[cma]

Reproduction causes a loss of half of the chromosomes. If he only has one offspring (unless it is a lot more sexually successful than him), his line dies out.

Different organisms have evolved different reproduction strategies through selection:

https://en.m.wikipedia.org/wiki/R/K_selection_theory

[jdmichal]

You're being pretty pedantic at this point. If an individual reproduces, then none of that individual's traits were sufficiently selected against. That's also not a guarantee that all their traits will carry on in new lines. There's also no guarantee that their children will be fit, due to differing traits or changing environment.