Poor Willi Hennig?

Erich Schwarz schwarze.ccomail at starbase1.caltech.edu
Thu Sep 21 20:24:28 EST 1995

Ulrich Melcher wrote:

>      Here is my concern.  If we have a tree whose statistics suggest 
> that the star topology is not applicable, how can we be sure that the 
> topology implying a line of descent is not due to limited sampling?

     I don't think you *can* be sure: sensible people see trees as
estimates, not as revelations "written on stone tablets" (Yockey).  But
one can do bootstrap, log-likelihood ratios, or other tests to see how
statistically *robust* one's tree is.

> Is it possible that there are only a limited 
> number of regions of sequence space (corresponding to subtypes) 
> compatible with a successful HIV-1?  This would mean that the sequence 
> space between subtypes consists of HIV-1's with poor "fitness".  It 
> would also mean that the subtypes were generated by rare events of a 
> virus of one subtype jumping into another peak in sequence space. 

     Hmmm.  Anybody else got an answer?

> Arguing against this are the observations of apparently successful 
> recombinants between subtypes.

     Ah, a Usenet poster who provides his own caveats.  How refreshing.  :)

--Erich Schwarz

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