Biology Commons^™

The Past, Present, And Future Of Climate Adaptation In A Widespread Lizard Species, Matthew R. Mcternan

All Dissertations

Climate, as a selective force, shapes patterns of biodiversity globally. However, how species adapt to climate remains a central question of biology. The need to understand climate adaptation is paramount, as global climate change threatens a large portion of global diversity. Climate can impose selection on life by either controlling rates of energy intake and expenditure through effects on body temperature and activity, or by exposing organisms to conditions beyond their physiological limits. Studies of climate adaptation have identified a wide-range of putatively adaptive phenotypic patterns, but genomic evidence is increasingly being used to investigate these patterns and better understand …

The Evolution Of Hymenopteran Recombination Rates, Timothy John Delory

All Graduate Theses and Dissertations, Fall 2023 to Present

Individuals of some species mix their DNA frequently when producing sex cells, while others do so much less. Hymenopterans (ants bees and wasps) are especially useful for understanding this variation for several reasons. They show large differences in this frequency of shuffling, or rate of recombination, have well-studied genomes, and vary widely in how they live and reproduce. I capitalized on these features examines how recombination rates have evolved in this group at the trait, and gene level.

First, I revisited long-standing ideas about why recombination rates differ among these species, incorporating more than a decade of new research. This …

Cytoplasmic Shift Of Interferon Regulatory Factors Co‐Evolved With Jawed Vertebrate Innate Immunity, Vanessa M. Hubing

Honors Program: Senior Projects (Public)

The emergence of jaws in early vertebrates introduced a novel feeding apparatus and powerful oral defenses, but it also increased the risk of physical injury and pathogen exposure. Interferon regulatory factors (IRFs) play critical roles in orches-trating innate immunity and inflammation in response to invading microbes and tissue damage, with their subcellular local-ization being essential to some IRFs' function. Our results indicate that IRF members underwent independent expansion and diversification in two distinct vertebrate lineages: jawed and jawless vertebrates. The jawed vertebrate-specific factor, IRF5, has maintained conserved nuclear export sequences throughout evolution, while newly diversified IRF members in jawed verte-brates …

Evolution As Spatial Projection, Charles H. Smith, Ngoc Nguyen

Faculty/Staff Personal Papers

A theory combining explanations for the nature of three-dimensional systems and evolutionary processes is advanced, set to a geometric simulation, and then discussed in the context of several empirical studies bearing on its validity. The concept “evolution” is first discussed, then related to Baruch de Spinoza’s ideas on natural philosophy, including his concept of the conatus. These ideas are then extended by posing the possible existence of a general form of natural systems subsystemization leading to the extended space condition. A geometrical/topological simulation study projecting spatial relations among subsystem structures interpretable through entropy maximization and multidimensional scaling methods is presented, …

Alfred Russel Wallace Notes 39. What About Wallace's 'Agnosticism'...?, Charles H. Smith

Faculty/Staff Personal Papers

Alfred Russel Wallace (1823−1913) seems to have distinguished his earlier years of agnosticism from his later period as a spiritualist, but a closer look at the situation suggests he actually remained an agnostic all the way through to the end of his life. The confusion is occasioned by a lack of terminology that can be applied to his position, which most closely resembles a Spinozian manner of thinking.

Regeneration Of Swimming Antennae After Partial Amputation In Long- And Short-Lived Daphnia, Charles Schumpert, Rekha C. Patel, Jeffry L. Dudycha

Faculty Publications

Regeneration, the ability of an animal to restart a developmental process and thus rebuild itself following injury or loss, is generally thought to be inversely related to aging, the progressive decline of organismal functions and fitness that occurs as adults get older. We sought to test whether recently evolved differences of aging in the crustacean Daphnia were accompanied by evolutionary divergence of regenerative ability. Using the short-lived D. pulex and the long-lived D. pulicaria, we conducted an assessment of regenerative ability in which we amputated part of the swimming antenna and observed subsequent regeneration. In four clones isolated from …

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 …

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 …

Species Boundaries Of The Rare Menzies’ Wallflower (Brassicaceae: Erysimum Menziesii), An Endemic Of The Northern California Coast, Cameron M. Jones

Cal Poly Humboldt theses and projects

Morphological similarity among geographically isolated populations can obscure deep evolutionary divergence, especially when convergent evolution under similar environmental conditions yields comparable phenotypes across independent lineages. Such cryptic diversity is likely underestimated in hotspots like the California Floristic Province (CFP), a global biodiversity hotspot, defined by its Mediterranean-like climate and encompassing most of California, southwestern Oregon, and northwest Baja California. The CFP is home to a disproportionate number of narrow endemics whose origins and evolutionary relationships remain poorly understood. Here, I investigate the evolutionary origins of Erysimum menziesii (Brassicaceae), a federally endangered California coastal dune endemic whose fragmented distribution has led …

Systematics, Evolution, And Species Delimitation Of Ichneumonidae (Hymenoptera) Based On Ultraconserved Element Phylogenomics, Brandon Ross Claridge

All Graduate Theses and Dissertations, Fall 2023 to Present

The diversity of life on Earth is highly skewed towards a few key groups of organisms. Parasitoid wasps are among the most species-rich yet understudied organisms on our planet. Ichneumonidae, the largest parasitoid wasp family, includes 25,000 known species out of an estimated total of 100,000, far exceeding the nearly 70,000 species of vertebrates. As parasitoids, ichneumonids lay a single egg onto or inside their hosts, and the resulting ichneumonid larva consumes its host, ultimately killing it. Most hosts are the larvae or pupae of moths, butterflies, flies, beetles, and other wasps, including many pest species injurious to agriculture and …

Evolutionary Biomechanics In Cetartiodactyla: Impacts Of Ecological Shifts On Bone Material Properties And Control Surface Morphology, Danielle S. Adams

All Dissertations

Extreme ecological transitions expose organisms to novel selective pressures that can reshape morphology and performance. This dissertation investigates how the transition from land to water has influenced form and material properties in cetaceans (whales, dolphins, and porpoises), a clade that has undergone dramatic morphological and physiological adaptations to a fully aquatic lifestyle. I integrate comparative morphology, material property testing, and phylogenetic analyses, to explore how ecological demands, particularly related to foraging mode and prey detection, have shaped multiple aspects of cetacean morphology and function. Using nanoindentation and microCT, I measured elastic modulus and bone density of the skull and mandible …

Functional Morphology Of The Primate Knee And Its Implications For Hominin Bipedal Mechanics, Catherine K. Miller

Dartmouth College Ph.D Dissertations

Bipedal locomotion is central to the human condition, having shaped our evolutionary trajectory since its early emergence in the hominin lineage. Despite its importance, key questions remain about its origins and evolutionary trajectory. While many studies have focused on locomotor-related anatomies, comparatively less attention has been paid to the knee joint – a structure critical to the primate locomotor repertoire. This dissertation aims to clarify the form-function relationship of the knee in extant primates to better infer the locomotor behaviors of Miocene hominoids and Plio-Pleistocene hominins. To address these questions, this research employs a multifaceted analytical approach, integrating linear measurements, …

Investigating Evolution Through The Lens Of Ai-Driven Protein Exploration And Phylogenetic Modeling, Mataya Duncan

Graduate Theses and Dissertations

Recent advances in computational biology, artificial intelligence, and sequencing technologies have enabled new perspectives for addressing longstanding questions in evolutionary biology. Increased computational power has made large-scale simulations feasible for investigating diverse aspects of evolutionary and phylogenetic modeling. Similarly, deep learning algorithms now allow for the prediction of reasonably accurate tertiary protein structures, unlocking the potential for investigating diversity and evolution of protein structure across a broad range of organisms. This thesis presents two studies that target different aspects of evolutionary inference from unique perspectives. Yet, the share an overarching goal of presenting new perspectives on the evolutionary basis of …

Learning In Nonleafcutting Fungus-Gardening Ants, Elizabeth D. Boshers

Biology Theses

Social complexity influences learning and other cognitive behaviors, but for insects, this influence is not well understood. Delayed rejection is an aversive learning behavior previously studied exclusively in leafcutting ant species, the most socially complex of the fungus-gardening ants. Fungus-gardening ants are unique in that they do not directly consume the material they forage, using it instead as substrate to cultivate a symbiotic fungus on which the ants are obligately dependent. Here, I attempt to induce delayed rejection in several fungus-gardening ant species that exhibit a range of social complexity, then compare the characteristics of delayed rejection behavior among species. …

Avian Adaptation To Thermal Gradients, Justin Wheeler Baldwin

Arts & Sciences Graduate Student Theses and Dissertations

Life on Earth has adapted to extremely different temperatures worldwide. However, across distant branches of the tree of life, animals in similar temperature environments often share similar phenotypic traits. Specifically, traits that bear on the ratio between an individual’s surface area (e.g. appendage length) and its volume (e.g. body size) are particularly important for temperature regulation and are codified in canonical biogeographical rules. Although these global patterns of finding larger-bodied (Bergmann’s Rule) and shorter-limbed (Allen’s Rule) animals in colder regions are widely upheld, they also show substantial variation. It remains poorly understood why some animals conform to these biogeographical rules …

Study Of The Brain Anatomy Of Three Extinct Marsupials: Thylacinus Cynocephalus, Thylacoleo Carnifex, And Silvabestius Johnnilandi, Francisco Garcia

Honors Program Theses and Research Projects

Marsupials are pouched mammals that today are mainly found in Australasia and South America. Marsupials have proven to be quite intriguing to evolutionary biologists who note how some marsupials resemble placentals in anatomy due to convergent evolution, with both marsupials and placentals filling similar niches in their respective environments. As of today, studies interested in marsupial brain evolution have published descriptions of cranial endocasts for several species of marsupials, with the number of descriptions seeing a massive boost over the last 20 years with the arrival of CT imaging technology. However, no comprehensive study of brain evolution in marsupials has …

Evaluating The Current State Of Evolution Acceptance Instruments: A Research Coordination Network Meeting Report, M. Elizabeth Barnes, Rahmi Q. Aini, James P. Collins, Ryan D.P. Dunk, Emily A. Holt, Jamie Jensen, Joanna R. Klein, Taya Misheva, Louis S. Nadelson, Michael J. Reiss, William L. Romine, Andrew Shtulman, Amanda L. Townley, Jason R. Wiles, Yi Zheng, Sara E. Brownell

Biological Sciences Faculty Publications

Hundreds of studies have explored student evolution acceptance because evolution is a core concept of biology that many undergraduate biology students struggle to accept. However, this construct of “evolution acceptance” has been defined and measured in various ways, which has led to inconsistencies across studies and difficulties in comparing results from different studies. Many studies and essays have offered evaluations and perspectives of evolution acceptance instruments, but publications with a focus on consensus building across research teams is still needed. Further, little attention has been paid to how evolution acceptance instruments may be interpreted differently by students with varied religious …

Interspecific Selection In A Diverse Mycorrhizal Symbiosis, Megan A. Rúa, Jason D. Hoeksema

Biological Sciences Faculty Publications

Coevolution describes evolutionary change in which two or more interacting species reciprocally drive each other’s evolution, potentially resulting in trait diversification and ecological speciation. Much progress has been made in analysis of its dynamics and consequences, but relatively little is understood about how coevolution works in multispecies interactions, i.e., those with diverse suites of species on one or both sides of an interaction. Interactions among plant hosts and their mutualistic ectomycorrhizal fungi (ECM) may provide an ecologically unique arena to examine the nature of selection in multispecies interactions. Using native genotypes of Monterey pine (Pinus radiata), we performed a common …

Alfred Russel Wallace Notes 33. The Story In Evolution., Charles H. Smith

Faculty/Staff Personal Papers

Alfred Russel Wallace (1823-1913) is best known for his independent formulation of the principle of natural selection. In this work I first review my understanding of Wallace’s intellectual development on this subject, including the notion that he had no model for the evolution of higher consciousness as of his first treatment of natural selection in 1858. This leads to some conclusions about his approach to the subject, and links to parallel ideas inherent in the philosophy of Baruch de Spinoza (1632-1677).

What Drives Gut Microbial Diversity And Community Structure Among Closely-Related Host Species?, Rylee Jensen

All NMU Master's Theses

The gut microbiome (GMB) of mammals hosts an important community of microbes that perform countless micro-ecosystem services for the host and are influenced by numerous factors including host physiology, environment, and phylogeny. Phylogeny may have a unique effect on GMB diversity and community structure (i.e., a GMB profile) via phylosymbiosis, a theory in which the evolution of hosts matches the evolution of their associated microbiota. Elucidating phylosymbiosis in mammals is difficult because multiple intrinsic and extrinsic factors collectively drive individual GMB variation. Thus, there is a need to simultaneously analyze the role of physiology, environment, and phylogeny on shaping host …

Life, Death And Energy: What Does Nature Select?, James H. Brown, Chen Hou, Charles A.S. Hall, Joseph R. Burger

Biological Sciences Faculty Research & Creative Works

Evolutionary biology is poised for a third major synthesis. The first presented Darwin's evidence from natural history. The second incorporated genetic mechanisms. The third will be based on energy and biophysical processes. It should include the equal fitness paradigm (EFP), which quantifies how organisms convert biomass into surviving offspring. Natural selection tends to maximize energetic fitness, formula presented, where formula presented is mass-specific rate of cohort biomass production, formula presented is generation time, formula presented is fraction of cohort production that is passed to surviving offspring, and formula presented is energy density of biomas. At steady state, parents replace themselves …

Island Hopping In The Tropics: Conservation Genetics, Speciation, And Biogeography In The Iconic Flowering Plant Group Hibiscus Sect. Lilibiscus, Brock Mashburn

Arts & Sciences Graduate Student Theses and Dissertations

Islands have played a crucial role in evolutionary biology, providing key insights for both Charles Darwin and Alfred Russel Wallace in formulating their theories of evolution. The development of Island Biogeography Theory and the General Dynamic Model of oceanic island biogeography have formed the theoretical foundation of island studies over the last sixty years, leading to substantial advancements in our understanding of biodiversity evolution. Despite their critical value for evolutionary theory, islands face unprecedented ecological collapse, with species on islands facing significantly higher extinction rates than on continents. The island extinction crisis highlights the need for integrating conservation perspectives into …

The Evolution Of A Response To Smoke Within The Arthropoda, Adam Miles

Masters Theses & Specialist Projects

Many animals have a survival instinct to flee in response to fire, but do they respond to smoke alone? Many arthropods respond to fire or smoke by moving in the opposite direction (a negative taxis) to obtain shelter. At the species level, taxa that have adapted a behavioral response to fire increase their fitness. This response behavior has been observed in many terrestrial arthropods. Still, the behavior is currently unknown for marine, aquatic, or cave arthropods, which are atypically exposed to smoke or fire. This project assesses how often behavioral adaptation to smoke avoidance may have evolved within Arthropoda. Twenty-two …

Venom Complexity Within Garter Snakes And The Role Of Diet In Toxin Diversification, Tucker Heptinstall

All Theses

Complex traits, such as body size and venom, are often under strong selection by

dietary ecology and can increase efficiency of prey capture and processing. To investigate relationships between ecology and trait evolution in Thamnophis, we amassed nearly 10,000 diet records for 32/35 Thamnophis species and classified each species’ dietary repertoire. We categorized 15/32 species as generalist predators and 17/32 species as specialist predators of varying prey groups and investigated the hypothesis that generalist predators have larger body size. However, we found no significant relationship between body size and dietary specialization. Venom has evolved over 100 times across the Tree …

Support For Climate Shaping The Mitochondrial Dna Contact Zone In The Audubon's Warbler, Kyana Nina Montoya

Biology ETDs

Mitochondrial introgression has potential consequences for physiology and adaptation, but its causes are poorly understood. The Audubon’s Warbler (AUWA; Setophaga coronata auduboni) provides a case study to examine those causes as mitochondrial introgression has swept through part of the range. The northern mitochondrial genome (mtDNA) introgressed from the Myrtle Warbler (MYWA; S. c. coronata) and is 4% divergent from the southern mtDNA. Incomplete introgression suggests discordant AUWAs conferred a selective advantage in the north; it was hypothesized that energetic demands associated with migration formed this advantage. We tested two hypotheses to explain partial introgression and the mtDNA distribution …

Inter-Kingdom Communication And The Sympoietic Way Of Life, Scott F. Gilbert

Biology Faculty Works

Organisms are now seen as holobionts, consortia of several species that interact metabolically such that they sustain and scaffold each other’s existence and propagation. Sympoiesis, the development of the symbiotic relationships that form holobionts, is critical for our understanding the origins and maintenance of biodiversity. Rather than being the read-out of a single genome, development has been found to be sympoietic, based on multigenomic interactions between zygote-derived cells and symbiotic microbes. These symbiotic and sympoietic interactions are predicated on the ability of cells from different kingdoms of life (e.g., bacteria and animals) to communicate with one another and to have …

Feather Mites Through Genomic And Ecological Lenses: Host Specificity And Symbiosis At Multiple Levels Of Organization, Alix Elizabeth Matthews

Student Theses and Dissertations

Symbionts, or organisms that form close and persistent associations with hosts, are ubiquitous across the tree of life, and symbioses are among the most common interspecific interactions in the natural world. Symbionts play a fundamental ecological and evolutionary role across multiple levels of biological organization – from individuals to ecosystems – and can have strong effects on global biodiversity. However, many aspects of these relationships are poorly understood including symbiont genetic diversity (inter- and intraspecific), host specificity, and the mechanisms underlying their functional nature or any context-dependent patterns. This dissertation uses a model symbiosis between permanent, obligate, ectosymbiotic vane-dwelling feather …

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 …

Evolution Repeats Itself In Replicate Long-Term Studies In The Wild, Patrik Nosil, Clarissa F. De Carvalho, Romain Villoutreix, Laura S. Zamorano, Marion Sinclair-Waters, Nicholas P. Planidin, Thomas L. Parchman, Jeffrey Feder, Zach Gompert

Biology Faculty Publications

The extent to which evolution is repeatable remains debated. Here, we study changes over time in the frequency of cryptic color-pattern morphs in 10 replicate long-term field studies of a stick insect, each spanning at least a decade (across 30 years of total data). We find predictable “up-and-down” fluctuations in stripe frequency in all populations, representing repeatable evolutionary dynamics based on standing genetic variation. A field experiment demonstrates that these fluctuations involve negative frequency-dependent natural selection (NFDS). These fluctuations rely on demographic and selective variability that pushes populations away from equilibrium, such that they can reliably move back toward it …

Ultraconserved Elements Based Phylogeny Of The New Zealand Mite Harvester Genus Rakaia, Zade Alafranji

Biology Honors Projects

New Zealand is home to a remarkable number of endemic taxa, some of which existed on the archipelago before the breakup of Gondwana. The mite harvesters (suborder Cyphophthalmi), tiny arachnids which dwell in forest leaf litter and caves, are one such group. The mite harvester family Pettalidae exhibits a classic Gondwanan distribution, informative for describing ancient patterns of diversification. Within New Zealand, there are three genera of pettalids; our research focuses on the phylogeny of the most widespread and diverse of these: Rakaia. Through phylogenetic analysis, we provide a window into patterns of ancient diversification and infer historical biogeographic trends. …