Master of Science (MS), Wright State University, 2023, Biological Sciences

Invasive species threaten ecosystems and economies. Globally, biological invasions are estimated to have cost over $2.1 trillion since 1970. In Eastern North American woodlands, invasive plants are rapidly displacing natives. This is concerning, because invasive plants may not support the diverse and abundant arthropod communities essential to ecosystem function. Despite the conceptual understanding of invasive shrubs' potential to transform forest communities, scant research has focused on the effect of invasive plants on higher trophic levels here in Ohio. To address this gap, I examined the diversity and abundance of arthropod communities, caterpillar performance, and caterpillar predation on two invasive shrubs, Amur honeysuckle (Lonicera maackii) and border privet (Ligustrum obtusifolium), relative to native counterparts. Lo. maackii supported a depauperate community; however, Li. obtusifolium hosted a surprisingly robust community. Nevertheless, both invasives proved poor hosts for caterpillars and were less preferred by foraging insectivores.

Committee: John O. Stireman III, Ph.D. (Advisor); Don Cipollini Jr., Ph.D. (Committee Member); Volker Bahn Ph.D. (Committee Member) Subjects: Biology; Ecology; Entomology; Environmental Science; Plant Sciences; Zoology

Master of Science, The Ohio State University, 2021, Environment and Natural Resources

Environmental heterogeneity in stream conditions and anthropogenic stressors, such as species introductions, can lead to intraspecific variation in traits of stream-dwelling crayfish. The rusty crayfish, Faxonius rusticus, and virile crayfish, Faxonius virilis, are distributed across a wide geographic range largely due to introductions outside of the native ranges. Previous research on these two species have demonstrated significant intraspecific variation in behavior traits across populations of both species. In this study I investigated: 1) whether behavioral differences across populations of the rusty crayfish are associated with their invasion status (e.g. native vs non-native), and 2) what environmental drivers (predation risk, resource availability, and climate) are associated with variation in behavior of both rusty and virile crayfish. I predicted that selection during the invasion process would result in non-native rusty crayfish being bolder, more active, and foraging more than native rusty crayfish, and that there would be less variance in behavior in non-native crayfish than native crayfish. I predicted that crayfish behavioral traits would be predictably associated with differences in predation risk, resource availability, and climate across populations. Furthermore, I predicted that crayfish from sites with lower predation pressure, sites with poor resource availability, and colder sites would be more bold, active and forage more than crayfish from sites with higher predation pressure, sites with abundant resource availability, and warmer sites respectively. To test whether behavior varied as a function of invasion status and environmental drivers, I quantified behavioral differences across multiple populations of rusty and virile crayfish from streams across the Midwest. Furthermore, at each stream, I measured predation pressure, macroinvertebrate resource availability, benthic algal resource availability, stream temperature, and crayfish density. I f (open full item for complete abstract)

Committee: Lauren Pintor (Advisor); Mažeika Sullivan (Committee Member); Lindsey Reisinger (Committee Member); Robert Gates (Committee Member) Subjects: Aquatic Sciences; Behavioral Sciences; Ecology; Environmental Science

Master of Science, The Ohio State University, 2018, Environment and Natural Resources

Although many predators forage adaptively in response to changes in the abundance of their prey, some predators may be slow to adapt to a novel prey that is added through biological invasion. The invasive Green Porcelain Crab (Petrolisthes armatus) is an abundant potential prey resource for native predators within oyster reef communities along the southeastern coast of the U.S. Yet the species' invasion success suggests that native predators may not readily consume this novel prey. Here I used an individual learning experiment to examine whether evolutionary history, short-term exposure and previously learned handling skills influenced the foraging behavior and consumption of P. armatus by two native predators, the Atlantic Mud Crab (Panopeus herbstii) and the Blue Crab (Callinectes sapidus). Individual predators collected from populations where predators were either naive or experienced with P. armatus were trained on morphologically similar (e.g. native crab) or dissimilar (e.g. native mussel) prey and then exposed to the invasive P. armatus for five consecutive days. Both species exhibited improvements in aspects of their foraging behavior, which suggests that both species have the ability to learn following short-term exposure to a novel prey. However, naive P. herbstii did not forage on P. armatus as efficiently as experienced individuals, which suggests that learning occurs over a longer time scale in this species. In contrast, there were few differences in foraging behavior between experienced and naive populations of C. sapidus, and both populations consumed a high number of the invasive species, which suggests that C. sapidus are relatively neophilic and will readily consume a novel prey species. Finally, naive C. sapidus trained on similar native prey were quicker to approach the invasive P. armatus, and C. sapidus trained on similar native prey had shorter handling times on the invasive species, suggesting that the predator's previous diet can influence f (open full item for complete abstract)

Committee: Lauren Pintor PhD (Advisor); Suzanne Gray PhD (Committee Member); Susan Gershman PhD (Committee Member) Subjects: Animals; Aquatic Sciences; Climate Change; Conservation; Environmental Science; Environmental Studies

Master of Science, The Ohio State University, 2016, Environment and Natural Resources

While the direct effects of non-native species as predators and competitors have been widely studied, the indirect effects of invasive species as novel prey are relatively unexplored. Yet, these novel energetic pathways are of great importance to long-term community response to biological invasions. Novel prey, as supplemental resources for native predators, can positively influence predator abundances. These changes in predator populations, and the associated shifts in predation risk, may result in concomitant effects upon native prey. These indirect effects may impose significant consequences on native prey populations. Aquatic systems are among the most impacted by biological invasions. Globally, freshwater crayfish are among the taxa most at risk to the effects of invasive species. In Ohio, the invasive rusty crayfish (Orconectes rusticus) has been implicated in the decline of a native congener, O. sanbornii. This research aimed to evaluate the influence of indirect effects of invasive O. rusticus on patterns of replacement of the native O. sanbornii in Ohio streams. I used a combination of field observations and experimental manipulations to fulfill three objectives. First, I quantified population demographics of O. sanbornii from streams invaded and not yet invaded by O. rusticus. I also measured and compared the body size of O. rusticus in streams where they currently co-occur with O. sanbornii or have replaced the native species. Second, I conducted a within stream tethering experiment to test for differences in predation risk between these two species. Finally, I used a laboratory experiment to explore the effect of predation risk, competitor identity, and the interaction of the two factors on the behavior of both O. sanbornii and O. rusticus. Results of field surveys indicated a significantly smaller average O. sanbornii body size in streams where they are found co-occurring with O. rusticus. However, there was no detectable difference in O. r (open full item for complete abstract)

Committee: Lauren Pintor (Advisor); Suzanne Gray (Committee Member); Stephen Matthews (Committee Member) Subjects: Ecology; Environmental Science

Doctor of Philosophy (PhD), Ohio University, 2001, Plant Biology (Arts and Sciences)

Introduction of non-native species is the oldest form of human-induced global change. From the exchange of agricultural crops and domestic animals, to the accidental introduction of weeds and microbes, non-native species have been incorporated into the floras and faunas of all continents and most oceanic islands. These organisms can have marked effects on ecosystems. I wanted to address the following facets of non-native species invasion: (1) What characteristics of ecosystems make them more susceptible to non-native species invasion? and (2) What characteristics of the invader allow invasion? To address these questions, I used a gradient of anthropogenic disturbance common in southeastern Ohio forests: intact secondary forest, forest edge, and aggrading clear cuts. Paulownia tomentosa is a tree native to Asia and thought to have been introduced to North America in the 1840's. The species has naturalized throughout Appalachia. I studied the growth, allocation, establishment, and seed persistence across habitats. I also became interested in the basic ecology of P. tomentosa, particularly the ability of the species to resprout and phenotypic plasticity in naturalized populations. The most important factors in determining the invasive potential of P. tomentosa were disturbance and herbivory. Paulownia tomentosa is an early successional species that can grow rapidly under high light conditions. Seed ecology suggests that the species can form a persistent seed bank. However, light is required for germination and seeds responded positively to soil disturbance. Large gaps may be sufficient to allow seeds in the seed bank to germinate and grow to the canopy. However, the species is very susceptible to herbivory. Plants had to be protected from mammals in order to persist. Even though above- and below-ground competition affected plant growth and allocation, it did not affect the overall success of plants. Paulownia tomentosa can resprout at an early age and initially invests (open full item for complete abstract)

Committee: Brian McCarthy (Advisor) Subjects:

Master of Science (MS), Ohio University, 2009, Environmental and Plant Biology (Arts and Sciences)

Molecular markers can be used to find the genetic relatedness of an invasive species and reconstruct certain aspects of the path of invasion. Japanese knotweed, Fallopia japonica (Houtt.) Ronse Decr. (Polygonaceae), was used as a model to test how sexual reproduction and clonal propagation have affected the species‚ invasion history in the eastern United States and what model of spread is likely. Three microsatellite markers and reciprocal transplants were used to assess the genetic variation in three regions of the eastern United States: Michigan, Ohio, and the Southern Appalachians. Knotweed was found to be highly clonal but also reproducing sexually. No path of invasion could be ascertained and the patterns of genetic similarity were such that a hierarchical model of spread (with long-distance dispersal implicated as very important) has mostly likely occurred in the three regions as well on the continental scale.

Committee: Glenn R. Matlack (Advisor); Harvey Ballard Jr. (Committee Member); Brian McCarthy (Committee Member) Subjects: Biology; Botany; Ecology