Mutations large affect evolution

[kitkat]

For mutations to occur evolution they have to be in the germ line for natural selection to take this process from here. Please help me with the math:

 

My understanding is there are 50 and 500 billion mutations in humans in every generation. At 1/10 of 1% rate there is 2 to 20 million mutations per year.

 

Out of these numbers how many actually occur in the germ line?

 

 

The average female produces 2 million eggs at birth but by the time she can reproduce she only has 200 and 300 viable eggs in her lifetime. On average women produce 2 children in their lifetime.

 

 

I don't see how natural selection works in evolution regarding mutations. If anything it works against it. Many other species can produce alot of offspring but the percentage that actually make it to reproduction is very low so again this works against mutation as being the primary driver for evolution to occur.

[CharonY]

The estimates are out of context and I cannot easily comment of them (i.e. do you refer to total mutations in the total population, etc.).

However, mutation itself is not a driver for evolution, but for diversity. During your life you accumulate mutations arguably in most of your cells. Especially ova are vulnerable as they are formed very early and accumulate mutations over time. Thus almost inevitably all kids are mutants of some sorts. Cells simply do not stay pristine forever.

 

However there is no immediate selection as the vast majority of mutations will not have any effects at all. So they just sit there doing basically nothing until it affects the genetic network in some tangible way. Even then we do not have a sudden fixation (usually) but at this point population effects kick in. Nonetheless, even before the phenotype arises there may be plenty of alleles around that by themselves are neutral, but may, in some combination result in them.

There is a nice recent paper that illustrates that a bit more:

 

Bard J (2010) A systems biology view of evolutionary genetics. Bioessays 32: 559-563.