Taxonomic Congruence

Abstract

Mickevich, M. F. (Department of Ecology and Evolution, State University of New York, Stony Brook, New York 11794) 1978. Taxonomic Congruence. Syst. Zool. 27:143–158.—The congruence (similarity in groupings) between classifications of the same organisms based on different characters measures the stability of classification as new sources of information are considered. Pheneticists have claimed taxonomic stability for their approach and instability for the cladistic system, but have not compared the stability of the results of phenetic and phylogenetic methods. The stability of five phenetic and three numerical phylogenetic methods was assessed using nine pairs of data sets. A phylogenetic method resulted in statistically demonstrable higher stability. All phenetic methods have essentially the same instability behavior. Of the phylogenetic methods, that of Wagner shows consistently greatest stability. The stability of phenetic methods is demonstrably more sensitive to the amount of homoplasious evolution than the Wagner method. Yet, the number of characters has no effect on stability either for the phenetic methods or the Wagner method. Since phylogenetic methodology is more stable than phenetic clustering, the cladistic system should be used as a general reference system for biology.