Why is it bad for a group to be polyphyletic? What type of traits can be used in a cladistic analysis? Solution Polyphyletic group doesnot involve grouping of all the desendents of a common ancestor. This kind of grouping arises when analogous characters of the organisms were misunderstood. The organisms placed under polyphyletic group have similar characteristics, however they donot share these characters from a common ancestor. Cladistic analysis takes into consideration of shared characters i.e; synapomorphies, evolutionary relationship, common ancestor.