Semester

Spring

Date of Graduation

2020

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

James Lamsdell

Committee Co-Chair

Brendan Anderson

Committee Member

Craig Barrett

Abstract

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.

pbdb_data_full.csv (3884 kB)
Bivalve Data

volatility_v4.0.R (33 kB)
R code

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