help on evolution

[cambrian_exp]

evolution of new species can occur only when genetic variation occurs. but how will species evovle if it is reproducing asexually ( genetic variation cannot occur) and since genetic variation can occur only on mutations. and mutations are rare and most of them are harmful for living organisms and does not make much impact on genepool .according to this evolution site...

 

http://evolution.berkeley.edu/evosite/evo101/IVBMechanisms.shtml

 

"Mutation: Some “green genes” randomly mutated to “brown genes” (although since any particular mutation is rare, this process alone cannot account for a big change in allele frequency over one generation)."

 

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see this para from that site states that mutation ( the basic principal on which evolution functions ) is rare and cannot account for big change, then how did asexually reproducing species evovled during edicaran times? for genetic drift and gene flow to happen there must be genetic variation happaning first! and that basic principal of genetic variation is rare and harmful! ( i m talking about asexual reproduction because they cant exchange genes by sex , i think they only have 1 way that is mutations)

if u have any link then send me which will better explain this problem

[swansont]

If asexual reproduction tends to happen for organisms with short reproduction cycles and the ability to generate really large populations, even a small probability of a beneficial mutation translates into that mutation becoming fixed in a subpopulation.

[Dak]

^^^ Bacteria are a good example of that.

 

Plus, im not aware of any species which reproduces entirely without a means of swapping at least the occasional gene.

[Daecon]

^^^ Bacteria are a good example of that.

 

Yeah, just look at MRSA.

[Mokele]

but how will species evovle if it is reproducing asexually ( genetic variation cannot occur) and since genetic variation can occur only on mutations.

 

Because mutations can and do occur in asexual reproduction too (just less frequently).

 

and mutations are rare and most of them are harmful for living organisms and does not make much impact on genepool

 

Actually, they're much more common than we used to think, as are beneficial mutations. In eukaryotes, the vast bulk of mutations are simply neutral, and don't event affect the final structure of the protiens. However, when one comes along that *does* cause the final structure to change, it might change quite a bit because of the accumulated changes in neutral areas (which are now no longer neutral).

 

see this para from that site states that mutation ( the basic principal on which evolution functions ) is rare and cannot account for big change,

 

Yes, mutation itself doesn't cause large changes in the overall population's genetics, but it *does* allow natural selection to eliminate or replicate the mutant allele, and *that's* where the big effects come from.

 

Think of evolution like a car. There's an engine (natural selection) which runs on gas (mutations). The car can be stationary of moving if the engine is running, but without the engine running, it goes nowhere. The engine runs on the fuel, and when that runs out, it stops. Mutation is the process of filling up the gas tank, and the engine is what's really doing the work and moving the car.

 

Mokele