HABITAT CHANGE DROVE RATES OF PREDATION IN CARIBBEAN NEOGENE BIVALVE COMMUNITIES

The causes of major shifts in trophic structure and predation intensity in the fossil record are poorly understood due to lack of paleoenvironmental data. We quantified incidence of predation by drilling gastropods on more than 100,000 bivalve shells from 28 Caribbean benthic communities in the context of the major well-documented oceanographic and habitat changes associated with the closure of the Central American Seaway over the past 11 MA. Contrary to the prevailing productivity hypothesis, incidence of predation significantly increased towards the Recent, despite declining productivity, due to increases in heterogeneity of habitats, and differences in predation rates associated with each habitat. The extent of seagrass, reef, and mixed habitats increased greatly in the Late Pliocene, and bivalves from these habitats have significantly higher incidence of drilling than those in soft sediments. Bivalves characteristic of these habitats also exhibit significantly higher incidence of drilling than soft-sediment bivalves. Our results emphasize the importance of detailed environmental reconstruction for studies of predation through time since seemingly minor differences in habitat among samples can easily overwhelm long-term evolutionary trends in the types and intensities of biologic interactions.