Blackwell Publishing

Classification and evolution - What are the advantages of cladism?


Cladism is theoretically the best justified system of classification.

Cladism has a deep philosophical justification that phenetic and partly phenetic systems lack. Cladism is objective, and objective classifications are preferable to subjective ones. Moreover, it is the only school that in theory will produce perfectly natural classifications: all sets of correctly identified shared derived characters must fall into the same phylogenetic hierarchy.

Despite these theoretical advantages, cladism can run into practical problems. The uncertainties of phylogenetic inference make cladistic classifications liable to frequent revision.

There is no orthodoxy among evolutionary biologists about the best kind of classification: some biologists are more concerned that taxonomy's practical procedures match its theoretical ambitions. In this case they may prefer phenetic classification. Others are concerned that not too much violence should be done to existing classification, in which case they will probably prefer evolutionary classification.

Figure: a cladistic interpretation of main vertebrate groups can be unsettling: reptiles are a paraphyletic group, made up of turtles, lizards, snakes and crocodiles and thus are removed from a cladistic classification.

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