[_ Old Earth _] Evolution and asexual reproduction.

[VenomFangX]

Evolution is a result of variation in a community where some genes and traits are more adapted to the environment than other traits and give a slight increase in the chance of a populations survival over huge geological time. This is a result of sexual reproduction and the mechanism is well understood.
We also know that bacteria multiply rapidly by asexual reproduction by binary fission like many micro organisms. There is evidence that Stromatolites in Australia are fossilized evidence of some of the earliest life forms on Earth billions of years ago.

The earliest stromatolite of confirmed microbial origin dates to 2,724 million years ago.[2] A recent discovery provides strong evidence of microbial stromatolites extending as far back as 3,450 million years ago.[3]

Wikipedia http://en.wikipedia.org/wiki/Stromatolite
As bacteria breed asexually via binary fission, all of the offspring are clones or exact replicas of the parent. The mechanism for variation does not exist only mutation. I am wondering how these organisms can change form or evolve so rapidly to form superbugs and so on when their method of reproduction is asexual. This may mean that the stromatolites which supposedly gave rise to higher organisms would have had problems in variation as well which would have hindered evolution. I knew I should not have lent out my Zoology University text.
Any ideas
yours
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[Atriamax]

The only thing that asexual reproduction cuts out is genetic drift. This has its pros and cons. While the bacteria can only clone itself, it does so at a very rapid rate. Some bacteria have generations separated by 20-30 minutes, creating a much higher chance of mutations in a shorter time. If even just a single bacterium has a highly beneficial mutation, it can create its own strain of itself in a very little time.

The reason stromatolites have lasted so long is because, they are so well adapted to their environment and are not affected by genetic drift to neutrally alter their genetics. Once they reached their most adapted form (so far) , They continued to produce (that most adapted form).

That answer anything?

 

[VenomFangX]

Thank you, yes it does explain it.

 

[Barbarian]

As bacteria breed asexually via binary fission, all of the offspring are clones or exact replicas of the parent. The mechanism for variation does not exist only mutation. I am wondering how these organisms can change form or evolve so rapidly to form superbugs and so on when their method of reproduction is asexual.

Lateral gene transfer. It's fairly common in prokaryotes. One form is known as "conjugation". Two bacterial contact, and through pili, transfer some genetic material. It's the way antibiotic resisitance moves so swiftly, and the way the ability to metabolize nylon was transfered across species and even genera in some bacteria.