Genomics Commons^™

Investigating Cryptic Diversity In The Hawaiian Endemic Plant, Psychotria Mariniana (Rubiaceae), Uyen Thi Hoang Nguyen

Master's Theses

Islands, with their isolation and steep environmental gradients, serve as natural laboratories for studying speciation. Molecular phylogenetic and population genetic methods utilizing Next-Generation Sequencing (NGS) have revolutionized our ability to document patterns of genetic divergence and diversity. Cryptic diversity, genetically distinct populations that were previously unrecognized as unique, and cryptic speciation, where divergent genetic populations may be deserving of status as unique species, have been observed in many taxa. The Hawaiian Islands provide an ideal setting for studying divergence and speciation due to their extreme isolation, known ages, and volcanic origin. Previous work has investigated the evolutionary relationships of the …

The Hitchhiker's Guide To The Host: Fleas And The History Of Pikas In North America, Josh Pletcher

All NMU Master's Theses

Parasite phylogenetics can offer windows into the cryptic evolutionary history of hosts, often highlighting events that are not recorded by the phylogenetics of the host. Pikas (small lagomorphs) host a diverse parasite community comprising endoparasites (e.g., coccidians, nematodes, and cestodes) and ectoparasites (e.g., fleas and mites). Phylogenetic analysis of pika endoparasites has revealed pikas evolved in Asia and colonized North America in two waves, and that contact between these two pika lineages allowed parasites to be transferred from one lineage to another and to survive the extinction of their original host. To uncover these cryptic histories, understanding the biogeography of …

Comparing Gngt1 Expression In Eye Tissue Of Polymorphic Salamander Species Through Development, Fiona Coulbourne, Camila Cardozo, Macarena Machado, Ruben Tovar

Posters - 2026

The effect of the environment on organisms and their adaptations is widely studied. When exposed to different environmental niches, phenotypic adaptation is observed even within species. Animals that live in dark cave environments show a loss of their eyesight, since this sense is no longer useful to keep. Previous research has studied salamanders of the clade Eurycea and compared gene expression to subterranean and surface phenotypes1. E.pterophila is observed to express these two phenotypes depending on its environment, either Preserve Cave (subterranean) or Comal Springs (surface). Subterranean variant shows reduced eye volume and assumes to have decreased eyesight. Utilizing RNASeq …

Equid Major Histocompatibility Complex (Mhc) Evolution & Genome Organization, Lauren C. Johnson

Theses and Dissertations--Veterinary Science

The evolution of modern horses has a well-documented fossil record and has long been of interest to the genetics community. Although non-caballine equids (e.g. zebras, donkeys, and asses) can hybridize with horses, the resulting offspring are typically infertile. Despite these reproductive barriers, genomic analyses reveal regions of high sequence similarity among equid species. This dissertation investigates the role of historical introgression in the evolution of modern Equus species. The first chapter re-evaluates earlier findings derived from a limited horse population and a single reference genome. The variants of the identified regions were pushed through Ensembl’s Variant Effect Predictor to assess …

Phylogeography, Fungal Host Specificity, And Fitness In The Corallorhiza Maculata Species Complex, Hana Thixton-Nolan

Graduate Theses, Dissertations, and Problem Reports (ETD)

Mycoheterotrophic plants exploit fungi for most or all nutritional needs, providing a compelling system to address the evolutionary consequences of genome reduction, population-level variation, and germination requirements. I am using the widespread Corallorhiza maculata species complex to address questions of genomic variation, fungal host specificity, morphological variation, and germination requirements across the broad geographic range from Mexico to northern North America. This complex contains C. bulbosa, C. macrantha, and C. mertensiana, the latter with three varieties (maculata, occidentalis, and mexicana). These taxa vary in flowering time, floral morphology, and fungal associations. However, the degree …

Systematics Of Disk-Winged Bats (Thyroptera), Courtney L. Klumpp

Capstone Showcase

This thesis investigates the evolutionary relationships among disk-winged bats in the genus Thyroptera, a small group of Neotropical bats known for the adhesive suction disks on their wings and feet that allow them to roost inside tightly rolled leaves. The distinctive morphology and behavior of these bats have not been extensively documented, and their phylogenetic relationships remain only partially resolved. The goal of this research is to better understand how these species are related to one another and to determine whether the five recognized species of Thyroptera form a single monophyletic group. To address this question, morphological and genetic …

Dosage Sensitivity And The Evolution Of Dosage Compensation: Tests Of The Insensitive Sex Chromosome Hypothesis In Flour Beetles, Shana Pau

Biology Dissertations

Sex chromosome evolution generates imbalances in gene dosage that can disrupt gene expression and organismal function. These imbalances are often resolved through dosage compensation mechanisms, yet the factors that drive the emergence and diversity of these systems remain poorly understood. This dissertation addresses a central question in evolutionary genomics: what governs the evolution of dosage compensation?

Focusing on dosage sensitivity as a potential driver, I evaluate the Insensitive Sex Chromosome Hypothesis (ISCH), which predicts that chromosome-wide compensation is more likely to evolve in genomic contexts that are not depleted of dosage-sensitive genes. Using flour beetles (Tribolium spp.) as a …

Population Structure Analysis Of Four Basal Higher-Attines Using Bioinformatic Approaches, Gabriel Mcdanield

Biology Theses

Metapopulations within the family Formicidae are unique among other animals due to the large colonies they build, and the mating strategies required to fertilize a specialized reproductive caste that will often produce young for the life of the colony. One group of ants, the fungus-gardeners (tribe Attini). The population structure of North American non-leafcutting, fungus-gardening ants has been understudied, especially in the southwest of the United States. Additionally, not much is known about their dispersal biology, so the dynamics of dispersal of these species and how they affect population structure is likewise not well known. To shed light on the …

The Island Biogeography Of Mangrove-Dwelling Vertebrates: Isolation, Specialisation, And Extinction, Jian Xiong David Tan

Biology ETDs

Mangroves are highly dynamic ecosystems that are widely distributed across the coastlines of the tropics and subtropics. Despite their low plant diversity, mangroves host a disproportionately high number of terrestrial vertebrate taxa. However, mangrove specialists — taxa that only occur in mangrove habitats — exhibit a global distribution that is incongruous with the broader background distribution patterns of mangrove-associated fauna, exhibiting higher diversity in Australia and Southeast Asia. This dissertation therefore aims to assess how the diversity and distribution of mangrove specialist fauna may have been shaped by the historical biogeography of mangroves, and the effects of mangrove specialisation on …

Network Analysis Of Antimicrobial Resistance In Staphylococcus Aureus: Characterization Of Hub Genes And Their Functional Implications, Md Imran Hasan, Davida Smyth, Jeong Yang, Ashley Teufel

Masters Theses (Archived)

Antimicrobial resistance is a major cause of morbidity and mortality in patients with S. aureus infections. In this study, we analyzed genes, molecular mechanisms, and pathways driving drug resistance in S. aureus using network analysis. Using whole-genome sequencing (WGS) data and systems biology approaches, we identified 229 AMR-associated genes and constructed a protein-protein interaction network among these genes. Through network topology and functional enrichment analyses, we not only confirmed their association with resistance, but also highlighted the central roles of these genes in resistance pathways, such as efflux, target replacement, and target protection, which are directly linked to multiple drug …

A Phylogenomic Investigation Of The Historical Biogeography Of Livebearers (Cyprinodontiformes: Poeciliidae), Sheila Rodríguez Machado

LSU Doctoral Dissertations

The Neotropics contain several biodiversity hotspots and harbor the highest diversity of freshwater fishes globally. Yet, recognizing the patterns and processes driving this richness remains a challenge. Similarly, all groups and subregions have not received the same attention, especially in the genomics era. Addressing these knowledge gaps will help us to better understand the region’s evolutionary and biogeographic complexity. The goal of this dissertation is to examine phylogenetic and biogeographic patterns of Neotropical freshwater fishes, with emphasis on the Greater Antilles, across multiple taxonomic and geographic scales. To achieve this goal, I generated a genomic dataset of hundreds of ultraconserved …

Uncovering The Evolutionary Origins Of Neo-Sex Chromosomes In The Insect Family Membracidae, Mary Kumah

2025 Spring Honors Capstone Projects - Archive

This research explores the evolution of the neo-XX/XY sex chromosome system of Amblyophallus exaltatus, a treehopper insect in the family Membracidae. Neo-XX/XY sex chromosome systems can evolve from an XX/X0 sex chromosome system via fusion events between the X chromosome and an autosome. Although cytological work has indicated the presence of a neo-XX/XY system within A.exaltatus, the chromosomal identity of the fused autosome and the molecular drivers behind this chromosomal fusion remain poorly understood. By performing a coverage analysis with whole genome sequence data, the parts of the A.exaltatus genome that fused with the X chromosome will be better …

Gene Model For The Ortholog Of Glys In Drosophila Simulans, Madeline L. Gruys, Madison A. Sharp, Zachary Lill, Caroline Xiong, Amy T. Hark, James J. Youngblom, Chinmay P. Rele, Laura K. Reed

Faculty Journal Articles

Gene model for the ortholog of glycogen synthase ( Glys ) in the Drosophila simulans May 2017 (Princeton ASM75419v2/DsimGB2) Genome Assembly (GenBank Accession: GCA_000754195.3 ). This ortholog was characterized as part of a developing dataset to study the evolution of the Insulin/insulin-like growth factor signaling pathway (IIS) across the genus Drosophila using the Genomics Education Partnership gene annotation protocol for Course-based Undergraduate Research Experiences.

Snake Venoms As Models For Understanding The Origins And Evolution Of Gene Regulatory Networks, Siddharth S. Gopalan

Biology Dissertations - Archive

Understanding the relationship between genotype and phenotype is a fundamental goal of biology. However, the vastly complex nature of eukaryotic gene regulation can make deriving precise relationships between genotype and phenotype challenging. The gene regulatory architecture of snake venom systems provide an opportunity to study this problem in a phenotypic system with immense variation in phenotypes and the underlying genetics. Using a set of integrated functional genomic approaches with snake venoms as a central model, in this dissertation, I provide several examples of the regulatory mechanisms by which diversity in phenotypes arises. Specifically, I identify how gene expression heterogeneity between …

Testing Vivo-Morpholino Mediated Gene Knockdown Of Stat6, Spi1b, And Hnf4Α In Adult Threespine Stickleback, Stella Dipippo

Honors Scholar Theses

The fibrotic immune response to the cestode parasite, Schistocephalus solidus, varies among threespine stickleback populations. Fibrosis suppresses parasite growth but has costly effects on the fish. Previous genomic studies in stickleback have suggested potential roles of Spi1b, STAT6, and HNF4α in modulating fibrosis severity, but there is presently no evidence for this in-vivo. We used antisense vivo-morpholino oligonucleotides (MOs) to attempt to knockdown the expression of each gene in the liver, spleen, and intestine of adult stickleback. Vivo-MOs have been proven effective in other species of teleost fish, as well as in mice and humans, but …

The Influence Of Environmental Change On Genetic Diversity Across Spatial And Taxonomic Scales, Connor M. French

Dissertations, Theses, and Capstone Projects

The spatial distribution of genetic diversity is of interest to biodiversity scientists and conservationists and is a fundamental metric of biodiversity. Genetic diversity patterns across spatial and taxonomic scales contain information about population and assemblage dynamics that can convey their resilience to environmental change. Ectotherms are especially linked to their environments and may be especially sensitive to fluctuations in the environment over time. Herein, I investigate global and regional patterns of genetic diversity in two groups of ectotherms, insects and lizards, to understand the relationship between environmental change and genetic diversity, from populations to assemblages. Overall, my research aims to …

The Role Of Elevation In The Migration, Physiology, And Genomic Diversification Of Birds, Jessie L. Williamson

Biology ETDs

Elevational gradients cause profound eco-climatic variation across short distances. Partial pressure of oxygen (PO₂) is a severe challenge that organisms face at high elevations; due partly to specialization on PO₂, most Neotropical bird species have narrow elevational ranges. However, a small fraction are elevational generalists that span sea level to high elevations, and a subset undertake extreme migratory journeys from low to high elevations biannually. My dissertation combines diverse approaches across levels of biological organization to understand how elevation impacts the ecology, evolution, physiology, and migration of montane birds. I examined ‘extreme’ elevational …

Isolation Of Gametophytic Selection And Selective Embryo Abortion In Mimulus Guttatus, Desmond C. Willson

University Honors Theses

A lack of genomic studies examining gametophytic selection (GS) and selective embryo abortion (SEA)--which occur during the reproduction of angiosperms--leaves questions regarding the adaptive and evolutionary effects of these processes. Analyzing deviations from Mendelian segregation offers an avenue for identifying loci targeted by GS and SEA, and their contributions to purging of genetic load. However, other selective processes such as meiotic drive and cytonuclear interactions, as well as pollen and ovule abortion, can cause distortion. To distinguish the effects of GS and SEA from other causes of distortion, we will perform reciprocal crosses between highly homozygous and highly heterozygous individuals …

Evolution And Adaptation To Temperature In Thermotogota, Anne Amelia Farrell

Dartmouth College Ph.D Dissertations

Life thrives across incredibly diverse environmental conditions, yet most organisms are restricted to growing within a narrow range around their optimum growth temperature (OGT). The evolutionary events leading to changes in OGT are poorly understood, and it is uncertain if specific genes are required to thrive at a particular temperature. The bacterial phylum Thermotogota is an excellent model for the evolution of OGT. It comprises mesophilic, thermophilic, and hyperthermophilic members that collectively grow between 20°C and 90°C.

In this work, I analyze the history of OGT in the Thermotogota phylum and show how horizontal gene transfer contributes to the evolution …

Omani Camels From A Cultural And Genomics Perspective, Al Muatasim Al Zadjali

Electronic Theses and Dissertations

The Dromedarian camel, Camelus dromedarius, is native to the Arabian Peninsula, including the Sultanate of Oman. These camels are used for food, milk, as well as show and racing competitions. Despite their economic and cultural importance research on camels in Oman is limited. The goal of this study was to examine their genomic variation, relationship with camels in other parts of the Arabian Peninsula, and to determine if selective breeding has led to the establishment of distinct breeds in Oman. Information was compiled from multiple sources to produce a comprehensive review on the breeding, management, economic and cultural use, …

Crossing The Ocean: The Importance Of Gene Flow In Island Evolution, Ethan F. Gyllenhaal

Biology ETDs

Islands have long been a critical arena for the development of ecological and evolutionary theory, particular due to persistent open-water gaps between them. In this dissertation I demonstrates how these caps are permeable, which can be leveraged to understand evolution on islands and more broadly. The first chapter develops this connection between ongoing, overwater gene flow and island biogeographic theory, and tests it on an archipelago species. The second take a three-pronged approach in demonstrating how over-water gene flow can bias phylogenetic inference, and how many phylogeographic metrics in islands are likely shaped by long-term gene flow. The final two …

Understanding The Origin Of Parthenogenesis Via Crossing And Crispr Gene Editing In Daphnia Pulex, Thinh Pham

Biology Dissertations - Archive

Daphnia has been used as a key model system for studying ecological changes, evolution, and genomics for the past few decades due to its rapid turnover time in reproduction. The organism possesses two fascinating modes of reproduction: obligate parthenogenesis and cyclical parthenogenesis. This dissertation delves into the intricate reproductive strategies of Daphnia pulex, focusing on hybrid F1s from different reproductive modes. The first aim is to investigate 31 hybrid F1s generated from obligate parthenogenesis (OP) and cyclical parthenogenesis (CP) parental lines. Transcriptomic analysis reveals misexpression patterns and regulatory divergences, highlighting meiosis-related genes like CDC6 as potential parthenogenesis regulators. The …

The Evolution Of The Metazoan Circadian Molecular Mechanism And The Conservation Of Canonical Circadian Elements, Olivia Waldridge

Theses and Dissertations--Biology

The temporal organization of biological activities through circadian rhythms is pivotal for the survival of organisms. Significant progress has been made in understanding the molecular foundations of animal circadian clocks through the characterization of key components such as Clock, Bmal1/Cycle(Cyc), Period (Per), Timeless, and Cryptochrome (Cry) in several model organisms. To determine the universality of this conservation, we investigated the sequences of these genes and their paralogs across 46 animal species that encompass multiple phyla in the metazoan kingdom to resolve the relative timing of duplication and loss events that have diversified core clock components in the metazoan kingdom. Using …

Reproductive Isolation And Gene Flow Across Space, Time And Genomes In Neodiprion Lecontei And N. Pinetum, Ashleigh Nicole Glover

Theses and Dissertations--Biology

To explain biodiversity, evolutionary biologists must understand how independent lineages arise via the evolution of reproductive isolation during the speciation process. Hybridizing taxa provide an excellent opportunity to investigate the evolution of reproductive isolating barriers and genomic divergence, thereby enhancing our understanding of speciation. However, hybridization between diverging taxa can vary across geographic space, the genome, and time. Thus, understanding the factors that promote or inhibit hybridization can provide insight into the biotic, environmental, and genetic causes of divergence and gene flow. Importantly, the mechanisms responsible for generating variation in hybridization dynamics and the consequences of such hybridization remains unknown …

A Multimolecular Perspective On The Success Of Wolf Recovery And Relocation, Samuel D. Hervey

Dissertations, Master's Theses and Master's Reports

With global biodiversity in decline and many species isolated in fragmented habitats, conservation efforts increasingly rely on natural recolonization and translocation to restore ecosystems. These strategies face challenges such as genetic erosion and habitat limitations, highlighting the need for effective monitoring practices. This research assesses the success of wolf recovery initiatives by examining long-term genetic and genomic health using both traditional and advanced molecular methods. First, we investigated the genetic health of 19 gray wolves (Canis lupus) relocated to Isle Royale National Park to restore ecosystem balance. Initial genetic assessments with microsatellites found that these wolves had genetic diversity metrics …

Tracing Evolution Of Gene Transfer Agents Using Comparative Genomics, Roman Kogay

Dartmouth College Ph.D Dissertations

The accumulating evidence suggest that viruses and their components can be domesticated by their hosts, equipping them with convenient molecular toolkits for various functions. One of such domesticated system is Gene Transfer Agents (GTAs) that are produced by some bacteria and archaea. GTAs morphologically resemble small phage-like particles and contain random fragments of their host genome. They are produced only by a small fraction of the microbial population and are released through a lysis of the host cell. Bioinformatic analyses suggest that GTAs are especially abundant in the taxonomic class of Alphaproteobacteria, where they are vertically inherited and evolve …

Population Genomics, Ecology And Conservation Of Asterias Sea Stars In The North Atlantic, Melenia I. Giakoumis

Dissertations, Theses, and Capstone Projects

Uncovering how species respond to environmental change is a central question in biology (Ehrlén & Morris 2015; Habibullah et al. 2022). It is the key to elucidating the past, understanding the present and predicting the future of species’ population dynamics. This dissertation investigates the influence of environmental change on intertidal species’ distributions and genomics at several timescales, with implications for conservation.

Environmental changes have occurred throughout history, on a geological scale, and have shaped the global patterns of species’ distributions and population sizes. Biologists have long studied how geological history has shaped species distributions (Sanmartín 2012) in both terrestrial (Liu …

Anomalies In The Mitochondrial Genomes Of Members Of Aliciidae, Boloceroididae, And Gonactiniidae (Actiniaria:Metridioidea), Isabel Pen

2023 Midwest Ecology & Evolution Conference

Analysis of gene sequences from three mitochondrial and two nuclear genes for a broad sampling of actiniarian taxa proposed a novel grouping of the families Aliciidae, Boloceroididae, and Gonactiniidae. (Rodríguez et al., 2014). Although previously unlinked, the association of these taxa was credible given the consistency of the genetic data and the shared occurrence of anatomical traits, including complex column structures (Aliciidae and Boloceroididae), tentacular sphincters (Boloceroididae and Gonactiniidae), and retention of juvenile musculature in adults (Boloceroididae and Gonactiniidae). Although the mitochondrial genome structure of actiniarians is generally conserved, complete mitochondrial genomes identify unusual gene orders (Alicia sansibarensis: …

Convergent Evolution Of Antifreeze Proteins In Two Insect Families Supported By Whole Genome And Gene Family Loci Analyses, Shaw Kagawa

2023 Midwest Ecology & Evolution Conference

Various Coleoptera (beetles) and Lepidoptera (moths) insects are known to produce highly active antifreeze peptides (AFPs), an adaptive trait that enabled them to avoid freezing and survive severe winters. These include the grain pest Tenebrio molitor (yellow mealworm), pine-boring Rhagium beetles, the fire-colored Dendroides beetles, a stag beetle, and the Choristoneura spruce budworms (moths). Insect AFPs are small peptides of ~8 to 15 kDa, consisting of several tandem 13-amino acid repeats of similar sequences, each ending with a conserved tripeptide Thr-Cys/aa-Thr motif, found to be important for ice binding. Except for the eastern spruce budworm, the evolutionary origin/s and process/es …

Geographic Analysis Of Sex Chromosome Polymorphism In The Virginian Wild Strawberry, Trezalka A. Budinsky

2023 Midwest Ecology & Evolution Conference

The evolution of sex chromosomes is a ubiquitous and essential diversifying mechanism in eukaryotes. Yet early stages of sex-chromosome differentiation are poorly understood. The subdioecious octoploid, Fragaria virginiana, provides a rare opportunity to study the beginnings of sex chromosome evolution due to its young, polymorphic ZW sex system. Females are ZW and males/hermaphrodites are ZZ. F. virginiana has a small sex-determining region (SDR) located on the female W chromosome that has undergone three transposition events between the strawberry's four subgenomes, resulting in three SDR haplotypes: alpha (the result of a first transposition and closest to a pre-sex chromosome ancestral …