[Taxacom] An improved definition of cladogenesis

[Kenneth Kinman]

Hi Hubert,
       I totally agree with you that what matters is what actually
happened (there was a split).  Where we disagree is whether the split
has created a new species (your view) or just a new subspecies (my
view).  These kind of splits happen all the time, but only occasionally
does the daughter population become a separate species.  And even then,
it usually takes a large number of generations (as in species of Homo,
for example).    
       The only cases which seem to eliminate this subspecies interlude
would be a diploid mother species giving rise to a polyploid daughter
species.  I fear that the tendency to oversplit (especially with a
phylogenetic species concept) will result in far too many divergent
populations being named full species just because a subspecies "might"
occasionally become a species in the future.  As an extreme example, see
how many dozens of brown bear species are listed in "The Mammals of
North America", and many of those are no longer even regarded as
subspecies. 
           -----------Ken
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Hubert wrote:
What might/could/should/ought/is supposed to have happened is
irrelevant: what matters is what actually happened.
Systematics/phylogeny reconstruction is a historical science,
interpreting past events, not possibilities.  If two lineages are split,
they are split, regardless of the possibility they will reunite in the
future or whether under artificial circumstances members of both
lineages might/... produce (viable, fertile) offspring.