[Taxacom] Read... and believe...

Bob Mesibov mesibov at southcom.com.au
Sun Sep 6 21:46:17 CDT 2009


I'm having a little trouble understanding how you project your wish for well-organised comparative data over time, i.e. over the many decades that a particular group has been (and will be) studied. So, the comprehensive organising of character data works fine at Time N, but at Time N+1:

a) Old methods give consistent and reliable character states, but with new methods, you find that many of the states were incorrectly recorded.
b) Individual characters are shown to be more complex than previously thought, and require reworking as multiple characters with new and different states, and the Time N set needs to be chucked out.
c) Many new characters are discovered which have to be added to descriptions.
d) Some old characters really need to be discarded, e.g. they were believed to be apomorphic but are now known to be plesiomorphic.

The paper you quote IMO confuses inadequate description with outmoded description. I think those are two different things. One specialist I know bravely created a matrix with many more characters than any one previous description had ever included, then went back to types to fill in the states for a *lot* of species. (This was for a phylogenetic analysis.) He dealt with all 4 of the time-related issues above, but he isn't naive enough to think that his matrix will be 100% correct, or even useful, in 100 years' time.
Dr Robert Mesibov
Honorary Research Associate
Queen Victoria Museum and Art Gallery, and
School of Zoology, University of Tasmania
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 64371195; 61 3 64371195
Website: http://www.qvmag.tas.gov.au/mesibov.html

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