Evolution 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 …

Quantifying Genetic Diversity In Nematode Feeding Rate, Jacob King

Honors Theses

Understanding how populations persist under changing environmental conditions is a central question in ecology and evolutionary biology. Variation in traits related to resource acquisition may play a key role in determining population survival when resources are limited or fluctuate over time. In this study, I investigated how variation in feeding-related traits influences population persistence using a combination of computational modeling and laboratory experiments. I developed a stochastic, individual-based consumer–resource model to simulate population dynamics across varying levels of trait variance and resource regimes. Across 60,000 simulated populations, increased trait variation consistently reduced extinction risk and extended persistence time, although 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 …

Variation In Infection Prevalence Of Splendidofilaria Pectoralis Across Alaskan Grouse Populations, Anahi Garcia Valdez, Diego Martinez

Create@State

In recent years, rapid climate change has altered species distributions worldwide and influenced parasite transmission dynamics in wildlife systems. Parasite infections play an important role in shaping patterns of disease distribution across species and populations. Understanding variation in infection prevalence across geographic regions and host demographic groups is essential for interpreting these patterns. Splendidofilaria pectoralis is a filarial nematode that infects the connective tissues of grouse (Aves: Tetraonini) in Alaska and has been moving northward as the climate warms. However, relatively little is known about the variation in prevalence of the nematode across geography and demography. This project examines variation …

Analysis Of Mitochondrial Dna Haplotype Groups For South Texas Canids, Canis Rufus, After Past Hybridization Events, Isabella Lopez

Presentations - 2026

mtDNA: mitochondrial DNA; passed from maternal parent to offspring (Haplotype)

Haplotype:  a group of genes or genetic markers inherited together from a single parent (Haplotype)

Mitochondrial DNA haplotypes specific sequences of mtDNA that is passed exclusively from maternal parent to offspring (Giles et al. 1980)

Pro's:

It is passed unchanged from mother to offspring, meaning it is fairly stable (Giles et al. 1980)

Each cell has multiple mitochondria vs one nucleus , which means mtDNA it is more likely to be recoverable from degraded samples like scat (Templeton et al. 2013)

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 …

A Novel 3d Imaging Approach To Study Evolutionary Innovations In Solanaceae Inflorescences, Devin L. Jackson, Joonseog Kim, Wenheng Zhang Dr.

Undergraduate Research Posters

Understanding the relatedness of angiosperms and the evolution of their inflorescence remains challenging, as these structures are highly modified and prone to convergent evolution. The current research describing inflorescence architecture, whether genetically or morphologically focused, typically relies on text based explanations, 2D images, or 3D based models created with CAD modeling software. This creates a disparity in the reader's understanding of these models since descriptions rely heavily on the author's interpretation of the inflorescence. The goal of our study is to bridge this disconnection by producing anatomically and color-correct 3D inflorescence models using Solanaceae flowers that readers can explore directly, …

Sex In Plants: Birth, Death, And Trying To Survive In Changing Climates, Elena M. Meyer

Theses and Dissertations

Plant mating systems are key determinants of fitness. Angiosperms exhibit a wide variety of reproductive strategies, including self-fertilization (or selfing), outcrossing, and mixed mating. It has been estimated that up to 43% of plant species are capable of selfing, and selfing has been hypothesized to provide reproductive assurance where opportunities for mating may be limited, such as in marginal environments. However, questions regarding the overall distribution of selfing rates across angiosperms, the maintenance of mixed mating in the face of inbreeding depression, and the impact of self-fertilization on diversification rates remain incompletely resolved. Here, we explore the dynamics of self-fertilization …

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 …

Overview And Methods Of Molecular Paleontology: A Review, Shelby Touchstone

Williams Honors College, Honors Research Projects

Molecular paleontology—the study of ancient biomolecules preserved in fossils and sediments, including ancient DNA, lipids, and proteins—has motivated researchers since the 1950s, inspiring both scientific inquiry and broader cultural imagination. Think Jurassic Park. This honors thesis presents a comprehensive review of the history, current state, and methods of the field of molecular paleontology. Drawing on peer-reviewed literature and scholarly resources accessed through databases such as EBSCO and Bierce library, this review examines key techniques such as Next Generation Sequencing and amino acid racemization and will go over limitations and controversies in the field. It will also explore potential new …

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 …

Function Of Drosophila Melanogaster Domesticated Transposable Element Protein Dplg3 In Oogenesis And Total Fitness, Aron Herrera

2025 Fall Honors Capstones Projects - Archive

Transposable elements (TEs) are selfish DNA segments capable of self-replication and reinsertion within genomes, often harming hosts. Rarely, host genomes can adopt TEs and use their proteins for new cellular functions through molecular domestication. One example primarily expressed in Drosophila melanogaster ovaries is DPLG3. Previous Betrán Lab students generated DPLG3 loss-of-function flies and found that their ovaries misregulated one primordial and 14 testis-specific genes, leading to variable ovarian malformations. However, it is unclear when during oogenesis these misexpressions occur. We will extract RNA from non-rudimentary ovaries at early and late stages to generate cDNA for qRT-PCR analysis of three …

Immunological Surveillance Against Cancer Across Mammals, Orsolya Vincze, Piotr Minias, Alexandre Corthay, Fernando Colchero, Jean-François Lemaître, Louise Maille, Tamás Malkócs, Justus Hagemann, Dalia A. Conde, Samuel Pavard, Antoine M. Dujon, Beata Ujvari, Frédéric Thomas, Amy M. Boddy, Carlo C. Maley, Damien Chevallier, Tuul Sepp, Thomas Pradeu, Mathieu Giraudeau

Presidential Fellows Articles and Research

Contrary to expectations based on their higher cell numbers, larger and longer-lived species do not face dramatically increased risk of cancer. This strongly suggests that evolution has fashioned natural cancer resistance mechanisms, yet our knowledge remains limited on what these mechanisms might be. The cancer immunological surveillance hypothesis, proposed by Burnet and Thomas in the 1950s, highlights immunity as a key factor determining species-specific cancer resistance. Here we address the original, evolutionary interpretation of this hypothesis by investigating the relationship between cancer mortality risk and markers of efficient antigen presentation. Our results show that the expansion of the MHC class …

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 …

Using Rattlesnake Venom To Model Complex Trait Evolution Across Ecological And Evolutionary Scales, Samuel R. Hirst

USF Tampa Graduate Theses and Dissertations

A central challenge in evolutionary biology is understanding how genetic variation leads to phenotypicdiversity, particularly for complex traits that strongly influence fitness. Traits form the substrate of natural selection, but it is genes, that are inherited across generations. To fully understand the evolutionary process, we must therefore connect the molecular basis of trait variation with the evolutionary outcomes of such traits.

For relatively simple traits, the genotype–phenotype relationship is well understood. Classic systems, such as coat color in beach mice or toxin resistance in garter snakes, have provided effective examples of how relatively few loci underlie conspicuous adaptive differences across …

Mhc Gene Analysis And Immune Variation In Lepidodactylus Lugubris (The Mourning Gecko), Helen T. Vu

2025 Fall Honors Capstones Projects - Archive

The major histocompatibility complex (MHC) plays a central role in vertebrate immune defense by enabling pathogen recognition and initiating adaptive immune responses. While MHC diversity has been extensively studied in sexually reproducing species, comparatively little is known about its evolution in asexual lineages. The parthenogenetic gecko Lepidodactylus lugubris provides a unique opportunity to investigate how clonality and hybrid origins influence immune gene diversity. By leveraging whole-genome data, this study overcomes the limitations of previous transcriptome-based analyses and provides a more comprehensive view of MHC diversity in a clonal vertebrate. As the first step towards understanding MHC evolution in parthenogenetic lizards, …

Exploring The Role Of Ecological Traits In Shaping Spatial Patterns Of Genetic Diversity, Rilquer Mascarenhas Da Silva

Dissertations, Theses, and Capstone Projects

The field of comparative phylogeography aims at uncovering common underlying causes for shared patterns of diversity and diversification at the population level. However, it is now widely accepted that intraspecific genetic diversity patterns can differ considerably across co-occurring taxa due to ecological processes acting at the population level (and influencing individual movement and abundance). To model the processes underlying lineage diversification and demographic shifts in response to environmental changes, phylogeographers and population geneticists are now faced with the challenge of incorporating measurements of species ecological traits into their molecular studies. This dissertation aimed at investigating how different types of ecological …

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 …

Elucidating The Role Of Transposable Element Derived Gene, Dplg3, In Drosophila Melanogaster, Kaisy A. Martinez

2025 Spring Honors Capstone Projects - Archive

A big fraction of most eukaryotic genomes is comprised of transposable elements (TEs). TEs are mobile genetic sequences often causing deleterious effects as they increase in copy number. On rare occasions, TEs can undergo molecular domestication, where the TE proteins are co-opted by the host to serve cellular functions. In Drosophila melanogaster, domestication from PIF/Harbinger TEs has resulted in five Drosophila PIF-Like Genes (DPLG1-4 and 8). This study focuses on investigating the function of DPLG3. In DPLG3 knock out lines, DPLG3-KO, a fraction of the progeny shows an abnormal gonad phenotype. We sought to confirm …

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 …

Chromosome Evolution Model Reveals Hidden Variation In Karyotype-Driven Speciation In Ferns, Thomas Buchloh

All Theses

Because karyotype change commonly generates reproductive isolation between diverging species, rapid karyotype evolution, like that seen in plants, may increase the total rate of diversification. However, few studies have investigated this predicted relationship. Tests of this prediction have identified a positive correlation between the rate of karyotype change (specifically whole genome duplications) and diversification, but tests have been restricted to relatively small and young clades. Fortunately, novel macroevolutionary models have recently become available to investigate patterns of karyotype evolution in large phylogenies, providing new opportunity to investigate variation in karyotype driven diversification. Ferns are one of the most karyotype rich …

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 …

Using Rna Sequencing To Examine Encephalic Gene Expression In Cactus Mice, Sarah A. Nicholls

Honors Theses and Capstones

Many of the exact mechanisms by which desert-adapted animals avoid dehydration-induced complications are unknown, though there are likely ties to the general mammalian dehydration response, a multisystem process spearheaded by the brain. Peromyscus eremicus, the cactus mouse, can survive its whole life without intaking water and is commonly used as a model to study desert adaptations. In this study, we have used bulk transcriptomics to characterize the differential gene expression across hydrated and dehydrated P. eremicus in five major regions of the brain: the cerebral cortex (referred to throughout much of this paper as the cortex), hippocampus, thalamus, midbrain, …

Karyotyping As A Method To Verify Phylogenetic Relationships Among The Enneacanthus Species, Ophelia A. Anderson

Theses and Dissertations

The Enneacanthus genus consists of three species of freshwater fish endemic to eastern North America: E. obesus (Banded Sunfish), E. gloriosus (Blue Spotted Sunfish), and E. chaetodon (Black Banded Sunfish). Previous studies using molecular data suggest that E. obesus and E. gloriosus are more closely related, with E. chaetodon as the most distantly related species in the genus. This study investigates the phylogenetic relationship among the Enneacanthus species, using karyotype characteristics - chromosome number, morphology and fundamental number - as comparative metrics. Chromosome spreads were obtained from scale and gill epithelium samples collected between 1993 and 1994. Prepared slides …

Hidden Markov Model For Identifying Local Variants In Human Genomes Using Simulated Data, Scott Mccallum

Electronic Theses and Dissertations

Identifying adaptive mutations in genetic data is challenging due to the low frequency of occurrence of such events, and because signatures of selection are intertwined with the footprints of various other evolutionary forces that shape our genomes. Even when a larger region appears to be under selection, genomic sites that are linked to adaptive mutations have similar statistical signals, and thus can obfuscate the identification of the actual adaptive mutation. The new method described here uses a Hidden Markov Model that allows for classification of neutral, linked, and sweep (adaptive mutation) genomic sites. This model is general and can be …