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Old 06-22-2002, 04:24 PM   #11
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Vorkosigan: Type "Venus Flytrap convergent evolution" and watch the sites tumble out.
I did...using "Google". And seven sites "tumbled out", two or three of them repeats of the others. None really addressed how the Flytrap might have got its start.

Quote:
Vorkosigan: It cannot subsist on photosynthesis; that is why I advised you to run a search.
Well, that's not what one of the primary information sites on the "Venus Flytrap" said (I can't remember which one said it, but it was some kind of Internet science "encyclopedia" or what-not...probably on the level of an introductory college biology textbook). Of course, perhaps they forgot to add, "...can subsist on photosynthesis alone, as long as there is plenty of nitrogen in the soil", or something.

Quote:
Vorkosigan: As for the Design hypothesis, that is laughable. It was clever of the Designer to put the plant in a nitrogen-poor soil, but make it so that it still needs nitrogen to live.
Well, shoot, why would that not be an indication of "Design", especially if the Designer made a way for the plant to obtain nitrogen when it was located in nitrogen-poor soil? But please, there's no need to describe the "Design hypothesis" as "laughable" - we are trying to have a civil, reasoned discussion, aren't we? Or maybe we're not?

Quote:
Me: Why would evolution be so "sensitive" as to "select" the Venus Flytrap mechanism, yet be so "insensitive" as to fail to "select out" the poor, and seemingly sometimes fatal, blood circulation "design" in mammalian fetuses?

Vorkosigan: Your use of the term "sensitive" is entirely subjective. Why is one more "sensitive" than the other?
That's what I was asking.

Quote:
Vorkosigan: The reason the poor fetal circulatory system does not get selected out is that its benefits outweigh its costs.
That doesn't address my question, actually. The implied "comparison" is to "fetal circulatory systems" which AREN'T so "poorly designed" - why didn't evolution produce and select those "systems", but instead "stuck with" the sometimes fatal system? My point was that evolution was apparently so "sensitive" to various "survival advantages" that it was capable (supposedly) of "selecting" early, very simple, stages of the Venus Flytrap (unless evolutionists are proposing that the Venus Flytrap essentially "poofed" into existence when an unusual series of random mutations just happened to all occur at the same time in a particular seed/plant), when those "early, very simple stages" would have added very, very little "survival advantage".

Along these lines, why would evolution be so "selective" as to be able to "select" the hooks in bird feathers, yet not "select out" something which is apparently sometimes fatal (the fetal circulation system I earlier mentioned)? Surely you aren't going to claim that evolution couldn't "detect" a higher proportion of deaths in certain fetuses, and that this should not have resulted in the elimination of such features? With all the "random mutating" and "convergent evolution" supposedly going on, and all the "competition for scarce resources", why didn't mammals evolve a more efficient and less deadly fetal circulatory system?

Quote:
Vorkosigan: Evolution doesn't produce perfect systems, it produces ad hoc systems that work. Like the Venus Fly-Trap, whose trap is made from a leaf.
"Ad hoc systems that work". I like that. Cells, DNA, the human brain, etcetera. "Ad hoc systems that work". Would that NASA engineers could take this to heart.

In Christ,

Douglas

[ June 22, 2002: Message edited by: Douglas J. Bender ]</p>
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Old 06-22-2002, 04:50 PM   #12
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KCdgw,

Quote:
I posted the title of a paper on the evolution of carnivorous plants on ARN for Douglas, but I guess he thought I was joking:
Albert VA, Williams SE, and Chase MW (1992). Carnivorous Plants: Phylogeny and Structural Evolution. Science 257: 1491-1495 .
No, I tried to find that article on the Internet, and couldn't find it. I'm not that efficient at researching on the Internet, actually (kind of a "broad brush stroke" kind of attack). Perhaps you could be of some help, and provide a link?

In Christ,

Douglas
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Old 06-22-2002, 04:59 PM   #13
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Originally posted by Douglas J. Bender:
<strong>KCdgw,



No, I tried to find that article on the Internet, and couldn't find it. I'm not that efficient at researching on the Internet, actually (kind of a "broad brush stroke" kind of attack). Perhaps you could be of some help, and provide a link?

In Christ,

Douglas</strong>
Hi Douglas,

Unfortunately,there is no link, and as I said, I hadn't read the article either, but that it might be an interesting place to start.

So I gave a proposed scenario of my own here

Cheers,

KC
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Old 06-22-2002, 05:12 PM   #14
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scigirl: I like the title of this thread, Douglas.
Thank you. I took hours trying to think up a catchy but humorous title. Then, I said, "These are all worthless", and chose that one.

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scigirl: I still say - if there was a divine creator of life on this earth, it sure as hell isn't the Christian God.
Please. You know that saying things like "sure as hell" offends me, my being a (true) Christian and all. Couldn't you just say, "it sure as thesis isn't the Christian God"?

Quote:
scigirl: Nope, the god (goddess?) who made life on this earth does not believe in good and evil, likes homosexuality, and has a very strange sense of humor (as evidenced by venus fly traps, hippos, etc). Doesn't sound like good ol' Yahway to me.
And what makes you think that the God Who made life on this Earth "does not believe in good and evil", and "likes homosexuality"? And after all the discussion we've had, do you mean to tell me you still don't realize that the Bible indicates that mankind fell into sin, that this resulted in the Earth being "cursed", and that sin and death, and Satan, now "rule" this Earth (to a degree, which would take a heavy-duty theological discussion to detail).




Quote:
scigirl: BTW Douglas - any comments on my last two replies to you here regarding the human/chimp chromosome fusion event?
No. But only because I'm very tired, and trying to wrap up my responses here on this thread. Hopefully, I'll feel more energetic and motivated tomorrow, though I'm beginning to get disinterested in the whole Internet thing (every part of it, actually).

[quote]Me: However, if it was clear that there was no known natural process which could reasonably account for your existence, then either you don't exist, or you were "supernaturally" created.

scigirl: Oh, but I think you said it yourself quite precisely in another thread:

Douglas (from the "New Debate with Douglas Thread):
[...]we KNOW that human beings are created through two "parents", and have never observed human beings being "miraculously created" out of "thin air".


I should have added, to the above, that, "...however, if we have solid testimony as to the origins of humans, and that the orinal humans were 'miraculously created' out of 'thick dust', but humans are now 'reproduced' naturally, then we can be confident in that testimony, especially if it comes from God".

Quote:
But seriously though, that line of reasoning is baloney. Before we understood gravity, does that mean that God was moving the planets around the sun with his hands?
Maybe; maybe not. Maybe the craters on the Moon are His fingerprints.

Quote:
scigirl: Just because we don't have a natural explanation for something yet, does in fact NOT automatically mean that there isn't one.
"Does NOT, in fact, automatically mean that there isn't one." Right. But I wasn't intending to use that "universal" of an argument - I should have said:
Quote:
...if it was clear that there was no natural process which could reasonably account for your existence....
Of course, I thought evolutionists have claimed to have it all pretty much figured out, so that if it could be shown "clearly" that evolution and normal "reproduction" could not have resulted in whomever it was I was speaking to, then either they don't exist, or they were supernaturally created (or evolutionists are still completely in the dark about origins).
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Old 06-22-2002, 05:31 PM   #15
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Quote:
Originally posted by Douglas J. Bender:
KCdgw,

No, I tried to find that article on the Internet, and couldn't find it. I'm not that efficient at researching on the Internet, actually (kind of a "broad brush stroke" kind of attack). Perhaps you could be of some help, and provide a link?

In Christ,

Douglas
Hey Doug,

The article was in a journal, actually:

Quote:
Science 1992 Sep 11;257(5076):1491-5

Carnivorous plants: phylogeny and structural evolution.

Albert VA, Williams SE, Chase MW.


The carnivorous habit in flowering plants represents a grade of structural organization. Different morphological features associated with the attraction, trapping, and digestion of prey characterize a diversity of specialized forms, including the familiar pitcher and flypaper traps. Phylogenetic analysis of nucleotide sequence data from the plastic rbcL gene indicates that both carnivory and stereotyped trap forms have arisen independently in different lineages of angiosperms. Furthermore, these results demonstrate that flypaper traps share close common ancestry with all other trap forms. Recognition of these patterns of diversification may provide ideal, naturally occurring systems for studies of developmental processes underlying macromorphological evolution in angiosperms.
The link is <a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=152340 8&dopt=Abstract" target="_blank">here at PubMed</a>.

And in fact, it was just the first article in a series of them during the 1990's that have greatly clarified the relationships between the various carnivorous plants (so actually, a comment by a previous poster that the molecular studies hadn't been done yet isn't quite accurate).

You'll get some if you click on "<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Display&dopt=pubmed_pubme d&from_uid=1523408" target="_blank">Related articles</a>" in pubmed, although you have to dig through a lot of less relevant stuff.

But you probably don't want to mess with the library. Online, the only two good resources on the evolution of carnivorous plants, and the Venus Flytrap specifically, are:

1) This article:

<a href="http://www.steve.gb.com/vegetable_empire/index.html" target="_blank">http://www.steve.gb.com/vegetable_empire/index.html</a>

...or rather, this subarticle specifically on carnivorous plants, "<a href="http://www.steve.gb.com/vegetable_empire/murder.html" target="_blank">When plants kill</a>".

2) Various threads on the talk.origins usenet newsgroup, which you can find by searching the google archives. E.g. <a href="http://groups.google.com/groups?q=%22carnivorous+plant%22+evolution+group:t alk.origins&hl=en&lr=&ie=UTF-8&scoring=d" target="_blank">look at these threads</a>.

I need to write up a long and horrendously detailed article on how the evolution of traps like the Venus Flytrap, which puts Behe's mousetrap to shame, constitute yet another refutation of the IC argument. But it will take some time. For now I'll <a href="http://groups.google.com/groups?q=%22carnivorous+plant%22+evolution+group:t alk.origins&hl=en&lr=&ie=UTF-8&scoring=d&selm=74227462.0206072200.70c30029%40po sting.google.com&rnum=1" target="_blank">quote my own t.o. post</a>:

(with some added formatting and pics)

Quote:
Yet another reason that Behe's argument is flawed is the "removal of scaffolding" objection -- e.g., a system needs a "part" for function at a certain time, but then additional "parts" get added, and one or more earlier-necessary parts gets discarded -- e.g., glue in Venus' flytraps (and most pitchers BTW). Can you think of a way to evolve directly from a plain-old-leaf to a trigger-hair equipped venus' flytrap? No -- but if you look at close relatives, you discover that (a) they are sticky flypaper traps, and (b) they have varying degrees of movement from nil to rather fast; we can then see that once a trap specializes on movement to an extreme degree, then the "glue" become superfluous and is lost -- or on the analogy, the scaffolding has been removed from the arch.

Here are a coupla Droseras next to a coupla Venus Flytrap pics:









(a young VFT)



(Behe even says in Darwin's Black Box that glue traps are not IC, but clearly a Venus flytrap is at least as impressive as a snap-mousetrap; ergo, IC can evolve and therefore identifying IC doesn't imply ID)

[...]

As I mentioned, recent molecular evidence not only confirms the sisterhood of the carnivorous plant snaptraps (Dionaea and Aldrovanda) with glue traps (Drosera; there are also more distantly related nonmotile sticky-trap carnivorous genera). This was expected; however somewhat less expected was the sisterhood of most pitcher-plant carnivorous plants to sticky traps also.

E.g.:

Nepenthes (vine pitcher trap) sister to numerous sticky genera in the Drosera & relatives

Sarracenia (& related pitcher Darlingtonia) closely related to Roridula (a "pseudocarnivore" -- stickiness is probably mostly defensive in this genus but Roridula is clearly preadapted to carnivory & could easily have extinct gluetrap relatives)

Utricularia (active bladder trap) & Genlisea ("lobster-pot" trap) -- both of these are probably miniature pitchers specialized on tiny soil critters -- are sister to Pinguicula, a glue trap.

This leaves just 2 groups of pitchers not closely related to known sticky plants: Cephalotus, which is just one rare species in a monotypic genus in Australia anyhow (sticky relatives presumed extinct; and even here I think that related plants have odd nutritional habits generally, a common trend in near relatives of carnvirous plants); and the few species (2 known, maybe a few others suspected) of carnivorous bromeliads. Bromeliads are preadapted to
form pitchers (e.g. the numerous "tank bromeliad" species collect water & detritus already) so a sticky-leaf intermediate is not necessary to hypothesize here.

Pinguicula gives us an idea of how a sticky trap could begin to convert to a pitcher trap:



it has a somewhat broad, flat leaf that naturally "dishes" somewhat, and when a bug is captured it begins to grow around the bug to dish more, preventing the escape of the nice
tasty digested bug juices.

A not-very-advanced true pitcher, on the other hand:



A more advanced pitcher, Darlingtonia:

(from "<a href="http://bss.sfsu.edu/geog/bholzman/courses/Fall01%20projects/pitcherplant.htm" target="_blank">The Biogeography of the California Pitcher Plant</a>", an actual useful online class essay)


Sources:

Ellison, A. M. and Gotelli, N. J. (2001). "Evolutionary ecology of carnivorous plants." Trends in Ecology & Evolution, V16(N11): 623-629. Link: <a href="http://www.sciencedirect.com/science/journal/01695347" target="_blank">see here</a>

Quote: "Sequence data also provide insights into the origins and evolution of carnivorous structures, with some surprises. Although
carnivory has long been considered to be a highly derived character 9, within the carnivorous clade of the Caryophyllidae (Fig. 2) carnivory is a basal trait within the Droseraceae (flypaper traps; Fig. 1a) that is retained in the Nepenthaceae (as pitfall traps; Fig. 1b), but is
lost in the derived Ancistrocladaceae and Dioncophyllaceae (except in Triphyophyllum peltatum) 10. In other unrelated families, more elaborate carnivorous structures, such as bladders and pitfalls, also evolved from ancestors possessing simpler, flypaper type traps [i.e. Roridula (flypaper) – Sarraceniaceae (pitfall; Fig. 1d); Drosera (flypaper) – Nepenthes (pitfall); Byblis (flypaper; Fig. 1c); and the butterworts Pinguicula (flypaper; Fig. 1e) – Utricularia (bladder; Fig. 1f)] 3."

Meimberg, H., Dittrich, P., Bringmann, G., Schlauer, J. and Heubl, G. (2000). "Molecular Phylogeny of Caryophyllidae s.l. Based on MatK
Sequences with Special Emphasis on Carnivorous Taxa." Plant Biology, 2(2): 218-228. Link: <a href="http://www.thieme-connect.com/BASScgi/4?FID=Start&URL=JournalTOC&Level=Journal&JournalKe y=67" target="_blank">see here</a>
Nic
[edit to add figures, which came from here:
<a href="http://www.sarracenia.com/" target="_blank">http://www.sarracenia.com/</a> , a great website for pics and general CP info]

[ June 22, 2002: Message edited by: Nic Tamzek ]

[ June 22, 2002: Message edited by: Nic Tamzek ]</p>
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Old 06-22-2002, 06:24 PM   #16
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so actually, a comment by a previous poster that the molecular studies hadn't been done yet isn't quite accurate).

I figured, if I made a dumb comment like that, somebody would come along to show me up....

That was a wonderful post! I hope you stick around to spread enlightenment. The T.O crowd is definitely a cut above -- does Ted Holden still show up there?

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Old 06-22-2002, 06:49 PM   #17
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"Ad hoc systems that work". I like that. Cells, DNA, the human brain, etcetera. "Ad hoc systems that work". Would that NASA engineers could take this to heart.


I don't know what you've studied about NASA, but NASA systems are extremely ad hoc; like evolution, NASA must work within constraints, in its case, political, budgetary and engineering. The result is often not optimal -- for example, have you looked at the design of the current Int'l Space Station? I'd decribe it, but my knowledge is now out of date -- like bacteria, the ISS mutates every generation.

The human brain is entirely ad hoc. If you were building an intelligent animal from scratch, would you use a chimpanzee as a basis? Would you make it susceptible to strokes and other diseases? Would you design the visual processing system so that it has to flip images from the retina in order to see them properly? Would you limit the language learning period to the first few years of its life? Would you design it so that the left side of the brain controls the right side of the body? I am sure a brain expert could give you many examples of ad hoc approaches in brain design. But these should suffice.

Well, that's not what one of the primary information sites on the "Venus Flytrap" said (I can't remember which one said it, but it was some kind of Internet science "encyclopedia" or what-not...probably on the level of an introductory college biology textbook). Of course, perhaps they forgot to add, "...can subsist on photosynthesis alone, as long as there is plenty of nitrogen in the soil", or something.

That is the case -- as long as there is sufficient nitrogen in the soil, then the plants can use it. But the soils they are usually found in are nitrogen-impaired:

<a href="http://waynesword.palomar.edu/carnivor.htm" target="_blank">http://waynesword.palomar.edu/carnivor.htm</a>
"But why would some insectivorous plants need an additional supply of nitrogen, particularly when they are living in organically-rich bogs? The answer to this question may involve the pH of the water and soil which is too acidic for nitrifying bacteria that convert ammonia from protein decay into nitrite and nitrate ions. This important bacterial process is called nitrification. The nitrite and nitrate ions made available by the bacteria are readily absorbed by the roots of plants. If the nitrification process is impaired, there could actually be a shortage of these nitrite and nitrate ions; hence, the carnivorous plants have evolved a mechanism to obtain a supplemental supply of nitrogen."


<a href="http://www.uvm.edu/news/?Page=News&storyID=2656" target="_blank">Here is a story on how nitrogen is related to plant size</a>

I think the point is clear -- carnivorous plants live in nitrogen--poor environments and have evolved their strategy to enhance their nitrogen intake. They retain the ability to obtain nitrogen from the soil, and to photosynthesize. Just like other plants. That strong hints at common ancestry.

Well, shoot, why would that not be an indication of "Design", especially if the Designer made a way for the plant to obtain nitrogen when it was located in nitrogen-poor soil?

This is why nobody uses ID in science, Doug. No matter what the situation, an auxiliary hypothesis like this can explain it. Why make a plant for nitrogen--poor soils, and then make it require nitrogen to live?. Obviously, the whole problem can be eliminated with the right design that eliminates the need for nitrogen.

Of course, other solutions exist -- some plants take nitrogen from the air, while others fix their own. Why not use those designs? And why reuse the same genes as in all angiosperms? Why build the trap from a modified leaf that only works a couple of times, rather than design a dedicated one that can be re-used? The questions are endless. ID is a bad idea, Doug. It provides no framework for explanation -- it simply says "Things are the way they are because that's the way they are."

But please, there's no need to describe the "Design hypothesis" as "laughable" - we are trying to have a civil, reasoned discussion, aren't we?

I apologize for using the term "laughable" to describe an idea that was decisively refuted over two centuries ago, and went out of science over 150 years ago, and owes its current vogue to a the resurgent political clout of the Christian Right.

...when those "early, very simple stages" would have added very, very little "survival advantage".

This is a profound misunderstanding of how evolution works. Evolution is a compound interest problem, Doug, where small advantages pay huge dividends over time. Let's suppose you invest a million at 5% and I invest a million at 5.01% annually. In fifty thousand years, I will have many times more money than you.

I know you're good at math; run the numbers for this:

There are two groups in a population. Group A reproduces at a 1% higher rate than Group B. How many generations before A constitutes 99% of the population? See how those tiny advantages add up?

Those tiny advantages add up, iterated again and again after each generation. What good is 5% of a wing? Precisely 5% better than no wing at all. That's why there are fully winged animals, like plovers and dragonflies, and animals that can glide, like squirrels and snakes, and animals that obtain a slight lift and stabilization from having a small bit of wing.

..why didn't mammals evolve a more efficient and less deadly fetal circulatory system?

Because the one they have now works fine enough. Evolution doesn't produce the most efficient systems for performing something, it produces ones that work. "Efficiency" is a value that has no meaning, except with respect to some arbitrary engineering standard that humans create. Evolution, like NASA, is a constraint-driven process. If more resources go into one system, fewer resources are available for another.

Further, the system may not be able to become more efficient; the necessary material and genetic basis might not be there.

Finally, how do you know the fetal circulatory system is not becoming more efficient?

Of course, it is your claim that this system that kills a certain portion of its users was in fact Intelligently Designed.

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Old 06-23-2002, 03:23 AM   #18
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Scigirl sez:
"I still say - if there was a divine creator of life on this earth, it sure as hell isn't the Christian God. Nope, the god (goddess?) who made life on this earth does not believe in good and evil, likes homosexuality, and has a very strange sense of humor (as evidenced by venus fly traps, hippos, etc). Doesn't sound like good ol' Yahway to me."

'Twas Quetzacoatl, obviously.

Now that that's cleared up, I'd like to thank Nick Tamzek for a mavelous post! Great pics, also!

I live not too far from flytrap country. Here in NC, this plant is protected by law, with a ridged quota for licensed collectors.

Plant fosslis other than trees, particulary small, soft plants that live in or near swamps, are not easy to come by. But, it is not hard to see where a 'sensitive' leaf might evolve into a carnivorus one, as has been mentioned above. I say "might" because this is another species that has an incomplete record. Nobody knows. Yet.

For some reason, I find the sundews, which have turned the sticky, movable leaf-trap into an art form, more interesting than the flytraps. And pitchers are just downright pretty.

doov

[ June 23, 2002: Message edited by: Duvenoy ]</p>
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Old 06-23-2002, 05:51 AM   #19
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Quote:
Originally posted by Vorkosigan:
<strong>so actually, a comment by a previous poster that the molecular studies hadn't been done yet isn't quite accurate).

I figured, if I made a dumb comment like that, somebody would come along to show me up....

That was a wonderful post! I hope you stick around to spread enlightenment. The T.O crowd is definitely a cut above -- does Ted Holden still show up there?

Vorkosigan</strong>
Nic rules.

Cheers,

KC
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Old 06-25-2002, 06:36 AM   #20
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I've been out of town, otherwise I would have addressed this. As it is, it seems to be pretty well addressed by others. Perhaps when I have some more time I'll be able to add something that hasn't already been discussed, but for now here's a question:

Since the only substantial difference between the venus flytrap and its closest relatives--e.g., sundews--is the speed with which the trap closes (we already have the sensory hairs, the digestive juices, and the closing mechanism, albeit a slow one) do creationists deny that this speed is something that could have evolved? In other words, would the evolution from something like a sundew to something like a venus flytrap be "macroevolution", would it involve "more information", and most importantly, would it imply the evolution of a new "kind" of plant?
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