So if an individual who is less fit for survival due to behavior is still able to reproduce, the traits that reduce that individual's fitness, or their results, are passed on and could still stop that line due to a descendant eventually not being able to reproduce due to their apparent unfitness.
but if an individual is able to reproduce, as far as Mother Nature is concerned, that individual was fit for purpose. She really doesn't care about the rest.
I don't think so. Non-optimal results are always possible at any moment. What I'm suggesting is that natural selection doesn't merely manifest at the moment of reproduction (and that any result at that moment is circularly optimal because it happened), but that in addition, degrees of selection can also gradually deter traits over a series of descendant reproductive opportunities.
The under-fit grandfather may have reproduced in his moment because there wasn't anyone better around to displace him, in that moment, but there are more chances to repress that particular under-fitness in any descendants that carry it.
"...but there are more chances to repress that particular under-fitness in any descendants that carry it.."
And Mother Nature wouldn't care about that either, even if it were likely to happen. Which it isn't.
Reproduction has nothing to do with any "fitness" other than the biological ability to reproduce. Mother Nature really doesn't care whether we think an organism is "fit", she just wants more kids. In fact, the poor could be considered "less fit" in a certain view, but they reproduce the most. Because in the eyes of Mother Nature, they are perfectly "fit". There will never be a time that Mother Nature deems them "unfit". The unfit will always have the ability, the inclination, and the opportunity to reproduce. That's just how she works.
We don't have to like it, but that doesn't make it any less true.
