>
> 1. Fecundity does not ensure reproductive success.
>
>
> ^^^^^
> CB: If one population has significantly higher number of offspring per
> capita, they have taken a very critical step toward what you refer to as
> "reproductive success", and biology terms reproductive fitness or
> differential fertility. It's true that there is a further step , that the
> "babies" have "babies", i.e. that the offspring be fertile themselves. But ,
> all things being equal, more offspring per capita is likely to produce more
> offspring per capita in the third generation.
The point I'm making is that all things are not equal. Whether or not high fertility leads to reproductive success is an empirical question; it is completely consistent with the theory of evolution to claim that under certain environmental conditions, high fertility is not the optimal reproductive strategy. (Example: elephants. Natural selection has produced a species with low fertility, compared to most mammals.)
> the times people spend not having sex that is potentially fertile
> can make a "differential" that is an advantage/disadvantage. At times of
> sharp competition especially, the fact that A's are constantly trying to
> have potentially fertile sex, and B's are only occasionally trying to have
> potentially fertile sex because much of the time B's are having sex that is
> not potentially fertile is a differential that is the basis for selection
> for A's over B's.
Only if the natural selection favors the "high fertility" strategy for that species in that environmental context! (This is the r-strategy and k-strategy distinction that evolutionary theorists have developed.) Again, put aside what you've read in a blurb on a website, the theory of evolution clearly emphasizes that the k-strategy (investing a great deal of time and effort to protect and nurture a few offspring to maturity) can lead to greater reproductive success than the r-strategy (having as many offspring as possible). Thus it is quite possible that natural selection could favor the B's over the A's in your example.
> The phrase "population fecundity at the individual level" is on its face
> self-contradictory. Perhaps you mean that with two populations, one may
> have fewer offspring per capita than the other, but the population with the
> fewer offspring per capita brings more of those offspring to the point of
> having fertile offspring themselves. Yea. Species with litters can in the
> long run have less success than a species with single births
No, you're not getting it. If I am genetically related to someone, and my traits help my genetically related relatives to survive and reproduce, then natural selection would select for my traits, even if those traits did not directly increase my own fertility. This is a common explanation for prosocial behavior in primates.
> You are sort of elevating unusual exceptions to the general rule to the
> status of the "rule". In general, greater fecundity is associated with
> greater reproductive fitness. Then there are some interesting exceptions.
This is a gross oversimplification of the theory of evolution. This is what disappoint me in this thread: here is this wonderful, complex theory with a great deal of startling, creative, and insightful research to back it up, and some people what to reduce it to a simplistic bromide like the one you provide above. People much smarter than anyone on this list have developed an impressive and well-supported scientific theory, and I think they deserve our admiration and respect. That means that we should study the theory in detail before we make assertions or critique the theory. Frankly, I don't think you've done that; if you did, I wouldn't have to provide basic introductory material about r-strategies and k-strategies here.
Miles