Date of Graduation
Eberly College of Arts and Sciences
Geology and Geography
Evolutionary volatility is a trait that encompasses a clade’s combined capacity for origination and extinction. High volatility increases extinction risk, and declining global extinction rates are thought to be linked to declining volatility. Despite volatility’s scientific importance, there is no standardized way of measuring it. This study provides a new method, derived from a stochastic birth-death model, of estimating evolutionary volatility from fossil data. Simulations indicate that the method produces accurate and precise estimates for large fossil datasets. Analysis of fossil data for five bivalve families (Lucinidae, Mytilidae, Pectinidae, Pholadomyidae, and Veneridae) indicates that diversity projections made from the estimates lack precision and do not capture important aspects of the data. However, this method of estimating volatility serves as a simple and computationally efficient null model for comparisons against more complex hypotheses.
Tybout, Samuel Warren, "Estimating Evolutionary Volatility in a Maximum-Likelihood Framework" (2020). Graduate Theses, Dissertations, and Problem Reports. 7520.