Darwinian and panbiogeographic frameworks

[John Grehan]

You may correct me, but at the time that Darwin visited the Galapagos
Islands and observed the variatins, he had not yet come up with the
selection theory. Further, I understand that he had not even turned to
evolution. If these points are correct Darwin could not be said to have
observed the results or consequences of a series of events, since these
events were not recognized by Darwin at the time.

>You implied earlier that such might not be the case, so I was compelled to
take
>issue with your statement.

I would consider the possiblity that the evolution differentiation is not
necessarily through natural selection but that orthogenesis also takes
part, and if variation is orthogenetic, then the role of natural selection
may be different in the long-term than which is generally assumed.


>Well, actually I derived it from a definition found in the American Heritage
>Dictionary of the English Language,which my knowledge of the theory and its
>historical discussion and its rejection is consistent with my
understanding of
>contemporary useage.

What defines "contemporary usage" to justify your acceptance of the American
heritage Dictoinary definition of orthogenesis?


 If one alternately defines orthogenesis to so that it
>includes the notion that the descent of organisms is not independent of their
>natural environment, I am having difficulty in understanding how your
theory of
>"orthogenesis" is different from that proposed by Darwin in which
selection is the
>arbitor of survival of hereditable differences.

The assumption of selection theory, as I understand it, is that selection
works on random variation - i.e. no selection no evolution - that mammalian
ears for example, would not evolved without differential reproduction
through selection. Orthogenesis is a model where new structures, taxa,
etc., can evolve without requiring differential survivial. The only
constraint is if such a feature is detrimental in some way with respect to
other variants, in which selection would indeed play an active role in the
outcome.

Darwin's orthogenesis was not natural selection. It was laws of growth.

>Again I ask, what specific prediction?

The compostie geology of the Americas would be one example.


>Yes, but one would be incorrect.  Again, I ask.  What mechanisms in what
systems?

Molecular drive mechanisms.

John Grehan