title: What is a virus species? Radical pluralism in viral taxonomy.
abstract: Early attempts in the 1960s at constructing a classification scheme for viruses were phenetic and focused on structural properties of the virion. Over time, the International Committee on the Taxonomy of Viruses (ICTV) has refined its definition of a virus species to include an appeal to evolutionary history. The current ICTV definition defines a viral species in terms of monophyly. The existence of prolific horizontal genetic transfer (HGT) among various groups of viruses presents a challenge to this definition. I argue that the proper response to this mode of evolution is to allow for radical pluralism. Some viruses can be members of more than one species; others don't form species at all and should be classified using new reticulate categories.
authors.affiliation: College of Arts and Letters, Stevens Institute of Technology, 1 Castle Point Terrace, Hoboken, NJ 07030, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Morgan
mesh_terms: D005075:Biological Evolution; D022761:Gene Transfer, Horizontal; D049810:Genetic Speciation; D010802:Phylogeny; D014780:Viruses / Q000145:classification* / Q000235:genetics
keywords: Horizontal gene transfer; ICTV; Mosaic genomes; Radical pluralism; Viral species; Viral taxonomy; Virus classification; Virus species