orthogenesis

John Grehan jgrehan at SCIENCEBUFF.ORG
Thu May 19 11:42:04 CDT 2005


I never thought to take Zander's description that way. However,
according to some I would not be a genuine biogeographer. A couple of
years ago the editor of Systematic Biology objected to publication of an
article I wrote because she declared that panbiogeography had been
refuted by molecular systematics - which is another way of declaring
that I am not a genuine biogeographer and panbiogeography is not genuine
biogeography. 

John Grehan

> -----Original Message-----
> From: Taxacom Discussion List [mailto:TAXACOM at LISTSERV.NHM.KU.EDU] On
> Behalf Of Richard.Zander at MOBOT.ORG
> Sent: Thursday, May 19, 2005 11:30 AM
> To: TAXACOM at LISTSERV.NHM.KU.EDU
> Subject: Re: [TAXACOM] orthogenesis
> 
> Opp. Rereading my post of a couple minutes ago, the last sentence
implies
> that Grehan is not a genuine biogeographer. He is. I'm not.
> 
> R.
> ______________________
> Richard H. Zander
> Bryology Group, Missouri Botanical Garden
> PO Box 299, St. Louis, MO 63166-0299 USA
> richard.zander at mobot.org <mailto:richard.zander at mobot.org>
> Voice: 314-577-5180;  Fax: 314-577-9595
> Websites
> Bryophyte Volumes of Flora of North America:
> http://www.mobot.org/plantscience/bfna/bfnamenu.htm
> Res Botanica:
> http://www.mobot.org/plantscience/resbot/index.htm
> Shipping address for UPS, etc.:
> Missouri Botanical Garden
> 4344 Shaw Blvd.
> St. Louis, MO 63110 USA
> 
> 
> -----Original Message-----
> From: Richard.Zander at MOBOT.ORG [mailto:Richard.Zander at MOBOT.ORG]
> Sent: Thursday, May 19, 2005 10:14 AM
> To: TAXACOM at LISTSERV.NHM.KU.EDU
> Subject: Re: [TAXACOM] orthogenesis
> 
> 
> John Grehan asks fundamental, challenging questions. One must always
posit
> initially poorly supported hypotheses to explain something natural,
and
> some
> may appear quasi-essentialist until, surprise, some experimentalist
> detects
> a mechanism. On the other hand, really simple explanations that
explain
> everything can border on the supernatural. And what is proof? or
> likelihood?
> 
> It may not be necessary to have one explanation of everything;
physicists
> (e.g. F. Dyson) are toying with the idea that a unified field theory
may
> be
> impossible and not necessary, given what we know of the universe.
> 
> For a theory to stand, however, it must have some point or pragmatic
> value.
> I've inveighed at length here on Taxacom against the T. Aquinas-style
> logic
> that once you've chosen the correct first principles, all deductions
must
> be
> correct. Presuppositionalists, also, first conceive that their
assumptions
> are correct and if they can come up with a coherent, well structured,
> really
> neat theory, their assumptions must have been correct; contrary to
this,
> other first principles can also be used to come up with coherent, well
> structured, really neat but different theories.
> 
> Do we have a coherent, well structured, really neat theory to compare
with
> J. Grehan's? Even if not terribly coherent, is our theory more
predictive
> or
> passes some test better than orthogenesis? What is the test? We do not
> have
> to prove orthogenesis unreasonable, just find something better and
more
> valuable in practice.
> 
> For a nice review of a recent tome on historical biogeography, see the
> recent Systematic Biology 54(2): 338-340. 2005. It touches on
> panbiogeographic method, seems clearly thought out, and the writer is
> apparently a genuine biogeographer.
> 
> 
> ______________________
> Richard H. Zander
> Bryology Group, Missouri Botanical Garden
> PO Box 299, St. Louis, MO 63166-0299 USA
> richard.zander at mobot.org <mailto:richard.zander at mobot.org>
> Voice: 314-577-5180;  Fax: 314-577-9595
> Websites
> Bryophyte Volumes of Flora of North America:
> http://www.mobot.org/plantscience/bfna/bfnamenu.htm
> Res Botanica:
> http://www.mobot.org/plantscience/resbot/index.htm
> Shipping address for UPS, etc.:
> Missouri Botanical Garden
> 4344 Shaw Blvd.
> St. Louis, MO 63110 USA
> 
> 
> -----Original Message-----
> From: John Grehan [mailto:jgrehan at SCIENCEBUFF.ORG]
> Sent: Thursday, May 19, 2005 8:39 AM
> To: TAXACOM at LISTSERV.NHM.KU.EDU
> Subject: [TAXACOM] orthogenesis
> 
> 
> Steve Manning wrote:
> 
> > >7. Orthogenetic development (phylogenetic constraint by molecular
> drive)
> > >is of primary importance in evolution.
> >
> > Can you be more specific as to what this really means (relatively
> > briefly)?  I have often thought that actually evolution is just one
> > energy-driven manifestation of the second law of thermodynamics.
This
> > sounds like a similar concept.
> 
> Orthogenetic development, or orthogenesis, is basically a concept of
> evolution taking place in a concerted manner without requiring natural
> selection to drive it along. The concept encompasses the idea that
there
> is a biological bias in mutation so that there may be a sequence of
> changes that result in what can retrospectively be described as a
> 'trend'. Thus, the development of the mammalian ear, or the transition
> from five toes to one in the horse for example, is seen as a series of
> sequential mutations rather that a series of fortuitously sequential
> 'random' mutations that happened to appear at the right time to be
> selected for through differential reproduction.
> 
> Orthogenesis was decried by Darwinians because it did not have a
> 'mechanism' (a bit like saying the bumble bee could not fly because
> physicists could not provide the mathematical proof). A minority of
> biologists saw life being structured in such a way that invoking
natural
> selection or drift seemed inadequate, especially when considering
> speciation over broad geographic areas (Croizat). Historically, the
term
> orthogenesis does have some baggage because a variety of biologists
> mixed the term up with teleological ideas (as Zander correctly noted),
> but this was not the original intention of the term or represents its
> use by other biologists.
> 
> Croizat probably developed the concept more than any other biologist
by
> integrating it into an overall evolutionary synthesis of space, time,
> and form and the concept of vicariant recombination of characters
which
> may affect new or different trends. In recent times molecular genetics
> has introduced concepts of molecular drive which may be concordant
with
> orthogenesis in some respects.
> 
> For some further reading take a look at Craw et al (1999) on concerted
> evolution, and for a historical overview (which I think may be still
one
> of the broader comparisons) take a look at Grehan and Ainsworth
(1985).
> A pdf copy is available at
> http://www.sciencebuff.org/grehan_publications.php
> 
> John Grehan
> >
> >
> > >8. Natural selection is of secondary importance, pruning but not
> creating
> > >evolutionary trends.




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