Matching Items (6)
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- All Subjects: Urbanization
- Creators: McGraw, Kevin
- Creators: Aggarwal, Rimjhim
Description
Human-induced rapid environmental change (HIREC) influences nearly all of Earth's ecosystems through processes such as urbanization. Previous studies have found that urbanization influences biodiversity patterns, often yielding an increase in the abundance of a few urban-adapted taxa at the expense of native species diversity. The western black widow spider, Latrodectus hesperus, is a medically-important pest species that often forms dense urban subpopulations (i.e., infestations) relative to the low-density subpopulations found throughout undisturbed, desert habitat. Here, I employ field and laboratory studies to examine the population ecology and stoichiometry of this urban pest to increase our understanding of the mechanisms underlying its success. The population ecology of ten black widow subpopulations spread across metropolitan Phoenix, AZ was examined during the peak breeding season (June-August). This study revealed that arthropod prey abundance, female mass and population density of females showed significant spatial variation across the ten subpopulations. Additionally, prey abundance and foraging success, measured as the number of carcasses found in webs, were a strong determinant of female mass and population density within each subpopulation. To test the mechanisms that drive black widow infestations, I used ecological stoichiometry to examine the nutrient (nitrogen and phosphorus) composition of spiders and arthropod prey from urban habitat, desert habitat and a laboratory diet regime. These studies revealed that (1) spiders are more nutrient rich than cricket prey in the field, (2) spider subpopulations exhibit significant spatial variation in their nitrogen composition, (3) nutrient composition of urban spider subpopulations does not differ significantly from Sonoran desert subpopulations, (4) laboratory-reared spiders fed a diet of only laboratory-reared crickets are more nitrogen and phosphorus limited than field-captured spiders, and (5) cannibalism by laboratory-reared spiders alleviated phosphorus limitation, but not nitrogen limitation, when compared to field-captured spiders. This work highlights the need to examine the population ecology of species relationships, such as predator-prey dynamics, to fully understand the fecundity and population growth of urban pest species. Moreover, the integration of population ecology and stoichiometry illustrates the need to address mechanisms like nutrient limitation that may explain why urban pest populations thrive and native species diversity suffers following HIREC.
ContributorsTrubl, Patricia (Author) / Johnson, James C. (Thesis advisor) / Rutowski, Ronald (Thesis advisor) / McGraw, Kevin (Committee member) / Arizona State University (Publisher)
Created2012
Description
Self-maintenance behaviors, like preening in birds, can have important effects on fitness in many animals. Birds produce preen oil, which is a mixture of volatile and non-volatile compounds, that is spread through their feathers during grooming and influences feather integrity, waterproofing, and coloration. As urban areas grow and present conditions that may demand increased feather self-maintenance (e.g. due to soiling, pollution, elevated UV exposure due to natural habitat alterations), it is important to examine how preening and preen oil may be affected by this process. I assessed variation in preen oil composition in house finches (Haemorhous mexicanus) as a function of sex, urbanization, and plumage hue, a sexually selected indicator of male quality. Preen oil samples from birds captured at urban and rural sites were analyzed using gas chromatography-mass spectrometry. We detected 18 major peaks, which we tentatively identified as esters, and found that, although there were no sex or urban-rural differences in preen oil constituents, there was a significant interactive effect of sex and urbanization, with rural females and urban males having higher amounts of some components. This suggests that factors that vary with sex or urbanization, such as the timing of seasonal cycles, are affecting preen oil composition. There were no significant relationships between coloration and preen oil composition, suggesting that preen oil composition does not vary with male quality.
ContributorsBrooks, Ellen Elizabeth (Author) / McGraw, Kevin (Thesis director) / Liebig, Juergen (Committee member) / Weaver, Melinda (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Urbanization exposes wildlife to many unfamiliar environmental conditions, including the presence of novel structures and food sources. Adapting to or thriving within such anthropogenic modifications may involve cognitive skills, whereby animals come to solve novel problems while navigating, foraging, etc. The increased presence of humans in urban areas is an additional environmental challenge that may potentially impact cognitive performance in wildlife. To date, there has been little experimental investigation into how human disturbance affects problem solving in animals from urban and rural areas. Urban animals may show superior cognitive performance in the face of human disturbance, due to familiarity with benign human presence, or rural animals may show greater cognitive performance in response to the heightened stress of unfamiliar human presence. Here, I studied the relationship between human disturbance, urbanization, and the ability to solve a novel foraging problem in wild-caught juvenile house finches (Haemorhous mexicanus). This songbird is a successful urban dweller and native to the deserts of the southwestern United States. In captivity, finches captured from both urban and rural populations were presented with a novel foraging task (sliding a lid covering their typical food dish) and then exposed to regular periods of high or low human disturbance over several weeks before they were again presented with the task. I found that rural birds exposed to frequent human disturbance showed reduced task performance compared to human-disturbed urban finches. This result is consistent with the hypothesis that acclimation to human presence protects urban birds from reduced cognition, unlike rural birds. Some behaviors related to solving the problem (e.g. pecking at and eying the dish) also differed between urban and rural finches, possibly indicating that urban birds were less neophobic and more exploratory than rural ones. However, these results were unclear. Overall, these findings suggest that urbanization and acclimation to human presence can strongly predict avian response to novelty and cognitive challenges.
ContributorsCook, Meghan Olivia (Author) / McGraw, Kevin (Thesis director) / Bimonte-Nelson, Heather (Committee member) / Weaver, Melinda (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Bioindicators of wildlife health are useful tools for studying the viability of various organisms and populations, and can include a range of phenotypic variables, such as behavior, body size, and physiological parameters, such as circulating hormones and nutrients. Few studies have investigated the utility of total plasma protein as a predictor of environmental or nutritional variation among birds, as well as variation across different seasons and life-history stages. Here I examined relationships between plasma protein and season, urbanization, sex, body condition, molt status, and disease state in house finches (Haemorhous mexicanus). I sampled blood from house finches across three seasons (winter, summer and fall 2021) and measured plasma protein levels using a Bradford assay. I also collected data including condition, sex, and poxvirus infection state at capture, as well as fecal samples to assess gut parasitism (coccidiosis). During the fall season I also estimated molt status, as number of actively growing feathers. I found circulating plasma protein concentration to be lower in the fall during molt than during winter or summer. I also found a significant relationship between circulating protein levels and capture site, as well as novel links to molt state and pox presence, with urban birds, those infected with pox, and those in more intense molt having higher protein levels. My results support the hypotheses that plasma protein concentration can be indicative of a bird’s body molt (which demands considerable protein for feather synthesis) and degree of habitat urbanization, although future work is needed to determine why protein levels were higher in virus-infected birds.
ContributorsDrake, Dean (Author) / McGraw, Kevin (Thesis director) / Sweazea, Karen (Committee member) / Jackson, Daniel (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2022-05
Description
Diarrheal diseases caused by poor water, sanitation and hygiene continue to kill more children in Sub-Saharan Africa's burgeoning informal urban settlements than in any other part of the world. In recent years, Delegated Management Model (DMM), a partnership in which a utility delegates service management to slum residents have been promoted as new models to improve services.
This dissertation examines the benefits of DMM by comparing water services in three informal settlements in Kisumu city, Kenya: two slums where DMM has been implemented, and one, a control, where it has not. In addition, the research examined how school-based hygiene interventions could be designed to improve safe water and hygiene knowledge in urban informal settlements. This study compared outcomes of two approaches to hygiene education, one which combined messages with participatory water testing; the second used hygiene messages alone.
Results of the DMM study showed that DMM implementation had lowered water cost and improved provider accountability. However, unhygienic water collection and handling practices on the part of the service users could contaminate drinking water that was clean at the delivery point, thus preventing the intended health outcomes of DMM from being realized. Results of the hygiene education intervention showed that one week after the inventions, hygiene knowledge among students who received the intervention that combined hygiene messages with participatory water testing was significantly improved. Evaluation of the intervention 12 months after implementation showed that the hygiene knowledge gained was sustained.
The research findings suggest that: i) regular monitoring of water quality at the kiosks is essential to ensure that the DMM model achieves intended health outcomes, ii) sanitation conditions at kiosk sites need to be regulated to meet minimum hygiene standards, and iii) customers need to be educated on safe water collection and storage practices. Finally, school-based hygiene education could be made more effective by including hands-on water testing by students. Making sustainable impact on health and wellbeing of slum residents requires not only building effective partnerships for water delivery, but also paying close attention to the other points of intervention within the water system.
This dissertation examines the benefits of DMM by comparing water services in three informal settlements in Kisumu city, Kenya: two slums where DMM has been implemented, and one, a control, where it has not. In addition, the research examined how school-based hygiene interventions could be designed to improve safe water and hygiene knowledge in urban informal settlements. This study compared outcomes of two approaches to hygiene education, one which combined messages with participatory water testing; the second used hygiene messages alone.
Results of the DMM study showed that DMM implementation had lowered water cost and improved provider accountability. However, unhygienic water collection and handling practices on the part of the service users could contaminate drinking water that was clean at the delivery point, thus preventing the intended health outcomes of DMM from being realized. Results of the hygiene education intervention showed that one week after the inventions, hygiene knowledge among students who received the intervention that combined hygiene messages with participatory water testing was significantly improved. Evaluation of the intervention 12 months after implementation showed that the hygiene knowledge gained was sustained.
The research findings suggest that: i) regular monitoring of water quality at the kiosks is essential to ensure that the DMM model achieves intended health outcomes, ii) sanitation conditions at kiosk sites need to be regulated to meet minimum hygiene standards, and iii) customers need to be educated on safe water collection and storage practices. Finally, school-based hygiene education could be made more effective by including hands-on water testing by students. Making sustainable impact on health and wellbeing of slum residents requires not only building effective partnerships for water delivery, but also paying close attention to the other points of intervention within the water system.
ContributorsNzengya, Daniel (Author) / Aggarwal, Rimjhim (Thesis advisor) / Hartwell, Leland (Committee member) / Boone, Christopher (Committee member) / Arizona State University (Publisher)
Created2014
Description
The science community has made efforts for over a half century to address sustainable development, which gave birth to sustainability science at the turn of the twenty-first century. Along with the development of sustainability science during the past two decades, a landscape sustainability science (LSS) perspective has been emerging. As interests in LSS continue to grow rapidly, scholars are wondering what LSS is about and how LSS fits into sustainability science, while practitioners are asking how LSS actually contributes to sustainability in the real world. To help address these questions, this dissertation research aims to explore the currently underused problem-driven, diagnostic approach to enhancing landscape sustainability through an empirical example of urbanization-associated farmland loss (UAFL). Based mainly on multimethod analysis of bibliographic information, the dissertation explores conceptual issues such as how sustainability science differs from conventional sustainable development research, and how the past, present, and future research needs of LSS evolve. It also includes two empirical studies diagnosing the issue of urban expansion and the related food security concern in the context of China, and proposes a different problem framing for farmland preservation such that stakeholders can be more effectively mobilized. The most important findings are: (1) Sustainability science is not “old wine in a new bottle,” and in particular, is featured by its complex human-environment systems perspective and value-laden transdisciplinary perspective. (2) LSS has become a vibrant emerging field since 2004-2006 with over three-decade’s intellectual accumulation deeply rooted in landscape ecology, yet LSS has to further embrace the two featured perspectives of sustainability science and to conduct more problem-driven, diagnostic studies of concrete landscape-relevant sustainability concerns. (3) Farmland preservationists’ existing problem framing of UAFL is inappropriate for its invalid causal attribution (i.e., urban expansion is responsible for farmland loss; farmland loss is responsible for decreasing grain production; and decreasing grain production instead of increasing grain demand is responsible for grain self-insufficiency); the real problem with UAFL is social injustice due to collective action dilemma in preserving farmland for regional and global food sufficiency. The present research provides broad implications for landscape scientists, the sustainability research community, and UAFL stakeholders.
ContributorsZhou, Bingbing (Author) / Wu, Jianguo (Thesis advisor) / Aggarwal, Rimjhim (Committee member) / Anderies, John Marty (Committee member) / Janssen, Marcus Alexander (Committee member) / Turner II, Billie Lee (Committee member) / Arizona State University (Publisher)
Created2020