know was simply absorbed by hanging around biologists for a couple decades. Edited by jar, : add bladderworts stuff Anyone so limited that they can only spell a word one way is severely handicapped!
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New Cat's Eye Inactive Member |
Wiki has a page on Protocarnivorous Plants that is interesting and gets into what the intermediate forms could be like. For example:
quote:
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Dr Adequate Member (Idle past 284 days) Posts: 16113 Joined: |
Interesting, but I think that that might have worked the other way round from the way that I think that you're thinking.
In any case, the question is about gross morphology.
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Taq Member Posts: 9970 Joined: Member Rating: 5.6 |
From the wiki page: "many sun pitcher plants (Heliamphora) and the cobra lily (Darlingtonia californica) would not be included on a roster of carnivorous plants because they rely on symbiotic bacteria and other organisms to produce the necessary proteolytic enzymes." That seems a bit stringent. By the same definition a ruminant mammal is not a true herbivore because it relies on symbiotic bacteria to supply the enzymes necessary to break down plant matter.
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New Cat's Eye Inactive Member |
Heh, don't humans rely on bacteria in their belly for digestion too?
That seems a bit stringent. By the same definition a ruminant mammal is not a true herbivore because it relies on symbiotic bacteria to supply the enzymes necessary to break down plant matter. Unless herbivory is defined by what you eat as opposed to how you digest it Conversely, it seems they're definining protocarnivorous plants by how they digest what they "eat". Regardless, your point is not lost. Edited by Catholic Scientist, : No reason given.
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Blue Jay Member (Idle past 2697 days) Posts: 2843 From: You couldn't pronounce it with your mouthparts Joined: |
Hi, Tupinambis.
Like Dr Adequate said, plant development allows a lot more deviance from the "norm" than animal development. It isn't all that unusual in plant evolution to see a feature or even an organ switch locations on the plant between closely-related species. But, even without that, I could see a bowl-shaped flytrap easily transitioning over evolutionary time into a pitcher by simply becoming deeper and abandoning the sticky stuff. I could also see curled leaves easily transitioning over evolutionary time into a pitcher. -Bluejay (a.k.a. Mantis, Thylacosmilus) Darwin loves you.
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Tupinambis Junior Member (Idle past 4655 days) Posts: 18 Joined: |
Ahh, now that you described the cupped-leaf process this is now much easier to visualize. All of the other pitcher plants (Cephalotus is again an exception) were formed from rolled up leaves. Not Nepenthes though, which is why I had so much trouble understanding it.
Thank you all for your input!
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