Topic 1: mechanisms of evolution
On the topic of micro and macro mechanisms. Yes I believe that the
assumption in most minds is that the proposed sources of both are thought
to be the same, however there is debate at this point.
The rate of micro-evolution seen over and over again is really FAR TOO
FAST to be the mechanism of proposed large scale evolutionary processes.
See Steven J. Gould, Natural History, Dec 97-Jan98, p. 12. There he
makes the claim that the rate of change measured in "Darwins" (who said
scientists don't have a sense of humor) which are computed from the %
change in a characteristic over time is far greater, 10,000x and more,
than that estimated from fossils.
Gould's final claim is that real macro-evolution occurs at a rate just
too slow to be seen in human time-frames, yet too fast to be clearly seen
by fossil transitional forms. This is just the ideas that forced Gould
and Eldridge (sp?) to propose Punctuated Equilibrium.
In the current issue of PSCF, I have a small review of that article with
several more references.
Topic 2: random mutations
Whether mutations are really "random" events is now up for discussion in
research circles. The "adaptive mutation" camp seem to be finding
evidence that when under stress, bacteria seem to be able to accelerate
the occurrence of mutations in the right part of their genetic coding
likely to produce a useful result. A good place to start here is with
the article by Cairns in NATURE (335), 1988, p. 142-145.
In the previous issue of PSCF, I wrote a short review of this topic with
references.
I hope this adds to the discussion
Al McCarrick