Coupling of predation intensity and global diversity over geologic time

The geologic history of earth's biodiversity, and the origins of this pattern, are central problems in paleobiology and evolutionary biology. The basic picture for marine organisms was outlined in 1860 (1) but was considerably refined in the 1980s and 1990s by the late Jack Sepkoski. His databases of marine animal families and genera produced an iconic pattern of an early Paleozoic rise in diversity, followed by a late Paleozoic plateau or slow decline, a low after the end-Permian extinction, and a final protracted rise through the Mesozoic and Cenozoic (2, 3). The explanation for this pattern has been an active area of research, with interpretations ranging from preservational artifacts to a host of biologically mediated processes (4–7). Predation has been regarded as potentially important, but the data to establish its significance have been limited in scope (8–11). The work of Huntley and Kowalewski (12) in this issue of PNAS demonstrates for the first time a strong correlation between predation intensity and marine biodiversity throughout the Phanerozoic Eon. Their results are particularly compelling because the data are independent of the global-scale taxonomic lists used to generate diversity curves, making a spurious correlation between the two unlikely. The authors' evidence strongly suggests that predation and biodiversity are highly correlated in the marine realm, although which is cause and which is effect …

*E-mail: stratum{at}uga.edu