On Tue, 6 Feb 1996, Michael Hobbs wrote:
[...]
> That said, I still disagree with you about being able to name branches
> in a meaningful way without needing lumping and splitting.
>
> Consider the case of the Western Flycatcher, where birders thought
> there was one species, but the birds thought otherwise. If we don't
> change the way we refer to these birds, we miss a point that is
> apparently very important to the birds themselves.
[...]

"Splitting" is when a taxon assigned one categorical rank is divided
into two or more taxa that are accorded the same rank as the original.
"Lumping" is when multiple taxa of a given categorical rank are subsumed
under one taxon of that rank. Consider the case of Baltimore and
Bullock's orioles. Originally these populations were recognized as
distinct species. Later, the AOU decided they were really subspecies of
a single species, so they lumped two "species" into a single one,
Northern Oriole (also Abeille's oriole was lumped in here, too, I
think). But the *taxa* involved -- the populations in question and the
more-inclusive taxon that embraces them -- remain unchanged; all that
has changed is which one(s) we call species. Now the AOU is reversing
its early conclusion and splitting/unlumping Northern Oriole. Now the
AOU is reversing its earlier conclusion and splitting/unlumping Northern
Oriole. If you remove the labels "species" and "subspecies," there is
nothing to split or lump. In this case, the branches we recognize remain
unchanged; all we are doing is shifting the label "species" up and down
the branches.

The case of the Western Flycatcher is slightly different, as what we
once thought a single branch is now recognized as two, that is, what
was thought to be one homogeneous population is recognized to be two
distinct populations. Since the smallest evolutionarily distinct
populations we recognize are "species," the newly recognized
populations are species, and the original "species" is history. In
this case, splitting resulted from a change in perception of the
distinctness of the populations involved, not simply a change in what
ranks we accord to previously recognized taxa (as in the oriole case).
But splitting in this case is still a consequence of recognizing
a category (species) in addition to a taxon (the branch in question).

Birders are probably most aware of splitting and lumping of species, but
splitting and lumping also occur at higher categorical levels such as
genus, family, etc. I hope it is clear that removing these categories
from our nomenclature would remove the need for splitting and lumping
at these higher levels. But as long as we recognize species, there
will be splitting and lumping of this category. There are too many good
reasons to recognize the "branch tips" as being special, so we will
probably always recognize "species," and there thus there will probably
always be splitting and lumping of taxa assigned to this category (but this
is still a consequence of recognizing ranks). Note however, that if we did
away with "subspecies" and simply called the smallest diagnosable/nameable
branches "species" (i.e., recognized only one category), much of the
splitting and lumping of species would cease (i.e, no need to shift
species + subspecies labels up and down the branhces of the tree). Any
splits in such a system would reflect recognition of new taxa (as in the
Western Flycatcher case). The stablizing effect of doing away with
subspecies is another reason some systematists favor the PSC, which
simply calls the smallest recognizable (diagnosable) branches on the tree
as species.

David Wright
dwright at u.washington.edu



Bill and Nancy LaFramboise
Richland, WA
wlafra at oneworld.owt.com