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Mutations

Discussion of everything related to the Theory of Evolution.

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Mutations

Postby supersport » Mon Aug 13, 2007 5:08 am

Can anyone show me an example of a mutation that can either create a new structure or add a beneficial, selectable modification to an existing structure? I realize mutations can create duplications of already-existing structures and I know mutations can kill and/or deform organisms, but I'm looking for any actual scientific evidence that mutations can perform as advertised....I'm looking for evidence that mutations can create a beneficial modification to a physical structure.

ToE says centipedes evolved from worms. Centipedes have 100 legs, while worms have no legs. So can someone give me a synopsis as to how the legs formed? Did the legs all form at the same time from one mutation in one lucky organism?...or did the legs form slowly over time by way of multiple mutations?
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Postby mith » Mon Aug 13, 2007 4:07 pm

If you study the development of centipedes you might find out that all the segments are related so if legs evolve on one segment, it's more than likely the other segments will also have legs.

http://www.salk.edu/labs/mnl-t/clh/pede2.html
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Postby TheHomeWorkKid » Tue Aug 14, 2007 2:00 am

I have a related question. Is it possible in principle for a vertebrate to develop a functional set of extra limbs? Like, a bird with an extra pair of wings? I realize nothing like this has ever actually happened, or if it has there apparently isn't a fossil record of it, but is there any concrete reason that couldn't happen?
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Postby kotoreru » Tue Aug 14, 2007 3:03 pm

Hmm well it's not quite the same but search Google for the dolphin that has pelvic flippers.

There are also quite a few cases of children born with an extra arm or two, so yes it is possible.
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Postby Darby » Tue Aug 14, 2007 4:33 pm

On the worm / centipede front, research onycophorans.

Just because worms don't have legs, it doesn't mean they don't have appendages. Look at polychaete annelids.
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Postby mith » Tue Aug 14, 2007 10:07 pm

@homeworkkid

Look up hox genes and what they've done with fruit flies.
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Postby supersport » Sun Aug 19, 2007 4:02 am

mith wrote:@homeworkkid

Look up hox genes and what they've done with fruit flies.


I don't believe any of those mutations created anything that would be considered an upgrade or a beneficial, selectable modification. There are duplications, but as far as I've seen nothing that would qualify as something that would be selected for because of a benefit given to the organism. Also, legs have appeared sticking out of the head of a fly, but I'm not sure that would be too helpful either.
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Postby mith » Sun Aug 19, 2007 2:22 pm

The question was "Can an organism develop an extra pair of functional limbs?" and the answer is yes, but depending on how the mutation happened your limbs might not be in the spots you want.

But what you want to know is about an example of an adaptation of a functional component that is also beneficial? Well lookup the panda's thumb. Dr Gould had a whole book dedicated to that subject.
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Postby supersport » Sun Aug 19, 2007 10:48 pm

mith wrote:The question was "Can an organism develop an extra pair of functional limbs?" and the answer is yes, but depending on how the mutation happened your limbs might not be in the spots you want.

But what you want to know is about an example of an adaptation of a functional component that is also beneficial? Well lookup the panda's thumb. Dr Gould had a whole book dedicated to that subject.


how do you know that was a mutation? I'm asking for scientific verification that a mutation can create a new, functional body part or a new, beneficial modification to an existing body part. Simply observing one population of animals without thumbs and another population with thumbs does not qualify as scientific verification of anything.
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Postby mith » Mon Aug 20, 2007 1:50 am

How can you tell that it's a mutation? Morphology.
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Postby Darby » Mon Aug 20, 2007 1:58 am

The genes for related but different physical structures are themselves related but different, but the timeframe means that we aren't seeing the actual transitions, we're reconstructing them.
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Postby david23 » Mon Aug 20, 2007 2:04 pm

or you can always do DNA comparison between worms centipedes and whatever and get a phylogenic tree to show who originated from who. There are a lot of premade models of mutation, gene drift and all the other evolution causing agents. You basically then compare your data to them.
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