THE ROLES OF CLIMATE AND PLATE TECTONICS IN CONTRASTING PATTERNS OF REGIONAL POOL HISTORIES OF CENOZOIC REEF CORALS

The search for a general theory of diversity in both space and time continues to be of interest and importance to palaeontologists, ecologists and conservationists, but clear answers have proved elusive. Palaeontologists have concentrated on analysing global diversity through time but the results are ‘black box’ integrations of the synergistic effects of numerous geological and biotic processes. Statistical analyses are used to establish relative probabilities of different causal processes (e.g. area effect, climate, eustasy). At the other extreme of scale, ecologists have concentrated on directly observable community-level interactions, but are admitting that since structure and diversity of a community are a sub-set function of its respective regional pool of taxa, community studies alone cannot explain diversity patterns. Ecologists have therefore called for more attention to be paid to the history of regional pools - in essence, biogeography. Biogeography should complement both community-level and global-level studies. Thus standing global diversity must be a function of the number of regional pools, their respective richness, and endemic disparity between them. This implies a combination of ecological and historical factors, i.e. maintenance (short-term, ecological, local, contemporaneous processes), (2) distributional change (short- to long-term historical processes causing the biogeographical ranges of organisms to change), and (3) originations (long-term evolutionary processes giving rise to new taxa).

While climate and climatic change appear to influence all three groups of processes, realization of climatic potential must also depend on geographic patterns of availability of suitable habitats within a favourable climatic zone, e.g. the most dense and extensive concentrations of suitable habitats should have more potential than a very fragmented pattern. In the talk, we use these models to look at contrasting diversity patterns of three different regional pools of reef corals (Caribbean, Mediterranean and Indo-West Pacific) through the Cenozoic. Particular attention will be paid to climatic change and the effects of plate tectonics in controlling changing availability of suitable habitats in these regions through time.