Doctor of Philosophy (PhD), Ohio University, 2015, Plant Biology (Arts and Sciences)

The herbaceous layer of eastern deciduous forests is highly diverse, influences tree regeneration, plays a role in nutrient cycling and provides forage for animals. Seed dispersal is essential for the long-term persistence of many forest herbs, especially in light of threats including habitat fragmentation, climate change, and deer overabundance. In this study, I have sought to understand the mechanisms of forest-herb dispersal and their potential effects on plant fitness using the common fleshy-fruited forest herb mayapple (Podophyllum peltatum L.). Mayapple fruit are ingested by white-tail deer (Odocoileus virginianus) and raccoons (Procyon lotor). This study compared the dispersal effectiveness of these two potential dispersal agents. I examined the effects of ingestion on germination, and the relative quality of seed deposition sites. I also examined the movement of seeds after deposition in dung. Both deer and raccoons have a non-random spatial pattern of defecation. Due to premature fruit removal, seed destruction, and unfavorable locations of seed deposition, deer appear to be seed predators of mayapple. Raccoon consumption destroys some seeds but increases germination. Raccoons also appear to center the distribution of seeds on specific microsites that are favorable for mayapple growth and germination. After deposition in dung, seeds are moved by a variety of means on a scale of centimeters to meters, in ways that are enhanced by the presence of dung. As a consequence of secondary dispersal, negative density-dependent effects resulting from mayapple seed deposition in dung are likely reduced. A contrast in dispersal effectiveness, as shown in this study, should create selective pressure for a single high-quality frugivore. The results of this study make an important contribution to the understanding of the seed dispersal of forest herbs and highlight another consequence of a historically high deer population in eastern-North American deciduous forests.

Committee: Glenn Matlack (Advisor) Subjects: Botany; Ecology

Master of Science, The Ohio State University, 2011, Civil Engineering

Seed dispersal of plants is short-term phenomenon with long-term implications to population survival and spread. Determining spread rates of plant populations is critical for future estimates of population diversity, density, and their ability to adjust to an ever changing climate. Current methods for estimating population movement entail a dispersal kernel, which is a probability density function of seed dispersal distances. Although these models accurately estimate short, modal dispersal distances, their estimates generally underestimate long distance dispersal (LDD), known to have the greatest effect on population spread rates. This underestimation can be attributed to the many scales at which plant movement is affected. Seed maturation (days-season), abscission (milliseconds), dispersal (minutes) and establishment (days-years) operate at different timescales and are affected by both small-scale (e.g. localized atmospheric conditions and nutrient availability) and large-scale (e.g. spatially and temporally mean wind conditions and time of day/year) phenomena. Integrating all of these scales into dispersal models has been a large challenge thus far. In this study we use short-term seed-trap and meteorological observations (30 minute means over 10 days) and long-term (season long) wind and seed availability measurements to investigate the effects of the timing of seed release at different temporal scales on long-term dispersal estimates. We show that the seeds of a wind dispersed tropical tree, Luehea seemannii, are released more than would be expected by the seasonal seed availability, in conditions of strong updraft and high temperature. Seeds also rarely release at night. We use phenomenological (super-WALD) and mechanistic (CELC) models to estimate the relative strengths of such effects and to integrate the effects of fast processes to season-long dispersal kernels. We find that that abscission in updrafts largely increase the probability of long-distance dis (open full item for complete abstract)

Committee: Gil Bohrer (Committee Chair); Peter Curtis (Committee Member); Ethan Kubatko (Committee Member) Subjects: Civil Engineering; Ecology; Environmental Engineering

Doctor of Philosophy (PhD), Ohio University, 2024, Biological Sciences (Arts and Sciences)

Plant communities that occur on restrictive soils are characterized by stressful soil conditions and isolated patches of habitat, both of which have important consequences for the ecology and evolution of the species that occur on them. Despite their restrictive nature, edaphic communities contain high biodiversity, comprising a unique assemblage of plants, many of which are rare. Edaphic communities contain numerous, distantly related species that evolved under similar stressful conditions, but we still do not understand how the evolutionary process of edaphic specialization and speciation unfolds or the myriad of ecological and evolutionary consequences of occurring on restrictive soils. I examined species that occur on and off gypsum-edaphic communities to answer four questions, each as its own chapter: (Chapter 2) What fitness consequences do plants that occur on restrictive soils experience, (Chapter 3) how do diversification rates change for clades where gypsum endemism occur, (Chapter 4) how have dispersal syndromes and dispersion changed in edaphic communities because of their restrictive, fragmented substrate, and (Chapter 5) has selection favor limited dispersal in gypsum endemics? To answer those questions, I compared plant communities on gypsum outcrops (which contained both endemics and tolerators [= plants that grow on and off gypsum]) with surrounding, non-gypsum communities, and analysed selection and diversification rates of various gypsum associated clades. To determine the fitness consequences of inhabiting gypsum, I measured fitness for gypsum tolerating species across an edaphic gradient of gypsum to non-gypsum soils. I found negative and neutral fitness effects for species growing on gypsum soils. Various physical and chemical properties control fitness of tolerator species, but no common soil property was identified between the species that explained fitness changes on gypsum soil. To answer my second question, I gathered pre-constructed clado (open full item for complete abstract)

Committee: John Schenk (Advisor); James Dyer (Committee Member); Rebecca Snell (Committee Member); Jared DeForest (Committee Member) Subjects: Biology; Ecology; Plant Biology

Doctor of Philosophy, The Ohio State University, 2004, Evolution, Ecology, and Organismal Biology

In this study, we explore large-scale movements in ruffed grouse (Bonasa umbellus) in Ohio by characterizing juvenile and adult dispersal, investigating the effect of landscape characteristics on movement behavior and examining the relationship between movement and the risk of predation. Our first objective was to investigate the natal and adult dispersal characteristics of ruffed grouse throughout the entire annual breeding cycle, using a behavioral definition of dispersal. Once dispersal movements could be accurately identified, we explored whether landscape variables measured at coarse-grained scales could help explain general movement characteristics. We used Akaike Information Criterion (AIC) techniques for model selection to explore the relationship between metrics of both landscape composition and configuration and the decision to disperse by adults and juveniles, their net dispersal distances and rates of movement, and their home range sizes. Ecologists often assume that dispersing individuals experience an increase in predation risk due to increased exposure to predators while moving. We tested the hypothesis that predation risk is a function of rate of movement and site familiarity using a Cox's proportional hazards model. Overall, we documented a surprisingly high proportion of adults undertaking seasonal dispersal movements and juveniles undergoing dispersal in the spring, particularly compared to grouse studies conducted in the northern portion of its range (Chapter 1). We also found that coarse-grained landscape characteristics affect movement behavior, but effects varied considerably among specific behaviors and across spatial scales. While large-scale landscape composition (i.e. % forest) and edge density significantly affected dispersal behavior little evidence was found for landscape configuration per se affecting movements (Chapter 2). Finally, we found evidence indicating that increased movement rates may increase the risk of predation for adult (open full item for complete abstract)

Committee: Elizabeth Marschall (Advisor) Subjects: Biology, Ecology

Ph.D., Antioch University, 2009, Antioch New England: Environmental Studies

I describe the relative effectiveness of two primates in dispersing large-seeded tree seeds (> 0.5 cm) in the Nyungwe National Park (NNP), Rwanda. My objectives are three-fold: (1) to describe the relative effectiveness of primates in dispersing the seeds of five large-seeded tree species, (2) to evaluate the influence of primate seed-handling method on seed fate, and (3) to determine the influence of deposition site on seed fate. I employed focal tree observations, day-follows of habituated primate groups, in situ monitoring of primate-dispersed seeds, and experimental plots to achieve these objectives. Data were collected over the course of one year (April 2006 – April 2007).Frugivore assemblages dispersed the seeds of four of the five focal tree species. Chimpanzees and cercopithecines spent the most time in trees and had the largest group size. Large-bodied birds (LB) and chimpanzees dispersed the highest number of seeds per minute. LB and cercopithecines potentially disperse the greatest number of seeds for Ekebergia capensis, and chimpanzees for Syzygium guineense. My study highlights the complexities of determining a disperser's effectiveness and suggests that large-bodied birds and primates are relatively important dispersers of large-seeded trees. Primates deposit seeds most often in open forest where seeds experience the highest establishment. In addition primates deposit seeds in five habitats that are likely dispersal-limited suggesting that primates contribute to the regeneration processes of otherwise dispersal-limited areas. My results suggest that the former emphasis of seed dispersal studies on defecations is not representative and should be expanded to include orally-discarded seeds. Furthermore my study highlights that primates do not deposit seeds randomly and that the characteristics of the deposition site are a reflection of primate seed handling. I found no relationship between the top five fruiting tree species found in chimpanzee feces and f (open full item for complete abstract)

Committee: Beth Kaplin PhD (Committee Chair); Peter Palmiotto DF (Committee Member); Joanna Lambert PhD (Committee Chair) Subjects: Animals; Biology; Ecology; Education; Teacher Education

Doctor of Philosophy, The Ohio State University, 2013, Entomology

Laboratory studies have identified a dichotomy in foraging behavior of entomopathogenic nematodes (EPNs) but little is known about their dispersal patterns in the field. Overall goal of this dissertation research was to examine the dispersal behavior of two EPN species with contrasting foraging strategies, cruiser, Heterorhabditis bacteriophora and ambusher, Steinernema carpocapsae from nematode-infected host cadavers in soil in laboratory and field conditions which will expand our knowledge of EPN field population dynamics to fully utilize their biological control potential. Objectives of this research were to assess the rate of active lateral movement and dispersal patterns of the two EPN species from nematode-infected host cadavers in soil in the absence of hosts, in the presence of vegetation and mobile and non-mobile hosts in the greenhouse conditions and further, quantify their short-term dispersal potential in the field and finally, artificially select ambusher, S. carpocapsae for enhanced dispersal. The results revealed that the two species differed in the spatio-temporal pattern of dispersal but showed similar average population displacement (~6 cm/day) in the absence of hosts. While a majority of S. carpocapsae dispersed <3.8 cm from the source cadaver, a majority of H. bacteriophora dispersed between 7-15 cm away from the source cadaver. However, a greater percentage of S. carpocapsae (~2.5 times) travelled faster than the fastest H. bacteriophora to larger distances, 15-61 cm. These apparent ‘sprinters' may represent an adaptive dispersal strategy by the otherwise ambush forager S. carpocapsae in the absence of hosts. Vegetation enhanced dispersal of both species but more so for H. bacteriophora. Mobile hosts enhanced dispersal of both species. S. carpocapsae showed significantly greater average displacement than H. bacteriophora in the presence of mobile and non-mobile hosts. A greater percentage of S. carpocapsae (~14.5%) than H. bacteriophora (~0.4%) (open full item for complete abstract)

Committee: Parwinder Grewal PhD (Advisor); Casey Hoy (Committee Member); Luis Canas (Committee Member); Andrew Michel (Committee Member); Robin Taylor (Committee Member) Subjects: Entomology

MS, University of Cincinnati, 2024, Arts and Sciences: Biological Sciences

Movement is a fundamental process in the life of many organisms, and is necessary for individuals to acquire resources, avoid predation, find mates, and thermoregulate. Movement allows individuals to track suitable temperatures; movement, however, can be impacted by meteorological conditions. Due to climate change, global temperature is predicted to increase by 1.5 °C between 2030 and 2052, resulting in higher mean temperatures and more frequent extreme temperature events. Increasing temperatures may decrease the ability of organisms to move in response to these higher temperatures. Understanding how species will respond to climate change requires understanding how temperature and environmental conditions affect their movement. The first chapter of this work looks at the literature that examines the effect of temperature on the flight of butterflies at their northern- and southernmost ranges, given reported thermal flight limits of each species. Due to their limited life spans, sensitivity to environmental changes in their habitats, and relatively rapid responses to these changes, butterflies are often used as biodiversity indicators to gauge shifts in ecological processes, making them a popular group of ectotherms used to examine the effect of temperature on movement. Current (2010-2019) daily maximum temperatures during flight seasons were significantly greater than those reported in the 1950s at both northern and southern range limits. At the southernmost ranges, the current average number of days that maximum temperatures exceeded the upper thermal limits for butterfly flight were significantly greater than in the 1950s, while there was no statistically significant difference at the northernmost ranges. Increases in ambient temperatures can restrict an organism's ability to escape extreme local temperatures. While I found very few papers that state the effect of ambient temperature on flight, my analysis shows that incorporating the environmental temperat (open full item for complete abstract)

Committee: Stephen Matter Ph.D. (Committee Chair); Elizabeth Hobson Ph.D. (Committee Member); Patrick Guerra Ph.D. (Committee Member) Subjects: Biology

MS, Kent State University, 2023, College of Arts and Sciences / Department of Biological Sciences

Eastern red cedar (Juniperus virginiana; ERC) is native to eastern North America, but is expanding into grassland and prairie ecosystems of the midwestern United States. ERC produces small cones that are retained on the trees for several months that changes in coloration from green to purple. This change in coloration can act as a visual signal to attract foraging birds and mammals, driving ERC range expansion through seed dispersal. For successful seed dispersal, temporal overlap of dispersers and ERC trees that have cones containing mature/viable seeds is critical. To understand the interaction between ERC and foragers, I characterized ERC cone phenology and seed availability/viability monthly while simultaneously documenting foraging by birds and mammals. The first goal of my thesis was to characterize ERC phenology and the cone maturation process to better understand encroachment of ERC by examining changes in cone color, nutrient content and seed viability. ERC female trees with cones were visited monthly to monitor the maturation of ERC cones. Female ERC cones begin the maturation process in the early spring (April). As cones mature in the early Fall the cones shift from a green color to a purple/blue color. After cones mature, they remain on the trees until the new cone crop forms. I analyzed ERC cones in different stages of the maturation process for protein and sugar content. While sugar/starch levels are relatively consistent regardless of cone color, protein content declines significantly from early green cones to purple/blue cones. Foragers gain similar rewards whenever cones are available. The viability of ERC embryos were tested in different stages of maturation to examine changes in viability. Overall, the number of viable embryos tested was low but viable embryos were present throughout the cone maturation season. The likelihood of viability increased after cones had completed the maturation process (green to purple/blue). Germination of ERC was ex (open full item for complete abstract)

Committee: Oscar Rocha (Advisor); Mark Kershner (Advisor); David Ward (Committee Member) Subjects: Ecology

MS, Kent State University, 2023, College of Arts and Sciences / Department of Biological Sciences

Eastern redcedar (Juniperus virginiana L. var. virginiana) is a native species currently invading open areas and grasslands outside of its original range in the United States. I studied the eastern redcedar's (ERC) invasion patterns in the Lakeside Daisy State Nature Preserve (LDSNP), a short grass prairie located on the Marblehead Peninsula in Ohio, examining the changes in the genetic diversity and structure of the encroaching population. I investigated the relative importance of long-distance dispersal vs. diffusion in the invasion of this short grass prairie by ERC. I used eight microsatellite marker loci and a database of single nucleotide polymorphisms to infer gene flow from external sources vs. within-population recruitment. I found that the older trees in this preserve were less than fifty-years-old, indicating that the population was established between 1970 and 1980. When I grouped trees into five age categories of 10-year increments, we found that the allelic diversity, as indicated by the average number of alleles per locus, increased as the age of the trees decreased. Principal Coordinate Analysis showed two distinct groups of trees in the LDSNP that I investigated further using soil type. Analysis of the population structure of the ERC trees using ADMIXTURE revealed three ancestral clusters in the ERC populations. All ancestral clusters are present in all age groups, suggesting that there is continual input of genetic information from the ancestral clusters. Overall, my findings indicate that ERC encroachment of the LDSNP results from multiple and reiterated gene flow events from the edge of the range through animal-mediated seed dispersal at short and intermediate distances.

Committee: Oscar Rocha (Advisor); David Ward (Committee Member); Sangeet Lamichhaney (Committee Member) Subjects: Bioinformatics; Conservation; Genetics; Natural Resource Management; Plant Biology; Plant Sciences; Range Management

Master of Science, The Ohio State University, 2023, Entomology

Bumble bees (Bombus) are essential pollinators for wildflowers and crops worldwide, but many species are currently in decline. Habitat loss and fragmentation are leading factors in these declines. Urbanization is a source of habitat loss and fragmentation; however, robust and abundant bumble bee populations are often found in metropolitan areas. Though prior research has broadly examined bumble bee abundance and diversity in urban areas, little work has focused on individual abundances of different species, which may differ in their relationships with urban land. Furthermore, the potential impacts of urban land on gene flow and other genetic health factors in bumble bees remain largely unknown. The first goal of this research was to evaluate and compare the abundances of three target species—Bombus impatiens Cresson, 1863, B. griseocollis De Geer, 1773, and B. bimaculatus Cresson, 1863—along an agricultural-to-urban gradient in Madison, WI, USA. Bumble bees were collected from 16 sites during the summer of 2019 and 19 sites during the summer of 2020. The second goal was to evaluate genetic differentiation, heterozygosity, allelic richness and colony numbers among populations of these species along the same gradient. Percentage of impervious surface cover was used as a metric for urbanization, and this percentage was measured within both 500 m and 1500 m buffers around each study site to account for both local-scale and landscape-scale effects. Impervious surface cover showed no relationship with abundances of B. impatiens or B. griseocollis, but showed a positive relationship with abundance of B. bimaculatus. Impervious surface cover also showed no relationship with genetic differentiation, allelic richness or colony number for all three species in both years, and no relationship with heterozygosity for any species in 2019. In 2020, heterozygosity was negatively correlated with impervious surface cover for B. impatiens at the 500 m buffer but not the 1500 m buffer. (open full item for complete abstract)

Committee: Jamie Strange (Advisor); Andy Michel (Committee Member); Mary Gardiner (Committee Member) Subjects: Entomology

Doctor of Philosophy, Miami University, 2022, Ecology, Evolution and Environmental Biology

Dispersal is an important ecological process that enables the persistence of populations in the environment and reduces both demographic and genetic isolation. In the context of rapid anthropogenic land use/land cover change, understanding how individuals and populations across multiple species respond to changing, heterogeneous landscapes is instrumental in assessing current and future land use/land cover affect species movement. The objective of my dissertation was to assess factors affecting individual movement behavior in multiple habitats and habitat configurations, and then link those individual movement behaviors to patterns of population genetic structure and landscape-scale conductance. My central hypothesis was that intrinsic and extrinsic factors affect the movement, dispersal, and population connectivity of anuran species both individually and in tandem. Therefore, by assessing the interaction of these factors, we can link factors that affect behavior at an individual scale to patterns of connectivity at a broad scale. To test this hypothesis, I conducted a suite of three experiments addressing desiccation tolerance and individual movements of three anuran species at two distinct size classes in multiple habitat combinations. Further, I assessed population genetic structure and landscape conductivity of two anuran species utilizing individual behavioral data to parametrize my conductance models. Both body size and habitat type affected individual movement behavior, though the effects of habitat type, and especially orientation at habitat edges had relatively stronger affects. Parameters based on movement data were informative in landscape-scale models of conductance, though natural and anthropogenic landscape features such as road and river networks were found to strongly affect functional connectivity. Even so, I explicitly linked movement behavior and landscape level patterns of connectivity, and showed that over the same landscape, species specific r (open full item for complete abstract)

Committee: Michelle Boone (Advisor); Thomas Crist (Committee Member); Amélie Davis (Committee Member); Ann Rypstra (Committee Member); William Peterman (Committee Member); David Berg (Committee Member) Subjects: Behavioral Sciences; Biology; Ecology; Molecular Biology

Doctor of Philosophy, The Ohio State University, 2021, Evolution, Ecology and Organismal Biology

Humans engineer their environments by transporting species around the planet. In a new environment, most introduced species will perish, but a small proportion can become invasive, spreading widely and impacting their environments. My dissertation explores how evolutionary processes shape invasive species. I studied two mechanisms of invasive species evolution that can induce rapid evolutionary change: hybridization (mating between genetically distinct individuals) and whole genome duplication (WGD, when offspring inherit an extra set of chromosome pairs). In Chapters 1 and 2, I describe experiments with members of the model plant genus Arabidopsis differing only in genome size and status as either parent or hybrid, effectively isolating the independent effects of WGD and hybridization on traits. I grew plants together under controlled conditions and measured traits and phenotypic plasticity (the change in trait values across imposed environmental gradients). For the handful of traits and gradients in which WGD shifted plasticity values, WGD consistently increased plasticity (Chapter 1). This study provides the most controlled experimental evidence to date in support of the hypothesis that WGD increases plasticity, a hypothesis invoked to help explain how WGD has driven evolution. In contrast to WGD, I found that hybridization produced larger effects on both mean traits and plasticity (Chapter 2). This experiment is the first to fully isolate hybridization and WGD effects on plasticity. In nature, genetic and trait variation provide the raw material allowing invasive species to initially prevail in and, potentially, adapt to the introduced environment. I examined patterns of variation related to hybridization and WGD for two invasive plant systems (Chapters 3 and 4). Chapter 3 focuses on purple loosestrife (Lythrum salicaria), a well-studied species for which other authors have documented post-introduction changes in traits and genetics. A little-studied, mo (open full item for complete abstract)

Committee: Stephen Hovick (Advisor); Alison Bennett (Committee Member); Andrea Wolfe (Committee Member); Kristin Mercer (Committee Member); Amanda Simcox (Committee Member); Robert Klips (Committee Member) Subjects: Biology; Botany; Conservation; Ecology; Evolution and Development; Genetics; Horticulture; Morphology; Organismal Biology

Master of Science (MS), Ohio University, 2021, Plant Biology (Arts and Sciences)

Anthropogenic climate change will require all species to adapt in place to changing conditions or track climate shifts into new range boundaries. The paleo-ecological record suggests that despite the long generation times and sessile life forms of trees, tree species have migrated in response to previous climate change by expanding from refugia or shifting their entire range. In eastern North America, trees appear to be failing to track current climate changes poleward. I used the United States Forest Service's Forest Inventory and Analysis (FIA) data and Little Range boundaries for nine eastern tree species to investigate the influence of disturbance and the species' dispersal mechanism on the establishment of seedlings both within and beyond the species' range. Major findings include that establishment rates increase in response to harvest application within FIA plots but not in response to recorded natural disturbances. Additionally, bird- dispersed species colonize new plots outside their Little Range more than mammal- dispersed or wind-dispersed tree species.

Committee: Rebecca Snell (Advisor); Jared DeForest (Committee Member); James Dyer (Committee Member) Subjects: Biology; Ecology; Environmental Management; Geography; Plant Biology

Master of Science, University of Toledo, 2019, Biology (Ecology)

Hydrilla (Hydrilla verticillata), an aquatic invasive plant, threatens to invade the Great Lakes Basin. Hydrilla creates dense webs that out competes native vegetation, reduces flow in canals, clogs intakes, and interferes with navigation of watercraft. Recreational boating has acted as a primary vector of spread for other aquatic invasive species and is expected be a primary vector for hydrilla spread. The goal of this project was to analyze the current distribution of hydrilla and identify the risk of introduction in the Great Lakes Basin via overland recreational boat transport. This goal was achieved by 1) assessing the current distribution of hydrilla to determine likely vectors of spread and 2) predicting the potential spread of hydrilla to the Great Lakes Basin via recreational watercraft and boat trailers and 3) identifying high risk areas for introduction. This analysis will aid in predicting and detecting the spread of invasive hydrilla into new waterways in the Great Lakes Basin.

Committee: Jonathan Bossenbroek PhD (Committee Chair); Richard Becker PhD (Committee Member); Daryl Moorhead PhD (Committee Member) Subjects: Environmental Science

Doctor of Philosophy, The Ohio State University, 2017, Evolution, Ecology and Organismal Biology

Every year, there is at least one widespread news story documenting a “virgin birth” in a variety of animals as diverse as snakes and sharks. These events capture our attention because they represent departures from an assumed necessity of vertebrate life: having sex. Yet, vertebrates do not always reproduce via sex, and biologists have long studied the evolutionary costs and benefits of this type of reproduction. One of the main costs of sex are males, who cannot directly generate offspring and use up resources from reproductive females that cannot be put towards additional offspring. Eastern North America is home to one of the strangest vertebrates that lack males and appear to be sexual and asexual at the same time: an all-female group of salamanders that appear to “steal” sperm from males of other species. These all-female salamanders can potentially retain the advantage of gaining new genetic diversity from other species without males of their own. However, the extent and flexibility of this mating systems is still not understood, and the factors that promote the coexistence of all-female salamander lineages and the sexual species from which they use reproductive material are mysterious. I have investigated three primary questions concerning these unusual animals. First, how do we identify an all-female salamander in Ohio? Because of their cryptic morphology compared to similar sexual species, all-female Ambystoma salamanders are only reliably identified by sequencing their mitochondrial DNA, which is independently transferred maternally. However, mitochondrial sequences that closely resembled those of all-female salamanders were previously found in salamander individuals across Ohio that were identified morphologically as either the smallmouthed or streamside salamander. I gathered microsatellite data from these potentially misidentified animals and evaluated three hypotheses for why the mitochondrial data does not match the nuclear DNA or morphological specie (open full item for complete abstract)

Committee: H. Lisle Gibbs (Advisor); Bryan Carstens (Committee Member); Peterman William (Committee Member) Subjects: Biology; Ecology; Evolution and Development; Organismal Biology

Master of Mathematical Sciences, The Ohio State University, 2017, Mathematical Sciences

Two cases of species competition were considered. The first was the case of two-species-in-two-patches with both species being drifted from patch 1 to patch 2 at the same rate with the assumption that the organisms have an unconditional dispersal strategy (i.e. migrating from patch 1 to patch 2 at the same rate as from patch 2 to patch 1). In this case, ideal free distribution (IFD) only exists if the carrying capacity of patch 2, K2, is greater than K1, the carrying capacity of patch 1. If K2 is less or equal to K1, then, the resident species may have an evolutionarily stable strategy (ESS) only if it migrates from patch 1 to patch 2 at the rate d = infinity or d = 0, depending on the drift rate. The second case, was also two-species-in-two-patches; both species are assumed to migrate (drifted) from patch 1 to patch 2 at the same rate, but have a different rate of dispersal from patch 2 to patch 1. Furthermore, we assume that there is travel loss (i.e. species die during migration). In this case, although we showed that IFD does not exist, we analytically proved the existence of an ESS strategy. If the resident has such an ESS strategy, we proved that the equilibium point, at which the resident survives and the mutants vanish, is globally asymptotically stable.

Committee: Yuan Lou (Advisor); Adrian Lam (Committee Member) Subjects: Mathematics

Master of Science, University of Akron, 2017, Geology-Environmental Geology

Lake sediment can provide records of past changes in climate, water budget and lake level, ecosystems, and human impacts to the environment. This study uses the sediment from Brady Lake, a kettle lake in northeastern Ohio, to determine Late Holocene natural and anthropogenic environmental variability. Because no bathymetric map of the lake was available, one was created in ArcMap by collecting 7,507 latitude, longitude, and water depth measurements with a Garmen 125 fathometer and GPS unit. Sediment dispersal processes were studied by collecting surface samples throughout Brady Lake. Dense, sandy sediment, having low organic content (<5%), were present in water less than 1.5 m deep where wind-wave orbital motion prevents muds from accumulating. Low density, porous muds, having high organic content (30%), accumulate below 1.5 m due to sediment focusing. A 4.13-m-long Livingston piston core was collected from the central deep-water basin to evaluate 2840 Cal yr of environmental change. Age control was determined through radiocarbon dating and correlating event stratigraphy datums to other dated Ohio kettle lake sediment records. Between 4.13 and 1.9 m core depth (2840-210 Cal yr BP), low density gyttja having 70% organic content and a C/N ratio of ~13.7 is present. These sediment characteristics are interpreted as the pre-Euro American settlement period when the watershed was forested and sediment yield was low. Within this interval, five lows in organic content, having increased sediment density, suggests a decrease in vegetation and increased watershed erosion. These changing watershed conditions may reflect fluctuations in atmospheric circulation and moisture balance during the Late Holocene. Furthermore, these lows agree with the timing of globally distributed rapid climate change occurring between 3500-2500; 1200-1000; and 600-150 Cal yr BP identified by Mayewski et al. (2004). At 1.9 m core depth, the gyttja abruptly changes to bedded mud having increased concen (open full item for complete abstract)

Committee: John Peck (Advisor); John Senko (Committee Member); Linda Barrett (Committee Member) Subjects: Environmental Geology; Environmental Science; Geochemistry; Geology; Limnology; Paleoclimate Science; Sedimentary Geology

Doctor of Philosophy, The Ohio State University, 2016, Entomology

Disturbances alter habitat structure, energy and nutrient flow, and species composition in ecosystems, thereby shaping patterns in community dynamics and ecosystem processes over time. In forests of eastern North America, natural disturbances (e.g. fire, wind, insect and disease outbreaks) create a mosaic of differently aged habitat patches that maintain structural complexity at multiple spatial scales through the creation of biological legacies such as standing and downed woody debris and patches of understory vegetation intertwined with undisturbed forest. Anthropogenic disturbances (e.g. exotic species, land-use change, management practices) may alter the abundance or spatial patterns of these important structural features in the landscape, potentially impacting forest communities such as populations of ground-dwelling invertebrates. Ground-dwelling invertebrates are abundant in forest ecosystems, and their responses to natural and anthropogenic disturbances have significant implications for ecosystem services such as decomposition and nutrient cycling. Therefore, the overarching goals of this dissertation research were to evaluate the effects of disturbance to the forest canopy and understory on the ground-dwelling invertebrate community. Objectives of this research were to investigate the impacts of tree mortality caused by disturbances characterized by different properties on invertebrate diversity, community composition, and dispersal potential. Three dynamic models were proposed (Chapter 1) to describe the temporal relationships in the magnitude effects of canopy gap formation, accumulation (and removal) of coarse woody debris, and soil disturbance caused by the exotic emerald ash borer (Agrilus planipennis Fairemaire) (Chapters 2-4), wind, and salvage logging (Chapter 9) on ground-dwelling invertebrate communities. Canopy and understory vegetation disturbances that typically occur simultaneously when trees die were decoupled via a manipulative experim (open full item for complete abstract)

Committee: Daniel Herms (Advisor) Subjects: Ecology; Entomology

PhD, University of Cincinnati, 2016, Arts and Sciences: Biological Sciences

Tropical and temperate plant species in forests around the world are threatened by human-induced land-use changes which produce various outcomes such as increased spread of invasive species, habitat fragmentation, and alterations of community structure among others. These factors can lower population sizes and genetic diversity levels of native plant species, making the risk of extinction imminent. Methodologies to mitigate such effects can involve introducing endangered plant species back to their native habitats either via in situ management of exploited species, or ex situ conservation. To study such species conservation, highly-replicated predictive computer modeling can be an inexpensive tool to suggest those scenarios that can better maintain viable population sizes and genetic diversity levels over the long term, since field studies are less feasible given the limited time and resources available. I used a species-specific, spatially-explicit, individual-based computer program (NEWGARDEN) capable of modeling and monitoring plant population growth and genetic diversity patterns in simulated stands over time to comparatively model various restoration methodologies for different threatened tree species. Specifically, I examined: 1) effective reintroduction geometries of the American chestnut; 2) sustainable spatial deforestation patterns for long-lived canopy tree species in tropical lowland rain forests (TLRFs); and 3) seed collection strategies capable of maximizing the harvest of genetic variation from rare TLRF tree species for use in developing ex situ rescue populations. These species conservation methodologies were tested under differing offspring and pollen dispersal distances, as this life-history trait can affect the spatial distribution of allelic diversity in populations. Results indicate that for reintroductions of the American chestnut, planting and stewarding a limited number of individuals at least 100m in from the preserve border (for (open full item for complete abstract)

Committee: Steven Rogstad Ph.D. (Committee Chair); Theresa Culley Ph.D. (Committee Member); Stephen Matter Ph.D. (Committee Member); Eric Maurer Ph.D. (Committee Member); Stephan Pelikan Ph.D. (Committee Member) Subjects: Botany

Master of Science (MS), Bowling Green State University, 2016, Biological Sciences

As toxicants move into aquatic systems, the concentration at any point in space or time is heavily influenced by the flow dynamics. The dispersion of these chemicals creates a toxicant concentration that fluctuates widely in time and is highly dependent on the spatial heterogeneity of turbulence. Despite this knowledge on the movement of toxicants in natural systems, most ecotoxicological studies use static exposure paradigms that ignore the spatio-temporal dynamics of toxicants in aquatic systems. Although recent studies have begun to use pulsed paradigms in an attempt to mimic natural conditions, the heterogeneity of real concentrations in natural systems is rarely considered for use in these tests. Thus, understanding how organisms are impaired by naturally distributed toxicants is relatively unknown. The purpose of this experiment was to determine how turbulent dispersion of a toxicant negatively impacts a behavioral task and if altering the nature of turbulence will change the negative impact of the toxicant. Crayfish were exposed to a turbulent plume of carbaryl, an insecticide, under two different turbulent conditions and two different spatial conditions. Turbulence was altered by placing an obstruction within the flow which mimics a natural obstruction in lentic systems. Crayfish were exposed to sublethal concentrations of carbaryl for 48 hours under these different dynamic conditions. After toxicant exposure, crayfish foraging ability was measured in a flow-through Y maze. We hypothesized that crayfish exposed to the toxicant under more turbulent conditions would exhibit more detrimental responses due to the increased variation in chemical fluctuations. The fine-scale chemical distribution of the toxicant as well as the three dimensional velocity profile were characterized for each of the turbulent conditions and each of the spatial locations. Analyses of these data showed that changes in turbulence or spatial location created a unique exposure condition. P (open full item for complete abstract)

Committee: Paul Moore PhD (Advisor); Paul Drevnick PhD (Committee Member); Jeffrey Miner PhD (Committee Member) Subjects: Aquatic Sciences; Biology; Ecology; Environmental Management; Environmental Science; Environmental Studies; Experiments; Freshwater Ecology; Limnology; Toxicology