"crown taxa"

pierre deleporte pierre.deleporte at UNIV-RENNES1.FR
Tue Apr 23 16:59:14 CDT 2002


A 07:35 23/04/2002 -0600, Una Smith wrote:
>Crown taxa are those members of a clade that share (recognizable)
>synapomorphies.  Stem taxa are members of the (larger) clade that
>instead have plesiomorphies.  Usually, crown taxa are numerous,
>stem taxa are few (this is a product of the concept of crown and
>stem, not a definition thereof).
>
>Hope this helps,
>
>         Una Smith

Crown taxon would thus be strictly synonymous to monophyletic group (= clade),
and stem taxon to paraphyletic group ? But then why would they regularly be
more numerous in crown than stem? Something else should be implicit in the
definition if this is the rule, because para / monophyletic groups do not
include notions of numbers of terminals.

Just a question, concerning this frequently encountered terminology, which
I do not use (but this is possibly a "cladistic bias" ?).

Pierre




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