Farewell to Species - reticulation

[P.Hovenkamp]

Let me point out that it is quite useless to continue this thread without
realizing that units delimited strictly by splits in the genealogical
network (considering peripheral isolates, local extinctions etc.) are
necessarily <bold>extremely</bold> short-lived (as was pointed out by
Kornet & McAllister, referred to earlier in this thread), and not only in
annual species. They certainly do not correspond to anything that we have
come to recognize so far (be it in systematics or in population genetics).
That simple fact should be taken as a starting point for all further
analysis of this type of problem.

Peter Hovenkamp

BTW - Those of you planning to attend the XIXth meeting of the Hennig
Society, May 29- June 2, in Leiden, are advised to book accomodation well
ahead - rooms cannot be held indefinitely without confirmations.
see:
http://nhncml.leidenuniv.nl/symposia/HennigXIX/home.htm


At 06:50 PM 02-02-00 -0800, Curtis Clark wrote:
>At 10:43 AM 00.02.02 -0500, Thomas DiBenedetto wrote:
>>I would say that we have two species, but three taxa. The original species
>>should not be "relegated to nomenclatural extinction", but recognized as a
>>higher taxon. My view of a taxon is that it represents a lineage (branch,
>>or
>>system of branches)emanating from a common ancestor. The original taxon
>>still exists, and will continue to exist until all of its descendants are
>>extinct. The original taxon is, however, more complex than a simple
>lineage
>>branch; that original single branch has given off a sublineage. [...]
>
>From a genetic standpoint, this is ludicrous. In many groups (e.g. annual
>plants), species form peripheral isolates all the time. Only occasionally
>do these become new species. To suggest that a taxonomic system should
>treat the ancestral species differently depending on whether peripatric
>speciation succeeded or failed effectively removes the system from the
>realm of real-world events. I'm no anti-cladist (Kinman has accused me of
>being a radical cladist), and I am a firm advocate of monophyletic higher
>taxa, but IMO shoehorning observed biology into a system that misrepresents
>it is on a par with accepting paraphyletic groups just because they are
>"grades".
>
>
>----------------------------------------------------------------
>Curtis Clark                  http://www.csupomona.edu/~jcclark/
>Biological Sciences Department             Voice: (909) 869-4062
>California State Polytechnic University      FAX: (909) 869-4078
>Pomona CA 91768-4032  USA                  jcclark at csupomona.edu
>
P. Hovenkamp
Rijksherbarium, Leiden
The Netherlands
hovenkamp at nhn.leidenuniv.nl
http://nhncml.leidenuniv.nl/rhb