Why is taxonomy placeless?

Robert Mesibov mesibov at SOUTHCOM.COM.AU
Fri Feb 1 10:18:11 CST 2002

Recent threads in TAXACOM have been very educational, and IMO,
participating taxonomists have explained the philosophical underpinnings of
their approaches very clearly. Something seems to be missing, however, and
I wonder if someone more taxonomically knowledgeable than myself could
explain why it isn't there. What's missing, in a word, is place.

Everyone seems to agree that we would like to know the structure of the
Tree of Life, which is a history of relationships. The Tree is a
tremendously useful abstraction because it ignores all the little fiddly
bits in Life, like how many setae are on the ventral surface of the basal
segment of the antenna, etc etc. That setal number may be a taxonomically
important character, but once it's played its role in building the Tree, we
can ignore it.

Also ignored are spatial locations. Looking at the Tree at highest
resolution, every single organism, past and present, has had an address or
a series of addresses. As we blur the Tree, going from individuals to
populations to subspecies to species to clade 1 to clade 2, etc, the
associated spatial information gets blurred, too, but not so much that it
isn't taxonomically useful. No taxa, except perhaps Kingdoms, live
everywhere on Earth, and many lower groupings, including many families, are
geographically restricted.

Spatial locations, like morphological and molecular characters, are not
randomly distributed in the world of Life. Yet locations, unlike other
characters, aren't part of the input in analytical methods for guessing the
Tree's structure. Why? Geography figures large in all the evolutionary
mechanisms (micro and macro) I've seen proposed, but it seems to vanish
when taxonomists attempt to clarify the results of evolution. Place becomes
an afterthought: 'This is taxon A, distinguished by these apomorphies,
related to taxa B and C in such and such a way. Incidentally, it lives in
the Atlas Mountains.'

Yes, I do understand that place isn't an obvious character when a
taxonomist studies a specimen. Place is on the specimen label, not on the
specimen. I also understand that incorporating place in the Tree of Life
would complicate the structure of this elegant abstraction. What surprises
me, though, is that taxonomists seem to be able to think very clearly about
phylogenetic relationships in a 'placeless' conceptual universe. Aren't
they missing something important?

Dr Robert Mesibov
Honorary Research Associate
Queen Victoria Museum and Art Gallery
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 64371195; 61 3 64371195

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