Browsing by Subject "Ecology"
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Item 8(2011) Rapoport, BernardItem Art and ecology : an exploration of the nature of art through my own(2021-09-27) Menendez-Pidal, Miguel Alejandro; Tejera, Januibe, 1979-I pose the argument that all artistic mediums have the same underlying storyline but with varying details. My purpose in writing this paper is to explore this curious phenomenon I felt working in the state park: When I decided to stop composing almost entirely for a duration of nine months and fill that void with recording, filming, and producing a “wildlife documentary”, I didn’t stop composing. It was curious to see how many of my colleagues innocently questioned the nature of my work, while I felt that constructing the project was really no different than writing a fugue, a contemporary piece, or any other classification of music. The harmless questioning, I should add, was integral for me to look within myself and question the nature of art so rigorously. This paper essentially answers why I, through my own experience and perception of things, was able to switch between two “genres” of art -- music composition and film production. There are components of this paper that meander from the project to allow preception of art to be broad, and open to discussion. I stress that the principles, conceptions, and opinions presented speak best to my own processes of synthesis.Item Balance between humanity and ecology(2009) Spears, Steven Joseph, 1974-; Catterall, KateIncorporating aspects of public and environmental art practices into my professional endeavors as a landscape architect and urban designer has provided me with opportunities to work at a human scale, consider human needs, and focus on environmental issues that are closely interwoven with those needs. The public and environmental art process has presented greater opportunities to balance the sublime with the pragmatic and allows for a more overt communication between designer and audience, viewer or user. Functioning in this interstitial space allows me to communicate ideas clearly and to initiate a broader discussion on how society might find a balance between the stewardship of the natural environment in the face of the exponential growth of communities and the desire to own and develop land. My aim is to strike a balance between economic development and environmental imperatives through work bridging the practice of landscape architecture and public art. My objective is to use art and design work in the environment to persuade people to utilize all of their senses and to realize the undiscovered in their own journey, to stop and notice the world around them, and to act to protect the delicate balance between contemporary civilization and precious ecosystems. Using a method to register and then to make overt ephemeral elements in the environment, I aim to both demonstrate the ever-changing quality of nature and, more importantly, abuses of the natural environment in our society. Although my interest in the natural environment is multifaceted, water quantity and quality is a focus for my work. It is fast becoming a global issue with dire environmental and social ramifications. In the southwest United States and Australia, water is scarce. In the northwest United States and Finland, water quality remains an issue. In parts of Africa and Asia, water is being privatized and villages are left without a source of life and livelihood that has been a constant for generations. The more poetic aspect of my work focuses on natural time and revealing the abstract beauty of the environment. Shadows, sun, water and wind are all environmental systems that we can learn from and are revealed to us through natural time. It is through natural time that we may learn, respect and come into balance with the environment. In order for my work to succeed on all levels and reach the broadest possible audience, it needs to exist in the public realm. In order for it to communicate effectively it needs to be both, persuasive and poetic; while revealing possibilities for harmony between humanity and ecology. This can be achieved by communicating natures’ equilibrium surrounding environmental issues in the face of human civilization and time.Item Behavioral and molecular mechanisms of pheromone transmission in the honey bee (Apis mellifera)(2017-08) Ma, Rong, Ph. D.; Mueller, Ulrich G.; Hofmann, Johann; Gilbert, Lawrence E; Jha, Shalene; Grozinger, Christina MThe European honey bee (Apis mellifera) has a sophisticated system of pheromonal signals that mediate a wide range of behaviors important for their fitness, including reproductive dominance, nest defense, and cooperative brood care. In honey bees, there are two distinct pheromones emitted by larvae, brood pheromone and (E)-beta-ocimene. By integrating behavior, chemical ecology, and transcriptomics, this dissertation analyzes several key stages in signal transmission in a systematic effort to understand how these two pheromones affect behavior, and in the process, generates a synthetic understanding of a highly complex system of communication. Previous studies have explored behavioral and gene expression patterns related to honey bee pheromones; however, none have compared the roles that two divergent pheromones from a common source play in rapid regulation of foraging behavior. Furthermore, while previous studies have investigated the mechanisms of pheromone detection and the factors involved in regulation of foraging behavior, it remains unclear how individual responses to pheromone exposure scales to colony-level changes in behavior. By investigating the behavioral, physiological, and genomic influences of honey bee chemical communication, this dissertation links phenotypic plasticity in behavior to gene expression profiles in the brain and provides insights into the evolution of a sophisticated chemical language.Item Bioassessment of sediment quality near storm water outfalls and other sites of concern in Corpus Christi Bay, Texas(1999) Burgess, Robert Stockton, 1965-; Montagna, Paul A.The goal of this project was to determine if the ecological integrity of meiofaunal communities was being affected by storm water outfall sediment chemistry, hydrographic parameters, or physical disturbance. Fifteen of 36 study sites were near storm water outfalls. The other 21 sites were reference or highly polluted sites to contrast the outfall sites with background levels and known chemically stressed sites. Because Corpus Christi Bay is a shallow open bay system, physical disturbance due to sediment re-suspension was also estimated. Contamination from non-point sources at storm water sites produced the highest concentrations of both trace metals and cyclic organic pollutants found in this study. Trace metal contaminants were tightly bound to the sediments, and their effects on the biotic communities can only be distinguished from background at one outfall site. Cyclic organic pollutants concentrations were elevated at 66% of the outfall sites, and effects on biotic communities can be distinguished from background at 88% of these sites. The four most contaminated storm water sites exhibited extreme reductions in measures of both macrofaunal and meiofaunal community integrity. Re-suspension was a confounding factor with organic pollutants at five relatively clean outfall sites, where it eliminated the harpacticoid copepod community, and negatively affected the macrofaunal community. In general, of the 36 sites, the 4 most degraded sites were storm water outfallsItem Community assembly, stability and food web structure(2009-05) Pawar, Samraat Shashikant, 1975-; Sarkar, SahotraNatural communities of species embody complex interrelationships between the structure of the interspecific interaction network, dynamics of species' populations, and the stability of the system as a whole. Studying these interrelationships is crucial for understanding the survival of species in nature. In this context, studying the food web (the network of who-eats-whom) embedded in each interaction network is particularly important because trophic interactions are the main channels of energy flow in all ecosystems. Using a combination of mathematical modeling and empirical data analyses, this study explores the interrelationship between food web structure and multi-species coexistence in local communities. Chapter 1 of this thesis places the overall dissertation study in context of the history of research on species interaction networks and food webs. In Chapter 2, I use a population dynamical model to show how the requirements of stable multi-species coexistence results in the emergence of specific, nonrandom configurations of food web structure during community assembly. These structural "signatures" can be used to empirically gauge the importance of interaction-driven dynamical stability constraints in natural communities. In Chapter 3, I extend the model analyzed in Chapter 2 by imposing biologically feasible constraints on its parameters. This is made possible by the allometric scaling between individual metabolism and body size, and the constraints on interspecific trophic interactions due to body size differences between pairs of interacting species. I show that, using this approach, it is possible to interlink three aspects of local communities that have typically been studied in isolation: the species' body mass distribution, the distribution of ratios of body sizes of consumer and resource species (e.g., predator and prey), and certain food web structural features. Some of these features have previously lacked explanatory models. Finally in Chapter 4, using empirical data from nine communities across a range of habitats, I test some theoretical predictions of the previous chapter. The results provide strong evidence that the food web structure of natural communities do indeed exhibit signatures of dynamical stability constraints, and that the model developed in Chapters 2 and 3 is successfully able to predict a number of empirically observed food web structural features.Item Ecological mechanisms underlying soil microbial responses to climate change(2013-12) Waring, Bonnie Grace; Hawkes, Christine V.Soil microbes influence the global carbon cycle via their role in the decomposition and formation of soil organic matter. Thus, rates of ecosystem processes such as primary production, soil respiration, and pedogenesis are sensitive to changes in the aggregate functional traits of the entire microbial community. To predict the magnitude and direction of microbial feedbacks on climate change, it is necessary to identify the physiological, ecological, and evolutionary mechanisms that underlie microbes’ responses to altered temperature and rainfall. Therefore, I examined microbial community composition and function in relation to manipulations of resource availability and precipitation in two contrasting ecosystems: a tropical rainforest at La Selva Biological Station, Costa Rica, and a semi-arid grassland in central Texas. I conducted a leaf litter decomposition experiment at La Selva to identify the physiological constraints on microbial allocation to extracellular enzymes, which degrade organic matter. I found strong evidence that microbial enzyme production is decoupled from foliar stoichiometry, consistent with weak links between leaf litter nutrients and decomposition rates at the pan-tropical scale. Next, to examine whether ecological trade-offs within microbial communities may drive shifts in carbon cycling at local spatial scales, I quantified changes in soil fungal and bacterial community composition in response to an in situ precipitation exclusion experiment I established at La Selva. Although drought-induced shifts in community structure were small, large increases in biomass-specific respiration rates were observed under dry conditions. These findings suggest that physiological adjustments to drought may constitute an important feedback on climate change in wet tropical forests. Finally, I focused on microbial community responses to climate change within a meta-community framework, using a reciprocal transplant experiment to investigate how dispersal shapes bacterial community structure along a natural rainfall gradient in central Texas. I found that soils from the wet end of the precipitation gradient exhibited more plastic functional responses to altered water availability. However, soil bacterial community composition was resistant to changes in rainfall and dispersal, preventing functional acclimatization to precipitation regime. Together, the results of these experiments emphasize the potential for physiological plasticity or microevolutionary shifts within microbial populations to drive ecosystem carbon cycling under climate change.Item Ecological parameters concerning the zooplankton community of the San Antonio estuarine system(1967) Cooper, David C. (David Clayton), 1943-; Copeland, B. J., 1936-Item Ecological relationships between invasive grasses, native grasses, and wildfire(2022-08-11) Whiting, Carolyn; Fowler, Norma L.; Jha, Shalene; Farrior, Caroline E.; Crews, Kelley A.Grasslands and savannas are ecosystems that require frequent wildfires, or modern vegetation clearing methods, to maintain a low density of trees and shrubs. Invasive grasses have become more common in such ecosystems, and although invasive grasses are known to have harmful ecological effects, the direct and indirect relationships between invasive grasses, native grasses, and wildfires in such ecosystems are poorly understood. We studied the effects of wildfire on invasive and native grasses and the effects of invasive grasses on wildfire characteristics in the southern Great Plains. We also studied the immediate impacts of a wildfire on a population of an endangered grass species in a sky island in west Texas. We found that invasive grasses are one of the most important factors in determining fuel loads and fire temperatures in degraded grasslands and savannas of the southern Great Plains (Chapter 2). However, the changes to the wildfires caused by invasive grasses did not cause negative effects on native species that were growing in a grassland dominated by the invasive grass Bothriochloa ischaemum (King Ranch bluestem, yellow bluestem); native herbaceous plants, especially native perennial grasses, increased where B. ischaemum experienced high mortality in summer and fall prescribed fires (Chapter 1). Lastly, the population size of the rare grass Festuca ligulata was substantially smaller immediately post-fire than it was two years before, but fire severity did not appear to cause the decline. These studies can inform land management decisions. Summer or fall prescribed fires in B. ischaemum-dominated ecosystems can cause high mortality of the invasive grass. Seeding native plants after summer or fall prescribed fires may not be necessary if native herbaceous species are present, even if they are not abundant, because native species are not negatively affected by the high fire temperatures caused by B. ischaemum. Finally, the effects of fire severity on the rare grass F. ligulata may not be detectable immediately after a fire, especially because, like with all rare species, relationships are harder to detect with small population sizes. Continued monitoring will be necessary to determine if the population will rebound.Item Evolution of microbial populations with spatial and environmental structure(2010-05) Miller, Eric Louis; Meyers, Lauren Ancel; Bennett, Philip C.; Bull, James J.; Hawkes, Christine V.; Hillis, David M.Rarely are natural conditions constant, but generally biologists study microbes in artificially constant environments in the laboratory. I relaxed these assumptions of constant environments through time and space as I investigated how microbial populations evolve. First, I examined how bacteriophage evolved in the presence of permissive and nonpermissive hosts. I found that bacteriophage evolved discrimina- tion in mixed environments as well as in one of two environments with homogeneous, permissive hosts. This showed the asymmetry of host-shifting in viruses as well as the possibility of large, and somewhat unpredictable, pleiotropic effects. Secondly, I reconstructed ancestral environmental conditions for soil bacteria groups using phy- logenetics and environmental variables of extant species’ habitats. These generaliza- tions suggested characteristic phenotypes for several phylogenetic groups, including uncultured Acidobacteria. Lastly, I collected genetic sequences and global collection information for 65 bacteria genera across the domain. In examining the relation- ship between genetic distance, environmental conditions, and geography, I observed positive relationships specifically between genetic distance and geography or genetic distance and environmental conditions for bacteria from land sites but not from wa- ter sites. Phylogenic classifications or phenotypes of the genera could not predict these correlations. In all of these projects, variations in the environment created evolutionary signals that hinted at past environments of microbial populations.Item The Exergy Flows of Siena: Lorenzettl' s Allegories as Ecosystems(2021-12-10) Wilkinson, Rhys WynnItem Hello Neighbor : cultivating relationships with your bioregion through neighborhood plants(2022-05-07) Graham, Kristen Janaye; Gorman, CarmaMost people notice and care about plants only when they are at their showiest and most colorful: covered in spring blossoms, in full fruit in late summer, or aglow with fall colors. The rest of the time—especially in the wintertime—plants fade into the background for most people. Western scientists Elizabeth Schussler and James Wandersee coined a term for this phenomenon: plant blindness (Allen 2003, 926). It refers to the fact that humans tend to not notice plants that are not actively serving human interests. This blindness has created an obsession with constant perfection and production from plants ranging from manicured, green lawns to having certain produce like berries available year-round. My thesis builds on the work of Dr. Robin Kimmerer and other Indigenous scientists, who argue for the importance of seeing plants in ways that are not agricultural or exploitative, but symbiotic, even neighborly. Community, in my mind, goes beyond a single species and includes all the species that live in an area: a community is an ecosystem that includes every level of life from humans, to birds, to snails, to plants that grow between the cracks in the concrete, and even to the insects and fungi that break down organic matter. The book I wrote, designed, and bound for my thesis project, Hello Neighbor: cultivating relationships with your bioregion through neighborhood plants, shows plants during a stage of their life cycle that is usually ignored and overlooked in field guides and books about botanical illustration. It emphasizes the ecological benefits of leaving dormant plants in place, and suggests what less exploitative and more “neighborly” and symbiotic relationships with plants might look like.Item Itsuko Hasegawa Guest Lecture(1991-04-08) Hasegawa, ItsukoAudio files are EID restricted. Individuals without an EID should send an email request to apl-aaa@lib.utexas.edu.Item Links to Pianka Web Pages(2017) Pianka, Eric R.Item Medium of modulation: the contradictory configurations of power in video games(2016-05) Fong, Byron Tuck; Scott, Suzanne, 1979-; Mallapragada, MadhaviVideo games have formal structural properties that create tensions between simplicity and complexity, transparency and obfuscation, systems of power and individual empowerment. This thesis investigates these tensions in two directions of inquiry: 1) video games as software and 2) video games as assemblages within media ecologies. One dives into video games’ code. The other challenges video games’ boundaries to understand how they intertwine with other media systems. These two perspectives complement each other to expose the contradictions of power within video games as a medium. Drawing on Wendy Chun and Alexander Galloway, this thesis uses software studies to investigate how the properties of software condition video games’ ludological structures. A theoretical approach to video games’ existence as software exposes that they are not media objects with clearly defined, static boundaries. Instead, a video game is an assemblage of many component parts and interacting systems. Using Gilles Deleuze and Felix Guattari’s understanding of assemblages, I argue that video games are constituted not only of the software contained within the game’s executable code; they are always-already interacting with other media systems, which in turn become component parts of the game. Matthew Fuller’s theorization of media ecologies provides a framework for conceptualizing video games as software-based assemblages within intersecting media ecologies. Player-encoders, a term I develop in the thesis, are a site where both perspectives visibly intersect. Player-encoders are players who create paratextual media to complement existing video games. They decode games’ structures, and then re-encode this knowledge into paratexts that other players can utilize. By encoding new media objects through the process of decoding existing games, player-encoders expose the tensions between powerful systems and individual empowerment. Video games as software, as assemblages in ecologies, and as affected by player-encoded paratexts, reveals them to be unstable media objects modulating within contradictory configurations of power.Item The origins, maintenance, and conservation of biodiversity in spatial networks(2009-08) Economo, Evan Philip; Keitt, Timothy H.Biodiversity is distributed unevenly across geographic space and the tree of life. A key task of biology is to understand the ecological and evolutionary processes that generate these patterns. I investigate how the structure and geometry of a landscape, for example the sizes and arrangements of islands in an archipelago, affects processes contributing to the generation and conservation of biodiversity patterns. In the first chapter, I integrate two disparate bodies of theory, ecological neutral theory and network theory into a powerful new framework for investigating patterns of biodiversity in a complex landscape. I examine the consequences of network structure, such as size, topology, and connectivity, for diversity patterning across the metacommunity. The second chapter focuses on how the position of a node within a network controls local community (node) diversity. Network statistics, such as node centrality, are found to predict diversity patterns with more central nodes accumulating the most diversity. In the third chapter, I use the theory to evaluate how well fundamental concepts in conservation biology perform when neutral metacommunity processes generate diversity patterns. I find that contemporary diversity patterns are poor predictors of the long-term capacity of a network to support diversity, challenging a host of conservation concepts and applications. In the fourth chapter, I consider biodiversity dynamics in a network with a different model of speciation, where spatial structure is needed for divergence. In this case, speciation hotspots form where the dispersal properties of an organism and the spatial structure of the landscape coincide. In the final chapter I study the biodiversity of a natural structured metacommunity, the ants of the Fijian archipelago. I used a variety of collecting techniques to inventory the ant species occurring across a system of islands in the southwest Pacific. Approximately 50 new species were discovered, and the distributions of the ant species across the islands are firmly established. Radiations are observed in the genera Pheidole, Camponotus, Lordomyrma, Leptogenys, Cerapachys, Strumigenys, Poecilomyrma, and Hypoponera.Item Parques do Pleistoceno: recriando o cerrado e o pantanal com a megafauna(2005) Galetti, M. (Mauro)Nos últimos anos diversos pesquisadores tem sugerido a introdução de grandes predadores e herbívoros para a reconstrução de ecossistemas naturais. A introdução de lobos, ursos, pumas e até mesmo espécies exóticas como elefantes e camelos têm sido sugerida pelos pequisadores para reestabelecer processos ecológicos de diversos ecossistemas norte-americanos, de florestas a desertos (Martin and Burney 2000). Mesmo os bem equipados parques nacionais norte-americanos falharam em proteger toda a diversidade de grandes mamíferos como ursos, coiotes e lobos (Newmark 1987). Esses predadores de topo de cadeia alimentar são considerados “chaves” para a manutenção de todo o ecossistema, pois regulam as populações de herbívoros. Sem esses predadores, há uma aumento desproporcional nas populações de herbívoros e mesopredadores (como raposas, mão-peladas e esquilos), que sobrecarregam as populações de plantas e pequenos animais que são seus alimentos (Terborgh 1992, Crooks & Soulé 1999).Item Sex and social hierarchies affect populations across landscapes(2016-05) Shaw, Roger William; Leibold, Mathew A.; Bolnick, Daniel; Jha, Shalene; Keitt, Timothy; Rudolf, VolkerEcologists have long been interested in the factors that drive the species composition of ecological communities. I propose that variation within species, particularly in dispersal behavior, plays an underappreciated role, as it affects population distributions across landscapes. To study this in the field, I censused dragonflies in a north Texas metacommunity, differentiating between adult males, adult females, and larvae. I found that while adult males were not well-explained by any environmental or spatial variables, adult females and larvae were significantly explained by their environment. Therefore, considering variation within species (in this case, sex and life stage) can clarify our understanding of species distributions. This is one example of sex-biased dispersal, which is universal amongst animals. However, research has mostly been focused on its potential benefits, while its costs remain largely unexplored. I developed an individual-based simulation model, to see how populations with varying degrees of sex-biased dispersal were able to persist in the face of frequent disturbances. I found that increasing sex-biased dispersal made it difficult for individuals to find mating partners in suitable habitat, and so these populations did not persist very long, in comparison to populations with equal dispersal. These heavy costs may be alleviated by habitat selection or alternative mating systems, however these costs should remain in the discussion of understanding sex-biased dispersal. Even within males, there may be significant variation in social status and physical condition, which can then affect dispersal strategies; these differences could then produce unique signatures in the distributions of populations. I developed another individual-based simulation model, in which individuals were sensitive to crowds, to environment, to both, or to neither. In comparison to passive dispersal, I found that crowd-sensitive populations were disproportionately abundant in medium-quality patches. In contrast, environment- sensitive populations were scarce in these patches. This approach requires fine-scale environmental data, but may be easier to acquire than the fine-scale demographic data that would otherwise be required. Overall, considering variation between individuals, particularly in their dispersal behavior, can improve our understanding of species distributions.Item The effects of ecology and climate change on the conservation of eastern Himalayan avifauna(2018-06-21) Surya, Gautam Sankar; Keitt, Timothy H.; Jha, Shalene; Miller, Jennifer; Liebold, Mathew; Hillis, DavidThe existence of biodiversity is central to all biological sciences, and especially ecology. Without it, an entire branch of knowledge would cease to exist. Despite this centrality, there is considerable debate on the mechanisms that create and maintain diversity. This is especially true of high-diversity areas. There is also considerable debate on how we can best protect biodiversity, in order to allow the science of biology to flourish into the future. Here, I present an investigation of the processes that allow biodiversity to be maintained in the Eastern Himalayas, a critically understudied high-diversity region, as well as a systematic analysis of the conservation priorities there. I focus on birds as a charismatic, speciose and conspicuous set of taxa. I spent several months gathering fine-scale occurrence data for the breeding bird community in Arunachal Pradesh, a state in Northeast India that is at the heart of the Eastern Himalayan ecoregion. Using this data, I first show that bird species on the steep elevational gradient present in the region segregate into narrow elevational bands. I also show that this segregation can best be explained by evolutionary processes resulting from interspecies competition in the long term, and by continued interspecies competition in the short term. I then go on to demonstrate that these narrow ranges of climate tolerance will be greatly affected by climate change, with species’ ranges shifting and contracting over the next 50 years. Moreover, when interspecies competition is taken to account, these extent of these predicted changes is intensified. Finally, I use these predicted distributions to create a spatially explicit map of conservation priorities. I present alternatives based on different conservation goals, as well as different projections of the extent of global climate change. I also present an idealized map of areas most in need of protection, and compare that to the existing set of formally protected areas. Taken in their entirety, these studies present a cogent explanation for the existence of high biodiversity in one of the most special regions of the planet, as well as a roadmap toward protecting that diversity for future generations.Item The natural order : ecologies of social class in medieval British literature(2023-02-28) Heide, Melissa Louise; Heng, Geraldine; Birkholz, Daniel, 1967-; Houser, Heather; Robertson, KellieThe Natural Order offers a new framework for the study of economics and ecology in medieval British literature. This study uncovers the mechanisms whereby discourses of social class are expressed through ecopoetics. I argue that new philosophical approaches to the natural world that emerged during the twelfth century “renaissance” come to underwrite the vocabularies and iconographies of social class in creative works of the centuries following the twelfth. Instead of examining this phenomenon exclusively in the well-worn texts of “canonical” late-medieval authors, I consider a range of texts from the patristic and Scholastic commentary traditions to late-medieval British border narratives in order to demonstrate the many ways in which medieval class is understood, explored, and mediated through ecological thought. I argue that in times of increased socioeconomic instability—especially the fourteenth century—medieval works emerged that braided together economic and environmental systems of meaning. The Natural Order traces how nonhuman agencies—animals, wildernesses, and forests—were deeply enmeshed in the daily lives of medieval people and the imaginations of medieval creators.