The role of the biogenetic convergence rule in polarizing transformation series - arguments from nematology, chaos science, and phylogenetic systematics

The new term biogenetic convergence rule is suggested as a replacement for Haeckel’s old term biogenetic law. It works as follows: by converging on identical adult structures, polarizations of phylogenetic transformation series are determined by those of corresponding ontogenetic transformation series. Examples from nematology are presented. Cases of paedomorphosis are subject to a second rule suggested as the biogenetic suppression rule. A third rule, suggested as the adaptive convergence rule, refers to well-known cases in which adaptions to particular environmental conditions result in the similarity of otherwise different structures. Essential findings of chaos science are outlined and illustrated by Waddington’s epigenetic landscape in order to show that the biogenetic convergence rule fits to these new findings. Contrary to common belief, the popular outgroup algorithm reveals to be unsuitable for polarizing sequences of character states. For theoretical reasons, Hennig’s unsupported demand is rejected to accept only holophyletic taxa as valid. Paraphyletic taxa must also be accepted as valid. Therefore, phylogenetic systematics sensu Hennig and evolutionary systematics sensu Mayr are suggested as synonyms.