EAR-PF: Predator-driven evolution of shell structure at different scales during the Mesozoic Marine Revolution: An interdisciplinary experimental investigation

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The world’s marine ecosystems are currently experiencing many pressures from human activities. For example, warming global temperatures have changed ocean chemistry in ways that influence the strength of many mollusk shells. These shells are key to the survival of organisms like clams and snails, which use their shells as a defense mechanism against shell-crushing predators like fishes and crabs. In addition to climate change, marine ecosystems have been stressed by overfishing, where the preferential removal of predators has cascading effects on their prey. One way to anticipate the long-term impacts of climate change and changing marine predatory regimes is to study similar events from the past. During the Mesozoic (250-65 million years ago) the world was experiencing extremely warm, greenhouse conditions. Additionally, shell-crushing predators became increasingly powerful, putting increased selective pressures on their prey. This study will use physical and numerical experiments to analyze how increasing temperatures and changes in predation pressures impacted the shells of marine snails during the Mesozoic to inform modern ecosystem conservation efforts. Moreover, by studying the exceptional strength of snail shells, this research will have applications for the bio-inspired design of crack resistant materials. The use of physical models for this research will also enable the creation of accessible, interactive 3D printed museum displays applicable to educational modules across disciplines including paleontology, conservation, and biomechanics. While conducting this interdisciplinary research, Dr. Johnson will mentor underrepresented and underserved students from high school and undergraduate programs, who are interested in biology, ecology, paleontology, biomechanics, or related STEM fields.Changes in defensive snail shell morphologies are central to the Mesozoic Marine Revolution hypothesis—an event of predator-driven evolution during a period of greenhouse conditions. However, we lack rigorous quantitative metrics by which to evaluate predator-driven evolution throughout this time. This project will use an innovative approach to quantify prey response by experimentally determining how gastropod shells would evolve in a model system driven primarily by shell-crushing predators. This will be accomplished using a novel cross-scale approach, applying finite element analysis modeling incorporating both shell macrostructure (shape) and microstructural material properties, and validating the analysis with modern and fossil shells. This research will generate a theoretical morphospace which quantifies the defensive capabilities of a range of shell shapes and microstructural combinations. The model framework generated from this research will have fundamental applications for studies of predator-prey driven evolution, conservation paleobiology, and materials science. The world’s oceans are currently facing intense anthropogenic pressures from overfishing and a rapidly changing climate, which are highly likely to negatively impact mollusks and fishes. This study will inform conservation efforts which extend beyond the temporal scale of modern ecological studies. Furthermore, the results of this study will have implications for the development of stronger, crack resistant bioinspired materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.