Real Species

Richard Pyle deepreef at BISHOPMUSEUM.ORG
Tue Apr 20 12:35:22 CDT 2004

Thank you, Pierre!  This is EXCATLY the line of thought I was fishing for.

> Individuals are rather well circumscribed biological systems in
> themselves.

Yes -- certainly moreso than populations or taxonomic clusterings.  But,
even individuals are dynamic entities (cycling from a pair of gametes,
through a succession of material turn-over, through entropy and
dissolution).  Subtly so in mega-fauna; less subtly so in colonial and other
more "ambiguous" individual organisms.  But this is another philosophical
discussion, probably not suited for this forum.

> This said, it is not because you have a clear criterion (or unambiguously
> combinable series of criteria) that species limits will not sometimes
> appear fuzzy in the real world (see other posts). This is "real" too: the
> easiness with which natural features will fit (or not well fit) into your
> conventional classification grid. Part of the explanation is the ongoing
> evolutionary process, and possibly "speciation" process, which is
> progressive in populations and biotas (see many other posts).

Yes!  Agreed on all points!

> Thus, OK with Richard's hint that species "boundaries are (artificially)
> defined by us as a means to allow more effective communication". And
> "effective communication" (hence relevant criteria) may change
> according to
> different questions at stake. Classification implements useful
> conventions (at best!).

Exactly!  Your ability to communicate in the English language is far
superior to my own! :-)

> Some will call "real species" the classes of individuals fitting
> unambiguously their classification criteria; they rather should be called
> "well discriminated species" according to these particular criteria.

Yes -- the critical issue here being "their classification criteria".  Thus,
species (or any other taxonomic or other aggregate unit -- including
subspecies, populations, etc.) are "defined", not "discovered".  But even
here we have a semantic thorn, because given a definition of "species", one
could argue that boundaries between those defined units are "discovered", by
way of acquiring information relevant to the definition.

> Example: suppose you have a population of elephants.

Great example --

> - other question: an extreme proposition for phylogenetic analysis is to
> use individuals as terminal taxa. Seems it should work. Certainly for
> clonally reproducing organisms. And likely for other ones too (you simply
> expect fuzziness in the "tokogenetic" apical zone of the tree... and some
> extra computing time!).

Just allow Moore's Law a few more iterations....or better yet, wait for
quantum computing to become a reality.

> Hence classifications and their corresponding classes are not
> "real or not real" (they exist from the moment we forge them),

To be fair, I believe the implied meaning of "real" in this context is that
they (taxonomic entities like "species") exist and are identifiable outside
the scope "artificial" (=created by humans) definitions of taxonomic units.
I.e., they are "discovered" in nature; rather than defined.

> they are "useful or not useful" in a specified context,

This is a critical point that usually gets forgotten in the various debates
(e.g., cladistic vs. eclectic applications of Linnaean nomenclature).


Richard L. Pyle, PhD
Ichthyology, Bishop Museum
1525 Bernice St., Honolulu, HI 96817
Ph: (808)848-4115, Fax: (808)847-8252
email: deepreef at

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