[tdwg-content] Occurrences, Organisms, and CollectionObjects: a review

Richard Pyle deepreef at bishopmuseum.org
Thu Sep 8 10:52:15 CEST 2011

> As one of the primary brawlers on this topic, I've already said enough
> it, so I will restrain myself and just say that I fully support the

As another of the primary brawlers, I fully concur with Steve's comments
below.  Nice job, John!

> Well, mostly restrain myself...  I will make one comment about what John
> said below.  Although it is true that a CollectionObject (or "evidence")
> probably need to have been derived from an organism to be relevant in the
> Darwin Core context, there is no reason why a CollectionObject cannot
> simultaneously serve as evidence that the Organism existed, that an
> Occurrence occurred, and as support for an Identification.
> Particularly in the case of specimens, it is likely that the
CollectionObject will
> usually serve all three purposes at once.  A CollectionObject could
> serve as "evidence" for anything you want.  To some extent, that's one of
> the reasons for decoupling PreservedSpecimen from Occurrence.

I think I might agree with this, but I want to ask a simple question:

To what objects would an Identification instance apply?  In other words, an
Identification instance represents a link between an instance of Taxon to an
instance of [XXXXXXX].

In my mind, this should always be "Organism".  To me, neither an Occurrence
instance or a CollectionObject instance has a taxonomic identity.  Thinking
about it in database terms, an Occurrence represents a join-table between
Events (Place+time) and Organisms, and CollectionObjects represent the
providence for the Organism.

I agree with Steve that a CollectionObject can certainly provide evidence
that assists with Identifications and for documenting Occurrences.  However,
that doesn't mean that I think that there should be direct relationships
between instances of Occurrence or CollectionObject with instances of
Identification, or directly between CollectionObject and Occurrence (these
should happen through an Organism).

However, I also fully understand that assertions of this sort are outside
the scope of DwC (more an issue of onology), so this may not be the right
time & place to raise this issue.


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