Phylocode
Phylocode (noun,no plural;nomenclature term) – a (supposedly) rank-free system of biological nomenclature proposed as alternative to the Linnaean system; introduced to name clades within a phylogeny. Protagonists of the Phylocode suggests that clades are different from ranks because they are hypotheses about phylogenetic relationships and not subject to subjective assessment. The hierarchy of the Linnaean System is criticized because of the assumption that taxa of the same rank should be comparable to one another. This comparability of taxa of the same rank certainly was never achieved within the Linnaean System. Clades therefore represent a more accurate way for comparison than artificial ranks of the Linnaean System. However, the implication that clades do not constitute ranks might still be a misconception. In addition to the debate about taxonomic ranking, it is also argued that the Phylocode will present a more stable system of biological nomenclature. The renaming of taxa solely for nomenclatural reasons can be avoided in because taxa retain their names even if a new or altered phylogeny is introduced. However, this presumed advantage is not without problems. In the Linnaean System names are based on types and can (at least theoretically) be traced back to a particular specimen. Name changes are a consequence of a different ranking. This especially affects the binominal. Every time a species is transferred to a new genus, the species name automatically changes. In the Phylocode names are based on clades, not on types. With a change of the phylogeny, the names can therefore be retained even though these names then apply to a newly delimited group. With every changed phylogeny the group of taxa belonging to a particular clade change even though the name is retained. Thus, although names appear to be more stable, their biological meaning is subject to constant change until the "true phylogeny" of all taxa can reliably be deducted. The assumption that a "true phylogeny" can indeed be found is contrary to basic principles of the scientific method, namely the principle that every hypothesis is valid only until rejected and all theories are based on hypotheses that will continue to be challenged by new scientific evidence.
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