Place in taxonomy

Robert Mesibov mesibov at SOUTHCOM.COM.AU
Tue Jul 2 16:41:35 CDT 2002

Tom diBenedetto wrote:

"I don't think that anyone, including cladists, would object to a
re-examination of their character-based phylogeny if that phylogeny
indicated sister-group relationships that are geographically bizarre. Such a
re-examination however would entail a more-careful examination of the
character evidence, an effort to discover new characters, or perhaps a
broadening of the scope of the analysis with the inclusion of more taxa. It
would not admit "non-biological"
evidence into the analysis, because all phylogenetic insight does indeed
come from the evidence of heritable characters (what you mean by "biology",
I presume). Is it the position of panbiogeographers that spatial
distribution patterns should be allowed to influence the outcomes of
phylogenetic analyses?"

Back in February my post "Why is Taxonomy Placeless?" included the para:

"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

Tom obviously agrees with my summary of the current situation, and now I
have an answer of sorts to my "Why?", namely: "all phylogenetic insight does
indeed come from the evidence of heritable characters."

This is an extraordinary statement and I'm hoping Tom or another Taxacom-er
might like to expand on it. I would have thought there were legions of
instances where phylogenetic insights were aided and abetted by knowledge of
where the taxa came from. How many times have I heard plant and animal
taxonomists describe a group as "Gondwanan," for example? Is "Gondwanan"
simply a shorthand way to refer to heritable, placeless character states in
that group, or is something else ringing bells in the minds of the listeners
(or readers), like the notion that evolution in the group was constrained by

Dr Robert Mesibov
Research Associate, Queen Victoria Museum and Art Gallery
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 6437 1195; 61 3 6437 1195

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