Paraphyly=mistakes? (There's the rub)

Richard Pyle deepreef at BISHOPMUSEUM.ORG
Sat Jan 12 10:31:30 CST 2002

> One thing to note is is that Phylocode is more or less similar to Linnean
> nomenclature in that it is *not* (in fact, even less) able to communicate
> phylogenetic hypothese without text. Can anyone tell whether /Bombacaceae
> is included in /Malvaceae or not without looking at a cladogram?

I would venture to say that *any* practical nomenclatural system shares this
weakness; for any system that did, within a text string, explicitly
communicate every node back to the origin of life -- would almost cetainly
be wholly impractical!

The "names" themselves (text strings) are simply a communicative tool -- a
label to represent a concept.  We're not arguing about the information
contained within the characters of that text string, we're arguing about
what concept that (arbitrary) string of characters can be definied to
represent. It's the implied definitions that concern us here, not the
information concept of the names as written. One side of the argument
maintains that those definitions should be strictly limited to
"holophyletic" definitions, whereas the other side maintains that
definitions involving paraphyletic groups (i.e., certain subgroups excluded)
are acceptable in certain circumstances.

The fundamental difference (in my estimation) between Linnaean-style names
and Phylocode names, is that the Linanean names are ultimately defined by
only a single point (the holotype, type-species, etc.); whereas Phylocode
names are defined by two points (e.g., "the most recent common ancestor of
both 'A' and 'B'").  Because of the way Phylocode names are defined, those
definitions are better suited to maintain stability against the dynamic
"moving target" of hypothesized evolutionary relationships.

So no, neither Phylocode names nor Linnaean names include within their
text-strings information to identify evolutionary context (except in the
case of Linanean multinomials). However, stability of the *definitions* of
those names is better-maintained in the Phylocode system than in the
Linnaean system, when trying to have those definitions strictly reflect
evolutionary affinities.


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