Biological Systematics provides a critical overview of the state of the art in biological systematics and presents a broad perspective of the subject, covering its history, theory and practice. The most improtant current theoretical issues are reviewed with the emphasis on the species concept, the methodology of phylogenetic reconstruction and contrasting views on the relationships between phylogenetics and systematics. A large part of the book is devoted to a review of the current state of taxonomy of the main groups, concluding with a discussion of evolutionary patterns.