Date of Award

Spring 2015

Document Type

Restricted Thesis

Terms of Use

© 2015 Jonas J. Oppenheimer. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts



First Advisor

Vincent A. Formica


Population bottlenecks, or severe reductions in population size, can have profound and lasting effects on the genetics of populations. In this study, we take advantage of a natural experiment caused by a recent population collapse in the Bolitotherus cornutus population near Mountain Lake Biological Station to investigate how extremely recent bottlenecks impact the genetic diversity and structure of a population, and whether such events can be detected using genetic indicators. We observed subtle changes in the genetics of the population following the reduction, including an increase in private alleles belonging to subpopulations, slight structuring of the population based on species of fungus host, and loss of certain rare alleles. Bottleneck testing gave no indication of the population collapse, indicating that recently occurring bottlenecks may be difficult to detect through genetic signs alone. Following this population as it responds to the collapse will further indicate when genetic diversity and structure are impacted by population reductions, and when such events may be detected on the genetic level.