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Title: Ecology and diversity of the lichen symbiosis : following established patterns, or an exception to the rule?
Creator: Scharnagl, Klara
Date: 2019
Collection: Electronic Theses & Dissertations
Description: Few phenomena of biodiversity have perplexed researchers as much as the latitudinal diversity gradient. Though many taxa have been shown to follow this pattern of high species richness in the tropics and lower species richness towards the poles, no consensus has yet been reached regarding the drivers of this global pattern. Symbiosis, a long term and physically intimate interaction between two organisms, is a prevalent biotic interaction across the tree of life, yet few studies of the...
Show moreFew phenomena of biodiversity have perplexed researchers as much as the latitudinal diversity gradient. Though many taxa have been shown to follow this pattern of high species richness in the tropics and lower species richness towards the poles, no consensus has yet been reached regarding the drivers of this global pattern. Symbiosis, a long term and physically intimate interaction between two organisms, is a prevalent biotic interaction across the tree of life, yet few studies of the latitudinal diversity gradient have looked at symbiotic organisms. One example of symbiosis is the lichen symbiosis, an association between a filamentous fungal partner and a photosynthetic partner of green algae or cyanobacteria. Little is known about the latitudinal diversity gradient of lichens, yet their terrestrial ubiquity and symbiotic nature could provide insight into the drivers of this global pattern. To assess whether lichenized fungi follow a latitudinal diversity gradient, I compiled a dataset from three repositories for digitized herbarium specimen data: the Consortium for North American Lichen Herbaria, the Global Biodiversity Information Facility, and the Institutos Nacionais de Ciencia e Tecnologia. The fully compiled and quality-controlled dataset contained over 900,000 datapoints representing over 8,000 species. The raw species richness data revealed a peak in richness north of the equator outside of the tropics, however, this pattern mirrored the number of collections per latitudinal band. To correct for sampling effort biases in the digitized herbarium data, I rarefied species richness. I further corrected the rarefied species richness for land area, given the wide range of land area per latitudinal band in the Americas. This rarefied and land-area-corrected species richness data supports a latitudinal diversity gradient of lichenized fungi in the Americas. In a comparison to lichen checklist data at the country or state level, I revealed that tropical regions are underrepresented in the digitized herbarium data.To test the influence of sampling effort bias on the patterns revealed by the digitized herbarium data, I designed a field sampling approach directly targeted at the question of whether epiphytic lichens follow a latitudinal diversity gradient. This approach can help remove bias present in digitized herbarium data because they result from the compilation of many studies, each of which had its own taxonomic, regional, or ecological focus. To do so, I sampled from nine lowland forest sites across a 70-degree span of latitude in the Americas. At each site, I randomly chose ten plots, and sampled from ten trees within each plot for a total of nine hundred trees sampled. At each tree, I randomly chose a cardinal direction and placed a 20x40cm grid on the tree, collecting all lichens that fell within that grid. Thus, each site had the same amount of area surveyed for epiphytic lichen diversity. Lichens were identified to species in the lab. Data from systematic field sampling corroborate the latitudinal diversity gradient of (epiphytic) lichens. In a mixed effects model including tree and climate data, I found that this pattern is largely explained by host tree (substrate) diversity.With increasing land use change and impacts from climate change across the globe, it is increasingly important for us to set a baseline of patterns of diversity at large scales, as I did in my first two chapters, to then assess how these impacts are affecting the diversity of symbiotic organisms at different scales. For my third chapter, I applied my knowledge of lichen diversity to assess the impacts of three tropical forest restoration treatments on epiphytic lichens. The natural regeneration treatment had a small cohort of lichen species likely specialized to the high light and dry environment. The plantation and nucleation treatments had a mix of light and shade tolerant species and experienced higher competition from epiphytic bryophytes. The overall highest diversity of epiphytic lichens was found in the nucleation treatment, supporting this as the combination of the most cost-effective strategy that restores the greatest amount of tropical biodiversity.
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Title: Investigating the importance of vertebrate hosts for Lyme disease ecology : a natural experiment presented by Lake Michigan islands at Sleeping Bear Dunes National Lakeshore
Creator: Sidge, Jennifer Lois
Date: 2016
Collection: Electronic Theses & Dissertations
Description: ABSTRACTINVESTIGATING THE IMPORTANCE OF VERTEBRATE HOSTS FOR LYME DISEASE ECOLOGY: A NATURAL EXPERIMENT PRESENTED BY LAKE MICHIGAN ISLANDS AT SLEEPING BEAR DUNES NATIONAL LAKESHORE ByJennifer Lois Sidge In eastern North America, Lyme disease is caused by the bacterium, Borrelia burgdorferi, and is transmitted by the blacklegged tick, Ixodes scapularis. In Michigan’s Lower Peninsula, the blacklegged tick and the bacterium are invading from the southwest corner, northward along the Lake...
Show moreABSTRACTINVESTIGATING THE IMPORTANCE OF VERTEBRATE HOSTS FOR LYME DISEASE ECOLOGY: A NATURAL EXPERIMENT PRESENTED BY LAKE MICHIGAN ISLANDS AT SLEEPING BEAR DUNES NATIONAL LAKESHORE ByJennifer Lois Sidge In eastern North America, Lyme disease is caused by the bacterium, Borrelia burgdorferi, and is transmitted by the blacklegged tick, Ixodes scapularis. In Michigan’s Lower Peninsula, the blacklegged tick and the bacterium are invading from the southwest corner, northward along the Lake Michigan coast with the presumed leading edge at Sleeping Bear Dunes National Lakeshore (SLBE). How the tick spreads and becomes established is of great public health importance. White-tailed deer (Odocoileus virginianus) are believed to be the most important hosts for adult I. scapularis and critical for its spread and maintenance, but few opportunities exist to investigate tick and pathogen dynamics in their absence. Two Lake Michigan islands, at SLBE, one with deer and one without, presented this opportunity. The overall objective of this dissertation was to establish a baseline of abundance for the tick and pathogen on both islands and compare it to the ecologically diverse mainland, and assess the role of other mammals as alternative hosts for the adult stage of the tick in areas absent of deer. My hypothesis was that in locations devoid of deer, the blacklegged tick would not be established and/or would exist at much lower densities in comparison to areas with resident deer populations. Also, other medium-sized mammals would serve as hosts for the adult ticks that theoretically could support a tick population. In Chapter 1, I continued to track the invasion of the Lyme disease pathogen and vector at SLBE over a nine-year period. I found that there was a four year delay between the first detection of blacklegged ticks and the presence of B. burgdorferi and there was a trend illustrating an increase in I. scapularis and B. burgdorferi over time. At an additional site on SLBE’s mainland, the tick and the pathogen were detected at the same time supporting the “dual-invasion” scenario of invasion, yet, this may have been a consequence of when sampling began. At recently-invaded Lyme disease areas, such as these two SLBE mainland locations, I found eastern chipmunks (Tamias striatus) to be an earlier indicator of the pathogen’s presence in comparison to white-footed mice (Peromyscus leucopus). SLBE’s two offshore islands, one with white-tailed deer and the other devoid, were the focus of Chapter 2 as a means to evaluate the success of mammalian hosts for maintaining I. scapularis in the absence of deer. I found that although the island with the deer had a greater density of ticks and greater B. burgdorferi infection prevalence, the island that was deer-free had all three life stages of the blacklegged tick and B. burgdorferi was present. Thus, alternative hosts for the adult tick, including snowshoe hares (Lepus americanus), passerine birds, and coyotes (Canis latrans), were captured and it was determined that coyotes were maintaining the established tick population on the island. Eastern chipmunks played a crucial role with maintaining the juvenile stages of the tick on the islands. Chapter 3 then compared SLBE’s host-diverse mainland to the host-limited islands, testing the dilution and multiple niche polymorphism hypotheses. In order to test the dilution effect, the larval I. scapularis prevalence on white-footed mice between the two locations was compared. The proportion of mice infested with at least one I. scapularis larvae nor the larval burden on the mice supported the dilution hypothesis. However, on the islands and the mainland, more eastern chipmunks were captured than anticipated and this consequently reduced the larval burden on the mice in each community, thus, supporting the dilution effect at the location level. Host-seeking I. scapularis adult/nymphal infection prevalence and adult/nymphal density of infected ticks were greater on the host-limited islands, supporting the dilution hypothesis. However, B. burgdorferi IGS strain diversity was greater on the islands in comparison to the host-diverse mainland, which was unlike what was predicted by the multiple niche polymorphism hypothesis. Future studies to better estimate the island mammalian population sizes and diversity, in addition to comparing the B. burgdorferi island diversity to an area with a known long-established population of ticks would be advantageous to further our Lake Michigan island Lyme disease ecology knowledge. Also, given that SLBE is now most likely not at the leading edge of the Lyme disease invasion, future work should evaluate if the tick and bacterium have spread into neighboring counties.
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Title: The role of mycorrhizal fungi and soil nutrients in tropical reforestation
Creator: Holste, Ellen K.
Date: 2016
Collection: Electronic Theses & Dissertations
Description: With increasing awareness of large scale tropical deforestation and the ecological importance of mycorrhizae, incorporating fungal-plant symbioses into tropical restoration strategies has attracted considerable attention in recent years. In nutrient-poor landscapes, mycorrhizal fungi can help trees alleviate soil nutrient constraints to growth, and in particular, ectomycorrhizal fungi (EMF) may be more advantageous for nutrient capture than arbuscular mycorrhizal fungi (AMF) due to EMF’s...
Show moreWith increasing awareness of large scale tropical deforestation and the ecological importance of mycorrhizae, incorporating fungal-plant symbioses into tropical restoration strategies has attracted considerable attention in recent years. In nutrient-poor landscapes, mycorrhizal fungi can help trees alleviate soil nutrient constraints to growth, and in particular, ectomycorrhizal fungi (EMF) may be more advantageous for nutrient capture than arbuscular mycorrhizal fungi (AMF) due to EMF’s saprophytic capabilities and potential for increased nutrient uptake for their host trees. Establishing diverse mycorrhizal fungal communities is considered to be important to forest recovery, yet mycorrhizae may have complex effects on tree growth depending on the fungal composition of species present. Thus, the relative benefits that mycorrhizal fungi confer to host trees may be sensitive to changes in fungal type, fungal diversity and/or composition, and the soil nutrient environment. In this dissertation, I combined field and greenhouse-based experiments to examine fungal-tree-soil interactions and test the role of mycorrhizal fungi in restoring tropical trees in nutrient poor soils in southern Costa Rica. I tested: (1) the importance of fungal type (AMF vs. EMF) on tree growth, (2) the role of fungal type in nutrient acquisition (as reflected in tissue nutrient concentrations) under different soil nutrient availabilities, and (3) the effect of AMF diversity and fungal composition on tree growth in multiple reforested sites. My results showed variation in tree responses to fungal symbionts, depending on tree species, fungal type, and soil nutrient status. In the field, I found that differences in growth and tissue nutrient concentrations among four tree species were greater than fungal type differences (AMF vs. EMF) after two years of growth, highlighting the importance of tree species selection in reforestation. Soil nutrient availability via site variation (i.e., initial base cation availability) and nutrient treatments also were associated with differences in tree growth. After isolating fungal from tree species effects in the greenhouse, I did not find consistent effects of fungal type on plant growth and tissue nutrient content; AMF had greater tissue nutrient content compared to EMF- or non-inoculated plants in one tree species whereas another tree species’ growth responded more to EMF symbioses. In reforested agricultural lands, I found that increasing AMF diversity and spore numbers negatively correlated with reduced tree growth after 5 to 7 years, suggesting that more diverse and productive fungal communities could consume more tree carbon. In general, this dissertation provided greenhouse and field-based support for both positive and negative tree growth responses to mycorrhizal fungal community and demonstrated the importance of mycorrhizal fungi in reforestation efforts. This research also highlights that understanding specific fungal-tree symbioses, soil nutrient status, and site effects are crucial to making broader management recommendations for reforestation success.
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Title: Ecology of a carnivore community in an agricultural landscape in northeast Brazil
Creator: Dechner Sierra, Andrea Carolina
Date: 2016
Collection: Electronic Theses & Dissertations
Description: Understanding the factors that affect the presence and distribution of carnivores in human-dominated landscapes is one of the principal goals of conservation ecology. My research sought to determine those factors in a carnivore community inhabiting an agricultural landscape in Bahia, Brazil. To reach this goal I used camera traps and conducted semi-structured interviews in human communities in my study area. The carnivore community studied included eight species of the cat, weasel, raccoon...
Show moreUnderstanding the factors that affect the presence and distribution of carnivores in human-dominated landscapes is one of the principal goals of conservation ecology. My research sought to determine those factors in a carnivore community inhabiting an agricultural landscape in Bahia, Brazil. To reach this goal I used camera traps and conducted semi-structured interviews in human communities in my study area. The carnivore community studied included eight species of the cat, weasel, raccoon and dog families (puma (Puma concolor), ocelot (Leopardus pardalis), margay (Leopardus wiedii), tayra (Eira barbara), South American coati (Nasua nasua), crab-eating raccoon (Procyon cancrivorus), crab-eating fox (Cerdocyon thous), and domestic dog (Canis familiaris). Results indicated that habitat is a key factor determining the distribution of some species in the carnivore community. Some species, such as the crab-eating fox, had a high probability of using rubber crops and a low probability of using forested areas, whereas others, such as the South American Coati, had a low probability of using rubber crops and a high probability of using forested areas. Analysis at a larger scale indicated that in the case of the crab-eating foxes and the South American coatis landscape-related variables were the best predictors of the animals’ frequency of site use. The frequency of site use by tayras was best predicted by resource-related variables, and for the wildcats (Leopardus spp.) by human-related variables. Results from interviews with stakeholders showed that, the carnivore with the highest frequency of reported negative impacts was the puma due to the fear related to its presence. I also found that the factors that best explained tolerance for pumas were related to personal evaluative attitudes (likability) and perceived benefits. These findings elucidate the complexity of the actions required to propose more appropriate management strategies for carnivore conservation in tropical agricultural systems. The results make an important contribution to our knowledge of why carnivores adapt or fail to adapt to agricultural landscapes with applications for sustainable agriculture within and beyond the Northeast of Brazil.
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Title: EXPLORING SOIL ARTHROPOD ECOLOGY AND MANAGEMENT TACTICS IN PERENNIAL FRUIT CROP SYSTEMS DURING THE WINTER
Creator: Matlock, Jason
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Paralobesia viteana (the grape berry moth) and Venturia inaequalis (causal agent of apple scab) are two key pests of perennial fruit crops in Michigan and the Northeastern US. Both of these pests provide examples of the feedback potential of management decisions: they both overwinter within the cropping system and have multiple reproductive generations per growing season. This allows their populations to carry over from season to season, exacerbating any failures in management from previous...
Show moreParalobesia viteana (the grape berry moth) and Venturia inaequalis (causal agent of apple scab) are two key pests of perennial fruit crops in Michigan and the Northeastern US. Both of these pests provide examples of the feedback potential of management decisions: they both overwinter within the cropping system and have multiple reproductive generations per growing season. This allows their populations to carry over from season to season, exacerbating any failures in management from previous years. Both pests overwinter on the ground in leaf litter. During that time, these organisms are affected by physical changes of the ground habitat and interactions with other ground-dwelling organisms. Manipulation of that habitat to alter the physical properties and community dynamics to decrease overwintering survivorship of these pests may provide growers with additional management tactics. Indeed, there is historical precedent for such tactics originating in the early 1900s. Publications from that time mention grape growers in Northeastern, PA throwing furrows over the leaf litter beneath vine canopies in late fall or early spring and observing reduced grape berry moth emergence. During this same time period, it was discovered that spraying a urea solution onto fallen leaves in apple orchards decreased the spore density released by V. inaequalis in the following season. Unfortunately, our understanding of the mechanisms underlying these techniques are incomplete and their adoption by growers remains low. Furthermore, our general understanding of the activities of floor dwelling organisms during the overwintering period is also limited. Increasing knowledge both of how these specific tactics affect their associated target pests, and of how overwintering populations are structured are essential steps in the development and improvement of winter management tactics. With regard to P. viteana and grape vineyards, I explored the effects of physical damage and burial resulting from a rotary cultivator used at the end of the season. Survivorship of pupae recovered from the vineyard immediately after tillage and held until emergence was not significantly different from those recovered from an untilled control area, indicating little effect of mechanical damage on this pest. However, a single pass of the tillage implement buried three quarters of pupae under at least 1 cm of soil. A laboratory experiment to recreate these conditions resulted in significant increase in mortality when pupae were buried in more than 1 cm of sand. I conclude that interference with adult emergence of diapausing pupae via burial is the primary mechanism by which tillage controls grape berry moth.With regards to apple V. inaequalis and apple orchards, I observed the response of overwintering, ground-dwelling arthropods to 1) the application of urea to fallen leaves; and 2) organic versus conventional management strategies. In addition, I screened the gut contents of collected arthropods for the presence of V. inaequalis to identify potential natural enemy taxa. My primary finding was that orchards host a diverse, winter active arthropod community. Management strategy did not affect family richness or intra-community complexity (alpha diversity). There was also considerable overlap in the dominant families detected under both management strategies. However, the relative abundances of those families did respond to management strategy. These changes were associated with differences in the secondary and tertiary decomposer sub guilds. There was also evidence that organic management supported a greater arthropod population. Urea application caused an up-regulation of tertiary decomposers and a down-regulation of primary decomposers during the first month following application. I also found evidence that the absolute decomposer populations were greater in the urea treatments. I propose that urea application caused a trophic cascade in which increased microbial growth leads to a recruitment of fungal feeding arthropods into leaf litter from surrounding areas of the orchard.
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Title: THE EFFECT OF GENETIC AND ABIOTIC FACTORS ON THE GEOGRAPHIC VARIATION IN LIFE CYCLE PROCESSES OF IXODES SCAPULARIS IN THE EASTERN UNITED STATES
Creator: Pang, Genevieve C.
Date: 2019
Collection: Electronic Theses & Dissertations
Description: The blacklegged tick, Ixodes scapularis, is the tick vector species responsible for transmitting the Lyme disease pathogen (i.e., Borrelia burgdorferi) in the eastern United States (US). Although this vector species is established throughout the southern US, geographical patterns of Lyme disease incidence indicate that cases tend to be localized in the northeastern and north central US. Several hypotheses have been proposed to explain this gradient in incidence, including regional differences...
Show moreThe blacklegged tick, Ixodes scapularis, is the tick vector species responsible for transmitting the Lyme disease pathogen (i.e., Borrelia burgdorferi) in the eastern United States (US). Although this vector species is established throughout the southern US, geographical patterns of Lyme disease incidence indicate that cases tend to be localized in the northeastern and north central US. Several hypotheses have been proposed to explain this gradient in incidence, including regional differences in abiotic conditions, host diversity, tick genetics, and tick questing behavior. This dissertation explores how abiotic conditions and tick genetics may contribute to existing and future patterns of Lyme disease incidence, via their effects on I. scapularis life cycle processes. Using a four-year common garden experiment, I investigated the existing variation in life cycle processes (i.e., emergence and survival) among four widely-dispersed populations located within northern and southern areas of high and low Lyme disease incidence, respectively (Chapter 1). I then explored the potential mechanistic roles of abiotic and genetic explanatory factors underlying the observed among-population variation in emergence and survival. To address the observed among-site variation in emergence, I evaluated the accuracy of temperature-development models in predicting the emergence of ticks across populations, explored empirical evidence for the effects of genetics and plasticity on emergence, and identified potentially important explanatory factors contributing to the accuracy of temperature-development models in predicting emergence timing (Chapter 2). To address the observed among-site variation in survival, I explored empirical evidence for differences in survival among local and transplanted ticks, ticks placed at northern and southern sites, and ticks from northern and southern sites of origin; I also identified potentially important explanatory factors contributing to the observed variation in survival (Chapter 3). In Chapter 1, I found that there was significant among-site variation in emergence and survival, and that these life cycles may be extended at northern sites, relative to southern sites. This chapter also provided the first documentation of bimodal emergence for this species. In Chapter 2, I discovered that temperature-development models significantly under-predicted emergence timing across all life stages and populations used in this study, showed evidence of genetics and plasticity affecting emergence among sites, and identified genetics, plasticity, and key abiotic conditions as potentially important explanatory factors influencing the accuracy of these temperature-development models. In Chapter 3, I demonstrated that southern conditions may be less conducive than northern conditions to tick survival, based on observed larval survival patterns; I also showed that ticks of northern origin may be more robust than ticks of southern origin, based on observed nymphal survival patterns. I supported these trends in survival with the identification of the interaction between genetics and plasticity, abiotic conditions, and diapause as important explanatory factors in best-fitting models of I. scapularis survival. The findings of this dissertation highlight the potentially important contributions that abiotic and genetic factors have on variation in emergence and survival among I. scapularis populations. Understanding how these factors affect the life cycle processes of this may have important implications for predicting disease risk, as populations of this vector species invade new areas and are exposed to new abiotic regimes via climate change.
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Title: Impact of Predation Risk on the Behavior and Physiology of Insects in Agricultural Systems
Creator: Ali, Sara
Date: 2019
Collection: Electronic Theses & Dissertations
Description: ABSTRACTNon-consumptive effects are impacts on prey survival and performance that are related to investment in anti-predator defenses. Without considering direct consumption by predators, non-consumptive effects contribute a large portion of the net effects of predatory insects have on their prey. Because the central tenant of agricultural systems is to produce the highest profitable yield; understanding how we can harness, manipulate, and foster predator non-consumptive effects will be...
Show moreABSTRACTNon-consumptive effects are impacts on prey survival and performance that are related to investment in anti-predator defenses. Without considering direct consumption by predators, non-consumptive effects contribute a large portion of the net effects of predatory insects have on their prey. Because the central tenant of agricultural systems is to produce the highest profitable yield; understanding how we can harness, manipulate, and foster predator non-consumptive effects will be helpful in development of pest management techniques. While non-consumptive effects are now known to occur quite commonly, both the spatial and temporal scale of studies are limited (demonstrated in Chapter 1). It is therefore necessary to expand our work to better understand these interactions in natural systems over longer time periods. Here I examined the potential for non-consumptive effects in an important agricultural predator-prey system between a common herbivore prey (Pieris rapae) and ubiquitous predator (Harmonia axyridis) in both the laboratory (Chapter 2) and field (Chapter 3). Interestingly, even though these species overlap in spatial distribution and phenology, little to no effect of predation risk on prey behavior was found. Further, when examining their interactions in an open-field environment, no significant non-consumptive effects on Pieris rapae were found. However, manipulatively increasing predator cues in the open-field experiment did have significant impacts on a secondary insect pest (Aphidae spp). This work emphasizes the importance of examining community interactions at the field level. In addition, non-consumptive effects resulting from H. axyridis on aphids (Myzus persicae) were found to be strong, resulting from changes in both aphid behavior and physiology (Chapter 4). Overall, these studies demonstrate that predator non-consumptive effects are prey species dependent and that studies in natural settings, over larger spatial and temporal scales, will allow us to better understand these complex interactions.
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Title: Balancing white-tailed deer ecology with Michigan National Guard training at Fort Custer Training Center in Augusta, MI
Creator: Humphries, Joel T.
Date: 2011
Collection: Electronic Theses & Dissertations
Description: The Michigan Department of Military and Veteran Affairs (MDMVA) manage an array of natural resources at Ft. Custer Training Center (FCTC) in Augusta, Michigan, and their Integrated Natural Resources Management Plan (INRMP) promulgates management goals of ecosystem restoration and rehabilitation. White-tailed deer (Odocoileus virginianus) herbivory can influence the forest structure and composition. The hunter harvest period of white-tailed deer of approximately 75 days (the length of the...
Show moreThe Michigan Department of Military and Veteran Affairs (MDMVA) manage an array of natural resources at Ft. Custer Training Center (FCTC) in Augusta, Michigan, and their Integrated Natural Resources Management Plan (INRMP) promulgates management goals of ecosystem restoration and rehabilitation. White-tailed deer (Odocoileus virginianus) herbivory can influence the forest structure and composition. The hunter harvest period of white-tailed deer of approximately 75 days (the length of the season is subject to some minor annual variations) cannot take place since the FCTC functions as a military installation and its' needs dictate limited access to hunters, confounding the MDMVA's ability to meet their management goals. I evaluated the effectiveness of the current 5-day hunter harvest period by quantifying deer herbivory effects on structure and composition of forest types, and developed a suite of deer population indices. I captured, aged, ear-tagged and radio-collared 66 deer during winter from 2004 to 2008, and 14 neonatal fawns during spring in 2006 and 2007. The annual survival rate varied among the groups (adult females = 0.756, adult males = 0.493, yearling females = 0.443, yearling males = 0.379, fawns = 0.289). The short hunter harvest period is an effective and integral component of the ecosystem restoration and rehabilitation efforts of FCTC.
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Title: Earl Butz talks about the Department of Agriculture's jurisdictional disputes with the Environmental Protection Agency over the absolute ban on chemical pesticides and with Health, Education and Welfare over the food stamps program
Creator: Butz, Earl L. (Earl Lauer), 1909-2008
Date: 1975
Collection: G. Robert Vincent Voice Library Collection
Description: Earl Butz appears on Face the Nation with George Herman and Connie Chung.

Title: U.S. President Donald Trump speaks at the Ohio Republican Party State Dinner in downtown Columbus
Creator: Trump, Donald, 1946-
Date: 2018-08-24
Collection: G. Robert Vincent Voice Library Collection
Description: President Donald Trump speaks at the Ohio Republican Party State Dinner in downtown Columbus. Trump tells party members to encourage voters to cast their ballots in the 2018 elections and says that Democrats in Congress are obstructionists. He also talks about recent economic metrics, immigration policy and the environment and takes credit for reducing federal regulations.

Title: The devolution of military bases upon closure : a case study of Fort Sheridan, Illinois
Creator: Nathan, Vincent R.
Date: 1994
Collection: Electronic Theses & Dissertations

Title: Island-mainland and within-season comparisons of community level parameters and a model of their inter-relationships
Creator: Hall, Jerry Dexter, 1942-
Date: 1974
Collection: Electronic Theses & Dissertations

Title: Ecology of wild shiip (Ovis orientalis gmelini) on Kabudan Island, Iran
Creator: Mowlavi, Masood
Date: 1988
Collection: Electronic Theses & Dissertations

Title: Linking the forest-centered economic and ecologic systems of western Montana : a problem analysis
Creator: Pompi, Louis Walter, 1944-
Date: 1975
Collection: Electronic Theses & Dissertations

Title: A community experiment in dissemination models for citizen environmental action
Creator: Lounsbury, John William, 1947-
Date: 1973
Collection: Electronic Theses & Dissertations

Title: Behavioral, physiological and morphological similarity among populations of redside dace, a threatened species in Michigan
Creator: Novinger, Douglas Craig
Date: 1995
Collection: Electronic Theses & Dissertations

Title: Antibiotic resistance and bacterial microbiome in lettuce-soil systems
Creator: Shen, Yike
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Food safety challenges from emerging contaminants such as antibiotics and antibiotic resistance genes (ARGs) have received increasing attention due to rapid increases in their abundance in agroecosystems. This is particularly true in soil-vegetable systems as microbiomes and antibiotic resistomes of vegetables are important to their quality and safety and could be influenced by crop production with contaminated soil and water. Additionally, the food safety of vegetables may also drive...
Show moreFood safety challenges from emerging contaminants such as antibiotics and antibiotic resistance genes (ARGs) have received increasing attention due to rapid increases in their abundance in agroecosystems. This is particularly true in soil-vegetable systems as microbiomes and antibiotic resistomes of vegetables are important to their quality and safety and could be influenced by crop production with contaminated soil and water. Additionally, the food safety of vegetables may also drive consumers' preference and demand for certain food products (especially for labeled products such as USDA Organic, Raised Without Antibiotics, etc.). Using a soil-lettuce (Lactuca sativa) model system, the first study in this dissertation assessed how irrigation with antibiotics-contaminated water via overhead or soil-surface irrigation could influence bacterial communities and ARG profiles in lettuce shoots, roots, and soil, using 16S rRNA amplicon sequencing and high throughput qPCR techniques, respectively. The overall abundance and diversity of ARGs and bacteria associated with soil-surface irrigated lettuce shoots were lower than those under overhead irrigation, indicating soil-surface irrigation may have lower risks of producing food crops with high abundance of ARGs. ARG profiles and bacterial communities were sensitive to pharmaceutical exposure, but no consistent patterns of changes were observed. The second study examined the fate and transport of selected antibiotics through bulk soil, rhizosphere soil, and lettuce roots and shoots under soil-surface irrigation. Root concentration factors based on the antibiotic concentrations in bulk soil (RCFbs) were significantly higher than those based on antibiotic concentrations in rhizosphere soil (RCFrs) for ciprofloxacin, lincomycin, oxytetracycline, sulfamethoxazole, and tetracycline, similar for trimethoprim and tylosin, and lower for monensin. The third study investigated bacterial community assembly and ARG profiles in lettuce shoots, roots, rhizosphere soil, and bulk soil upon exposure to antibiotics. Bacterial communities were driven by stochastic processes upon exposure to low level antibiotics, and were more resilient in roots and rhizosphere soil than in bulk soil and shoots. The fourth study explored the importance of demographics, food-relevant habits, and foodborne disease perception to consumers' buy and pay preferences to labeled products by using conventional statistical and novel machine learning methods to analyze survey data. Consumers' willingness to buy or to pay more for certain labeled food products is dependent on certain demographic traits (e.g., urban living) and food-relevant habits (e.g., cooking fresh produce). Machine learning methods achieved sufficient prediction accuracy scores for estimating consumers' willingness to buy or to pay for labeled products, and thus could be useful tools for evaluating survey data and facilitating the development of strategies promoting healthy food production and consumption.
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Title: Defining and evaluating the spatio-temporal dimensionality of carnivore ecology
Creator: Moll, Remington J.
Date: 2018
Collection: Electronic Theses & Dissertations
Description: In this dissertation I defined and evaluated the spatio-temporal dimensionality of carnivore ecology via philosophical analysis, literature synthesis, and empirical study. In Chapter 1, I analyzed philosophical and empirical arguments that postulate model section techniques like AIC empirically justify a value for simplicity in statistical modeling of ecological phenomena. My analysis drew upon an extensive case study regarding the reintroduction of wolves into Yellowstone National Park, USA....
Show moreIn this dissertation I defined and evaluated the spatio-temporal dimensionality of carnivore ecology via philosophical analysis, literature synthesis, and empirical study. In Chapter 1, I analyzed philosophical and empirical arguments that postulate model section techniques like AIC empirically justify a value for simplicity in statistical modeling of ecological phenomena. My analysis drew upon an extensive case study regarding the reintroduction of wolves into Yellowstone National Park, USA. I showed that assumptions of stationarity required for the epistemic justification of simplicity are generally violated when considering complex ecological phenomena. I concluded that simplicity plays a greater epistemic role in explaining past events than it does in predicting future ones, thereby tempering the value traditionally lauded upon simplicity in ecological study.In Chapter 2, I evaluated the niche width of a mesocarnivore species commonly assumed to be a forest specialist (the pine marten Martes martes). I used a large-scale spatial occupancy model to show that although pine martens were positively associated with forested habitat, they occurred across a remarkable variety of habitats and exhibited no negative association with non-forested areas. I concluded that evaluations of species’ niche width should be informed by large -scale studies rather than local assessments. In Chapter 3, I examined the effects of large carnivores on the grouping behavior of African ungulates. I modeled spatial predation risk from two carnivore species in three ways: 1) as a function of habitat, 2) as a function of carnivore occurrence, and 3) as a function of where carnivores tended to kill prey. I found that prey behavioral response to risk varied across these three expressions in complex ways, highlighting the need for a multi-expressional approach to assessing risk effects in multi-species systems.In Chapter 4, I coupled a conceptual framework with a formal literature review to synthesize the ways that predation risk was measured and modeled in carnivore-ungulate systems. I found striking variability in methodological approach to measuring and modeling risk. I synthesized our findings into a cohesive framework based upon predator-prey theory and centered around long-term risk, short-term risk, and habitat characteristics. I concluded with a call for risk-related studies to employ a multi-dimensional approach and to evaluate multiple, competing hypotheses. In Chapter 5, I applied the recommendations generated in Chapter 4 in a study of human-carnivore interactions in an expansive semi-urban park system. I employed a multi-dimensional spatio-temporal framework that revealed how humans and carnivores share the city by avoiding one another in space and time.I conclude the dissertation with a summary of lessons learned and a look ahead to future research. Future studies that critically evaluate ecological phenomena across multiple spatio-temporal dimensions via a variety of variable expressions will be most efficient in separating out ecological signals from noise and locating the characteristic scales upon which such phenomena occur. Such research will bring clarity not only to ecological theory, but will facilitate more efficient conservation and management strategies by providing clear linkages between ecological processes and the scales at which they can be manipulated or influenced.
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Title: Physiological mediation of social behavior in group-living carnivores
Creator: Montgomery, Tracy M.
Date: 2020
Collection: Electronic Theses & Dissertations
Description: Social behavior and relationships between conspecifics have led to the characteristic of obligate group living in some species. Benefits of these longer-term social groupings include assistance with predator defense, foraging, and infant care, which often outweigh the associated individual costs of group-living, such as increased competition for mates, food and other scarce resources. Social interactions between peers in such social groups include affiliative, aggressive, communicative, and...
Show moreSocial behavior and relationships between conspecifics have led to the characteristic of obligate group living in some species. Benefits of these longer-term social groupings include assistance with predator defense, foraging, and infant care, which often outweigh the associated individual costs of group-living, such as increased competition for mates, food and other scarce resources. Social interactions between peers in such social groups include affiliative, aggressive, communicative, and/or cooperative behaviors. These behaviors are the result of both environmental factors and the individual's genetic, epigenetic, endocrine and neural mechanisms that affect fitness and that evolve through natural selection. My dissertation investigates the physiological mediation of these social behaviors and their relationship to the costs and benefits of group living in social carnivores. Chapter One reviews the endocrine mechanisms that mediate cooperative breeding in mammalian carnivores, focusing on reproductive suppression and alloparental care. My review indicates that breeding carnivores typically have higher levels of a suite of reproductive hormones than do non-breeders, while the effect of glucocorticoids on reproductive suppression appears to be sex specific. In my remaining chapters, I use the spotted hyena (Crocuta crocuta), a gregarious carnivore living in complex social groups, as my model organism in my study of the physiological mediation of complex social interactions. Chapter Two presents and validates a novel non-invasive method of collecting saliva from juvenile spotted hyenas that allows for detection of short-term fluctuations in glucocorticoid concentrations. I examine how social behaviors, such as aggression and play, affect glucocorticoid concentrations, and find that receiving aggression increases glucocorticoid levels while emitting aggression reduces them. Chapter Three investigates the social and physiological mechanisms that lead to hyenas' cooperative mobbing behavior, through exploration of when mobs occur, which hyenas participate, and what potential benefits might accrue. My findings indicate that individuals participate in this type of collective behavior primarily to obtain benefits for themselves, and that their decision to participate is a function of the characteristics and internal state of potential cooperators as well as their immediate social environment.
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Title: Ecodevelopment in Prespa National Park, Greece
Creator: Pyrovetsi, Myrto Domna
Date: 1984
Collection: Electronic Theses & Dissertations

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