Mutations

[supersport]

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?

[kclo4x]

Well, i know so little about evolution but this is probably how it went if its true that centipedes evolved from worms
and im almost sure that they didnt! perhaps from isopods or something...


But lets pretend they did

alright so worms have small spikes on them correct?
there rather rought and thats how they move, they stretch out and then they contract, the spikes being pointed away from the head, catch and pull the worm forwards i believe *based on just thinking about it now... don't quote me*

So, lets say for some reason the worms with the bigger spikes survived for whatever reason
so all the ones with bigger spikes on them, lived and the other ones died
eventually they would get legs
but i don't think they evolved from an all that close of an ancestor

And its important to note its not really from a worm, its from the same common ancestor of the worm, that may have looked more like a worm then a centipede but yeah i don't know really but i would tend to think they more likely evolved from the trilobite, or something related to that as most all arthropods did i believe

[mith]

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

[TheHomeWorkKid]

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?

[kotoreru]

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.

[Darby]

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.

[mith]

@homeworkkid

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

[supersport]

@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.

[mith]

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.

[supersport]

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.

[mith]

How can you tell that it's a mutation? Morphology.

[Darby]

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.