The vast majority of theses in this collection are open access and freely available. There are a small number of theses that have access restricted to the WWU campus. For off-campus access to a thesis labeled "Campus Only Access," please log in here with your WWU universal ID, or talk to your librarian about requesting the restricted thesis through interlibrary loan.

Date Permissions Signed


Date of Award

Spring 2020

Document Type

Masters Thesis

Department or Program Affiliation

Environmental Toxicology and Chemistry

Degree Name

Master of Science (MS)


Environmental Sciences

First Advisor

Landis, Wayne G.

Second Advisor

Bauman, Jenise

Third Advisor

Stark, John D. (Ecotoxicologist)


Ecological risk assessment has not been conducted for the proposed environmental applications of synthetic biology. To develop a quantitative framework for risk assessment of synthetic biology, I selected Southeast Farallon Island as a case study for modeling the deployment of gene drive modified house mice to reduce impacts to threatened species. Southeast Farallon Island is part of the Farallon Islands National Wildlife Refuge. The island is populated by invasive house mice that impact indigenous species. Gene drive technology has been proposed as a method to suppress invasive rodent populations through CRISPR-mediated genome editing. I applied the Bayesian Network – Relative Risk Model to predict the outcomes of a gene drive mouse eradication on Southeast Farallon Island. The Bayesian Network – Relative Risk Model is able to probabilistically evaluate multiple causal pathways, incorporating the influence of multiple stressors on multiple endpoints. I used a modified version of the R-based model MGDrivE to simulate population genetics and population dynamics of gene drive mouse eradication strategies. I conducted simulations for three unique gene drive mouse release schemes across two assumed gene drive homing rates and two levels of supplemental rodenticide use; for a total of twelve simulated scenarios. I compared the relative eradication probabilities of these scenarios within a Bayesian network. Sensitivity analyses were conducted to compare the relative influence of rodenticide use and homing rate on the probability of successful mouse eradication. I found that increasing the assumed homing rate of the gene drive had a higher influence on mouse eradication than the addition of supplemental rodenticide. For most scenarios, simulations showed successful mouse eradications as early as seven years after gene drive deployment, with high probabilities of eradication within ten years.




Bayesian network, Relative Risk Model, synthetic biology, gene drive, risk assessment, Southeast Farallon Island, integrated pest management


Western Washington University

OCLC Number


Subject – LCSH

Mice--Biological control--California--Farallon Islands--Case studies; Introduced organisms--Control--California--Farallon Islands--Case studies; Genetics--California--Farallon Islands--Case studies; Environmental risk assessment--California--Farallon Islands--Case studies

Geographic Coverage

Farallon Islands (Calif.)




masters theses




Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.