At 09:16 PM 06/09/2000 -0700, you wrote:
>Susan Brassfield wrote:
>
> >>> 3.It postulates that speciation is (usually) due to the gradual
> >>> accumulation of small genetic changes. This is equivalent to
> >>> saying that macroevolution is simply a lot of microevolution.
>
> >please take note of the word in parentheses--"speciation is (usually) due
> >to the gradual accumulation of small genetic changes." In other words,
> >sometimes evolution is not gradual at all, as you correctly point out.
Cliff:
>Macroevolution that is "simply a lot of microevolution" is not macroevolution
>at all. Gradual evolution can be rapid through a steady succession of
>mutations,
>but that is not macroevolution. Macroevolutionary events are saltations, real
>leaps in a single generation. Your loyalty to Darwinian gradualism makes you
>a fine ally for Stephen!
No need to be insulting!
The fossil record has lots of examples of finely graded transitions from
one organism to a radically different one. At the same time there is also
evidence of "leaps" but not true saltation. Please explain what you are
talking about. I read a Gould essay some years back that explained that
large morphological changes can sometimes be brought about by small genetic
changes--rate of growth, for example--but that's not what most people mean
by "saltation." Saltation as such, as far as I can recall, was popular in
the late 19th century before the discovery of genetics. Surely that's not
what you mean!
Susan
This archive was generated by hypermail 2b29 : Sat Jun 10 2000 - 13:56:29 EDT