outgroup determination

[Thorsten Burmester]

Hi,

I am wondering whether someone in the group can help me: Is there a
method to identify the likely outgroup of a tree when the substitution
rates greatly vary among clades? Or, in my case, to choose between two
clades? I think this could be done by comparing the relative distances
between lineages, but I neither know any program nor the theoretical
basis.

Thanks for your help.

Thorsten

-- 
Thorsten Burmester 
Institut fuer Zoologie, Universitaet Mainz, D-55099 Mainz, Germany
email: thorsten at erfurt.thur.de
       thorsten at uzomai.biologie.uni-mainz.de
       burmeste at ccr.jussieu.fr