| Abstract: | Using a computerized phylogenetic analysis of the Isopoda (Crustacea: Peracarida) as source of typical errors and misunderstandings, problems that may occur in computer cladistics are reviewed. It is concluded that in addition to the errors that are possible in a conventional Hennigian analysis some specific methodological problems exist in computer cladistics. It is recommended that the OTU be replaced by the groundpattern concept. Tree statistics are not useful for comparing different competing hypotheses. Arguments ought to concentrate on the hypo-thetico-deductive steps of the analysis, i.e. on character analysis. The use of computers does not add objectivity to character analysis. Single outgroup taxa should not be used in assessing the character states of ingroups. Concerning isopod phylogeny, it is argued here that the tail fan of the Isopoda can probably be derived from the eumalacostracan groundpattern and did not evolve de novo within the Isopoda. |
