Assessing predation through time and space

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Predation, the act of an organism killing another for food, is believed to influence the evolution and diversity of species greatly. Given the modern biodiversity crisis (70 species per day go extinct), we must understand better those factors that influence life's diversity. However, many influences, including predation, are hard to estimate, especially in marine settings, where it is difficult to count acts of predation directly. Similarly, direct observations of the past are impossible, but assessing predation in the fossil record would greatly expand our knowledge. Thus, we need a means of estimating predation without direct observations. One solution is to use traces of predation, such as scars on prey shells, to estimate predation. This research has two goals: first, to test the validity of using predation traces as an estimate of predation intensity, using in-field modern experiments; and second, to apply what was learned from the modern experiments to the fossil record to test for the influence of predation during the Mid-Paleozoic (380-290 million years). The modern component of the research will involve marking shelled invertebrates at multiple localities. At each locality, there will be a caged zone excluding predators and an uncaged zone; the difference in deaths between the two zones is attributed to predation. This mortality rate will be compared to rates of various predatory traces at each locality to determine if any traces successfully track mortality. If so, traces can be used to compare predation intensity from place to place, and through time. The paleontological component of the study will use the valid predation traces to test if the Mid-Paleozoic was a time of increasing predation intensity, and if Mid-Paleozoic marine invertebrates evolved new shapes and "armor" in response to predation, by comparing changes through time in trace activity and prey shape. Mid-Paleozoic organisms were not closely related to modern organisms, so if Mid-Paleozoic and Recent organisms were both influenced by the same factors, such a result would be more general, and thus of greater use to biology and conservation.