Biological Sciences Doctoral Work

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Curriculum design and assessment: the development of a nonmajor biology course-based undergraduate research experiences and its effects on students and instructors
(North Dakota State University, 2024) Falkner, William
The goals of nonmajor science education are to improve scientific literacy and produce pro-science attitudes. Together, these goals are expected to improve an individual’s ability to make evidence-based decisions based on newer understandings of the natural world as well as developing technologies. In a post-COVID-19 world, public understanding of science was brought to the forefront for public health but were also challenged by a deluge of misinformation to obfuscate these goals. General education science courses represent the last formal experience for our populace. Following a learning-science-by-doing-science approach, this dissertation describes the development, implementation, and assessment of a course-based undergraduate research experience (CURE) for nonmajor science students. The first objective of this dissertation was to review the outcomes and design elements of published CUREs. Through a systematic review of Biology-based CURE literature, several content, skill, and affective-based outcomes are identified resulting from eight proposed design elements. The second objective was to outline and highlight the decision-making process when designing a CURE for nonmajors. Here, historical perspectives on course design, both general and science-specific, are described and applied along with findings from the first objective to design a CURE for nonmajor biology students. The third objective was to survey graduate teaching assistants (GTAs) that instructed this nonmajor CURE to identify GTA benefits and challenges. Findings indicate that GTAs found CUREs to be beneficial to their current and future works and strongly believed this type of approach to nonmajor education is preferable to expository lab design. The final objective was to assess student scientific literacy and science attitudes after engaging with a CURE. Based on two surveys using a pre/post design, there were no significant differences between different laboratory course designs for neither literacy nor attitudes and only found some support between the association of scientific literacy and science attitudes. This dissertation demonstrates the complexity of cradle-to-grave course design, the difficulty in measuring large constructs such as scientific literacy and science attitudes, and implications for future evidence-based course design.
‘Omics’ approaches to understand ecology and physiology of bees
(North Dakota State University, 2024) Brar, Gagandeep
Bees face several ecological and physiological challenges due to poor nutrition and abiotic stress. This dissertation explores various aspects related to these challenges, including the microbial ecology of honey bees and the alfalfa leafcutting bee, as well as the cold physiology of the alfalfa leafcutting bee. The first study delves into the dynamics of gut microbiota in overwintering adult worker honey bees, Apis mellifera. Through 16S rRNA gene amplicon sequencing, variations in the microbial composition among the bee strains, due to types of storage conditions, and the month of storage were examined. Overall, in this study a stable gut microbiota was observed in the bees both in the indoor and outdoor storage conditions during the winter months with slight differences in the abundance of bacterial species between bee strains. This study highlights the resilience of honey bee gut microbiota under cold stress conditions. The second study was focused on assessing the gut microbial ecology in the solitary bee, Megachile rotundata. The study investigated the significance of gut microbiota in these bees and in particular the effect of the Apilactobacillus clade on the larval and prepupal development, their weight, and survival. Results indicate that reliance on non-host specific environmental bacteria may not significantly impact the fitness of M. rotundata. The study highlights the role of environmentally collected bacteria in shaping bee nutrition and health. The third study explored the regulation of diapause initiation in the M. rotundata. By analyzing the gene expression using RNA-seq during diapause initiation, the research identified differentially expressed genes associated with oxidative stress, cell signaling, and other diapause-related pathways. The study provides insights into the molecular differences between diapausing and non diapausing individuals, contributing to a broader understanding of the cold physiology of M. rotundata. Together, these multi ‘omics’ studies contribute invaluable knowledge to the fields of bee biology, ecology and physiology, offering insights into the intricate relationships between bees, their microbiota, and the environmental factors influencing their life cycle.
Short- and Long-Term Effects of Environmental Variability on the Ecophysiology of a Solitary Bee
(North Dakota State University, 2022) Earls, Kayla
Environments can vary across seasons. One characteristic of spring in temperate regions is fluctuations in temperature. Sudden bouts of low temperature can have lasting effects on ectotherms that rely on ambient temperature. For developing insects, being unable to avoid or manage these low temperatures puts them further at risk. For example, Megachile rotundata undergo active development in the spring. Exposure to low temperatures as pupae for short periods does not decrease survival but does affect adult morphology. Pollination services may also be affected if temperatures are too low to promote flight in adults. The overall question is what are the short- and long-term physiological effects of temperature in pupae and adults? The first objective of this dissertation is to investigate the long-term effects of low temperature stress by measuring flight performance, reproductive output, and offspring characteristics. After receiving a constant low temperature for a week, females were less likely to nest and changed their offspring investment. Additionally, offspring of bees exposed to fluctuating low temperature stress were more likely to enter diapause despite being early in the season. The second objective was to test if oxygen consumption across temperatures generated a thermal performance curve as a short-term effect in M. rotundata pupae. Results indicate that oxygen consumption scales non-linearly like a thermal performance curve; however, the negative slope at high temperatures was not observed. The third objective was to determine how microclimate conditions affect flight initiation in M. rotundata adults. Two different activity boxes were designed to measure environmental variables and to manipulate cavity temperature. The first activity box measured several environmental variables and showed that even at very close proximities, M. rotundata experience different temperature conditions. In the other activity box design, internal cavity temperature was manipulated to increase early in the morning. Results show that increasing the cavity temperature promoted earlier flight and at lower ambient temperatures. This dissertation shows that the life stage an insect experiences a thermal stress can affect short- and long-term effects on physiology and life history in M. rotundata.
An Investigation of Student Understanding and Acceptance of Evolution
(North Dakota State University, 2021) Harding, Rachel Leigh Salter
Evolution is central to biology education and yet, it is often one of the most misunderstood and controversial topics that biology educators must teach. Research spanning the last four decades has shown that students continue to struggle, even with direct instruction, to understand the process of evolution by natural selection. In my first chapter, I found that students enrolled in non-majors geology course did not increase in their understanding of evolution, even after instruction. This followed similar findings from research occurring over 30 years in the past. Discipline-based education researchers have theorized that students’ persistent difficulties understanding evolution may stem from the conceptual challenges inherent to complex biological systems. To meet the needs of biology instructors, I developed a new teaching tool, a rapid response rubric (3R: Evolution), to provide more opportunities for formative assessment and feedback in large-enrollment courses. I found the 3R: Evolution provided direct and actionable feedback, allowing students to modify their understanding of evolution in large-enrollment courses and exhibit large increases in their knowledge from pre- to post-assessment. However, knowledge of evolution is not the only challenge to biology education: students must also accept evolution. A lack of evolution acceptance can emerge from various social, cultural, and epistemological factors including religiosity and regional impacts, knowledge of the nature of science, openness to experience, and evolution exposure. In this work, I present a path analysis to illuminate the direct causal relationships from these individual factors to evolution acceptance. I found that while religiosity was the largest casual predictor of acceptance, the other chosen factors, including knowledge of evolution, were all significant predictors of evolution acceptance. Even though evolution remains a difficult topic, this work shows that students can increase both their understanding and acceptance of evolution, using new curriculum and increasing exposure to evolution content across their school career.
The Influence of Body Size on Metabolic Rates, Scaling, Telomere Dynamics, and Metamorphosis in Megachilid Bees
(North Dakota State University, 2021) Grula, Courtney Corinne
Body size is related to many aspects of a bee’s life history including foraging distance and pollination efficiency. Megachile rotundata, and Osmia lignaria are agriculturally important, solitary pollinators. Adult body size in solitary bees is variable because it is determined by the quantity of food available to the developing larva. The goal of this dissertation was to determine the effect of body size on metabolic rates, scaling, telomere dynamics, and entry into metamorphosis. Body size was manipulated under laboratory conditions by manipulating the amount of food provided during the final larval stage. First, I tested the effect of body size on allometry and amount of energy produced, measured indirectly through CO2 emission. The power required during flight was predicted using biomechanical formulas. I found larger bees had higher absolute metabolic rates at rest and during flight. Smaller bees had higher mass-specific metabolic rates at rest, but not during flight. As bees increased in size, their thorax and abdomens became disproportionately larger, while wings became disproportionately smaller. Smaller bees had more power available during flight as demonstrated by flight biomechanical formulas. Next, I measured telomere length in M. rotundata and O. lignaria throughout development. I also measured telomere length across a variety of body sizes, and life stages in both bee species, and found that body size does not affect telomere length. I found that telomere length increases in later life stages in both bee species. Lastly, I determined the cue for metamorphosis in M. rotundata by determining the critical weight. Entry into metamorphosis involves the insect’s ability to monitor its size. I found the cue for metamorphosis in M. rotundata is a critical weight which is influenced by nutritional condition. This was confirmed by declines in Juvenile Hormone titers, and upregulation of genes involved in metamorphic molts. This study found smaller-sized bees are not always at a disadvantage. Smaller bees had increased flight performance based on flight biomechanical formulas, did not show differences in telomere length based on body size, and enter metamorphosis at small sizes. Advantages to small body size may be a response to declines in resource availability.
Alignment of Genetic Variation, Plasticity, and Selection, and the Effects of Cost of Plasticity
(North Dakota State University, 2021) Berdal, Monica Anderson
Phenotypic expression depends on both the underlying genetics and the environment the phenotype is expressed in, i.e., plasticity. Adaptive theory predicts that selection should align with the dimensions of most genetic variation and plasticity because this will increase the evolutionary rate of a population, meaning that a population would reach its fitness optimum faster than if they were misaligned. Alignment with selection is only predicted if there is directional selection, and not under stabilizing selection. In addition, only adaptive plasticity is predicted to align with both selection and genetic variation, with the proportion of the plastic variation consisting of adaptive plasticity determining how well aligned plasticity should be. In the first chapter of this dissertation, I outline the evolutionary consequences of the relationship between selection, genetic variation, and plasticity, as well as what the predictions are for their alignments and how to estimate them. In my second chapter I empirically test the alignment between selection, among- and within-individual variation (used as proxies for genetic variation and plasticity respectively) for three behaviors in a wild population of deer mice (Peromyscus maniculatus). I found that selection, among- and within-individual variation were all misaligned, and that there was very little variation in all three behaviors. This could indicate that the behaviors have already reached their fitness optimum due to previous selection pressure. Consequently, this population might not be able to adapt to environmental change. In my last chapter I investigate the cost of plasticity in response to a predatory cue on reproductive outputs in isogenic lines of the banded cricket (Gryllodes sigillatus). Plasticity is assumed to have associated costs which would affect its alignment with selection and genetic variation. I found no evidence for cost of plasticity in G. sigillatus, and in addition there was no genetic variation in plasticity among the lines. Again, previous selection might drive the population’s mean plasticity to its fitness optimum, reducing the variation and the costs of plasticity, making it harder to detect.
Interaction and Innovation: The Impacts of Social Factors and Classroom Type on University Biology Instructor Classroom Assessment Decisions
(North Dakota State University, 2020) McConnell, Melody Dawn
Efforts to improve university science education continue to emphasize the importance of active learning, including frequent formative assessment and timely feedback that helps students reach desired learning outcomes. Yet, nationwide, many instructors continue to use primarily lecture-based teaching methods, with limited use of formative assessment and feedback. Factors that affect instructor adoption and implementation of new teaching techniques include departmental norms, peer interaction, and classroom environment. In this work, a model of the impacts of departmental teaching and social norms and peer interactions on instructor innovation decision is presented. This model is then used to explore 1) instructor teaching-related interactions within a single biology department, assessing the conditions for innovation diffusion, and 2) instructor perceptions of norms and interactions in that department and their impact on decision-making. Finally, introductory biology instructors’ use of assessment and feedback techniques were characterized in a lecture hall and an active learning classroom to see how innovation adoption translates to specific assessment practice and investigate the impact of the active learning classroom. Results indicate that perceptions and practices vary widely, but that both peer interactions and active learning classrooms may have a positive impact on teaching innovation adoption and practices in a university biology department. In addition, the pattern of interactions within this department allows instructors of varying assessment experience to interact, making it potentially conducive to the spread of teaching ideas. The model and results presented here will assist in understanding the factors involved in instructor decision-making and can be leveraged to help promote the use of formative assessment and other evidence-based teaching practices.
Using a Cross-Cutting Theoretical Framework to Explore Difficulties Learning Human Anatomy and Physiology
(North Dakota State University, 2020) Slominski, Tara Nicole
Across the United States, Human Anatomy and Physiology (HA&P) courses typically have some of the highest withdrawal and failure rates on college campuses. These high enrollment course typically serve as gate-keepers for those individuals with aspirations of entering the medical field. In light of the growing national shortage of healthcare professionals, there is a pressing need to improve the state of HA&P education at a national scale. The goal of this dissertation is to understand why undergraduate students struggle to succeed in HA&P courses. I leveraged multiple frameworks from biology education research, physics education research, and cognitive psychology to understand the source of student difficulty in HA&P. I used a mixed-methods approach to unpack how students reason about the complex phenomena covered in HA&P classes. The data presented here suggest student difficulties in HA&P are not the product of a culmination of individual conceptual difficulties. Rather, this work suggests students have difficulty reasoning with the many complex systems that are at the heart of HA&P curriculum. Students appear to frame these complex systems in a manner that activates reasoning strategies that are often in conflict with course goals. The findings from this work advocate for a dynamic view of student cognition that recognizes the implications of context features on student reasoning of complex systems.
Physiological Mechanisms Underpinning Growth and Aging in Wild Birds
(North Dakota State University, 2019) Sirman, Aubrey Erin
Life-history trade-offs have been well-documented within the literature through correlational and experimental studies. However, the physiological mechanisms underlying these trade-offs are less understood. Currently, there is great interest in shared mechanisms, specifically endocrine mechanisms, that might underlie the variation in life-history traits. Insulin-like growth factor-1 (IGF-1) may be one shared mechanism that is particularly important. IGF-1 is a metabolic hormone that is part of a highly conserved insulin-signaling pathway known to influence multiple life-history traits including growth and longevity across taxa, however, little is known about these trade-offs outside of laboratory populations. This dissertation focuses on the role of IGF-1 as a hormonal mechanism underlying the life-history trade-off between growth and aging in wild birds. While the causes of aging are not fully understood, telomere dynamics (length and change in length) are a potentially important mechanism underlying lifespan. To investigate the role of IGF-1 as a hormonal mechanism underlying the life-history trade-off between growth and aging in Franklin’s gulls (Leucophaeus pipixcan) and house sparrows (Passer domesticus). In Franklin’s gulls, dietary restriction reduced growth rate and IGF-1 levels but did not impact telomere dynamics. However, there was a significant negative correlation between IGF-1 levels and telomere length at the end of the post-natal growth period. In house sparrows, we found that nestling growth rates varied with respect to year, but IGF-1 levels did not. Telomere dynamics were not related to growth rates or IGF-1 levels, suggesting that during post-natal growth nestlings may be able to mitigate or even delay costs to later life stages. Finally, when exogenous IGF-1 was administered to house sparrow nestlings during the post-natal growth period, nestling growth was impacted but only in some years. Exogenous IGF-1 increased growth and final mass in 2016 and final mass in 2018. There was a trend suggesting experimental birds had shorter telomeres in 2016. Similarly, in 2018, experimental birds had significantly shorter telomeres than control birds. These effects were not observed in 2017, suggesting that trade-offs between growth an aging might only be visible under certain environmental conditions, which may vary with respect to year.
Peripheral Hormone Interactions with the Growth Hormone-Insulin-Like Growth Factor (GH-IGF) System in Rainbow Trout
(North Dakota State University, 2019) Dickey, Lindsey Ann
The growth of vertebrates is primarily regulated by the growth hormone-insulin-like growth factor (GH-IGF) system, but not in isolation. The central question of this dissertation was how do other hormones peripheral to the GH-IGF system interact with the system, including feedbacks by GH and IGF themselves on various tissues in rainbow trout (Oncorhynchus mykiss)? The representative hormones selected were thyroxine, cortisol, and the sex steroids testosterone and estrogen, along with GH and IGF. These hormones were chosen because they are known to affect overall growth and development during specific life events, but exactly what target genes and what mechanisms are involved are only at the early stages of being delineated in fish. Liver and gill tissues were selected as representative tissues to assess the in vitro effects on growth-related genes of the GH-IGF system. A total of more than thirty experiments were conducted, including time- and concentration-response, inhibitory studies, hormone combination studies, and radio-receptor binding assays. Hormones were applied to whole tissue cultures and real-time quantitative-PCR was used to measure hormonal effects on GHR, IGF, and IGFR1 genes. Microsomal preparations were treated with selected hormones and radio-labeled GH or IGF. A gamma counter was used to measure receptor-ligand activity. GH and IGF were found to possess autocrine and/or paracrine actions in self-regulating target growth genes. Thyroxine had no direct effects on targeted growth genes but may interact with other molecules or hormones to elicit its effects on growth and development. Cortisol directly influenced target growth genes in a tissue-specific and isoform-specific manner. Finally, sex steroids differentially regulated the growth genes: estradiol inhibited growth genes while testosterone directly stimulated growth genes. These findings contribute to understanding how hormones peripheral to the GH-IGF system interact with the growth system.
Low Temperature Stress in the Alfalfa Leafcutting Bee, Megachile Rotundata
(North Dakota State University, 2017) Torson, Alex S.
Dramatic changes in ambient temperature can have a significant impact on insect physiology throughout development. The accumulations of the deleterious physiological effects throughout low temperature exposure are collectively known as chill injury. The mechanisms underpinning the downstream physiological consequences of chill injury such as oxidative stress, perturbations in ion homeostasis, and changes in metabolism have yet to be elucidated. Brief, daily pulses of increased temperatures have been shown to repair and/or protect against the continued accumulation of chill injury, leading to an increase in survival across several insect taxa. Until recently, no transcriptomic-level assessments of gene expression during low temperature stress had been conducted. In this document I present a comparison of low-temperature stress response mechanisms across life stages in the alfalfa leafcutting bee, Megachile rotundata. RNA-seq, qPCR and oxidative stress assays were used to determine the physiological effects of low temperature exposure on two life stages: one adapted for low-temperature exposure and one that is not. Differential expression analysis revealed distinct gene expression profiles between life stages. The lack of overlap in expression profiles suggests different mechanisms are driving the response. Furthermore, an overlap in the functional classes of differentially expressed transcripts suggest that the response may be physiologically robust, even though the response is variable at the level of gene expression. Gene expression suggests oxidative stress may be a critical component in chill injury response and recovery. Antioxidant activity and lipid peroxidation, a common proxy for oxidative stress, were assessed in both life stages. M. rotundata’s ability to cope with an induced oxidative stress did not vary between treatments in either life stage. Furthermore, a lack of statistical differences between treatments in lipid peroxidative do not support the hypothesis that the benefits of fluctuating temperatures are, in part, due to reduction in oxidative stress.
Evidence of Climate Niche Creation in the Northern Great Plains: The History of Invasion, Population Genetics, Competitive Effect, and Long-Term Trends of Invasive Poa Pratensis L.
(North Dakota State University, 2016) Dennhardt, Lauren Alexsandra
Understanding the mechanisms of invasion is critical in order to control an invasive species. Poa pratensis L. (Kentucky bluegrass) is an invasive species that has been present in the northern Great Plains (NGP) for over 100 years, but has become a dominant species in the mixed grass region recently. My dissertation seeks to answer one critical question—why has P. pratensis become such a successful invasive species in the NGP? I first asked if the invasion was caused by adaptation and/or propagule pressure. I screened the genetic fingerprint of invasive P. pratensis in the NGP along with measuring the genomic content of wild plants and compared them to common cultivars. I found virtually no overlap between lawn cultivars and invasive P. pratensis populations. This was further supported by a narrow range of genomic content in wild individuals compared to the lawn cultivars. I also found no evidence of geographical patterning which is consistent with the hypothesis that local adaptation is not pervasive in P. pratensis. I then asked whether P. pratensis was a strong competitor compared to dominant plant species native to the tallgrass prairie. I studied competitive effect between Poa pratensis, Nassella viridula, Pascopyrum smithii, and Bouteloua gracilis through a species-pair competition experiment. Based on the relative interaction indices, P. smithii and P. pratensis were competitive against B. gracilis, and P. smithii was competitive against N. viridula. Additionally, P. pratensis was facilitated by all three species in the experiment. This study indicates that P. pratensis may be somewhat competitive. Finally, I asked whether the increase in the frequency of P. pratensis in the NGP may be attributed to environmental factors. In order to understand long-term correlations between P. pratensis invasion and environmental variables, I resampled plots that were previously sampled for species composition in 1978, 1979, and 1999. I found that P. pratensis levels did increase across plots and was corrrelated with higher levels of precipitation. My research indicates that increased precipitation in the NGP as a result of climate change is correlated with P. pratensis invasion in the NGP.
Population Dynamics and Management Implications for American White Pelicans (Pelecanus Erythrorhynchos) Breeding at Marsh Lake, Lac Qui Parle Wildlife Management Area, Minnesota
(North Dakota State University, 2016) DiMatteo, Jon J.
The American white pelican (Pelecanus erythrorhynchos) is a prominent breeding bird in Minnesota, but little information has been available on their production, population dynamics, growth and development, or demographic characteristics. I examined life-history traits of American white pelicans nesting colonially at Marsh Lake, Lac qui Parle Wildlife Management Area, Minnesota. Marsh Lake is an impounded river floodplain lake on the Upper Minnesota River that holds the largest American white pelican breeding colony in Minnesota (and one of the largest American white pelican breeding colonies in North America). An analysis of colony population levels and spring streamflow data indicated that more than 84% of the variation in the number of near-fledged chicks produced per nest was related to mean daily discharge during April. In years when high water floods preferred low-elevation nesting habitat on islands in the middle of the lake, American white pelicans are forced to establish nests on high-elevation sites that are closer to the mainland. The proximity to the mainland leaves the high-elevation sites accessible to mainland mammalian predators, and production rates decline. An examination of size at hatch and growth of American white pelican chicks showed little variation in initial size and growth rates between years. However, substantial variation in initial size and growth rates were detected within season depending on the timing of hatch. Initial mass did not vary throughout the nesting season, but initial tarsus and wing length were shorter in chicks hatched later in the season. However, growth rates for mass, tarsus, and wing were faster for late-hatched chicks, potentially allowing late-hatched chicks to fledge at an earlier age. An analysis of demographic characteristics of American white pelicans nesting at Marsh Lake indicated timing of nest initiation was not related to age or body condition of adults. However, nests were initiated earlier on the preferred nesting island at Marsh Lake. Although some individuals may nest at an earlier age, the estimated age of maturation for American white pelicans nesting at Marsh Lake suggests they are unlikely to begin nesting until they are at least five years old.
Social and Acoustic Behavior of the Leaf-Roosting Bat Thyroptera Tricolor
(North Dakota State University, 2015) Montero, Bianca Karina
The limited availability of refuges may represent an important factor promoting the evolution of sociality, particularly in bats. Spix’s disc-winged bats (Thyroptera tricolor) show highly specialized morphological adaptations that enable individuals to roost inside furled musoid leaves. This roosting ecology presents major challenges, as leaves rapidly unfurl, forcing bats to locate new roosts on a daily basis. Despite the reliance of T. tricolor on such ephemeral roosting resources, bats form stable group associations. The purpose of this study was to characterize the behavioral patterns associated with assessing roosts and any accompanying communication strategies of Spix’s disc winged bats. In the first chapter, I used video and acoustic monitoring to test the hypotheses that finding a high quality roost involves the regular assessment of leaf suitability within a group’s rooting range and that acoustic signals facilitate group interactions during nightly activity. The second chapter examines the patterns of geographic variation in two contact calls regularly emitted by T. tricolor. I evaluate the congruence of geographic variation in the acoustic features of contact calls with genetic differentiation of two populations in Costa Rica separated by a geographic barrier. In the third chapter, using an automated telemetry system, I examined the nocturnal movement patterns of all group members within the limits of the roosting range. I determined that bats regularly monitor furled leaves within their roosting range, during which they emit a number of distinct social calls. Among the acoustic signals produced by these bats, two calls are particularly common near furled leaves. When examining the relationship between genetic distance and acoustic divergence of these two contact calls I found discordant patterns of variation, suggesting the presence of distinct modes of vocal transmission within populations. The continuous assessment of movement patterns during foraging bouts provided evidence that in general, bats remain within close proximity of a group’s roosting range and the occurrence of dyadic encounters during the course of the night. This study contributes to our understanding of the behavioral strategies used by free-ranging bats providing valuable insight into the role of shelter stability in the evolution of the T. tricolor social system.
Ecophysiological Implications of Spring Conditions on the Alfalfa Leafcutting Bee, Megachile rotundata
(North Dakota State University, 2017) Bennett, Meghan Marie
Spring conditions stimulate development of many plants and animals after a period of winter dormancy. Climate change is predicted to cause earlier spring thaws, increasing temperature variability, and more frequent cold snaps. These conditions cause two problems for organisms. First, environmental cues may mislead organisms developing under these scenarios if temperature and photoperiod cues give conflicting information. Second, organisms outside of their overwintering stages can be less tolerant of cold exposure and may be at risk of injury or death. Little is known about the consequences of these conditions on bee species. Therefore, I examined these scenarios in a solitary bee species, Megachile rotundata. I hypothesized they would be sensitive to temperature changes to regulate spring emergence because of their cavity nesting life history where photoperiod cues likely buffered. I found light is buffered by the brood cell by approximately 80% and emergence can be synchronized by photoperiod. Furthermore, I demonstrated that M. rotundata may be more sensitive to temperature cues compared to photoperiod cues in regulating emergence. To understand how spring cold snaps during development affect adult bees, I comprehensively assayed M. rotundata cold tolerance. I discovered that cold exposure during development resulted in numerous sub-lethal effects in adult bees such as a decrease in flight performance and longevity. Furthermore, developmental cold stress affected adult thermal performance, such as chill coma recovery. Cold tolerance varies across development and the post-diapause quiescent stage was more tolerant to cold than pupal or emergence ready stages. Temperature fluctuations of spring may affect the timing of emergence but also the health of adult bees if they experienced a cold snap during development.
The Distribution and Habitat Use of North Dakota Bats
(North Dakota State University, 2014) Barnhart, Paul Roy
Prior to 2009, a comprehensive statewide survey of occurrence and distribution of bats in North Dakota had not been conducted. From 2009 to 2012, mist netting, radio telemetry, and acoustic monitoring were conducted to document species presence and habitat associations across North Dakota. We surveyed multiple sites at 17 locations, captured a total of 309 bats, documented habitat associations, and identified roosting sites. Data was then used to: 1) build habitat suitability maps (also called species distribution maps or SDMs) for each species in the state, 2) examine the environmental and climatic variables that influence bat habitat use along the periphery of their distribution, 3) assess the effect of sampling technique on habitat suitability models, and 4) determine if North Dakota's badlands region contains overwintering bat populations that may be susceptible to white nose syndrome, an emerging fungal disease of hibernating bats. We confirmed the presence of 11 species in the state and found that five species were present in areas outside their ND IUCN distribution. Maximum-entropy modeling showed that temperature was the most important variable for SDM production. We found that sampling technique (physical capture vs. acoustic detection) led to pronounced differences in habitat suitability maps for some species (33.9% overlap; Myotis septentrionalis) while models from other species were highly similar (80.4% overlap; Myotis lucifugus). Our findings show that acoustic detection results in better SDMs for Myotis spp. while physical capture was best for Eptesicus fuscus and Lasionycteris noctivagans. During the winter, we positively identified four species based on both acoustic detection and physical capture: E. fuscus, Myotis evotis, Myotis ciliolabrum, and Corynorhinus townsendii. Based on known and potential hibernacula locations, we produced a habitat suitability map that was successfully used to locate additional potential hibernacula. We also recorded temperature in confirmed and potential hibernacula, finding that temperatures were within the optimum range of fungal growth. The information gathered from these studies will be used to develop the first statewide conservation action plan for North Dakota bats. Also, the habitat suitability maps produced will be used by managers to target areas of high priority for conservation of bat communities.
Effects of Phylogenetic Tree Style on Student Comprehension
(North Dakota State University, 2017) Dees, Jonathan Andrew
Phylogenetic trees are powerful tools of evolutionary biology that have become prominent across the life sciences. Consequently, learning to interpret and reason from phylogenetic trees is now an essential component of biology education. However, students often struggle to understand these diagrams, even after explicit instruction. One factor that has been observed to affect student understanding of phylogenetic trees is style (i.e., diagonal or bracket). The goal of this dissertation research was to systematically explore effects of style on student interpretations and construction of phylogenetic trees in the context of an introductory biology course. Before instruction, students were significantly more accurate with bracket phylogenetic trees for a variety of interpretation and construction tasks. Explicit instruction that balanced the use of diagonal and bracket phylogenetic trees mitigated some, but not all, style effects. After instruction, students were significantly more accurate for interpretation tasks involving taxa relatedness and construction exercises when using the bracket style. Based on this dissertation research and prior studies on style effects, I advocate for introductory biology instructors to use only the bracket style. Future research should examine causes of style effects and variables other than style to inform the development of research-based instruction that best supports student understanding of phylogenetic trees.
Developmental Effects on Immunity: Hormonal and Proteinase Control
(North Dakota State University, 2016) Booth, Kimberly Katie
Insects are ubiquitous, diverse, and able to combat infections despite their lack of adaptive immunity. Insects have a robust innate immune system that is divided into two branches, cell-mediated and humoral. Activation of cell-mediated immune responses results in phagocytosis, nodule formation, and encapsulation by the insect’s immune cells, hemocytes. Activation of humoral immunity results in the production of anti-microbial peptides (AMPs) and phenoloxidase (PO). Insect immune responses can be plastic with development. However, research on how and why insect immunity changes with age as insects develop within a larval developmental stage (instar) is limited and contradictory. In my dissertation research, I answer two main questions: 1) how do immune responses vary within an instar and 2) what drives changes in immunity within an instar? My dissertation research showed that humoral immune responses are more robust at the beginning of the 5th and final instar in Manduca sexta (tobacco hornworm) compared to responses from animals later within that instar. Many changes occur within an instar that could affect immunity. For example, I found that protein expression of matrix metalloproteinase (MMP) in immune tissues of M. sexta decreases throughout the 5th instar. Though MMPs are involved in immune responses in other insects, MMP was not found to be immunostimulatory in M. sexta. Another important factor that changes within an instar is the level of juvenile hormone (JH). JH, a developmental hormone that prevents early molting, peaks early and decreases within an instar until molting. I determined that JH is necessary to survive an infection, control bacterial growth in hemolymph (insect blood), and mount an AMP activity immune response. My dissertation research has established that there is a development-immunity link, and that the naturally fluctuating levels of JH may mediate the effect of development on immunity.
The Evolution and Development of a Novel Trait in Sepsidae
(North Dakota State University, 2016) Melicher, Dacotah
Evolutionary novelty, the appearance of new traits with no existing homology, is central to the adaptive radiation of new species. Novel traits inform our understanding of development and how developmental mechanisms can generate novelties. Sepsid flies (Diptera: Sepsidae) have a sexually dimorphic, jointed appendage used for courtship and mating. The appendage develops from the fourth abdominal histoblast nest rather than an imaginal disc. Histoblast nests in other species produce the adult epidermis and lack three-dimensional organization. The sepsid system is an opportunity to investigate the evolutionary history of a novel trait and the developmental mechanisms that pattern epidermal tissue into a complex structure. The appendage has a complex history of gain, loss, and recovery over evolutionary time. Appendage morphology is highly variable between species and does not correlate to body size. I collected larval epidermal tissue from 16 species across Sepsidae and one outgroup to trace the evolutionary history of gain, secondary loss, and recovery. I characterized histoblast nests in all segments and sexes, determining the nest size, number, and size of cells. The appendage-producing nest is sexually dimorphic in species after primary gain. Loss of the appendage shows a return to ancestral state while regain shows an increase in nest size in both sexes. The loss of sex dimorphism may indicate that mechanisms involved in specification may be active in females while genes involved in patterning are not activated during pupation. I assembled and annotated a reference transcriptome for the sepsid Themira biloba at using a custom bioinformatic pipeline that uses a merged assembly approach to maximize quality. This pipeline demonstrated an improvement over other methodologies using multiple published metrics for determining quality and completion. This pipeline also demonstrates how cloud computing architecture can complete bioinformatic tasks quickly and at low cost. I used the T. biloba transcriptome to identify differentially expressed genes involved in appendage patterning during pupation. I sequenced the appendage producing fourth male larval segment and the third male and fourth female segments. Many of the differentially expressed transcripts are involved in cell signaling, epidermal growth, and transcripts involved morphological development in other species.
Examination of Age at Death Methods and the Effects on Estimation Accuracy when Applied to Computed Tomography Scans and Virtual Models of Mummies
(North Dakota State University, 2015) Schanandore, James
Three-dimensional (3D) medical imaging provides a method to non-invasively examine the sub-surface structures of a mummified body, particularly the skeleton. The unique nature of both natural and anthropogenic mummification processes causes inconsistencies for estimating accurate age at death for a particular mummy or group of mummies. These inaccuracies are compounded when age at death methods are used in relation to 3D virtual models. There is a need for the examination of methods being used in mummy case studies and how they are being applied to the 3D virtual models. My research encompassed three studies that addressed the relationship of and the variability when estimating age at death of mummies using radiological imaging. In one study, 146 published case studies were examined for which methods were used to estimate age at death. This study found that articles often provided an assessment of age, but many failed to specify the methods used to calculate the estimated age, and if specified methods were limited to certain areas of the body. In a second study, a cohort of age at death methods was applied to a sample of 17 adult mummies and it was determined that some methods do not transpose well and consequently provided inaccurate age at death estimations when applied to 3D virtual models. Modifications to traditional osteological approaches for age estimation were sometimes necessary due to the presence of soft tissue and post-mortem changes to the body. This study proposes that more methods are needed that utilize the tools available for radiological images in order to limit the variability of transposing a traditional age at death method to virtual 3D models. In the third study, the rim height of the auricular surface was measured using computed tomography scans of 97 living or recently deceased individuals’. These measurements targeted areas around the edge of the surface, for example the height of the apex above the surface. The rim height above the surface produced models that can accurately predict age at death.

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