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Transformed cladistics, also known as pattern cladistics is a proposed classification system within cladistics which excludes common ancestry from cladogram analysis. It was popularized by Colin Patterson in the 1980s, but has few modern proponents. ==Patterns vs. processes== The standard approach to cladistics which traces back to Willi Hennig (1950) groups together organisms based on whether or not they share characters or character states that derived from a common ancestor. Transformed cladists instead maintain that cladistics should be free from the assumption of common descent or the theory of evolution (as a process) altogether, and based only on empirical data: In other words, pattern cladists argue that the less information a classification presupposes, the fewer errors creep in, and greater objectivity results. They draw a distinction between patterns, which are observed, and processes, which may be inferred from patterns, but which should not be presupposed. Joseph Henry Woodger before the emergence of transformed cladistics as a school criticized phylogenetic systematics on the grounds that homology by way of common ancestry is "putting the cart before the horse, because descent from a common ancestor is something assumed, not observed. It belongs to theory, whereas morphological correspondence is observed." (Woodger, 1945). Colin Patterson later wrote similarly: Pattern cladists, like standard cladists, limit their classifications to nested sets (patterns) of synapomorphies, but they argue that the characters are irrespective to common ancestry: Nelson & Platnick (1981) also note that: "''all'' of Hennig’s groups correspond by definition to patterns of synapomorphy. Indeed, Hennig’s trees are frequently called synapomorphy schemes. The concept of ‘patterns within patterns’ seems, therefore, an empirical generalization.” Pattern cladists hence regard synapomorphies to be patterns free of processes. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Transformed cladistics」の詳細全文を読む スポンサード リンク
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