Contrasting the general with the particular in phylogenetics - A proposal to keep the meanings of mono/paraphyletic and clade/grade separated

Abstract

Clade and monophyletic group on one hand and grade and paraphyletic group on the other hand are commonly used as pairs of interchangeable terms. I question this apparent synonymy and propose that "monophyly" and "paraphyly" should refer to a property of a set, whereas "clade" and "grade" should apply to individuals resulting from evolutionary process.