VICARIANCE BIOGEOGRAPHY OF THE OPEN-OCEAN PACIFIC

The first cladogram to treat oceanic water mas ses as distinct geograp hic units presents a 'hydrotectonic' history of Pacific surface water masses. It is used to test the idea that the oceanographic subdivision of the surface waters of the Pacific Basin into separate water masses shaped pelagic biogeographic patterns in much the same way that the t ectonic fragmentation of Pangea influenced biogeographic patterns on l and. The historical water-mass relationships depicted by the surface w ater-mass cladogram resemble modern pelagic biogeographic regions. The prediction that the cladistic phylogenies of monophyletic groups havi ng allopatric taxa in three or more surface water masses will be consi stent with the topology of the surface water-mass cladogram is met by the pelagic fish genera Stomias and Evermanella.