Evolution Commons^™

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 …

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 …

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 …

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 …

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, …

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 …

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 …

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 …

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, …

A New Dioecious Bush Tomato, Solanum Nectarifolium (Solanaceae), From The Northern Tanami Desert, Northern Territory, Australia, With Reassessment Of S. Ossicruentum And A Change In The Circumscription Of S. Dioicum, Christopher T. Martine, Kym Brennan, Jason T. Cantley, Aiden Webb, Geoffrey Newton

Faculty Journal Articles

A new species of functionally dioecious bush tomato from the “Solanum dioicum + S. echinatum group” of Solanum subgenus Leptostemonum is described. Solanum nectarifolium Martine & Brennan, sp. nov., is a member of the taxonomically challenging Solanum dioicum W.Fitzg. species complex in Australia and differs from other species in the group by the presence of prominent and conspicuous extrafloral nectaries on the abaxial leaf surfaces, a tinge of purple on the new growth and young fruiting calyces, and curved prickles on young stems. Although fairly well represented in herbarium collections, this new taxon has historically been treated 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 …

Both Studying And Protecting Octopuses “On Their Own Terms”, Jennifer Jacquet, Janelle Kaz, Becca Franks, Christine Webb

Animal Sentience

Cephalopods – indeed, all animals – “must be seen on their own terms,” with respect for their autonomy and their ecological imperatives. This will provide greater scientific insight along with a more ethical and accurate understanding of minds beyond our own.

Cephalopod Consciousness On “Their Own Terms”: Who Are “They”?, Willa M. Lane, Victor Ajuwon, Nicola S. Clayton

Animal Sentience

Mather’s call to consider cephalopods’ consciousness “on their own terms” raises the question of the extent to which cephalopods can be considered a homogenous group. While coloeoid cephalopods share traits that strongly distinguish them from other molluscs and invertebrates, they show vast ecological and morphological diversity, with implications for the design of empirical investigations of consciousness. Extending Mather’s argument, we apply Birch et al.’s (2020) five-dimensional model to compare octopus, cuttlefish, squid, and nautilus. This comparison shows that even within a graded rather than categorical framework, putative consciousness profiles depend on which taxa are included in discussions of “cephalopod consciousness.” …

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 …

Phylogenetic Comparative Vocal Evolution, Casper W. Buchanan

Master's Theses

Vocal learning is a trait unique to humans, bats, cetaceans, primates, and birds (Jarvis & Nottebohm, 1997; McComb & Semple, 2005; Wilbrecht & Nottebohm, 2003). Although there has been extensive research on vocal learning in songbirds, parrots are an even closer proxy to human learning, as they are social, intelligent, and lifelong learners, with some having repertoires of over 300 sounds (Benedict et al., 2022; Péron et al., 2011; Thomsen et al., 2019; Toft & Wright, 2015). Elevated vocal learning can be attributed to the need for parrots to have strong communication skills through the sharing of information over foraging, …

Multilevel Selection In The Margins: A Review Of Its Representation In Undergraduate Biology Textbooks, C. A. Greene, S. J. Mcpeek, L. Mitchem, A. B. Clark, Vincent A. Formica

Biology Faculty Works

Multilevel selection (MLS) is a foundational framework that expands the concept of natural selection beyond the traditional focus on individuals or genes to larger units, like groups. Despite strong empirical support and applications in a broad range of biological fields, MLS, often referred to as group selection, has a controversial history, which has impeded its wide use and led to incorrect inferences on the sources and strength of selection. Here, we explore how MLS is currently presented to undergraduate biology students by analyzing the content of nine commonly used Evolutionary Biology and Animal Behavior textbooks. We ask whether and how …

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 …