[tdwg-content] tdwg-content Digest, Vol 20, Issue 17

[Richard Pyle]

> I think there may be a useful distinction to be 
> made between these two cases which match Rich's 
> most recent cases 1 and 2+3):
>
> 1. A jar of mixed semi-identified organisms 
> from known-to-be disjunct taxa (e.g. two molluscan 
> genera, a green alga, and some fish larvae).
> 
> 2. A jar of one or more organisms collectively 
> identified down to a single taxon of any rank 
> (e.g. a jar full of ophiuroids only, all of which 
> may or may not be the same species, but 
> they're all "known" to be ophiuroids).

That wasn't exactly the distinction I was making.  I started writing a
separate post on this issue, but only got about half-way through before I
discovered that I wasn't even sure what my own point was, so I shelved it
for a later time.

What concerns me, though, is that you're still effectively introducing
"rank-ism" in the distinction above; as if a set of mollusks, alga and fish
were somehow fundamentally different from a set of organisms from seven
different families of ophiuroids.  

My proposed solution is to rigidly maintain that an instance of "Individual"
can not be partitioned to have multiple separate but concurrently legitimate
Identifications associated with it. It can have multiple Identifications,
but they would be considered to either be competing with each other (when
different taxa are asserted) or reinforing each other (when the same taxon
is asserted). They would *not* be considered concurrent with each other, and
applying to separate "parts" or "members" of a single aggregated Individual
instance.  

When, we know what the taxonomic breakdown is with some additional
precision, we partition out "child" individuals down to the level at which
we are able to confidnetly discern distinct taxa (and have time/resources to
attach Identifications as such).  That way, we keep our basic agreement that
an Individual must represent an aggregate of the same taxon, but we don't
impose any rank limitiations to what that taxon might be.

So, in your example, we would have one instance of Individual representing
the whole jar (assuming we wanted such an instance to record the fact that
they're in the same jar, or whatever.  That Instance may have no
Identification instances associated with it, or maybe only one for
"Eukarya".  But if you wanted to acknowledge the specific representations of
mollusks, algae, and fihses, you would generate (at least) three "child"
Individual instances, derived from the one "parent", and then each of those
child instances would have its appropriate taxon Identification attached.

> Without (yet) wrapping my head around this entirely, 
> I think I agree with Rich that we definitely find it 
> useful to be able to search taxonomically for higher 
> level taxa as well as searching for species. Without 
> being able to do so, we are forced to ignore all 
> instances that are not identified to species, and 
> that's just not a happy solution.

It's a little more subtle than that. As Steve pointed out early on (in his
response to John), we can still leave an organism identified only to the
level of, say, Order or Family; but still "believe" (confidently?) that when
we do make a more careful determination, we will find only a single species
among that aggregate.  

The real question is:  when we *don't* know (with confidence?) that the
constituents of an aggregated "Individual" will ultimately be shown to
represent a single taxon at the rank of species (or lower) -- or going even
further, when we *already know* that more than one species-rank taxon is
likely to be involved -- we should not be discouraged from treating the
aggregate as a single instance of an Individual, with a single legitimate
Taxon Identification, at whatever rank (Animalia, Ophiuroida, whatever) --
IF and WHEN circumstances warrant it.  At the moment, the only such
circumstances for the latter sort (i.e., we know that more than one
species-level is probably involved) that I can imagine are when we have
material, but we do not have the time/staff/expertise/whatever to go through
and add more taxonomic precision to the Identification(s).
	
> I've made the claim that we sometimes find it interesting 
> to be able to search taxonomically for (actually, to find) 
> records that describe the mixed-taxon case #1 above. 
> However, without allowing a one-to-many relationship between 
> "Individual" and a determination, I don't see how to 
> accomodate it in a straightforward scheme, and nor do 
> I think it is necessarily a good idea to do so.

That was buried in my last big post on this. I agree that it's not a good
idea to do so.  The solution is, when you are aware of what the subgroups
are, you generate instances of "Individual" to represent each one, then
attach an appropriate Identification to each.  You can still keep them in
the same jar; it's just that your database knows that the "parent"
Individual instance (the whole jar) has no Identifications associated with
it, or maybe only "Eukarya" or "Animalia" associated with it; and further
that this one "parent" Individual has multiple (semantically linked)
"derived" (or "child") Individuals, each of which has a more precise taxon
Identification.
	
> Unless a simple solution presents itself to me, I'm 
> willing to accept the idea that my case #1 and 
> case #2 cannot be folded into one tidy model.

I think the solution I proposed in my earlier email is sufficiently simple
in all respects *except* in terms of trying to explain it using the English
Language rendered in ASCII.

When I get time, maybe I'll whip up some diagrams and a better articulation
of what I mean.  But first, read my earlier post and see if I managed to
explain it just coherently enough....

Thanks,

Rich