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Re: Question on morphological saltation

On Mon, Apr 20, 2009 at 09:51:11PM -0300, Augusto Haro scripsit:
> 2009/4/20  <dinoboygraphics@aol.com>:
> >>> I was referring to a morphological gradualism in terms of the
> > old-fashioned orthogenetic series of horses, carried to an infinitum
> > of intermediate forms (which I suppose nobody defended), without
> > referring explicitly to them (and only for simplicity neglecting
> > ramifications).<<<
> >
> > Of course people defended it; it was an actual hypothesis of decent.
> Admitting infinite intermediate morphological stages? I know they
> defended gradual change, but not to that extreme, which was what I was
> pointing to.

It can't be infinite; genes are digital.

But the viable variation space in, say, five thousand morphological
character-coding genes, is large enough that it won't be generally
distinguishable from infinitely fine graduation without having a full
understanding of all the genes.

> Sorry about my explanation difficulties, but my question is not that.
> It is: did somebody on a paper (preferrably recent) explicitly wrote
> that there do not need to be infinite intermediate morphological
> stages between an ancestral and a descendant morphology? And: did
> somebody on a paper (preferrably recent) explicitly wrote that
> morphological changes have necessarily to be gradual?

For finite time, there have to be a finite number of steps.

I think you might be wanting to talk about if the progression between
morphology A, at time T1, and morphology B, at time T2, has to be
continuous -- if it has to be composed of forms that would obviously be
con-specific with their immediate ancestors and immediate descendants?

I don't know if there's any recent strong statement about that one way
or another.

-- Graydon