Date of Graduation

Spring 2026

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Debra Finn

Abstract

Tremendous population declines may result in the loss of genetic diversity, which can, in turn, lead to reduced adaptive potential, overexpression of deleterious phenotypes, and further population declines. In this way, genetic drift from a severe demographic decline may ultimately lead to an extinction vortex. However, populations that avoid the loss of genetic diversity may remain viable, despite demographic crashes. Therefore, understanding genetic diversity is vital for assessing the conservation status of species that have undergone declines, and can even reflect the effectiveness of management actions. I investigated signatures of genetic bottlenecks in the gray bat (Myotis grisescens), a species that has been the subject of focused management efforts since its 1976 listing as endangered in the USA. I used whole-genome sequencing to calculate genetic diversity metrics, including inbreeding coefficients, Tajima’s D, and heterozygosity, and to infer effective population size and gene flow. I found heterozygosity excess and a loss of rare alleles. However, I did not detect inbreeding, nor loss of gene flow, and effective population size remained >13,000 (estimated), even at its lowest. Although the gray bat suffered a bottleneck, losing notable abundance relative to their 150-generation maximum (i.e., lost ~94% of initial effective population size), they may have avoided inbreeding through the continued presence of high absolute numbers (i.e., minimum effective population size of >13,000). These findings highlight the importance and effectiveness of timely conservation interventions for preserving the genetic diversity of species.

Keywords

genetic diversity, recovery, gray bat (Myotis grisescens), effective population, bottleneck

Subject Categories

Biodiversity | Genomics | Other Animal Sciences | Population Biology

Copyright

© Marxe Altman-Orbach

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