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Re: Convergence and Coding Characters



At 08:26 PM 1/25/99 -0800, Jaime A. Headden wrote:
>Jerry D. Harris wrote (in a response to Peter Wagner, which I
>gleefully snipped >:) :
        My name ain't Peter Wagner. Now, I understand your confusion over
various frothing-at-the-mouth-cladist, bannanas-for-phylogenetic-taxonomy
listmembers, but there's a Peter Buchholz and a Jonathan Wagner. Please pick
one of us to enthusiastically excise from your postings. Or, if you pick
both, do be sure to seperate us.

>  My problem with this is that the analysis would actually show that B
>had more characters than A.[...] This
>would suggest, at least to moi, that B was a more derived form of A,
        I'm not sure this is what you mean, so several responses:
        A)      "That B might be more derived THAN A" is not necessarily the
case. Remember, we only code for SYNapomorphies. A might have twenty
autopomorphies, in which case you'd probably say A was more dervied than B.
Of course, this assumes that a metric of degree of derivedness can be trusted.
        B)      "That B was a more derived for of A" implies an
ancestor-descendant relationship, which cannot be proven.
        C)      "That B was a more derived member of the CLADE including A"
is a bit tautological. They are in a clade, and one almost certainly more
derived than the other, by whatever metric you choose (e.g. normative
morphological difference from the ancestral state).

>or that A and B share a common ancestor for which streptostyly is a
>character and in B, the aquisition of additional distinct morphology
>would then be defining characters:
        Or synapomorphies linking it to other taxa not currently seen on
your cladogram.

>       B
>      /__3
>  A  /__2
>   \/__1
>
>  Tell me if I'm offbase here.
        Looks good.

        :)
        Wagner
--------------------------------------------------------------------------------
     Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
 "Only those whose life is short can truly believe that love is forever"-Lorien