I've said it many times before on this list elsewhere:
"A species is what community of taxonomists says it is."
It also happens to be the de-facto operational definition ever since the notion of "species" first began, all the way through (and including) today. Until we have another definition that is broadly adopted by the taxonomic community, then it will remain the de-facto operational definition.
What Darwin said in the 'Origin of Species' is still true today: "No one definition has as yet satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species."
And, by the way, here's how Darwin, in his characteristically overly verbose way, had to say on the matter:
"Hence, in determining whether a form should be ranked as a species or a variety, the opinion of naturalists having sound judgement and wide experience seems the only guide to follow. We must, however, in many cases, decide by a majority of naturalists, for few well-marked and well-known varieties can be named which have not been ranked as species by at least some competent judges."
In other words, "A species is what community of taxonomists says it is."
Aloha, Rich
-----Original Message----- From: Bob Morris [mailto:morris.bob@gmail.com] Sent: Sunday, January 25, 2009 7:28 AM To: Richard Pyle Cc: tdwg@lists.tdwg.org; Taxacom@mailman.nhm.ku.edu Subject: Re: [tdwg] Semantic Web: What is a species?
Ah, Rich, might I understand your position to be akin to that of the U.S. Supreme Court Justice the Honorable Potter Stewart whose concurring opinion in Jacobellis v. Ohio 378 U.S. 184 (1964) contains the famous words, refering to "obscenity":
"I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description; and perhaps I could never succeed in intelligibly doing so. But I know it when I see it, and the motion picture involved in this case is not that."
:-)
Bob Morris
On Sun, Jan 25, 2009 at 6:44 AM, Richard Pyle deepreef@bishopmuseum.org wrote:
First, I think the comment that I *most* agree with is the
one made by
Gurcharan Singh, that these conversations are endless (and will probably always be so). There are two reasons I can never seem to miss an opportunity to dive in and pontificate (Jim C.,
that's your cue...):
- I usually have a slightly different perspective at the end these
conversations, than I had at the beginning (always a good
thing); and
- I enjoy the intellectual challenge of trying to make the
same basic
points each time using a different tact, and coming from a
different
perspective.
Now, Pete:
When a medical entomologist states that a species X, breeds in shallow
ephemeral pools and
has a preference for human blood meals do they mean
The taxonomic hypothesis A. o. has these properties or
the "natural" unit currently called A. o. has these properties ?
Frankly, I don't think most medical entomologists think that deeply about it. In fact, I don't think most taxonomists even
think that deeply about.
I suspect most biologists/scientists/laymen think of
species as "things"
that exist in nature, and that these "things" have certain
properties
that are consistent enough to allow predictions and such.
And I would
wager that, in the vast majority of cases, they would do so
with good
success. That doesn't make species "real" in my mind (or
even any more
"real" than other taxonomic units -- in fact I think
populations are
probably more demonstrably "real" than species). It just makes the notion of "species as real" a practical one (as if we
didn't already
know that, after centuries of people thinking in those terms).
I think they mean the second and would benefit if the
statements made
about that natural unit
could stay linked to the natural unit species concept over time.
Unfortunately under the "species is the taxonomic
hypothesis" system
they
don't.
Does this help clarify the distinction I am trying to make?
I'm not sure -- partly because I've never quite understood
what people
mean by "species are hypotheses". By my reckoning, it's only an hypothesis if it's testable & falsifiable. As such, it only makes sense in the context of "species are real entities in
nature, and we
can test whether our circumscriptions (aka taxon concepts)
match those
real entities". So I've always thought of "species are hypotheses" and "species are real, natural entities" as being two sides
of the same coin.
So I guess I don't understand the distinction you're
drawing between
the two.
Aloha, Rich
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-- Robert A. Morris Professor of Computer Science UMASS-Boston ram@cs.umb.edu http://bdei.cs.umb.edu/ http://www.cs.umb.edu/~ram http://www.cs.umb.edu/~ram/calendar.html phone (+1)617 287 6466