revolution

Alexey V. Kuprijanov q at SN.PU.RU
Wed Oct 2 01:03:11 CDT 1996


Linnaeus said: 'Remember: not the character constitutes genus
but genus constitutes its character'. It should mean the following.
You should first recognise in some way units of diversity, then
find the characters to make these units recogniseable for other
taxonomists, and then protect your units against the mad cladists
using cladistic analysis. Such units will be immunised against
varying of datasets. The distribution of characters will be highly
consistent with the distribution of objects in units.

As to discordances:
It is obvious that 1) the apo- plesiomorph polarity of character-
states depends on the outgroup chosen by the author and 2) varying the
character-sets you could get various results. The latter is particularly
true for such cases when anybody having no idea about the structure of
diversity in the group under study simply put in the computer a bag of
characters and strikes the button. Of course several such persons
can obtain the very different results. I am not sure that comparison
of these results will lead us to important conclusions.

in-reply to:

>   Phylogenies published today seem to be primarily the shortest tree (or the
>   concensus tree) generated by PAUP.  A different dataset with the same
>   organisms may produce a different shortest tree, but how far off is this from
>   the previously-published one?  Is it nearly as short, or grossly complicated?
>   I wish someone would start examining this question for organisms for which
>   multiple datasets have been worked on.  If they are discordant, *how*
>   discordant are they?  I should think this would provide some evidence about
>   the validity of both trees (i.e., if they're slightly discordant, perhaps both
>   are nearly correct; if they're wildly discordant, there's something else going
>   on that needs to be understood).
>
>   Robin Panza                     panzar at clpgh.org

Sincerely yours, Alexey




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