I probably have not made it really clear here in my discussions with Jim, but
I agree that for the most part, there are large morphological gaps between the
major groups. But occassionally one of those gaps is filled with a more
gradual change. The whale is such a case. Brian, I believe that the nature
of the change is much like what is observe in my EVOLVE program. Most of the
time the mutation of my screen critter genome produces only minor alteration
in morphology. But every 4-9 mutations, a huge morphology barrier is passed &
the output looks nothing like the input. This is the way it works most of the
time. Occassionally in this program you will see only gradual change from
mutation to mutation but when the ends of the chain are compared, major
morphological change has occurred. That nonlinear dynamics that Goodwin is
talking about and what I am talking about is exactly what we see in the fossil
record.
My discussion with Jim as far as I am concerned are limited to the issues
of are there any transitional forms or not? How would one be recognized?The i
ssue is not are there no major gaps in morphology. There are, and I believe
that those gaps are bridged by a mechanism similar to what is seen in the
program, i.e. very sudden jumps. You see this in the horse evolution. Horses
have 3 toes or one toe. They do not have 2.75 toes. Three toed horses are
found in deposits together with one-toed horses. This was a population which
was in the process of changing. Both forms interbred at that time. Even
today horses are occasionally born with 3 toes.
Jim originally said that there were NO transitional forms. I challenged him
on that. There are some transitional forms. The discussion has evolved from
there.
glenn