Biological Reviews of the Cambridge Philosophical Society



Review Article

The grand game of metazoan phylogeny: rules and strategies


RONALD A. JENNER a1 and FREDERICK R. SCHRAM a1
a1 Institute for Systematics and Population Biology, University of Amsterdam, Post Box 94766, 1090 GT Amsterdam, The Netherlands

Abstract

Many cladistic analyses of animal phylogeny have been published by authors arguing that their results are well supported. Comparison of these analyses indicates that there can be as yet no general consensus about the evolution of the animal phyla. We show that the various cladistic studies published to date differ significantly in methods of character selection, character coding, scoring and weighting, ground-pattern reconstructions, and taxa selection. These methodological differences are seldom made explicit, which hinders comparison of different studies and makes it impossible to assess a particular phylogeny outside its own scope. The effects of these methodological differences must be considered before we can hope to reach a morphological reference framework needed for effective comparison and combination with the evidence obtained from molecular and developmental genetic studies.

(Received May 14 1998)
(Revised December 4 1998)
(Accepted December 16 1998)


Key Words: phylogeny; Metazoa; Animalia; cladistics; Articulata; Eutrochozoa; evolution.