Hi Gregor,
While I certainly agree there are many cases where both things happen in the same publication (i.e., the circumscription for the species "bus" changes, at the same time "bus" is moved from the genus "Aus" to the genus "Xus"); I see these as two unrelated things.
A classic (but rare) example of this would be when two different species, which are, respectively, the type species of two different genera, are synonymized as the same species. In this case, a new species-level concept is established at the same time that a genus-level name change is forced (one of the two genera becomes a junior synonym of the other genus). But this represents two different things, in my mind.
To change the circumscription of "bus" implies that the set of organisms included/implied within circumscription has either expanded or contracted. Doing so may inspire a taxonomist to synonymize genera, or to move a species circumscription from within one genus circumscription to another genus circumscription. But the act of doing either of these things (which directly affects the circumscriptions of the genera involved), does not have any impact on the circumscription of the included species.
The point is, the species may change genera as a result of re-defining the species circumscription; but the mere act of moving a species from one genus to another does not, by itself, affect the species circumscription (but it certainly does affect the circumscriptions of the affected genera). Thus, a change of the metadata of "GenusName" for a taxonID of a species does not require a new taxonID. But there are occassions where the change in a species circumscription (and hence, the need for a new taxonID) will also (coincidentally) involve a change to the "GenusName" metadata for one or more of the affected taxonID.
Aloha, Rich
-----Original Message----- From: tdwg-content-bounces@lists.tdwg.org [mailto:tdwg-content-bounces@lists.tdwg.org] On Behalf Of Gregor Hagedorn Sent: Monday, July 05, 2010 3:55 AM To: David Remsen (GBIF) Cc: tdwg-content@lists.tdwg.org Mailing List; Kevin Richards Subject: Re: [tdwg-content] Taxon Concept dilemma
Higher taxonomy
Is it generally agreed that higher taxonomy does not, in itself, impact the concept (circumscription) and therefore different classifications of a taxon are not criteria for a concept
identifier
change?
Yes and no, and I think this is the trouble with determining whether the circumscription was changed or not (your point 2 or 3).
In many cases, transferring a species into a new genus does implicitly change the description, because a set of previously unrecorded or misinterpreted characters has been studied and the genus description is now implicitly correct for these transferred species.
It may be that the diagnostic characters are still the same, it may be that previous option to misapply a name (previously undetected) now no longer apply.
For example, conidiogenesis in imperfect fungi is now routinely observed, and transferring a species into a genus with defined conidiogenesis in the last 50 years generally meant that the range of potential identification (correct or misapplied) was drastically changed. This occurs on all higher levels, not only but including genus.
I have therefore doubts whether the distinction between 2 and 3 should be made a priori; a system where a name change requires a new ID and where the reasoning is based on these IDs could be more flexible to adjust.
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Gregor _______________________________________________ tdwg-content mailing list tdwg-content@lists.tdwg.org http://lists.tdwg.org/mailman/listinfo/tdwg-content