Biological evolution is directly affected by geological evolution. The evolutionary relationship between organisms and their environments is interwoven to the extent that dispersal ability is a function of the ecological relationship between organisms and their environments. This is in contrast to the view expressed in Darwinian biogeography where dispersal ability is portrayed as a function of the organism (the different 'means of dispersal').
The above cartoon exemplifies the concept of biological distribution being constrained by factors that are inherent in neither the organism or environment alone, but organism/environment boundaries specific to particular places, times, and organisms.
Here the boundaries are represented metaphorically in the form of an organism-environment fence. Illustration prepared by Frank Climo, Wellington, New Zealand.
1. An attempt to reintroduce and reemphasize the importance of the spatial or geographic dimension of life's diversity for our understanding of evolutionary patterns.
2. An approach to biology that focuses on the role of locality and place in the history of life. Research goal: To recover the importance of places and localities as direct subjects of analysis in biogeography.
Core position: The acknowledgement that an understanding of locality is a fundamental precondition to any adequate analysis of the patterns and processes of evolutionary biology.
Research emphasis: The role of place in the process of the past as understood from the perspective of the present.
1. Distribution patterns constitute and empirical database for biogeographical analysis.
2. Distribution patterns provide information about where, when, and how animals and plants evolve.
3. The spatial and temporal component of these distribution patterns can be graphically represented.
4. Testable hypotheses about the relationship between the evolution of distributions and earth history can be derived from geographical correlations between distribution graphs and geological/geomorphic features.
A page from one of the numerous notebooks on biogeography and biology maintained by Croizat while at the Arnold Arboretum. These booklets were to provide a major source of information while Croizat wrote his books and articles in Venezuela.
Croizat wrote prolifically on biogeography. His first book, published by Junk in 1952, presented the first comprehensive global review of spatial congruence for plant and animal distributions. It now sells for about US$150 in the used book market.
Croizat's second major publication in 1958 was privately published in Caracas, Venezuela. This decision to publish privately was a necessity in order to avoid the anticipated editorial censorship that would otherwise have prevented publication of his novel approach to biogeography. It is no overstatement to say that panbiogeography would be considered heresy among biogeographers of his time.
Leon Croizat emigrated from Italy to the United States in 1924, and during the 1930's he met E. D. Merrill who became Director of the Arnold Arboretum in 1936. Merrill provided Croizat with the position of technical assistant, but when Merrill was forced out of office ten years later, Croizat was also dismissed, apparently in retaliation for publishing an article critical of work by Irwin Bailey of the Arboretum (Craw, 1984).
Croizat subsequently accepted an academic position with the Universidad Central de Venezuela and in the following years he continued to write on botany and biogeography with the support of his wife Catalina, a child psychologist and later a landscape architect. Together they developed a major botanical garden of xerophytic plants outside the town of Coro (Craw 1984; Grehan, 1990a; Zunino, 1992).
Croizat's formal training was in law, for which he received a doctorate (Zunino, 1992), but he had a long-standing interest in biology and botany. He was later to refer to his training in law as a critical foundation for presenting evidence in support of his biogeographic and botanical arguments.