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mimicry
Posted: 30 August 2007 03:52 PM   [ Ignore ]
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yesterday when I left the gym I saw a grasshopper that looked remarkably alot like a green leaf. with the veins and everything.

what i would like to learn more about evolution is, how does such mimicry come about.

anyone got some input to share?

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Posted: 30 August 2007 04:03 PM   [ Ignore ]   [ # 1 ]
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HERE is the Wikipedia article on mimicry. Fascinating subject. In general, it is believed that a species that by chance slightly resembles another may find some selective advantage in this. A non-poisonous butterfly, for example, that looks like a poisonous one will perhaps be preyed upon less often by birds who have previous experience of trying to eat the poisonous kind, and so may reproduce more effectively than butterflies not similar to the distasteful kind. Over time, changes in appearance that make the resemblence closer, and thus the protective effect stronger, will increase in frequency in the population because those individuals will pass on more genes than others that don’t resemble the model as closely. There are lots of variations, but this is the general idea as I understand it.

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Posted: 30 August 2007 04:46 PM   [ Ignore ]   [ # 2 ]
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this grasshopper looked like a leaf!

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Posted: 30 August 2007 04:56 PM   [ Ignore ]   [ # 3 ]
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I remember finding a walking stick when I was child. It looked just like a stick, but I seen it move, so I picked it up and see that it was a bug. It looked like a stick with two eyes. It moved kinda slow.

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Posted: 30 August 2007 06:42 PM   [ Ignore ]   [ # 4 ]
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truthaddict - 30 August 2007 04:46 PM

this grasshopper looked like a leaf!

... to hide itself from predators.

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Posted: 30 August 2007 09:35 PM   [ Ignore ]   [ # 5 ]
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Many birds eat grasshoppers voraciously.  Few birds eat leaves.  If I were a grasshopper, I’d love looking like a leaf.

Occam

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Posted: 31 August 2007 09:07 AM   [ Ignore ]   [ # 6 ]
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dougsmith - 30 August 2007 06:42 PM
truthaddict - 30 August 2007 04:46 PM

this grasshopper looked like a leaf!

... to hide itself from predators.

but wouldnt that imply - cuz i know you dont think this - that the grasshopper intentionally chooses to look like a leaf to avoid predators; that the evolution to look like such an object is teleological?

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Posted: 31 August 2007 09:35 AM   [ Ignore ]   [ # 7 ]
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truthaddict - 31 August 2007 09:07 AM
dougsmith - 30 August 2007 06:42 PM
truthaddict - 30 August 2007 04:46 PM

this grasshopper looked like a leaf!

... to hide itself from predators.

but wouldnt that imply - cuz i know you dont think this - that the grasshopper intentionally chooses to look like a leaf to avoid predators; that the evolution to look like such an object is teleological?

Well, sure ... although the word “intentional” is misleading in this context. It wasn’t a conscious decision of the grasshopper, nor its ancestors, obviously. But function-talk is essentially teleological. And one function of the grasshopper’s formed exoskeleton is to look like a leaf, so as to avoid predation.

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Doug

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Posted: 31 August 2007 09:37 AM   [ Ignore ]   [ # 8 ]
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[quote author=“truthaddict” date=“1188590865]
but wouldnt that imply…that the grasshopper intentionally chooses to look like a leaf to avoid predators?

No more than it implies that the grasshopper chooses to have wings, or chooses to have an exoskeleton.  It’s why they call it natural selection!

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Posted: 31 August 2007 09:40 AM   [ Ignore ]   [ # 9 ]
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dougsmith - 31 August 2007 09:35 AM
truthaddict - 31 August 2007 09:07 AM
dougsmith - 30 August 2007 06:42 PM
truthaddict - 30 August 2007 04:46 PM

this grasshopper looked like a leaf!

... to hide itself from predators.

but wouldnt that imply - cuz i know you dont think this - that the grasshopper intentionally chooses to look like a leaf to avoid predators; that the evolution to look like such an object is teleological?

Well, sure ... although the word “intentional” is misleading in this context. It wasn’t a conscious decision of the grasshopper, nor its ancestors, obviously. But function-talk is essentially teleological. And one function of the grasshopper’s formed exoskeleton is to look like a leaf, so as to avoid predation.

Doug, im with you. I just wanted to clarify so that some “conquer” doesnt come around and put words in your mouth, or confuse someone else.

i only wish my daughter was with me to see it. it was so effing neat looking!

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Posted: 31 August 2007 09:45 AM   [ Ignore ]   [ # 10 ]
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truthaddict - 31 August 2007 09:07 AM

but wouldnt that imply - cuz i know you dont think this - that the grasshopper intentionally chooses to look like a leaf to avoid predators; that the evolution to look like such an object is teleological?

It was the process of natural selection that made the grasshopper to look like a leaf. The grasshopper’s intentions have nothing to do with this. I don’t think the grasshopper even knows that it looks like a leaf. If it did, it would be very difficult for him to find a girlfriend: “Hi there. How about a drink tonight? Just you and I? Hello? Oh, damn it, not another leaf…”

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Posted: 31 August 2007 10:15 AM   [ Ignore ]   [ # 11 ]
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george and advocatus,

I realize that, fellas. Reread what I originally wrote and not just my response back to Doug. there is a reason I said “imply - cuz i know you dont think this.”

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Posted: 31 August 2007 10:22 AM   [ Ignore ]   [ # 12 ]
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I am confused, TA. What is it you’re asking? Why does the grasshopper hide from predators?

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Posted: 31 August 2007 11:39 AM   [ Ignore ]   [ # 13 ]
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george,

sorry, for the confusion. I actually meant this comment to Doug:

“but wouldnt that imply - cuz i know you dont think this - that the grasshopper intentionally chooses to look like a leaf to avoid predators; that the evolution to look like such an object is teleological?”

as for my original question, I figured it was natural selection. but I just wanted to hear from others. so when Doug made his comment I said the quote above to clarify for others that he was not talking about teleology.

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Posted: 31 August 2007 12:00 PM   [ Ignore ]   [ # 14 ]
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truthaddict - 31 August 2007 11:39 AM

so when Doug made his comment I said the quote above to clarify for others that he was not talking about teleology.

... but I was talking about teleology. To be clear, functional adaptations are teleological: they are adaptations for a particular end. (E.g., in this case, camouflage). That is teleological.

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Posted: 31 August 2007 12:08 PM   [ Ignore ]   [ # 15 ]
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Ahh… very good young Grasshopper.  cheese

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