Vicariance Biogeography

Vicariance biogeography seeks geo-physical explanations for disjunct distributions of organisms. Optimally, vicariance hypotheses are tested on the basis of the comparison of unrelated lineages of organisms that share geographic arenas. The fundamental approach is to marry geology and biology in the study of current and historical patterns of biodiversity. As a science, vicariance biogeography grew out of a synthesis of Alfred Wegener’s continental drift as realized by the plate-tectonic mechanism, Léon Croizat’s track analyses, and Willi Hennig’s phylogenetic systematics into a discipline with more readily testable hypotheses than those from classical dispersal biogeography. Vicariance biogeography, at the time of its emergence in the mid-1960s, offered a common explanation for many of the most puzzling disjunct-distribution patterns across the globe. From the 1960s to the early 21st century, vicariance biogeography dominated the field, marginalizing inquiries into geographic distributions on the basis of dispersal explanations, in part because center-of-origin ideas had fallen into disrepute. However, with the realization that vicariance hypotheses fail to explain an array of biogeographic patterns, including both isolated biotas on oceanic islands and many groups spread over previously connected landmasses, dispersal’s role in disjunct distributions of living things has been resurrected. The current consensus is that both processes play key roles in shaping the distribution of organisms through time.