The Implications of Phylogenetic Analysis for Comparative Biology: the Thirtieth Annual Systematics Symposium

This symposium brings together seven systematic biologists to discuss the relationship between phylogenetic systematics (cladistics) and various branches of comparative biology. Cladistic theory and method were not the focus of this symposium, but rather it addressed how the results of cladistics—that is, hypotheses about phylogenetic pattern—are an essential component of historical analysis. Thus, the papers presented here illustrate six specific problems that, directly or indirectly, rely on cladistic analysis for their solution. Cladistics became an important force within systematic biology following the English translation of Willi Hennig's "Grundzuge einer Theorie der phylogenetischen Systematik" (1950), which was updated in 1966 as "Phylogenetic Systematics." From that time, cladistics has steadily increased in influence, first within zoology, and somewhat later in botany (for an introduction to cladistics, see Eldredge & Cracraft, 1980; Wiley, 1980, 1981; Patterson, 1980; Nelson & Platnick, 1981; Cracraft, 1983; Humphries & Funk, 1984). During this period many workers have discussed the pros and cons of cladistics, and frequent misunderstandings about the theoretical and methodological content of cladistics have arisen. Perhaps contributing to this situation is the fact that the views of cladistic theoreticians have also evolved, often along divergent pathways so that the field of cladistics is now broader, and consequently more internally contentious, than it was 15 years ago. Despite this diversity, the question can be asked whether cladistics is united by any underlying principles so as to form a coherent research program. An answer to this question is of interest beyond being able to differentiate cladists or their work, because it also helps to place the various transformations of cladistics into a common framework and to gain a perspective on some of the arguments that are currently being expressed over the meaning and content of cladistic thought.