© 1982 by The Society for Integrative and Comparative Biology
Alternative Hypotheses in Biogeography: Introduction and Synopsis of the Symposium1
University of Utah Salt Lake City, Utah 84112
SYNOPSIS. Biogeography has had a long history, but only recently has it started to be more than a descriptive subject. Models have been developed which help to explain patterns of geographical distributions of animals and plants. Examples include dispersal, vicariance, and ecological determinism. The dispersal model proposes that present-day distributions were caused by long distance dispersal among disjunct localities. The vicariance model proposes that the distributions resulted from the fragmentation of formerly continuous distributions with accompanying speciation. Ecological determinism proposes that whatever the historical changes in distribution (dispersal or vicariance), present-day ecological factors are the major determinant of distributions. We too often see in the literature large bodies of data analyzed with respect to only one of these competing models. I organized the symposium to bring together what I thought were particularly interesting examples of each approach. It is obvious from the papers that there are multiple explanations for most species distributions, and that some effort should be made to integrate them.