[Taxacom] Evolutionary misconceptions

[Richard Pyle]

Yes, fair point.  I didn't mean to imply that we all agree that "speciation"
is the inevitable consequence of genetic isolation.  I guess I should have
framed it more that we all agree that the conditions conducive for
"speciation" via subsequent anagenesis are present.

I'm not sure that I fully endorse the statement, "The basis of taxonomy is
that taxa stay stable long enough to spread to some extent about the earth."
I would say that the basis of taxonomy is the heterogeny of forms of life on
Earth.  It's anybody's guess how stable any particular taxon is over periods
of time spanning more than a few centuries.

Aloha,
Rich

> -----Original Message-----
> From: Richard Zander [mailto:Richard.Zander at mobot.org] 
> Sent: Thursday, March 11, 2010 6:31 AM
> To: Richard Pyle; taxacom at mailman.nhm.ku.edu
> Subject: RE: [Taxacom] Evolutionary misconceptions 
> 
> Not all of us expect all species to anagenetically change 
> over time into something taxonomically new. There are many 
> species that appear to be in morphological stasis over 
> thousands or millions of years, fixed by maybe stabilizing 
> selection, habitat tracking, boredom, I don't know what. The 
> basis of taxonomy is that taxa stay stable long enough to 
> spread to some extent about the earth.
> 
> So, neutral morphological traits do exist, and certainly 
> surge about in the phenome within (particularly diploid) 
> species, and isolation of odd combinations of slowly changing 
> neutral traits can make a species. This may operate in some 
> taxa but not in others, so again I say that not all species 
> may be expected to anagenetically change over time into 
> something taxonomically new. 
> 
> *****************************
> Richard H. Zander
> Voice: 314-577-0276
> Missouri Botanical Garden
> PO Box 299
> St. Louis, MO 63166-0299 USA
> richard.zander at mobot.org
> Web sites: http://www.mobot.org/plantscience/resbot/
> and http://www.mobot.org/plantscience/bfna/bfnamenu.htm
> Modern Evolutionary Systematics Web site:
> http://www.mobot.org/plantscience/resbot/21EvSy.htm
> *****************************
> 
> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu
> [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Richard Pyle
> Sent: Wednesday, March 10, 2010 11:46 PM
> To: taxacom at mailman.nhm.ku.edu
> Subject: Re: [Taxacom] Evolutionary misconceptions 
> (was:Ladderisingphylogenetic trees)
> 
> We all seem to agree that eventually, with sufficient genetic 
> isolation, the descendants of that pregnant female will 
> anagenize into something with consistently different 
> morphological traits/DNA sequences/reproductive imperfections 
> to the point that we would regard the members of that 
> descendant population as a distinct "subspecies"
> from the descendants of the original population from which 
> the pregnant female came.