Dissertations and Theses - Natural Resources and Environmental Sciences http://hdl.handle.net/2142/14737 Sun, 24 Jul 2016 08:47:36 GMT 2016-07-24T08:47:36Z Interactions between cover crop residue and microbial community affect weed suppression http://hdl.handle.net/2142/89211 Interactions between cover crop residue and microbial community affect weed suppression Lou, Yi The environmental and health risks from the use of herbicides have led to interest in developing alternative methods for agricultural weed control. Incorporation of cover crop residues is an important approach that contributes to alternative weed management systems. The cover crop residue-associated allelochemicals can inhibit weed germination, growth and production. Soil microbial communities are especially important for the allelochemical potential of a cover crop residue, because microorganisms can modify residues and allelochemicals to make them more or less phytotoxic. In addition to their effects on allelochemicals, soil microbial communities can also directly suppress weeds. To improve weed biocontrol, it is critical to understand how soil microorganisms interact with cover crop residues to suppress weed. The goal of this dissertation is to evaluate the contributions of microbes, cover crop residues, and their interactions to weed suppression. The first experiment examined the temporal dynamics of weed suppression over time to determine the microbial suppression, residue suppression, and their interactions. Results show that microbial activity directly suppressed weed germination and seedling growth, but also indirectly helped weeds by degrading cover crop-derived allelochemicals. These results suggest that the weed suppression shifted from a predominantly chemical phase to a predominantly microbial phase. To identify putative weed suppressive microbes, the microbial communities associated with diseased and stunted seedlings were characterized, and organisms present were examined for desirable weed suppressive traits. The identified putative weed suppressive microbes can be considered as a starting point for future selection of biocontrol agents. To determine the effects of management practices on weed suppression, I investigated the interactions between microbial communities and cover crop residues in three agricultural management systems (tillage, no tillage and organic system). Overall, the organic and tillage management systems offered higher microbial and cover crop-derived weed suppression than the no-tillage system. Different microbial communities were associated with dead seeds and diseased seedlings. These microbes also differed among the three agricultural management systems. This result indicates the potential of managing the soil microbiome for desirable weed suppression. The cover crop associated allelochemicals negatively affected microbial attacks to seedlings. However, the allelochemicals also induced seedling leakage that made seedling more susceptible to microbial attacks by triggering microbial chemotactic behaviors. Understanding how soil microbial communities interact with cover crop residues in agricultural systems has important implications for the weed biocontrol strategies. This dissertation suggests that naturally occurring soil microbial communities can be used and managed for sustainable weed control in agricultural systems. Microbial ecology; Weed suppression; Cover crop Tue, 01 Dec 2015 00:00:00 GMT http://hdl.handle.net/2142/89211 2015-12-01T00:00:00Z Lou, Yi Distribution of non-native wetland plants is facilitated by urbanization and roads in the Chicago region http://hdl.handle.net/2142/89107 Distribution of non-native wetland plants is facilitated by urbanization and roads in the Chicago region Skultety, Dennis Phillip Human modification of the landscape, including urbanization and road construction, has facilitated the spread and establishment of non-native plant species. Urban areas have often been introduction points for species and have a combination of factors making them susceptible to invasion; including reduced habitat area, loss of unique habitat types, and increased nutrient run-off. Roads facilitate the spread of non-native plant species by providing locally disturbed habitat and a corridor for propagule dispersal. I conducted two analyses to assess how changes in the environment through urbanization and road construction facilitate the distribution of non-native plant species. For these analyses I used species occurrence data from over 2000 wetlands within the Chicago region. In the first analysis I examined the influence of urbanization and roads on the occurrences of 15 non-native plant species. I found that species, or groups of species, responded differently to the effects of urbanization and roads. For example, occurrences of halophyte species were best predicted by road variables; halophytes were more commonly associated with major roads such as interstates and federal highways, road types that are likely to receive greater applications of de-icing salts. For the second analysis I examined non-native species composition and identified non-native-dominated community types; I then conducted a similarity-based analysis to show that these novel communities are repeated across the landscape in a predictable way. I evaluated the contribution of surrounding land cover, roads, and geographic distances among wetlands to the similarity of plant communities. Non-native species were found to be widespread across the region. I found that non-native species similarity was most strongly correlated with similarity of land cover within 100 m of wetlands. This analysis was repeated for identified community types. My findings that similar changes to the landscape have resulted in similar combinations of non-native species is evidence that anthropogenic drivers are creating novel habitats and ultimately novel community types. Together my analyses have implications for understanding and managing non-native plant species within urban areas. wetlands; halophytes; non-native species distribution; dissimilarity Fri, 30 Oct 2015 00:00:00 GMT http://hdl.handle.net/2142/89107 2015-10-30T00:00:00Z Skultety, Dennis Phillip Environmental and economic impacts of UIUC food purchasing http://hdl.handle.net/2142/89083 Environmental and economic impacts of UIUC food purchasing Hunter, Dane William This work summarizes the increased attention American universities have paid to sustainability and reducing carbon emissions in recent decades through greenhouse gas (GHG) emissions inventories, as well as application of values based assessments such as the Real Food Challenge and then applies selected metrics to food procured by campus dining services at the University Illinois at Urbana Champaign (UIUC) in 2013. The American College and University Presidents’ Climate Commitment (ACUPCC) is a voluntary effort through which signatories have agreed to perform baseline carbon inventories and publish climate action plans with emission reduction targets. UIUC’s Climate Action Plan, iCAP, calls to increase the amount of local food, reduce agriculturally-related emissions by 50%, and to purchase more than 30% of food from within 100 miles by 2015. This is despite the fact that the ACUPCC inventory does not include food related emissions. This project used Life Cycle Assessment models to estimate GHG, and a Local Multiplier 2 (LM2) to consider local economic impact based on three ‘local’ purchasing definitions. In FY13, purchased food items accounted for 2.15% of the total UIUC footprint. Meat products accounted for around 50% of the foodprint, with beef comprising over 50% of that. Dairy accounted for about 15%. Packaging composed approximately 9% of an average product’s footprint. Transportation miles only composed 4% of the foodprint, so while reducing mileage does not offer the same GHG saving potential as altering consumption and production practices, LM2 models show economic benefits to the region derived from increasing local production and processing. Varying definitions of local show that UIUC’s local purchases range from composing <1% under the 2010 iCAP definition to 38% of food under the broadest definition. Despite prospective benefits of regional food systems, barriers have prevented large shifts in institutional spending to local food systems. Altering the requirements for institutional spending on locally produced goods to open new market opportunities as well as improved accounting of economic and environmental gains associated with local food procurement could facilitate transition to environmentally and economically sound regional food systems. Results from this work suggest purchasing and consumption scenarios that reduce meat consumption and capitalize on the region’s capacity for grain, legume, and oil crop production to support a local, sustainable food system. First steps towards realization of this transition include fostering new markets by beginning to purchase locally supplied dry beans which require minimal processing. Additionally, the Sustainable Student Farm and Food Science and Human Nutrition Pilot Processing Plant can model and refine practices of producing and processing grain and oil crops for a regional food system. Foodprint; Food Footprint; Local Multiplier; Food Carbon Wed, 09 Dec 2015 00:00:00 GMT http://hdl.handle.net/2142/89083 2015-12-09T00:00:00Z Hunter, Dane William Herbaceous and woody plant establishment across hydrologic gradients in bottomland reforestation sites http://hdl.handle.net/2142/89029 Herbaceous and woody plant establishment across hydrologic gradients in bottomland reforestation sites Krzywicka, Adrianna Ewa Flooding is an important determinant of plant establishment, as well as planted tree survival and growth, in restored floodplain forests. Thus, community assembly in a restored floodplain and, ultimately, restoration outcomes are likely constrained by the site’s hydrologic regime, along with other abiotic factors including light availability and the distance from potential colonization sources. However, trees are often planted in restorations without regard to the site’s hydrologic context and do not survive. Therefore, there is a need to understand the relative importance of abiotic factors on tree and herbaceous species establishment and growth, and there is a need for improved tools for identifying critical abiotic factors during pre-restoration planning. In order to determine the effect of hydrology and other abiotic conditions on plant community assembly, I surveyed plant communities within restored floodplain areas of three different ages. I assessed the density and composition of naturally colonizing tree species and the cover of herbaceous-layer plant species. I evaluated the relationship between tree and herbaceous species establishment and light availability, distance from a nearby seed source, elevation and flood regime. In order to determine the effect of hydrology on planted tree survival, I planted 400 bareroot tree seedlings of four commonly planted species along a hydrologic gradient in a recently restored floodplain. I evaluated the effect of exposure to flooding on planted tree survival and growth. I also evaluated the use of soil magnetic susceptibility (MS), a proxy for soil drainage (other factors being equal), as an easily measured, quantitative predictor of planted tree survival and growth. Lower values of soil MS result from long-term reducing (or anaerobic) soil conditions, and so soil MS might provide a guide to match individual tree species with site-specific soil moisture regimes during restoration planning. Despite the presence of an adjacent mature floodplain forest, passive tree seedling colonization in the restored areas was minimal. In the oldest restored area, tree seedling density increased with increasing elevation and decreased with distance from the seed source, suggesting that tree colonization was limited by both flooding and dispersal. The responses of herbaceous understory species composition to site abiotic conditions varied among the three restored areas, but hydrology was the most important predictor of species composition in all areas. In the first year, the overall survival rate of the planted tree seedlings was 55%. After two growing seasons, the overall survival rate was reduced to 24%. Of the four species planted, Quercus bicolor had the highest survival rate, followed by Quercus palustris and Carya illinoensis. None of the Juglans nigra seedlings survived to the end of the study. Elevation, along with time and species identity, were important predictors of planted tree survival; as elevation increased, probability of survival for each of the four species increased. For growth, flood exposure and species identity were the best predictors of changes in planted tree height, whereas planted tree diameter was not well explained by the measured predictor variables. Soil MS was significantly correlated to both total flood duration and elevation. Soil MS was able to predict planted tree survival, with more flood-tolerant species such as Quercus bicolor surviving in areas with a low soil MS reading, corresponding to poorly drained soils. Understanding how tree colonization, planted trees, and herbaceous understory vegetation respond to abiotic factors such as flood duration and distance from colonization sources, as well as developing tools for identifying critical abiotic factors, will allow for more accurate predictions of restoration outcomes and more targeted planting in floodplain restorations. Passive restoration; active restoration; hydrologic gradients; soil magnetic susceptibility (MS) Tue, 01 Dec 2015 00:00:00 GMT http://hdl.handle.net/2142/89029 2015-12-01T00:00:00Z Krzywicka, Adrianna Ewa Comparative reproductive biology of co-occurring endangered and common shrubland birds http://hdl.handle.net/2142/89023 Comparative reproductive biology of co-occurring endangered and common shrubland birds Kovar, Daniel George Black-capped vireos (Vireo atricapilla) and white-eyed vireos (Vireo griseus) are closely related and ecologically similar. Despite these similarities, white-eyed vireos are widely distributed and common, whereas the black-capped vireo has a restricted breeding range and is federally endangered. Here I address this apparent paradox with a comparative ecological study of co-occurring black-capped and white-eyed vireos. I studied vireos in shrublands and woodlands in central Texas, USA in 2013 and 2014. I used point count surveys (n = 256) and nest monitoring (n = 145) to determine arrival dates, settlement patterns, nest site selection, and, ultimately, nest survival relative to temporal and habitat factors. Additionally, I conducted reciprocal playback trials (n = 16) to test for the presence of interspecific aggression. White-eyed vireos arrived first and established territories in shrub and woodland habitat with equal probability. Black-capped vireos arrive after white-eyed vireos and settled in greater numbers in shrubland habitat. White-eyed vireos begin initiating nests earlier than black-capped vireos and selected nest sites surrounded by taller, more mature, and more densely wooded vegetation. Playback trials failed to detect evidence of interspecific aggression, suggesting that competition with white-eyed vireos is not currently limiting black-capped vireos. For both species, nest survival declined as the season progressed, and was greater for nests in taller, more mature habitat. Accordingly, overall nest survival appeared greater for white-eyed vireos than black-capped vireos suggesting that the flexibility demonstrated by white-eyed vireos in where and when they nest confers a reproductive advantage. comparative ecology; habitat selection; interspecific competition; endangered species management and conservation; avian ecology; nest site selection; nest survival; brood parasitism; black-capped vireo; Vireo atricapilla; white-eyed vireo; Vireo griseus Mon, 30 Nov 2015 00:00:00 GMT http://hdl.handle.net/2142/89023 2015-11-30T00:00:00Z Kovar, Daniel George The responses of subtropical nearshore fishes to climate change http://hdl.handle.net/2142/88975 The responses of subtropical nearshore fishes to climate change Shultz, Aaron D Global climate change is expected to alter seawater conditions and marine ecosystems. The Intergovernmental Panel on Climate Change (IPCC) predicts that sea surface pH will decrease by 0.06 - 0.32 pH units and temperature will increase by 0.6-2.0°C over the next 100 years, and extreme weather events, such as major storms (e.g., tropical cyclones), floods, heat waves, and cold spells, are expected to increase in intensity and frequency. Nearshore ecosystems serve as critical habitat for juvenile fishes (e.g., schoolmaster snapper, yellowfin mojarra) and function as foraging grounds for adults (e.g., bonefish, checkered puffer), yet it is unclear how nearshore fishes will respond to forecasted increases in temperature and pCO2. To fill this knowledge gap, I assessed the physiology, behavior, and thermal plasticity of nearshore species challenged by climate change stressors, and determined how the presence of a predator will influence habitat choice under forecasted conditions. Climate change research on marine organisms has primarily focused on species that inhabit the open ocean or coral reef environments. Elevated temperature, salinity, and acidity (reduced pH) have all been shown to result in varying degrees of physiological disturbance in organisms across ecosystems, yet little effort has been devoted to understanding the magnitude of these disturbances in nearshore fishes across seasons. Moreover, few studies have investigated the synergistic (or canceling) effects of combined climate-related challenges. Based on this background, the purpose of this aspect of the study was to assess the relative impacts of climate-related challenges across seasons on fishes that inhabit the nearshore ecosystem. To do this, blood-based physiological responses to elevated temperature, salinity, acidity, and temperature + acidity of adult bonefish, adult checkered puffer, and juvenile yellowfin mojarra were compared across seasons (i.e., summer and winter). Bonefish exposed to climate-related challenges experienced elevated Cl-, Ca2+, lactate, and glucose levels in the summer relative to winter, and elevated temperature resulted in glucose and ionic disturbances in both seasons. Similarly, independent of season, checkered puffer exhibited elevated hematocrit, glucose, and cortisol levels when exposed to elevated temperature relative to ambient conditions. Yellowfin mojarra experienced minimal physiological disturbance to the climate-related challenges, but independent of season, elevated temperature increased hematocrit values relative to ambient conditions. Interestingly, the combined stressor, temperature + acidity, did not result in a synergistic or additive physiological disturbance in nearshore fishes. Results indicate that adult bonefish exposed to climate-related challenges experience the greatest physiological disturbances in the summer relative to the winter, with temperature being the most challenging stressor. Collectively, temperature change will be the most challenging climate-related stressor for nearshore fishes, particularly in the summer, and may result in more energy being expended to maintain homeostasis, which could translate into altered behavior, performance, and/or habitat choice under forecasted conditions. Global climate change scenarios forecasted by the Intergovernmental Panel on Climate Change (IPCC) are expected to alter the performance of marine fishes and potentially disrupt ecosystems. Indeed, climate-related stressors have been shown to reduce metabolic performance in fish from coral reef environments, which may have consequences for growth, reproduction, and distribution of these fishes. Unfortunately, very few studies focus on more than one species or expose fish to several scenarios, which hinders our ability to predict how fish communities and ecosystems will respond to future climate change. The purpose of this aspect of the study was to define the performance of subtropical nearshore fishes to projected climate change scenarios and relate these findings to the ecology of nearshore ecosystem in the future. Adult bonefish, adult checkered puffer, juvenile yellowfin mojarra and juvenile schoolmaster snapper, were acclimated to ambient conditions, along with a range of elevated pCO2, salinity, and temperatures that coincide with, or exceed, the worst-case scenario predicted by the IPCC in 100 years. Post acclimation, fish performance was quantified by measuring standard metabolic rate (SMR) with intermittent-flow, static respirometry, and by chasing the fish to exhaustion (i.e., swimming performance (SP)). Bonefish and yellowfin mojarra experienced an increase in SMR of more than 65% when acclimated to seawater at 33ºC, and all species experienced an increase in SMR and a decrease in SP at 34ºC. Nearshore fishes acclimated to elevated pCO2 and salinity experienced minimal disturbances in SMR or SP. Results indicate that elevated temperatures that coincide with (33ºC), or exceed (34ºC), the worst-case scenario predicted by the IPCC increased standard metabolic rates and reduced swimming performance for a number of nearshore fishes, with elevated pCO2 and salinity resulting in minimal disturbances in performance. To avoid costs associated with elevated temperatures, nearshore fishes may choose to migrate to more thermally stable environments, allocate energy differently, or increase feeding rates to meet energetic demands. The capacity of fishes to offset these costs will determine ecological “winners” and “losers” in the future and potentially result in a slow restructuring of the nearshore ecosystem. The proximity of fishes to their thermal limits, coupled with their potential to acclimatize to future environmental conditions, will be additional factors influencing the structure of marine ecosystems as the climate changes. Species that have relatively high thermal maxima are expected to have a limited capacity to acclimatize to new conditions, but this assumption as not been tested on fishes in variable thermal environments in subtropical nearshore ecosystems. The goal of this aspect of the study was to assess the vulnerability of nearshore fishes to climate change and to evaluate the ability of these fishes to adjust their physiological limits across seasons (i.e., phenotypic plasticity). To do this, the critical thermal maximum (CTMax) and minimum (CTMin) of adult bonefish, adult checkered puffer, juvenile yellowfin mojarra, and juvenile schoolmaster snapper were determined across seasons. Acclimatization response ratios (AZRR; ΔCTMax ΔT-1 and ΔCTMin ΔT-1) were typically greater than 0.60 for all species, a value greater than most previously reported for fish species from variable thermal environments. Present day maximum and minimum temperatures in the nearshore environment are approximately equal to or exceed the thermal tolerance limits of the fish in this study, making thermal safety margins (TSM; i.e., the difference between thermal tolerance limit and extreme environmental temperature) very small or even negative for nearshore fishes (TSM upper = -4.9-0.5; lower = -0.2-0.4). The thermal landscape in the nearshore ecosystem in the future will likely benefit species with positive thermal safety margins that are capable of acclimatizing (e.g., schoolmaster snapper) while relatively intolerant species (e.g., bonefish) may select habitats in this ecosystem less frequently or will be absent from this ecosystem in the future. Habitat selection in fish is typically governed by the tradeoff between the benefit and cost of acquiring food. Nearshore fishes reside in shallow environments to reduce the threat of predation and/or take advantage of feeding opportunities and routinely experience challenging abiotic conditions. Little is known about the tradeoff between accepting the physiological costs of maintaining homeostasis in novel environments (e.g., elevated temperature associated with climate change) or risking predation by moving to new, less physiologically demanding habitats. The purpose of this aspect of the study was to define the relative cost of habitat selection by measuring temperature and pCO2 avoidance thresholds of nearshore fishes under altered abiotic conditions in the presence or absence of a predator, (i.e., a juvenile lemon shark). To do this, common subtropical nearshore fishes (i.e., juvenile schoolmaster snapper, juvenile yellowfin mojarra, adult bonefish, and adult checkered puffer) were acclimated to a behavioral choice arena (i.e., two chambers connected by a central corridor). Temperature or CO2 were manipulated in one chamber while the other chamber was maintained at ambient conditions. Results show that elevated temperatures and pCO2 alter habitat choice in all nearshore fishes in this study, and that temperature and pCO2 avoidance thresholds increase in the presence of a predator. Collectively, elevated temperatures and pCO2 may alter habitat use and distribution of fishes in nearshore ecosystems, with community structure in predator-rich environments looking very different from environments with low predator burdens. The outcomes of this research indicate that nearshore fishes exposed to elevated temperatures experience physiological disturbances in the summer, decreased swimming and metabolic performance, some plasticity in thermal tolerance limits, and altered habitat choice in the presence of a predator. Collectively, temperatures that coincide with and exceed future predictions will have species-specific impacts, potentially resulting in shifting community structure in the nearshore ecosystem. Blood chemistry; multiple stressors; nearshore; physiological response; stress; temperature; scope for activity; metabolic rate; performance; oxygen capacity limited thermal tolerance; carbon dioxide; salinity; acclimation; ocean acidification; respirometry; marine community; ectotherm; Critical Thermal Maximum (CTMax); Critical Thermal Minimum (CTMin); thermal scope; plasticity; climate change; extreme weather; physiological costs; behavior; predation Wed, 11 Nov 2015 00:00:00 GMT http://hdl.handle.net/2142/88975 2015-11-11T00:00:00Z Shultz, Aaron D Porcine rotavirus adsorption to 24 salad vegetables and sanitization by free chlorine http://hdl.handle.net/2142/88301 Porcine rotavirus adsorption to 24 salad vegetables and sanitization by free chlorine Lu, Lu Foodborne diseases are a persistent problem in the United States and worldwide. Fresh produce, especially those used as raw foods like salad vegetables, can be contaminated, causing illness. In this study, we determined the number of rotaviruses adsorbed on produce surfaces using group A porcine rotaviruses and 24 cultivars of leafy vegetables and tomato fruits. We also characterized the physicochemical properties of each produce’s outermost surface layer, known as the epicuticle. The number of rotaviruses found on produce surfaces varied among cultivars. Three-dimensional crystalline wax structures on the epicuticular surfaces were found to significantly contribute to the inhibition of viral adsorption to the produce surfaces (p=0.01). We found significant negative correlations between the number of rotaviruses adsorbed on the epicuticular surfaces and the concentrations of alkanes, fatty acids, and total waxes on the epicuticular surfaces. Partial least square model fitting results suggest that alkanes, ketones, fatty acids, alcohols, contact angle and surface roughness together can explain 60% of the variation in viral adsorption. The results suggest that various fresh produce surface properties need to be collectively considered for efficient sanitation treatments. Up to 10.8 % of the originally applied rotaviruses were found on the produce surfaces after three washing treatments, suggesting a potential public health concern regarding rotavirus contamination. produce safety; foodborne diseases; epicuticular layer; porcine rotavirus Tue, 21 Jul 2015 00:00:00 GMT http://hdl.handle.net/2142/88301 2015-07-21T00:00:00Z Lu, Lu Investigation of Miscanthus associated microbiome: effects of biotic and abiotic factors http://hdl.handle.net/2142/88261 Investigation of Miscanthus associated microbiome: effects of biotic and abiotic factors Li, Dongfang Long-term sustainable production of biofuel feedstock crops like Miscanthus species requires minimum anthropogenic energy inputs as well as the maintenance of soil fertility. Beneficial microbes, such as nitrogen-fixing bacteria, contribute to plant yield and fitness, representing under-explored plant nutrient sources. Optimizing the positive interactions between Miscanthus species and associated bacteria has high potential to support sustainable crop production. Bacterial community functions are directly related to community structures, which rely on surrounding biotic and abiotic factors. Therefore, before Miscanthus-bacteria interactions can be optimized for better plant productivity, it is necessary to investigate the factors that regulate community assemblage of these microbes. The goal of this dissertation is to identify factors that significantly explain the Miscanthus-associated bacterial community variation. To achieve this goal, a combination of observational and experimental approaches was used. Miscanthus plants were collected from native, naturalized and cultivated habitats. These habitats represent a broad range of biotic and abiotic factors. Both Miscanthus endophytic compartment (rhizomes) and their surrounding rhizosphere soil were collected from each plant because both endophytes and rhizosphere bacteria are known to contribute to mutualistic plant-microbe interactions. Here, I accessed and compared both endophytic and rhizosphere bacterial communities, and evaluated whether plant genotypes and soil edaphic factors may influence them differently. As one of the most important beneficial bacteria groups, Miscanthus-associated diazotrophs assemblages were also examined in this work. I found endophytic and rhizosphere communities correlated differently with their surrounding environment. Overall, I found that endophytic communities were more likely to be genotype-specific than the rhizosphere bacteria while the rhizosphere communities tended to change when soil conditions changed. The effect of agricultural practices could be hard to maintain and not significantly change microbial communities. Therefore, the goal of optimizing rhizosphere communities by changing soil conditions cannot be achieved easily. Instead, Miscanthus-associated endophytes are relatively stable to environmental change, and I identified some key endophytic-enriched taxa were shared among Miscanthus sites at a global scale. Hence, facilitate beneficial taxa to colonize Miscanthus endophytic compartment during rhizome propagation or pre-treatment of Miscanthus seeds with beneficial strains may be effective strategies to enhance the mutualism between Miscanthus and bacteria. Even closely related Miscanthus genotypes tended to harbor very different endophytic N-fixing bacteria. On one hand, this result indicates the possibility of identifying plant genetic markers that control endophytic bacteria recruitment. On the other hand, the contribution of beneficial bacteria to Miscanthus must be evaluated on a genotype-by-genotype basis. I observed many highly similar bacteria taxa from sites located on different sides of the world, indicating plant-associated taxa might not be dispersal limited. However, the interconnections between bacteria species are context-depend. Miscanthus-associated bacterial taxa were much more tightly connected with each other in the native sites than in the naturalized sites. This result indicates that the presence of similar bacteria taxa does not necessarily lead to similar functions. Understanding the plant microbiome assemblage is simply the first step exploring the plant-bacteria interactions. This work contributes to our knowledge of the plant-associated microbiome, which provides guidance for optimizing Miscanthus-microbe interactions for the long-term sustainable cultivation of Miscanthus species. Microbial ecology; Miscanthus Thu, 09 Jul 2015 00:00:00 GMT http://hdl.handle.net/2142/88261 2015-07-09T00:00:00Z Li, Dongfang Extrapair mating behaviors in the field sparrow: nocturnal singing and extraterritorial forays http://hdl.handle.net/2142/88235 Extrapair mating behaviors in the field sparrow: nocturnal singing and extraterritorial forays Celis Murillo, Antonio While there has been much research on the mating behaviors of birds, most attention has focused on elaborate and/or conspicuous mating displays, such as diurnal songs, ornaments, or mating dances. Much less attention has been devoted to investigating the role of more subtle behaviors, particularly nocturnal signing by diurnal birds and extra-territorial forays (movements off territory). My research explored the function of nocturnal singing and extra-territorial forays in the Field Sparrow (Spizella pusilla). I determined that nocturnal complex song serves to announce the presence of extra-pair males to females and that extra-territorial forays serve primarily in prospecting and soliciting extra-pair matings. While forays are common among both male and female Field Sparrows, a higher foraying rate did not result in greater extra-pair paternity (EPP). Rather, my data provide strong evidence that extra-pair matings are determined by current and previous relationships; females chose extra-pair sires that were current neighbors or neighbors or social mates during previous breeding seasons. Given female preference for extra-pair matings with neighbors, males who have information on the fertility status of neighboring females and coordinate their nocturnal vocalizations in relation to the fertility stage of neighboring females may be able to increase their EPP. Contrary to other studies, I did not find a relationship between the traits of males, females, or females’ social mates (age and tarsus length) and EPP. Thus, proximity to females, rather than male characteristics, appears to be key for a male’s success at acquiring extra-pair paternity. Finally, my findings are consistent with the hypothesis that female choice for extra-pair mates coupled with female foray behavior are driving patterns of extra-pair paternity and nocturnal singing behavior. By integrating research on nocturnal singing, extra-territorial foray behavior, and extra-pair paternity, my work has led to a more comprehensive understanding of extra-pair mating behavior in birds. Nocturnal Song; Extraterritorial Forays; Extra-pair mating behaviors; Field Sparrow; Nocturnal singing in diurnal birds; Foray behavior; Mating behaviors Thu, 16 Jul 2015 00:00:00 GMT http://hdl.handle.net/2142/88235 2015-07-16T00:00:00Z Celis Murillo, Antonio Songbird migration ecology in east-central Illinois http://hdl.handle.net/2142/88228 Songbird migration ecology in east-central Illinois Parker, Christine Marie Migration is a well-known phenomenon by which birds move to locations with favorable climates and abundant resources. The habitats and resources utilized by these birds throughout their annual cycle continue to be impacted by human activities, such as fragmentation and deforestation. These activities inflate the inherent consequences of migration (e.g., reduced survival, carry-over effects, and health) and contribute to the continued decline of migratory birds. I studied passerine migration across east-central Illinois from 2012 through 2014. During this time, birds were surveyed during spring and fall migratory periods to address two research questions: 1) what habitat characteristics are indicated by different metrics of habitat quality used to evaluate stopovers for migrants? 2) which birds play a larger role in tick dispersal, and how do habitat characteristics influence infestation? Although migrants were using fragmented study sites, I found little evidence to suggest that they were able to increase energy reserves, although I did detect a slight increase in condition among long-distance migrants in response to shrub-fruit abundance. Vegetation cover was positively related to migrant abundance and richness. I found that short-distance migrants experienced greater infestation prevalence than long-distance migrants. Birds that forage in the forest understory (< 10 m) experienced greater infestation prevalence than canopy foraging species. Ixodes spp. infestation prevalence was influenced by patch size and invasive shrub fruit abundance, while H. leporispalustris was unrelated to avian or habitat characteristics. This research indicates that variation in life-history traits among migratory birds may influence the quality and consequences of stopovers during migratory periods. stopover; tick-infestation Thu, 23 Jul 2015 00:00:00 GMT http://hdl.handle.net/2142/88228 2015-07-23T00:00:00Z Parker, Christine Marie