Gene Hunn:
> I'n not a professional in these matters but my impression is that the
> actual contrast in taxonomic assignments between proponents of these
> alternative species concepts is miniscule with respect to the totality of
> taxonomic categories recognized. The major disagreement seems one of
> semantics: what level of the taxonomic tree is to be called the "species"?
> The terminal contrast level or some level above that of terminal contrast
> at which "gene pool isolation" seems to be well established. There seems
> little real difference of judgment as to the actual SHAPE of the tree.
> Examples such as that of the orioles seem to me minor differences of
> interpretation or weighting of various subsets of the characteristic
> contrasts between branches of the tree.

As one who has lived and breathed formal language theory my entire
adult life, I've been tempted to jump in with some comments very
close to those of Gene's. I've enjoyed watching you bios stumble
about the argument too much to do so, thus far :)

However, Joe Morlan's recent note regarding evolution essentially
argues that it does NOT occur at the terminal nodes. He argues
that gene flow between terminal nodes (subspecies) means that
change within those nodes show up, intermixed, and therefore
evolution does not occur at the fringe of the tree, but higher
up (species).

True? I'm skeptical. For instance, spotted owl subspecies
are non-migratory and, I should think, rarely mix. There must
be some gene flow at the boundaries, but there must also be
significant portions of the range in which virtual isolation
occurs. One poster mentioned Bullock's and Baltimore oriole
of an example where gene flow across the hybridization boundary
is so slow that it is overwhelmed by the pace of incremental
change in the two populations (thus arguing they should be
split). But why wouldn't this be true for non-migratory
subspecies such as we find in the spotted owl, as well? I
agree with Joe Morlan that genetic flow occurs across the
boundaries separated them, but believe that the rate must be
very slow. In this case, divergence and eventually speciation
may well occur 'tween these subspecies. The most radical
position taken so far in these posts seems to be that yep,
this is true, and they're unlike to merge into a single
gene pool, so we should consider them species today (along
with a bazillion song sparrow populations, etc).

Of course, Joe may just want to argue that 'ole spotty should
be split as well, but since he seems to be taking a conservative
stance in the argument, I doubt it.

- Don Baccus, Portland OR <donb at rational.com>