HOW HAVE ECOSYSTEM ENGINEERS IMPACTED MARINE BIODIVERSITY THROUGHOUT THE PHANEROZOIC? (Invited Presentation)

Much of the structure of global marine Phanerozoic biodiversity arose from local- and regional-scale ecological dynamics. Ecosystem engineers – organisms whose behaviors impact resource availability and the physical characteristics of their environments – are involved in unique resource-dependent biotic interactions that can significantly influence community ecology. These influences include increasing taxonomic diversity, modulating trophic interactions, and constructing niches. Therefore, the evolution and proliferation of marine ecosystem engineers throughout the Phanerozoic would have impacted local-scale ecology which, in aggregate, scaled up to influence global-scale biodiversity dynamics. Here, I will highlight how bioturbating and reef-building animals have affected community ecology over the Phanerozoic. Bioturbators and reef-builders represent two major marine ecosystem engineering groups with robust Phanerozoic fossil records. Using the Paleobiology Database, I first reconstructed the proliferation of bioturbators and reef-builders through the Phanerozoic by assessing how common ecosystem engineered environments have become through time. The dominance of bioturbators has been steadily rising through the Phanerozoic, in contrast to reef-builders, which peaked and then stabilized in the Devonian. Then, I compared generic richness and Shannon’s Diversity in communities with and without ecosystem engineers to calculate Hedges’ g statistics of effect sizes per stage. Both bioturbators and reef-builders had persistently moderate to strong positive effects (Hedges’ g>0.5) on community diversity throughout the Phanerozoic, with weaker, albeit inconsistently trending, effects during mass extinction events. Finally, I compared the composition of communities with and without ecosystem engineers. Bray-Curtis dissimilarity indices indicate that marine ecosystem engineers are associated with their own suite of taxa by the middle Cambrian, but with significant declines in dissimilarity around hyperthermal events. Overall, these results highlight the role that marine ecosystem engineers have played in driving biodiversity and ecological dynamics that are ultimately reflected in our global diversity curve.