ASYNCHRONOUS RESPONSE OF CORAL REEFS TO LATE CENOZOIC GLOBAL ENVIRONMENTAL CHANGE

Global patterns of biotic change are the integrated product of the responses of ecosystems to environmental changes acting on global to regional scales. We have examined the long-term history of coral reefs and associated tropical shallow marine ecosystems to determine the relative importance of regional and global factors as controls of diversity and ecosystem function. During the Cenozoic, significant reef building provinces have been distributed among four major geographic regions defined by constricting tropical to subtropical ocean gateways. These regions include the Tropical West Atlantic (TWA), Eastern Atlantic/Mediterranean (EAM), Middle East/West Indian Ocean (MEWIO), and the Indo-West Pacific (IWP). New syntheses of historical collections and extensive new collecting efforts during the past few decades allow a rigorous comparison of the various responses of regional ecosystems to global change. Analysis of specimen-based occurrence datasets for the TWA and IWP combined with summary data published for the EAM and MEWIO suggests that regional responses are asynchronous for most Late Cenozoic intervals of accelerated biotic and environmental change. For example, during the Oligocene/Miocene transition there were extinctions of reef-corals and decline of reef-building in the TWA and EAM but diversification and increased development of reefs in the IWP. Likewise, the Late Miocene was a time of decline in diversity but extensive reef building in the EAM, but diversification and reduced reef building in the TWA. Maximum reef-coral diversity occurred in the Late Oligocene in the EAM, the Pliocene in the TWA, and the Recent in the IWP. These results suggest that the regional response of coral reef ecosystems to global environmental change is strongly modulated by regional conditions or that regional patterns are in fact largely forced by regional rather than global environmental changes. Therefore, attempts to understand long-term global patterns of diversity and ecosystem function as responses to global environmental change must include analysis of variation at regional to local scales.