Splitters and lumpers

Subject: Splitters and lumpers
From: "Wim Vader" <>
Date: Wed, 06 May 1998 10:04:38 +0200

                        TAXONOMY IS A FREE ENTERPRISE

        I have been a subscriber to several bird lists for some years now.
Regularly questions of taxonomy and nomenclature crop up, most recently on
EBN, after Dutch Birding has announced sweeping changes in the European
list of bird species, as the result of rigid adherence to the Phylogenetic
Species definition.Thios is an extreme case, but the same uncertainty is
behind questions of the type: "What is the right genus name for .....?
(Different books have different names)", or: "Are the Black Scoter and
Common Scoter the same species or two different ones?"

        As a taxonomist, albeit it of amphipods rather than birds, I have read 
recurring discussions about what species definition to use, and which
committee has the right to decide such things, with increasing incredulity.
In my opinion, problematic though that undoubtedly may be for all listers
and other users, no committee, even of the finest taxonomists of today,
will be able (should be able) to decide anything binding on species
definitions, or on which genus name to use. I`ll try to explain why I am so
adamant about this.

        In taxonomy, as in life generally, there have always been "splitters" 
"lumpers". The splitters are most impressed by the differences between
entities, and they therefore advocate small taxonomic entities and tend to
make more species, more and narrower genera etc.  The lumpers are more
impressed by similarities than by differences, and they will always prefer
larger species and fewer, broader genera.

On the genus level a good example is the genus Anas for all the dabbling
ducks:  early splitters have coined a lot of other genus names (Mareca,
Spatula,etc.), but in the last decades all dabbling ducks have been called
Anas (I expect a reaction soon). At the species level, the Scoters form a
good example: they are divided in 3, 5 or 6 species.

 There is fashion in taxonomy as there is other places in life: in some
periods the splitters are in fashion, in others the lumpers, and here as
elsewhere the children usually rebel against their parents, so that some
sort of pendulum movement results. Just now the pendulum is swinging from
an ascendancy of lumpers to a dominance of splitters: many genera are
broken up into smaller entities (See e.g. Larus, Parus), and the trend is
also to split up species into several smaller taxa. The theoretical
background this time is the phylogenetic species concept(i.e. one of the
several PSC´s in the running),-- and I must say that I am personally quite
impressed by many of the arguments of this school.
But it is the same old pendulum swinging inexorably from splitters to
lumpers and back again, of course superimposed on an ever-increasing
detailed knowledge of the field and an ever-growing number of described taxa.

So who is right and who can decide? It would be certainly great to have a
list of names that everybody has to keep to; now the birdlists are full
with questions as to whether the Silver Gull of Australia and the
Red-billed Gull of New Zealand are the same species or not. And what to do
with the sweeping revisions that the Dutch Birding Committee had proposed,
and that result in many more countable species in Europe; are they right or
are they wrong?
                 To such questions IMHO there IS no correct answer; every 
taxonomist is
free to apply his or her own species definition, with the resulting changes
in nomenclature, and no official body or committee can regulate this,
neither AOU nor Dutch Birding.

This "fact of life"  (Grandly called the freedom of science) is
self-evident for the small group of scientists toiling with the taxonomy of
amphipods, and the differences between individuals and schools of thought
constantly generate a lot of heat and not rarely also some light. But it
seems to be a very difficult concept for birders to grasp, primarily I
think because it would be so practical, nice and reassuring to have a
stable, all-accepted list of birds, that everybody could follow. IT WILL
NEVER HAPPEN! (And this is an advantage, from the scientific point of view).

Of course stability is a great good, and in communicating it is very
important to ensure that one does mean the same when using the same name.
Therefore the different ornithological and birding societies all have
guidelines and official lists to which they keep in their publications, and
to which listers have to keep in order to have their totals compatible. But
such lists can never constrain science! There is no right and wrong in most
of these questions; there are only different opinions!! That is often
infuriating in many ways, but it is not a pity! It is the way science

This is I think my first ever "Letter to the Editors" in my life. Not all
that constructive maybe, but it is meant as a defense of the freedom of
science, and the right to own opinions in these matters.

                                                Wim Vader, Tromsø Museum
                                                9037 Tromsø, Norway

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