Are Monotypic Genera Paraphyletic?-A Response to Norman Platnick

Abstract

Platnick (1976) suggested that in a phylogenetic classification it is not possible to have monotypic genera under any condition other than an unresolved tri- or polychotomy, and that "monotypic genera seem impossible as they must always exclude at least 1 other species that is a descendant of the most recent ancestor (i.e., they must always be paraphyletic)." A logical extension of Platnick''s reasoning that other monotypic supraspecific taxa (e.g., families, orders, etc.) are also paraphyletic, is contested and arguments are presented in support based on the evolution of Lepisosteus and the Actinopterygii.