Species diversity in the Phanerozoic: species-area effects

Abstract

Raup's (1976a) data on Phanerozoic species numbers are examined for species-area relationships, using published estimates of areas of continental seas. By means of multiple regression, species numbers are regressed on both estimated areas of seas and amounts of available rock for sampling, as measured by outcrop area and rock volume. Although the sampling effects apparently have the strongest influence on fossil species diversity, areas of seas substantially increase the total correlation, suggesting that Phanerozoic species numbers were in equilibrium with habitat area. This is further supported by the fact that estimated parameters in the regressions are fairly consistent with established island biogeographic theory. Much of the remaining residual variation can be explained by periods of disequilibrium.