ENVIRONMENTAL AND ECOLOGICAL DRIVERS OF DIVERSITY DYNAMICS AMONG CARBONATE- AND CLASTIC-LOVING GENERA

Environmental factors, such as habitat area and nutrient availability, are thought to be primary drivers of biodiversity dynamics. In marine systems, benthic habitats characterized by carbonate versus siliciclastic sedimentation differ with respect to many of these putatively important environmental variables. Previous work has found that marine animals with affinities for carbonate versus clastic substrates exhibit systematic differences in their rates of extinction and origination and in the associations between these rates and net diversification. Secular variation in the extent of different benthic habitats may thus be responsible for variation in taxonomic rates observed over geologic time. Differences in diversity dynamics between genera with affinities for carbonate versus clastic substrates have largely been attributed to environmental factors, yet ecology may also contribute. Ecological attributes of lineages, such as geographic range size, are often associated with differences in extinction and origination in the marine fossil record. Using data from the Paleobiology Database, we compare the geographic ranges of carbonate- versus clastic-loving genera and the associations between range size and extinction risk. Although geographic range distributions can differ in a given stage, over the Phanerozoic there is no systematic difference in the range sizes of carbonate- versus clastic-loving genera. Similarly, the relationship between range size and extinction risk is indistinguishable among genera grouped by their substrate affinity. Macroecological dynamics appear comparable among these benthic habitats despite apparent macroevolutionary differences. Although these findings may indicate that differences in taxonomic rates derive entirely from environmental controls, recalculation of taxonomic rates using the data currently available in the Paleobiology Database no longer shows a systematic difference in the diversity dynamics of carbonate- versus clastic-loving genera. These results suggest that secular trends in the diversity dynamics of marine animals are not driven by temporal variation in the extent of carbonate versus clastic environments.