Carnivorous Plants & Macroevolution

[CPman2004]

First, before I start I must say that I am not an expert on all the evolution theories, but I believe I have the general gist of it

Now onto my topic. I am wondering how macroevolution can explain the development of carnivorous plants. I doubt it can. I say this because of the extremly complex trap stuctures of various species (notably the Utricularia). How could such complex traps develop from simple leaves (roots in Utricularia's case)? People keep telling me that they evolved due to the poor soil requirments. However, I see the complex structures of the traps to be kinda unnessecary in such conditions. There are plenty plants that live in those conditions that do not lure, capture, and digest prey. So why evolve into such large and complex traps? So what am I getting at? Well I'll tell you. I believe carnivorous plants are an good example on how macroevolution is false.

 

[Karl - Liberal Backslider]

Do you really imagine that botanists are going to turn round and say "Gosh, he's right! We never thought of that!"

Like all supposed silver bullets against evolution, this one hinges on the same extremely unlikely situation - that people who've studied a field of science for a lifetime haven't noticed something that someone with only a cursory knowledge of the field has to point out to them.

I know you're after a complete pathway to current species, and unfortunately we simply do not have it; these plants do not fossilise well, being very soft. A tentative family tree can be drawn in the case of Aldrovanda - http://bestcarnivorousplants.com/aldrovanda/papers_online/Fossil.htm - but I know that's not what you're after.

I think you need to state your case. Demonstrate why the features that carnivorous plants have could not have evolved. That other plants living in the same habitat do not have these features is immaterial; not all animals living in a pond can swim, but it's clearly an advantage for those that can.

 

[notto]

Actually, these plants show how adaptation can change a plant to survive in poor soil. Not much of a stretch for evolution (they just get their fertilizer through decaying and decomposing victims instead of from the soil through roots). There are many different types of carnivourous plants, and their variety, and different mechanims (from simple to complex) also point to their possible evolutionary history.

Why couldn't they evolve?

 

[CPman2004]

Do you really imagine that botanists are going to turn round and say "Gosh, he's right! We never thought of that!"

Nope. Many scientists are just as hardheaded as the rest of us, so why should my idea affect them?

Like all supposed silver bullets against evolution, this one hinges on the same extremely unlikely situation - that people who've studied a field of science for a lifetime haven't noticed something that someone with only a cursory knowledge of the field has to point out to them.

Granted I am only 18 with an basic knowledge of evolution. So forgive my ignorance

Actually, these plants show how adaptation can change a plant to survive in poor soil. Not much of a stretch for evolution (they just get their fertilizer through decaying and decomposing victims instead of from the soil through roots). There are many different types of carnivourous plants, and their variety, and different mechanims (from simple to complex) also point to their possible evolutionary history.

They don't use decaying and decomposing victims. They produce digestive enzymes to break the prey down and then use the nutrients. True there are various traping mechanims (all are rather complex). They are the active traps (Venus Flytrap, Utricularia, Aldrovanda), semi-active traps(drosera, pinguicula are the major ones), and passive traps(sarracenia, nepenthes, darlingtonia). The Utricularia trap is indeed very complex. Botanists are still trying to figure out how it works.

I find it hard to belive that a plant could randomly evolve into a trap like Sarracenia or Utricularia. How could they randomly gain digestive glands, various types of lures, and the trap itself? Also, I don't see a reason why they would develope such traps if an simpler one could work just fine to get them the required nutrients?

 

[notto]

I find it hard to belive that a plant could randomly evolve into a trap like Sarracenia or Utricularia. How could they randomly gain digestive glands, various types of lures, and the trap itself? Also, I don't see a reason why they would develope such traps if an simpler one could work just fine to get them the required nutrients?

Evolution isn't random. Plants with better lures and traps would survive better. Variation within the population leads to selection of better design. This is not random. Better design leads to more prey (even if a simpler one would work). More prey equals more nutrients and a better adapted population.

They didn't randomly gain digestive glands. Some may have just kept the prey there until bacteria in the captured water decay the prey. As mutations either provided a better environment for this bacteria, or caused secretions to aid the bacteria in decay, they would become more efficient at procesing their prey, if enzymes showed up through mutation, this would create an even better design - and this design would have a selective advantage. If an organism could trap prey better (or attract more prey), this would also be selected for.

Evolution happens in small steps. Each individual in a population varies and each slight variation can possibly help a population survive better. Those variations that provide better design are selected for, ones that didn't provide a better design are selected against.

 

[Karl - Liberal Backslider]

What Notto Said.

Evolution is a bit like the two guys in the forest. They suddenly hear the sound of a bear charging towards them, clearly not happy and unlikely to be open to negotiation.

One of the guys pulls out his running shoes and puts them on.

"What are you doing?" his mate says "You'll never run faster than that bear!"
"I don't need to" replies the first guy "I just need to be able to run faster than you!"

 

[CPman2004]

Ok ok I guess I was confused I thought that evolution worked by random genetic mutations and the benifical mutations lived on, and that those mutations weren't guided by anything.

But my question in the "Two men in the woods" illistration is.... "Where did he get the running shoes?"

 

[gluadys]

Ok ok I guess I was confused I thought that evolution worked by random genetic mutations and the benifical mutations lived on, and that those mutations weren't guided by anything.

But my question in the "Two men in the woods" illistration is.... "Where did he get the running shoes?"

LOL.

You have part of the evolution story right. Mutations are random and they do play a part. But you left out natural selection. Natural selection is not random. And it is natural selection that winnows out the poor mutations and preserves the good ones.

The whole question of carnivorous plants is just one specific example of complex structures (the eye, the bombadier beetle's spray mechanism, the bacterial flagellum, the insect pollinator/flower relationship, any other complex feature you wish to name.)

The problem with complex features is that we have difficulty imagining the simpler forms from which they evolved. It's obvious that they didn't get to be what they are at one go, but we have difficulty imagining workable, beneficial intermediary steps from no-eye to complex-eye, no-trap to complex-trap.

But, as Darwin pointed out, that is a weakness of our imagination that we need not transfer to reality.

We can't offer a specific plausible answer for every complexity question, but we do have plausible answers for some (such as the eye), and a bit of study will usually lead to some ideas about more obscure cases.

For a great book on this whole area of how anything complex could have evolved read Dawkin's Climbing Mount Improbable.

 

[gluadys]

The Strangler Fungus
Some bizarre fungi can strangle worms called Nematodes. These fungi capture the worms for food. These fungi make ring-like nooses from their hyphae to capture the worms. Once the nematode is trapped, the fungus penetrates it, eating it.

http://commtechlab.msu.edu/sites/dlc-me/zoo/zdhhmain.html

This thread just reminded me that fungi can be carnivores too.

 

[CPman2004]

The Strangler Fungus
Some bizarre fungi can strangle worms called Nematodes. These fungi capture the worms for food. These fungi make ring-like nooses from their hyphae to capture the worms. Once the nematode is trapped, the fungus penetrates it, eating it.

http://commtechlab.msu.edu/sites/dlc-me/zoo/zdhhmain.html

This thread just reminded me that fungi can be carnivores too.

Yup.

Now. How about the Creationist veiw on CPs? Just wondering.