[From Rick Marken (940913.2250)]
Martin Taylor (940912 12:00) --
In a stable population, that one person [with the "good" mutation]
will have an expected number of surviving offspring in the next
generation greater than one.
Maybe. Maybe not. Shit happens, even to good mutations and their
offspring. Besides, nobody said natural selection couldn't work. It just
works very much more slowly than "E. coli" evolution to produce the
kind of adaptation that requires mutation-based change.
I think the fast changes produced by Darwin's Hammer type selection
(like the beak of the finch or the color of the moth) are _not_ based on
mutation; they are based on "selection" from already existing
variations that make it possible for the population to deal with certain
kinds of environmental change. Finches, for example, already come equipped
with various sized beaks; catastrophic drought drastically changes the
distribution of beak lengths in the population -- but it doesn't produce
a new kind of finch. I bet that after a long spell of no drought the
proportion of long and short beaked finches evens out again. Same
with moths; get rid of the birds and the distribution of light and dark
moths will even out regardless of the background color. These kinds of
changes are like distrubance resistance in a control system -- but
operating over a population rather than an individual. The range of
phenotypes on a certain dimension (like beak size) probably represents
the evolutionarily developed output variations (over the population
of individuals) that allow control in terms of survival of some
proportion of the individuals and, hence, resistance to disturbances to
crucial variables (droughts that disturb the type of food available to the
finches or changes in background color that disturb the contrast
between moth and background). Disturbances to these variables were
probably confronted during the evolutionary history of the population
and output (phenotypic) variations on certain dimensions evolved to
handle them.
Reorganization-type evolution (mutation-based ) probably occurs when
there are environmental changes (disturbances) that the population
does not have variations to deal with. Such disturbances cannot be delt
with by a redistribution of phenotypes in the population. It can only be
delt with by developing a new dimension of variation in the
population. This can only be accomplished by mutation. I imagine that
the population would be decimated if it had to wait for the "right"
mutation to occur. So "controlled" evolution is probably what goes on
in mutation-based evolution -- leading to the pronounced "punctuations"
in the fossil record. But, I agree, some simulations are necessary in order
to see what might be going on.
The soldier who dies in a successful defence of his tribe probably has
done more to ensure that his genes propagate than he would have by
impregnating every woman in the village.
Well, I still say "Make love, not war".
Peace
Rick