An application of the theory of island biogeography to fish speciation on seamounts

Seamounts can be considered as islands in the deep. For many species, depth is just as much a barrier to dispersal as is the water between oceanic islands. This leads to the hypothesis that seamounts could be places where speciation readily occurs. Recent advances in the theory of island biogeography have allowed some detailed predictions about the degree of endemism and the diversity of species on oceanic islands. We have adapted this theory to seamounts, as underwater equivalents of islands. Three elements of this theory were tested as an illustration of what could be done, using published data on the diversity of reef-dwelling and benthic fish species found along the Hawaiian-Emperor seamount chain in the Pacific. Poor sampling makes it impossible at present to test the hypothesis that endemism is a humped function of seamount age. The data agrees with a further prediction that the total number of species is a humped function of seamount age. Finally, the prediction that fish diversity should be a function of seamount age and area is unsupported. We propose that the theory we have attempted to test could serve as a guide to what fish diversity might be expected from further sampling work.