Archaeopterygid bird from China

[John Grehan]

> -----Original Message-----
> From: Taxacom Discussion List [mailto:TAXACOM at LISTSERV.NHM.KU.EDU] On
> Behalf Of Curtis Clark
> Groups don't originate. Clades originate, when their stem species
> originates, 

However you like to phrase it is ok with me, although the evolutionary
meaning you give to it might be debatable (which I won't as its not
accepted generally anyway).

but, unless our empirical view of evolution in extant
> organisms is seriously off-base, it all comes back to species. 

After saying one thing above, now I contradict myself to at least say
that I would disagree, but that's another story.

but it is well-known from empirical evidence
> of extant species that new species *can* originate in very localized
> settings. 

It is also well known that vicariant differentiation is the norm for
evolution so the distribution of vicariant descendants shows that the
'center of origin' is the combined range of each taxon - effectively the
center of origin is larger than any one descendant! Some would argue
that the center of origin concept is meaningless altogether, and perhaps
it is.

I'm assuming you agree that at any given moment a species has
> a "range", the cumulative area occupied by all its individuals. It
seems
> to me that both the "Darwinian" view that there *must* be a center of
> origin and the panbiogeographic view that it is meaningless to talk of
a
> center of origin are equally worthless in addressing this aspect of
the
> biology of an extinct species.

I've go with that. So does that mean we stop using the center of origin
concept? If so I would have no problem at all!

John Grehan
> 
> --
> Curtis Clark                  http://www.csupomona.edu/~jcclark/
> Web Coordinator, Cal Poly Pomona                 +1 909 979 6371
> Professor, Biological Sciences                   +1 909 869 4062