Copepod phylogeny: a reconsideration of Huys & Boxshall's ‘parsimony versus homology’

Abstract

A hypothesis of copepod phylogeny proposed by Huys & Boxshall (1991) was reanalyzed with the PAUP computer program by using TOPOLOGY and DELTRAN options to remove many character reversals. The remaining reversal characters were removed employing the Camin-Sokal Optimization Procedure. The resulting tree is two steps longer than the best fit tree (Tree C) obtained strictly by using parsimony criterion and optimizd with the same procedure. Further analysis revealed that the differences in these two cladograms are essentially due to the differential treatment of nine characters and varied assumptions of ‘missing state’ in another six characters as being apomorphies or plesiomorphies. Huys & Boxshall's hypotheses of character polarity in the copepods are shown not to be in conflict with the principle of parsimony. According to the principle of parsimony, their Tree C is the best supported phylogenetic hypothesis for Copepoda.