Panbiogeography 1981-91: development of an earth/life synthesis

Abstract

Contributions to the method and theory of panbiogeography are reviewed in relation to a New Zealand interest that arose from the late 1970s and early 1980s. Panbiogeography was developed by Leon Croizat in the 1950s, but ignored by prominent evolutionary theorists in favour of traditional explanations of geographic distribution established from Darwin's time. The New Zealand interest has provided a critical reappraisal of Croizat's work and its continued relevance to evolutionary theory through new developments in method and synthesis.

Panbiogeography is presented in this review as an exploration of Hooker's paradox - the problem of integrating contradictory aspects of earth and life in space/time. Croizat's approach to biogeography involved analyses of geographic distribution by linking localities together to form line graphs called tracks. Analysis and interpretation of tracks has been developed by application of graph theory techniques for quantitative and statistical measures of track inter-relationships and their biogeog raphic significance.

Panbiogeographic approaches have developed the application of defining features called 'baselines' that represent spatial characters for biogeographic homology. Ocean basins comprise important biogeographic features for the baseline orientation of tracks. This approach has resulted in a new classification system where ocean basins are the natural biogeographic regions while major landmasses are located at regional boundaries. This subsumes the conflicts and contradictions inherent in the geographic classifications developed from Wallace onwards.

Panbiogeographic correlation of tracks with tectonic features provides a geographic basis for interpreting the evolutionary relationship between earth and life. Different standard tracks are compared in reference to the associated tectonic features such as spreading ridges, fault systems and suture zones. Novel geological predictions generated from distributional and tectonic congruence illustrated for the Americas, and for New Zealand where a novel parallel arcs model has been proposed for its natural history and evolution.

The conceptual implications for evolutionary ecology are explored in terms of life evolving as a 'geological' layer where organism-environment relationships evolve through coconstruction of interdependent processes rather than by interaction of organisms and environments as separately preformed entities. Progress in panbiogeography over the last decade provides a significant contribution to evolutionary theory through the continued development of a spatiotemporal synthesis for understanding biological and geological processes responsible for local and global biodiversity.