Term of Award

Spring 2021

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

James Roberts

Committee Member 1

Christian Cox

Committee Member 2

Elizabeth Hunter

Non-Voting Committee Member

Jess Jones

Abstract

Maintenance of genetic diversity is a critical component to the management and recovery of imperiled species. By ensuring that a species’ genetic diversity is maintained, issues like inbreeding depression and loss of local adaptation can be prevented. However, the genetic diversity of many species are not well-characterized, and the factors that influence a species’ genetic diversity are often not well understood. In the case of imperiled unionid freshwater mussels, it is important to conduct conservation genetic assessments to aid in their management and preserve genetic diversity. This is the first study to conduct a comparative conservation genomic assessment for eight unionid species. By sequencing 3RAD libraries, I characterized single-nucleotide-polymorphism (SNP) variation in these species across their ranges in North Carolina and beyond. I obtained thousands of neutral SNPs across the genome for each focal species. With the newly obtained genomic data and associated spatial data I addressed three main questions: 1) What is each species’ population structure and how is genetic diversity distributed across the landscape? 2) Which landscape factors have the strongest influence on population genetic structure and diversity? 3) How do life-history traits mediate species’ genetic responses to landscape factors? I observed that population structure was rarely observed below the spatial scale of basin or watershed, suggesting substantial gene flow occurs among connected streams in the same watershed. I found that fluvial distance and the type of barriers between locations were the most significant drivers of genetic differentiation among individuals, whereas drainage area was the most significant, landscape variable, driver of genetic diversity within individuals. Individuals occupying sites with relatively small upstream watershed areas (2), little human development (70%) exhibited the highest heterozygosity. Life-history traits such as longevity and fecundity appeared to mediate genetic diversity within individuals. Species with “slower” life-histories (lower fecundity, longer lifespans) exhibited higher genetic diversity than species with “faster” life-histories (higher fecundity, shorter lifespans). Including life-history traits in a conservation genomic assessment provides novel insights into evolutionary ecology that helps to explain or predict the genetic response of a species to their environment.

Research Data and Supplementary Material

No

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