[knodi123]

To elaborate, if Sensible Sally's female descendants all produce one child, and Fertile Myrtle's descendants all produce 10 children each, then Myrtle's genes will multiply faster, and be less vulnerable to being wiped out by the odd plague or war.

[jdmichal]

You are repeating exactly what I said in the second and third paragraphs. I do not understand what you expect me to respond with. Your very own hypothetical scenario demonstrates that both lines will live on as long as the traits are not selected against.

[knodi123]

The fact that death is random and sometimes widespread is selection pressure. Did you read to the end of my comment, where I said "less vulnerable to being wiped out by the odd plague or war"? Ever heard the phrase "don't put all your eggs in one basket"?

Put 9 Smiths and a Johnson on a boat. Now kill half of them. What are the odds that Johnsons are extinct? Now repeat the experiment until my point sinks in.

[jdmichal]

You are talking about introducing a genetic bottleneck, which I already addressed. Having diversity is good because it helps prevent such bottlenecks from entirely eliminating a population.

Also, you are no longer discussing the fallacy. The fallacy is believing that something that allows an individual to survive better than another individual will be selected for, when in fact individuals can only selected against by preventing reproduction, thereby restricting the expression of those traits in the future population. The mere existence of a Johnson in the first place indicates that Johnsons were not previously selected against. An event killing the Johnson would then be the selection against.

The end result looks like Smiths were selected for, but the actuality is that not-Smiths were selected against.

[knodi123]

Okay, now imagine that Johnsons have a weird flap on their genitalia, and 9 times out of 10 it gets in the way during sex, and prevents conception.

Would THAT weird flap trait be selected against? After all, it "prevents reproduction, thereby restricting the expression of those traits in the future population."

And how is that scenario in any way different than the Smiths which merely reproduce 10 times as often, by virtue of the aforementioned century of fertility?

[jdmichal]

I'm pretty sure at this point that there is not a response I can give you to change your mind. This is my last attempt, because I'm tired and this is pretty simple logic.

If a individual does not successfully reproduce because of an individual trait, then that individual was selected against for not being fit. This is true no matter what the trait. As soon as an individual successfully reproduces, then that individual was not select against. This is a binary proposition: selected-against ⊕ ¬selected-against.

Now if some other individual happens to be capable of reproducing more, then that individual's traits will be proportionately better represented in the next generation. Over time, these different traits will spread throughout a population and become part of its natural variation.

HERE'S THE IMPORTANT PART: BUT they will both continue to exist within the population because there is no such thing as selecting for a trait. More successful traits will carry a higher proportion within the equilibrium than less successful traits, but all traits not selected against will exist in the population.

It's important to realize that this is a GOOD THING. If individuals were selected for, reductio ad absurdum, only the "best" individuals would survive. This would lead to lower variation within the population, which would make it extremely fragile to changes. What was a relatively unsuccessful trait yesterday might become a very successful trait today.