The Origins of the New Zealand Fauna and Flora: A Review

Abstract

IOGEOGRAPHICAL problems can be meaningfully discussed only within the context of biological systematics. A study of the origins, relationships, and biogeography of any part of the New Zealand biota must therefore include two basic considerations: first, real floristic and faunistic affinities must be distinguished from those that are merely apparent; and second, even when such affinities have been satisfactorily established, it is still necessary to demonstrate how the taxa in question came to be assembled in New Zealand. Although all biogeographical discussion is necessarily speculative, postulated dispersal routes must not be at odds with the geological evidence, and suggested dispersal mechanisms must be compatible with the known biological characteristics of the organisms. The search for true evolutionary relationships within a group or between groups must be guided by a scheme of phylogenetic systematic analysis such as that designed by Hennig.' This method has proved to be of such basic importance in taxonomic and biogeographical studies that a recent worker suggested that it should be called Hennig's Principle.2 Hennig believed that unassailable reconstruction of the history of phyletic groups could be carried out only through detailed comparative study of plesiomorphic (relatively primitive) and apomorphic (derived from, or advanced relative to, the primitive condition in any given instance) characters. By his reasoning, only a pattern of apomorphic characters could be used to demonstrate that species and genera formed truly monophyletic groups