With the introduction of metacommunity theory, the field of community ecology expanded its scope to include patterns and processes beyond the scale of local communities. Dispersal, or the movement of organisms between sites, can play an influential role in generating patterns of community assembly and stability. However, little is known about the role of dispersal in structuring and stabilizing freshwater communities. For my dissertation, I conducted a literature review of dispersal in stream metapopulations and metacommunities. Our current knowledge of the movement of freshwater taxa is limited due to difficulties in accurately monitoring dispersal. We have inferred the role of dispersal based primarily on organismal-based and graph-based proxies, although the body of work in modeling and experimental research is growing. Future research should incorporate innovative methods to directly monitor dispersal at finer spatial and temporal scales. To address this knowledge gap, we experimentally manipulated dispersal mode (aerial and drift) alongside the magnitude of dispersal (network location as a proxy) to investigate the role of these components of dispersal in community assembly and multiple metrics of stability. The results of my experiment suggest both factors may play a role in community assembly and stability patterns in stream metacommunities. Lastly, I conducted a mesocosm experiment with zooplankton mesocosms to investigate if biodiversity can generate asynchronous patterns of community dynamics that contribute to stability. There was a positive biodiversity-asynchrony relationship that, in turn, generated higher levels of stability. This effect was strongest in communities connected via dispersal. Overall, my dissertation demonstrates that dispersal plays a role in the assembly and stability of freshwater communities. / Doctor of Philosophy / Freshwater ecosystems and the abundance and richness of life that they support are threatened under global environmental change. One factor that may help maintain the diversity of stream-dwelling species is dispersal, or the movement of organisms between sites within networks of freshwater communities. The influence of dispersal on the formation and stability of freshwater communities is poorly understood. To determine the state of the science, I conducted a literature review on the study of dispersal in stream networks. We have only recently developed a limited knowledge of the direct movement of freshwater species within networks. The majority of what we know is deduced from patterns of diversity, the traits of organisms, or theoretical modeling. More direct measures of dispersal are needed to understand the dispersal of freshwater organisms. To address this knowledge gap, I conducted an experiment with streamside flumes throughout a stream network where I manipulated how a macroinvertebrate could colonize, or join, a stream community. I found that both position in a network and the use of various methods of colonization affect patterns of diversity and how stable stream communities are. Finally, I conducted an experiment where I manipulated the number of zooplankton and environmental conditions to detect the influence of dispersal on community dynamics and stability. Communities connected via dispersal had the highest level of asynchrony in dynamics and these community dynamics, in turn, produced the greatest amount of community stability. Overall, these findings demonstrate the role of dispersal in the biodiversity and stability of freshwater communities.

Wildlife biodiversity provides a variety of ecosystem services and is an important indicator of overall ecosystem health. This research investigates the relationship between wildlife biodiversity and landscape characteristics in Virginia. The goal is to produce predictive models of biodiversity within the Commonwealth using environmental characteristics, including fragmentation metrics at the class- and landscape-levels, as well as other environmental variables. The 1248 12-digit watersheds in Virginia are the sampling units for the analyses, with the state stratified into the seven US Environmental Protection Agency's Level III classification. Data on wildlife alpha diversity is based on two sets of species data maintained by the Virginia Dept. of Game & Inland Fisheries (VDGIF). The first chapter provides an introduction to the issue of biodiversity conservation and the background information for this work. The second chapter describes the study using the 2001 National Land Cover Data to calculate class- and landscape-level fragmentation metrics. Best subset regression is used to determine the best predictors for wildlife biodiversity using these metrics. Final selected models range in predictive power from R2 = 0.41 to 0.73 for each of the 7 ecoregions. The third chapter analyzes the relationship between wildlife biodiversity and various environmental variables in order to determine the strength of these factors as drivers for alpha diversity. These variables are then incorporated with the fragmentation metrics in an attempt to improve the biodiversity models. The environmental variable models had R2 = 0.22 to 0.65 across the ecoregions, while R2 = 0.28 to 0.72 when the environmental and fragmentation variables are combined. The last chapter focuses on the conclusions of the studies, the limitations of the data, and the benefits of this work. Overall, our results underline the importance of using fragmentation metrics in Virginia's wildlife models. / Master of Science

Privately owned lands provide a number of benefits to humans, including food, clean air and water, and building materials. Private lands are also home to a host of wildlife species and the habitats that they rely upon for survival. As such, balancing human and ecological needs on private lands is of critical importance. Stewardship is a term popularly used to refer to this balanced approach of managing land for a host of benefits. When landowners lack the interest, ability, or willingness to incorporate stewardship into their management strategies, incentives are often provided to spur greater conservation outcomes. This two-part case study is focused on private land stewardship. Using qualitative data analysis, I first examined the behaviors that a sample of production-oriented ranchers defined as stewardship. I then explored the environmental values underlying their behaviors. Utilitarian values dominated the four broad themes that emerged from respondents' operationalization of stewardship, including: maintaining economically productive rangelands, protecting water resources, maintaining an aesthetically pleasing property, and providing for wildlife. Next, I sought to better understand the impact of incentives on durable conservation behaviors. As incentives can reduce intrinsic motivation, I used Self-Determination Theory as a framework for surveying participants in an existing conservation incentive program. The results suggest that landowners maintained their willingness to continue protecting a threatened bird species following the removal of an incentive. Each paper concludes with an analysis of findings within the context of the empirical literature, and present potential practical implications for future conservation efforts. / Master of Science

Thesis advisor: Prasannan Parthasarathi / This thesis is a historical analysis of the various modes of thinking that developed in response to the Endangered Species Act of 1973. What was originally a law that received wide support from the government and the public soon became one of the most controversial environmental laws in the United States. Utilizing congressional hearings, government records, laws, legal cases, newspaper articles, photographs, and public surveys, this study rejects the common conception that economic self-interest was the sole driver of opposition to the Act. It argues, instead, that the reactive and narrow framework of the law fueled criticism. People responded negatively to the law's lack of proactive, long-term thinking and the consequent implications for short-term economic growth. This reactive approach to environmental legislation is a common trend in the United States, continuing to fuel the political partisanship and polarization of environmental movements across the nation. / Thesis (BA) — Boston College, 2024. / Submitted to: Boston College. Morrissey School of Arts and Sciences. / Discipline: History. / Discipline: Scholar of the College.

Since the 1970s, a growing body of research has suggested that bacteria play an active role in precipitation. These bacteria are capable of catalyzing the formation of ice at relatively warm temperatures utilizing a specific protein family which aids in the binding of water molecules. However, the overall biodiversity, concentration, and relationship of ice nucleation active (ice+) bacteria with air mass trajectories and precipitation chemistry is not well studied. Precipitation events were collected over 15 months in Blacksburg, VA and ice+ bacteria were isolated from these samples. From these samples, 33,134 total isolates were screened for ice nucleation activity (INA) at -8 °C. A total of 593 of these isolated positively confirmed for INA at the same temperature in subsequent tests. The precipitation events had a mean concentration of 384±147 colony forming units per liter. While the majority of confirmed ice+ bacteria belonged to the gammaproteobacteria, a well-studied class of bacteria, including ice+ species of Pseudomonas, Pantoea, and Xanthomonas, two isolates were identified as Lysinibacillus, a Gram-positive member of the Firmicute phylum. These two isolates represent the first confirmed non-gammaproteobacteria with INA. After further characterization, the two isolates of Lysinibacillus did not appear to use a protein to freeze water. Instead, the Lysinibacillus isolates used a secreted, nanometer-sized molecule that is heat, lysozyme, and proteinase resistant. In an attempt to identify the mechanism responsible for this activity, species type strains were tested for INA and UV mutants were generated to knock out the ice+ phenotype. Based on these results, only members of the species L. parviboronicapiens exhibit INA and the genes responsible for the activity may lie within a type-1 polyketide synthase/non-ribosomal peptide synthase gene cluster. This gene cluster is absent from the genomes of all non-ice+ strains of Lysinibacillus, and contains mutations in five of the nine ice nucleation inactive mutants generated from the rain isolated strain. To better understand the phylogenetic relationship among ice+ Lysinibacillus, a comprehensive reference guide was compiled to provide the most up-to-date information regarding the genus and each of its species. This reference will be available to other researchers investigating Lysinibacillus species or other closely related genera. / PHD / It is a common misconception that water freezes at 0°C (32°F). In clouds, water may remain liquid until -37 to -40°C (-35 to -40°F). At temperatures warmer than this, water molecules must collect around small particles that can help form ice, called ice nuclei. Numerous ice nuclei have been identified, ranging from dirt and dust, to volcanic ash, and even to pollen, fungi, and bacteria. One of these bacteria, Pseudomonas syringae, was identified as an ice nucleus in the 1970’s when it was discovered that it was increasing susceptibility of corn to frost damage. Since then, other Pseudomonas species as well as other bacteria within the same family of bacteria have been shown to have the ability to freeze water at relatively warm temperatures utilizing a specialized protein. Despite numerous studies on how these bacteria can exist in the atmosphere and how they can freeze water, the extent of this freezing ability, the concentration of bacteria in precipitation, and how cloud chemistry affects these bacteria has not been widely studied. In this study, precipitation was collected over the course of 15 months and the bacteria found within the collected precipitation were checked to see if they could act as ice nuclei. We found many of the previously described bacterial ice nuclei in the precipitation samples, but also identified a previously unidentified bacterium capable of freezing water. This bacterium, Lysinibacillus parviboronicapiens, does not use the same method of freezing as the other described bacterial ice nuclei. As such, we set out to determine the method it uses. We have determined that this bacterium utilizes a heat-stable, nanometer-sized particle that is not a protein. To better understand this molecule, representative strains of each species of this genus of bacteria were tested for their ability to freeze water, however, only this species has the ability. To further identify the molecule, UV radiation was used to disrupt the bacteria’s ability to freeze water, and the genes responsible were identified. Based on these results, we have tentatively identified the responsible genes as part of a polyketide synthase gene cluster. This gene cluster is responsible for producing small molecules that provide some survival advantage for the bacteria, in our case, possibly the ability to freeze water. As a final step, and to help serve other researchers, a comprehensive analysis of the entire Lysinibacillus genus has been performed and a reference guide has been generated to help describe and distinguish individual species.

No description available.

No description available.

Thesis (MSc (Conservation Ecology and Entomology)--Stellenbosch University, 2007. / A systematic conservation assessment is the first phase of a systematic conservation planning protocol; it uses spatial data and representation targets for the setting of priority areas and the assessment of risk to biodiversity. This thesis describes the findings of investigations on the use of data in systematic conservation assessments. Conservation planning can be done at different spatial scales (from global to local). Systematic Conservation planning can be done at different spatial scales (from global to local). Systematic conservation assessments rely on the use of surrogates for biodiversity and often, as well, socioeconomic criteria. Biodiversity surrogates can be classified as taxonomic, community and environmental. In Chapter 2, a literature review was performed (i) to quantify the use of biodiversity surrogates and socio-economic criteria in conservation assessments; and (ii) to test the hypothesis that surrogates are chosen in respect to the hierarchical organisation of biodiversity. In other words, fine scale conservation assessments are correlated with taxonomic surrogates, large scale conservation assessments are correlated with environmental surrogates, and assemblage surrogates are assessed at an intermediary scale. The literature review was based on a structured survey of 100 ISI journal publications. The analysis revealed that spatial scale had a weak effect on the use of biodiversity surrogates in conservation assessments. Taxonomic surrogates were the most used biodiversity surrogates at all scales. Socioeconomic criteria were used in many conservation assessments. I argue that it is crucial that assemblage and environmental data be more used at larger spatial scales. The allocation of conservation resources needs to be optimised because resources are scarce. A conservation assessment can be a lengthy and expensive process, especially when conducted at finescale. Therefore the need to undertake a fine-scale conservation assessment, as opposed to a more rapid and less expensive broader one, should be carefully considered. The study of Chapter 3 assessed the complementarity between regional- and local-scale assessments and the implications on the choice of biodiversity features at both scales. The study was undertaken in Réunion Island. A biodiversity assessment was performed at a regional scale and measured against a finer-scale assessment performed over a smaller planning domain. Two datasets composed of species distributions, habitat patterns and spatial components of ecological and evolutionary processes were compiled as biodiversity surrogates at each scale. Targets for local-scale processes were never met in regional assessments, while threatened species and fragmented habitats were also usually missed. The regional assessment targeting habitats represented a high proportion of local-scale species and habitats at target level (67%). On the contrary, the one targeting species was the least effective. The results highlighted that all three types of surrogates are necessary. They further suggested (i) that a spatial strategy based on a complementary set of coarse filters for regional-scale assessments and fine filters for local-scale ones can be an effective approach to systematic conservation assessments; and (ii) that information on habitat transformation should help identify where efforts should be focused for the fine-scale mapping of fine filters. Together with priority-area setting, the identification of threatened biodiversity features has helped to prioritise conservation resources. In recent years, this type of assessment has been applied more widely at ecosystem-level. Ecosystems can be categorised into critically endangered, endangered and vulnerable, following the terminology of the IUCN Red List of threatened species. Various criteria such as extent and rate of habitat loss, species diversity and habitat fragmentation can be used to identify threatened ecosystems. An approach based only on the criterion of the quantification of habitat loss was investigated in Chapter 4 for the Little Karoo, South Africa. Habitat loss within ecosystem type is quantified on land cover information. The study analysed the sensitivity of the categorisation process to ecosystem and land cover mapping, using different datasets of each. Three ecosystem classifications and three land cover maps, of different spatial resolutions, were used to produce nine assessments. The results of these assessments were inconsistent. The quantification of habitat loss varied across land cover databases due to differences in their mapping accuracy. It was reflected on the identification of threatened ecosystems of all three ecosystem classifications. Less than 14% of extant areas were classified threatened with the coarsest land cover maps, in comparison to 30% with the finest one; and less than 9% of ecosystem types were threatened with the coarsest land cover maps, but between 15 and 23% were threatened with the finest one. Furthermore, the results suggested that the identification of threatened ecosystems is more sensitive to the accuracy of habitat loss quantification than the resolution of the ecosystem classification. Detailed land cover mapping should be prioritised over detailed ecosystem maps for this exercise. This thesis highlighted the importance of ecosystems and processes as biodiversity surrogates in conservation assessments and suggested that results of conservation assessments based on these data, should be more widely presented in published articles. Finally, it also made apparent the important role of mapping habitat transformation for systematic conservation plans.

published_or_final_version / abstract / toc / China Area Studies / Master / Master of Arts

The purpose of the thesis is to describe international, EU and Czech wildlife trade laws by identifying the regulatory measures established at these levels of law and examining them from the perspective of each. It further seeks to analyze how CITES obligations governing these measures are incorporated into the EU and Czech legislation and investigate whether they are likely implemented inadequately or, conversely, more strictly. Additionally, it points out some of the potential problems of the current legal framework as well. The thesis is composed of six chapters. Chapter one explains the goals of environmental policy in the area of nature conservation and biodiversity protection related to wildlife trade and reasons for the very existence of its regulation. Chapter two is concerned with general aspects of wildlife trade law such as its objective, purpose, principles and role within environmental law. Chapter three outlines the main and also some other relevant sources of law. Chapter four determines the principal regulatory measures which are contained within the legal regime in order to enable it to achieve its objectives. The fifth chapter then focuses on two groups of legal means designed to ensure the compliance of CITES parties and to enforce the provisions of EU and Czech wildlife trade legislation...