Ontogeny and Systematics

Abstract

Literally hundreds of authors have attempted to interrelate ontogeny and systematics and to find the meaning in their connections (43). Few would doubt the inherent complexity of the subjects but clearly their study has been made overly difficult by imprecise and contradictory communication (34, 63). Even von Baer's laws (100; see below), the very bases from which many theses have been developed, are so vaguely stated as to allow more than one interpretation. Further, the tendency has increased to try to interpret the older literature as if it were a coherent discourse that always led to a better understanding, when in all likelihood at least some of the early workers were simply confused and matters were, more often than not, left unresolved. It is also apparent, especially recently, that history is being rewritten in order to support a particular point of view (10, p. 38). A final complication relates to the fact that systematics is not always placed in a theoretical framework of evolution and speciation. Of course this is to be expected in the pre-Darwinian literature; however, that position has unexpectedly been readopted by some of our contemporaries (54, p. 17). The difficulty lies not so much in the new version of the old position, but in the ambiguous and inconsistent communication justifying the change. Our review does not cover all relevant aspects of ontogeny and systematics, nor do we attempt to treat exhaustively any particular issue. Our effort is to survey some of the more important generalities. We also hope to clarify a few longstanding problems, as well as to highlight areas for further research. We focus largely on the descriptive issues of animal ontogeny. Processes and plants are well beyond our expertise. We assume that the genome and epigenetic phenomena produce a morphological superstructure, within which are embedded the traits we observe and describe. We do not consider the mechanisms