Evolution Commons^™

A Simple And Affordable Protocol To Assess Censer Seed Dispersal: First Confirmation Of The Mechanism In The Genus Solanum, Abigail J. Motter, Christopher T. Martine, Melody P. Sain

Faculty Journal Articles

The censer seed dispersal mechanism, whereby mature fruits are retained on plants and seeds dispersed by mechanical shaking, is among the most specialized wind-aided seed dispersal strategies employed by the flowering plants. An efficient, affordable, and easily repeatable protocol for determining whether a species uses this unusual mechanism of seed dispersal is lacking. Our focal species, Solanum tudununggae, is one of just two Solanum species (in a fleshy-fruited genus of ca. 1200 species) hypothesized to use this dispersal mechanism as a means to move seeds farther from parent plants than would gravity alone.

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 …

The Presence Of Predators Moderates Evolutionary Responses Of Trinidadian Killifish To A Novel Parasite, Anne E. Christian

Biology Dissertations

The Healthy Herds Hypothesis suggests the idea that prey populations derive a benefit from their predators: predators reduce the exposure of their prey to infectious disease, both by limiting prey population densities and by eliminating sick individuals. Much research has focused on the balancing effect that predators have on ecosystems. There is a current need for research into whether these effects cause evolutionary shifts in prey populations, where strong predation pressure prevents prey species from evolving physiological tolerance or resistance to infectious agents. Parasites especially often have rapid effects on host evolution, due to exploitative interactions.

I seek to address …

A Review Of Mockingbird Song, Jacqueline Milander

Student Theses

The northern mockingbird (Mimus polyglottos) is known for its large repertoire and highly versatile song patterns.  It is a frequent mimic that is thought to continue learning sounds from its environment for the duration of its life.  Utilizing available song studies, this is a comprehensive review of northern mockingbird song, including learning, mimicry, repertoires, song dependence on seasonal cyclicity, and song function, particularly interspecific territoriality. While much discussion has surrounded the idea that northern mockingbirds engage in interspecific territoriality and that vocal mimicry functions in intersexual selection, this review provides new insight into the possibility that latitudinal differences among populations …

The Impacts Of Wing-Flashing By Northern Mockingbirds On Foraging, Parental Care, And Reproductive Success, Anna R. Starman

Undergraduate Honors Theses

Foraging efficiency may be enhanced by flashing patches of white wing and tail feathers and has been documented in several avian species. Northern Mockingbirds (Mimus polyglottos, NOMO) exhibit this “wing-flashing” (WF) behavior while foraging, during displays, and in response to predators. In NOMOs, WF has been hypothesized to increase foraging success, but previous findings are inconclusive. To further investigate the biological role(s) of WF behavior in NOMOs, the ventral surface of white primary feathers of male NOMOs were artificially darkened, and the foraging and provisioning rates of undarkened (control) males and their mates were compared. While foraging, undarkened …

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 …

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 …

How Semiflightless Birds Adapt: A Survey From Barú, Costa Rica, Eli P. Laloudakis

Scripps Senior Theses

When we think of birds, we think of flight. Because of this, scientific research often focuses on how birds evolved flight and how their wings function during flight. However, not all birds can fly or fly well, as wings wax and wane on developmental, seasonal, and evolutionary time scales (Dial and Heers 2021). Consequently, rudimentary wings can be found in developing birds, secondarily flightless or semiflightless birds, birds that undergo simultaneous molts, and extinct theropods with “protowings” (structures that preceded fully functional wings). Secondarily flightless and semiflightless birds often evolve where there is no/low predation, abundant year-round food supply, and …

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 …

Genetics Of Mycangial Development And Host Colonization Within The Ambrosia Symbiosis, Mckeon James Laws

Graduate Theses, Dissertations, and Problem Reports (ETD)

Ambrosia beetles, a polyphyletic group of weevils, utilize pouch-like structures at various locations on the body to transport for their sole food source, their fungal partner. Ambrosia fungi are known to originate from multiple unrelated fungal lineages with no consensus of traits required to become a fungal cultivar. While the biology and ecology of both partners is in many cases well understood, the genetic underpinnings of this fascinating mutualism remain a mystery. The aim of this dissertation is to add to the understanding of the ambrosia symbiosis by providing insights into its molecular and genetic underpinnings through RNA sequencing data, …

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 …

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 …

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

UROP 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, …

Homoplasy Of Maxillary Orthognathism In Derived Homo, Jared Jordan

Graduate Studies Theses and Dissertations 2026

The evolution of the orthognathic condition in the genus Homo represents a monumental transition toward the facial morphology of modern humans from that of earlier hominins, but the phylogenetic positioning of this transformation remains poorly understood. This study investigated temporal trends in maxillary and mandibular prognathism in the genus Homo, and whether maxillary and mandibular shortening in East Asian H. erectus and later East Asian Middle Pleistocene Homo (e.g., Homo longi) represent independent derivations of orthognathic morphology, thereby making orthognathism a homoplasy in the genus Homo. Using a sample of roughly 109 cranial and mandibular specimens spanning …

Exploring Factors Mediating White-Nose Syndrome In Little Brown Bats, Carly R. Trujillo

Graduate Theses/Dissertations

The little brown bat (Myotis lucifugus) has experienced drastic population declines across North America due to the recent disease white-nose syndrome (WNS). Previous studies have identified putatively adaptive alleles (PAAs) that may give individuals a greater likelihood of survival. However, there could be geographic-specific adaptation, creating different adaptive landscapes. Additionally, there may be energetic trade-offs between disease survival and reproductive output, and it is not clear what the long-term survival outcomes for the species may be as a result. Long-term evolutionary outcomes are unclear because this species has a lifespan exceeding the arrival of WNS and is difficult …

Analysis Of Alternative Oxidase In Non-Angiosperm Plants, Anissa M. Francis

Theses and Dissertations (Comprehensive)

Alternative oxidase (AOX) is a mitochondrial terminal oxidase that provides an alternative pathway for electron transport, allowing plants to maintain respiratory flexibility under environmental stress conditions. While AOX has been extensively studied in angiosperms (flowering plants), little is known about its distribution and conservation in non-angiosperms. Based on gaps identified in the literature, this thesis investigated the distribution of AOX across non-angiosperm plant lineages. Although AOX is present in many green algae and is therefore considered to be an ancient protein that originated before the existence of non-angiosperm plants, it remains unclear whether the protein is uniformly distributed across these …

Stress And Reward Interactions In Substance Use Disorder: An Evolutionary Mismatch Framework, Nicholas L. Castrucci

Honors Theses and Capstones

Substance use disorder (SUD) is a major public health concern characterized by compulsive substance use despite adverse consequences. While contemporary models emphasize biological, psychological, and environmental contributors, stress- and reward-related systems are often examined in isolation. This review integrates these systems within an evolutionary mismatch framework to examine how chronic stress exposure and repeated substance use increase vulnerability to addiction. Stress and reward systems are evolutionarily conserved but may become chronically dysregulated under modern conditions characterized by persistent psychosocial stressors and highly potent rewarding stimuli. This is associated with converging neuroadaptations across stress and reward circuitry, resulting in altered affective …