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- Genre: Doctoral Dissertation
Description
Understanding why animals form social groups is a fundamental aim of sociobiology. To date, the field has been dominated by studies of kin groups, which have emphasized indirect fitness benefits as key drivers of grouping among relatives. Nevertheless, many animal groups are comprised of unrelated individuals. These cases provide unique opportunities to illuminate drivers of social evolution beyond indirect fitness, especially ecological factors. This dissertation combines behavioral, physiological, and ecological approaches to explore the conditions that favor group formation among non-kin, using as a model the facultatively social carpenter bee, Xylocopa sonorina. Using behavioral and genetic techniques, I found that nestmates in this species are often unrelated, and that non-kin groups form following extensive inter-nest migration.Group living may arise as a strategy to mitigate constraints on available breeding space. To test the hypothesis that nest construction is prohibitively costly for carpenter bees, I measured metabolic rates of excavating bees and used imaging techniques to quantify nest volumes. From these measurements, I found that nest construction is highly energetically costly, and that bees who inherit nests through social queuing experience substantial energetic savings. These costs are exacerbated by limitations on the reuse of existing nests. Using repeated CT scans of nesting logs, I examined changes in nest architecture over time and found that repeatedly inherited tunnels become indefensible to intruders, and are subsequently abandoned. Together, these factors underlie intense competition over available breeding space. The imaging analysis of nesting logs additionally revealed strong seasonal effects on social strategy, with social nesting dominating during winter. To test the hypothesis that winter social nesting arises from intrinsic physiological advantages of grouping, I experimentally manipulated social strategy in overwintering bees. I found that social bees conserve heat and body mass better than solitary bees, suggesting fitness benefits to grouping in cold, resource-scarce conditions. Together, these results suggest that grouping in X. sonorina arises from dynamic strategies to maximize direct fitness in response to harsh and/or competitive conditions. These studies provide empirical insights into the ecological conditions that favor non-kin grouping, and emphasize the importance of ecology in shaping sociality at its evolutionary origins.
ContributorsOstwald, Madeleine (Author) / Fewell, Jennifer H (Thesis advisor) / Amdam, Gro (Committee member) / Harrison, Jon (Committee member) / Pratt, Stephen (Committee member) / Kapheim, Karen (Committee member) / Arizona State University (Publisher)
Created2022
Description
Speciation, or the process by which one population diverges into multiple populations that can no longer interbreed with each other, has brought about the incredible diversity of life. Mechanisms underlying this process can be more visible in the early stages of the speciation process. The mechanisms that restrict gene flow in highly mobile species with no absolute barriers to dispersal, especially marine species, are understudied. Similarly, human impacts are reshaping ecosystems globally, and we are only just beginning to understand the implications of these rapid changes on evolutionary processes. In this dissertation, I investigate patterns of speciation and evolution in two avian clades: a genus of widespread tropical seabirds (boobies, genus Sula), and two congeneric passerine species in an urban environment (cardinals, genus Cardinalis). First, I explore the prevalence of gene flow across land barriers within species and between sympatric species in boobies. I found widespread evidence of gene flow over all land barriers and between 3 species pairs. Next, I compared the effects of urbanization on the spatial distributions of two cardinal species, pyrrhuloxia (Cardinalis sinuatus) and northern cardinals (Cardinalis cardinalis), in Tucson, Arizona. I found that urbanization has different effects on the spatial distributions of two closely related species that share a similar environmental niche, and I identified environmental variables that might be driving this difference. Then I tested for effects of urbanization on color and size traits of these two cardinal species. In both of these species, urbanization has altered traits involved in signaling, heat tolerance, foraging, and maneuverability. Finally, I tested for evidence of selection on the urban populations of both cardinal species and found evidence of both parallel selection and introgression between the species, as well as selection on different genes in each species. The functions of the genes that experienced positive selection suggest that light at night, energetics, and air pollution may have acted as strong selective pressures on these species in the past. Overall, my dissertation emphasizes the role of introgression in the speciation process, identifies environmental stressors faced by wildlife in urban environments, and characterizes their evolutionary responses to those stressors.
ContributorsJackson, Daniel Nelson (Author) / McGraw, Kevin J (Thesis advisor) / Amdam, Gro (Committee member) / Sweazea, Karen (Committee member) / Taylor, Scott (Committee member) / Arizona State University (Publisher)
Created2023
Description
A roofing manufacturer wants to differentiate themselves from other roofing manufacturers based on performance information. However, construction industry has revealed poor performance documentation in the last couple of decades. With no current developed performance measurement model in the industry, two roofing manufacturers approached the research group to implement a warranty program that measures the performance information of their systems and applicators. Moreover, the success of any project in the construction industry heavily relies upon the capability of the contractor(s) executing the project. Low-performing contractors are correlated with increased cost and delayed schedules, resulting in end-user dissatisfaction with the final product. Hence, the identification and differentiation of the high performing contractors from their competitors is also crucial. The purpose of this study is to identify and describe a new model for measuring manufacturer performance and differentiating contractor performance and capability for two roofing manufacturers (Manufacturer 1 and Manufacturer 2) in the roofing industry. The research uses multiple years of project data and customer satisfaction data collected for two roofing manufacturers for over 1,000 roofing contractors. The performance and end-user satisfaction was obtained for over 7,000 manufacturers' projects and each contractor associated with that project for cost, schedule, and quality metrics. The measurement process was successfully able to provide a performance measurement for the manufacturer based on the customer satisfaction and able to identify low performing contractors. This study presents the research method, the developed measurement model, and proposes a new performance measurement process that entities in the construction industry can use to measure performance.
ContributorsGajjar, Dhaval (Author) / Kashiwagi, Dean (Thesis advisor) / Sullivan, Kenneth (Thesis advisor) / Kashiwagi, Jacob (Committee member) / Arizona State University (Publisher)
Created2016
Description
Neurotoxicology has historically focused on substances that directly damage nervous tissue. Behavioral assays that test sensory, cognitive, or motor function are used to identify neurotoxins. But, the outcomes of behavioral assays may also be influenced by the physiological status of non-neural organs. Therefore, toxin induced damage to non- neural organs may contribute to behavioral modifications. Heavy metals and metalloids are persistent environmental pollutants and induce neurological deficits in multiple organisms. However, in the honey bee, an important insect pollinator, little is known about the sublethal effects of heavy metal and metalloid toxicity though they are exposed to these toxins chronically in some environments. In this thesis I investigate the sublethal effects of copper, cadmium, lead, and selenium on honey bee behavior and identify potential mechanisms mediating the behavioral modifications. I explore the honey bees’ ability to detect these toxins, their sensory perception of sucrose following toxin exposure, and the effects of toxin ingestion on performance during learning and memory tasks. The effects depend on the specific metal. Honey bees detect and reject copper containing solutions, but readily consume those contaminated with cadmium and lead. And, exposure to lead may alter the sensory perception of sucrose. I also demonstrate that acute selenium exposure impairs learning and long-term memory formation or recall. Localizing selenium accumulation following chronic exposure reveals that damage to non-neural organs and peripheral sensory structures is more likely than direct neurotoxicity. Probable mechanisms include gut microbiome alterations, gut lining
damage, immune system activation, impaired protein function, or aberrant DNA methylation. In the case of DNA methylation, I demonstrate that inhibiting DNA methylation dynamics can impair long-term memory formation, while the nurse-to- forager transition is not altered. These experiments could serve as the bases for and reference groups of studies testing the effects of metal or metalloid toxicity on DNA methylation. Each potential mechanism provides an avenue for investigating how neural function is influenced by the physiological status of non-neural organs. And from an ecological perspective, my results highlight the need for environmental policy to consider sublethal effects in determining safe environmental toxin loads for honey bees and other insect pollinators.
damage, immune system activation, impaired protein function, or aberrant DNA methylation. In the case of DNA methylation, I demonstrate that inhibiting DNA methylation dynamics can impair long-term memory formation, while the nurse-to- forager transition is not altered. These experiments could serve as the bases for and reference groups of studies testing the effects of metal or metalloid toxicity on DNA methylation. Each potential mechanism provides an avenue for investigating how neural function is influenced by the physiological status of non-neural organs. And from an ecological perspective, my results highlight the need for environmental policy to consider sublethal effects in determining safe environmental toxin loads for honey bees and other insect pollinators.
ContributorsBurden, Christina Marie (Author) / Amdam, Gro (Thesis advisor) / Smith, Brian H. (Thesis advisor) / Gallitano-Mendel, Amelia (Committee member) / Harrison, Jon (Committee member) / Vu, Eric (Committee member) / Arizona State University (Publisher)
Created2016
Description
Saudi Arabia has been facing issues with completing construction projects on time and on budget. It has been documented that 70% of public construction projects are delayed. Studies have identified the low-bid delivery method as an important factor in causing such delays. The procurement system (low-bid) ignores contractors’ performance, and that is reflected in projects’ performance. A case study was performed, at a University campus in northern Saudi Arabia, identifying the major causes of project delays and cost overruns. The University was experiencing delays from 50% to 150%. Also, the actual project costs for four projects were examined and found that all four projects’ costs were higher than the original bid. The delay and cost overruns factors were gathered from the University engineers. A literature research identified one construction management method, best value performance information procurement system (BV PIPS), has documented multiple times its ability to improve project performance. In a comparison using the result of a case study and the results of (BV PIPS), Saudi Arabia’s delivery system was identified as a potential cause of project performance issues. The current procurement system was analyzed and modified to adapt with the (BV PIPS). The proposed procurement system using BV PIPS, which can be implemented in Saudi Arabia, was created with owner side. A large survey was conducted of 761 classified contractors and 43 universities’ representatives who rated causes of delay factors and cost overruns. The delay factors were then compared to delay factors experienced on Saudi construction projects, identified by performing a literature research. The comparison identified 14 important causes of delays. Moreover, the survey showed that classified contractors and universities’ representatives unsatisfied with low-bid, and they agreed with BV PIPS which selecting vendors based on performance with price. The proposed model required a submitted level of experience (LE), risk assessment (RA), and value added (VA). Besides, project managers of vendors should be interviewed during the clarification phase. In addition, venders should submit the project’s scope, technical schedule, milestone schedule, and risk management plan. In the execution phase, vendors should submit a weekly risk report (WRR) and director’s report (DR).
ContributorsAlzara, Majed (Author) / Kashiwagi, Dean (Thesis advisor) / Kashiwagi, Jacob (Committee member) / Al-Tassan, Abdulrahman (Committee member) / Arizona State University (Publisher)
Created2016
Description
Recent studies have identified that contractors in the Saudi construction industry are not the main party that cause risks as owners and other parties have the major share of causing risks. However, with the identification that risks out of contractors’ control are a leading cause of low performance, there is a lack of efficient risk mitigation practices in Saudi to manage these risks. The main aim of this dissertation is to assess the current practices applied by contractors to minimize risk out of their control and develop a risk mitigation model to manage these risks. The main objectives of the study are: investigating the risks that are out of contractors’ control, assessing the contractors’ current risk mitigation and performance measurement practices, and finally developing and validating a risk mitigation model to minimize risks out of contractors’ control and measure performance of involved project parties. To achieve the study aim, a mixed methodological approach was adopted. Theoretical approaches were utilized to review previous research and to develop a conceptual risk mitigation framework followed by a practical approach that is considered with collecting data from contractors. The quantitative method was mainly used to meet the study objectives through distributing a survey in the form of a questionnaire. As a consolidation of the study findings, the top ranked risks that are out of contractors’ control were identified. Furthermore, the results identified that the contractors’ current risk management and performance measurement practices are not effective in minimizing projects risks caused by other parties and ineffective in measuring performance of all parties. The developed model focuses on increasing accountability of project parties through mitigating project parties’ activities and risks with measuring the deviations and identifying sources of deviations. Transparency is utilized in the model through sharing weekly updates of the activities and risks combined with updated information of performance measurements of all project parties. The study results showed that project risks can be minimized and projects’ performance can be increased if contractors shift their focus using the developed model from only managing their own activities and risks to managing all project parties’ activities and risks.
ContributorsAlgahtany, Mohammed (Author) / Sullivan, Kenneth (Thesis advisor) / Kashiwagi, Dean (Committee member) / Badger, William (Committee member) / Arizona State University (Publisher)
Created2018
Description
ABSTRACT
The current Saudi Arabian (SA) procurement system leads to many losses in money and benefits in projects. Also, the use of the traditional procurement system in SA has been identified as one of the causes for poor performance in the delivery of construction and the major risk to the SA government. A questionnaire has been developed and carefully designed based on literature review. The purpose of the survey was to identify the validity of the recent claims that the procurement system in SA is broken and to improve the current SA procurement system. The questionnaire was sent out to 1,396 participants including included 867 engineers, 256 consultants, 93 contractors, 35 owners and 132 architects and 13 academics.
All participants have been registered and licensed professionals at the SA Council for professional engineers, who work in both private and public sectors. The participants are interested in the SA procurement and contracts system with experience ranging from one to more than twenty-five years with the majority of twenty-five years of experience in common construction sectors such as; residential and commercial buildings, healthcare buildings, industrial building and heavy civil construction.
Most of the participants from both private and public sectors agreed with the survey questions subject matter regarding: zone price proposals, contractors' evaluation, risks, planning, projects' scope, owners concern and weekly risks reports (WRR). The survey results showed that the procurement system is the major risk to projects, affects construction projects negatively and is in need of improvement.
Based on the survey and literature review, a model, called Saudi government performance procurement model (SGPPM), has been developed in which the most expert contractor is chosen through four phases: submittals& education, vendors selection, illustration and execution. The resulting model is easy to implement by SA government and does not require special skills or backgrounds.
The current Saudi Arabian (SA) procurement system leads to many losses in money and benefits in projects. Also, the use of the traditional procurement system in SA has been identified as one of the causes for poor performance in the delivery of construction and the major risk to the SA government. A questionnaire has been developed and carefully designed based on literature review. The purpose of the survey was to identify the validity of the recent claims that the procurement system in SA is broken and to improve the current SA procurement system. The questionnaire was sent out to 1,396 participants including included 867 engineers, 256 consultants, 93 contractors, 35 owners and 132 architects and 13 academics.
All participants have been registered and licensed professionals at the SA Council for professional engineers, who work in both private and public sectors. The participants are interested in the SA procurement and contracts system with experience ranging from one to more than twenty-five years with the majority of twenty-five years of experience in common construction sectors such as; residential and commercial buildings, healthcare buildings, industrial building and heavy civil construction.
Most of the participants from both private and public sectors agreed with the survey questions subject matter regarding: zone price proposals, contractors' evaluation, risks, planning, projects' scope, owners concern and weekly risks reports (WRR). The survey results showed that the procurement system is the major risk to projects, affects construction projects negatively and is in need of improvement.
Based on the survey and literature review, a model, called Saudi government performance procurement model (SGPPM), has been developed in which the most expert contractor is chosen through four phases: submittals& education, vendors selection, illustration and execution. The resulting model is easy to implement by SA government and does not require special skills or backgrounds.
ContributorsAlofi, Ahmed Abdulrahman (Author) / Kashiwagi, Dean (Thesis advisor) / Sullivan, Kenneth (Committee member) / Kashiwagi, Jacob (Committee member) / Arizona State University (Publisher)
Created2017
Description
Public construction projects in Saudi Arabia have been experiencing performance issues for the past 30 years. There have been many research efforts and publications identifying the problem and potential causes, however, there have been minimal efforts identifying how to mitigate the problem and testing to validate proposed solutions. A literature search has shown that the academic research has had minimal impact in assisting the construction industry to improve its performance. This dissertation aimed to evaluate the impact of construction management research in Saudi construction industry (SCI), and to investigate barriers that hinder the diffusion of implementing the research outcomes in the construction sector in order to develop a research roadmap to bridge the gap between academic research and practice, using the experience of other organizations that have a successful experience in developing the impact of construction management research in the construction industry. In order to achieve the aim of the study, five main objectives were set up which are: evaluate the impact of construction management research in SCI, identify the barriers that affect the implementation of construction management research in SCI, develop a research roadmap to bridge the gap between the research and practice, validating the proposed solution, and proposed implementation plan and review the result from the implementation. A literature research was performed, using 5 academic databases, identifying the impact that R&D has had on the SCI. A questionnaire was also created surveying both researchers and industry professionals. The results show evidence that the current R&D process in Saudi Arabia is not helping the SCI to increase their performance, and needs to be improved. This study provides a potential solution, and an action plan that mirrors one of the most successful research and development programs in the construction industry in the world [+1915 tests, six different countries, 31 states in the U.S. and 98% customer satisfaction]. The solution proposed in this dissertation is unique to the strengths and weaknesses of the research and development programs at universities and research centers in Saudi Arabia. This study is the first study of its kind in Saudi Arabia.
ContributorsAlhammadi, Yasir (Author) / Kashiwagi, Dean (Thesis advisor) / Badger, William (Committee member) / Sullivan, Kenneth (Committee member) / Arizona State University (Publisher)
Created2017
Description
Research has shown that construction projects in Saudi Arabia have had a perceived poor performance for the past three decades, from 1970-2016. The Saudi construction industry relies on a Contractor Classification System (CCS) to determine contractors’ capabilities, and prevent underperformance. Through this study, a survey was conducted among persons involved in the Saudi Arabian construction industry to identify the perception of the performance of the Saudi Arabian construction industry, and the satisfaction with the CCS. The results of the survey showed that 71.59% of the participants agreed that the CCS does not accurately assess contractors’ capabilities for projects they are allowed to work on. A critical review of the CCS is presented through a case study and comparisons are made from worldwide CCSs found in a literature review. All the parts of the Kingdom of Saudi Arabia’s CCS, including the work flow and the evaluation criteria were reviewed. Several observations of the CCS include a lack of transparency in the process, no performance feedback, complexity of the system, the system being outdated in relation to the worldwide systems, and no continuous performance measurements. To develop an appropriate continuous performance measurement model and benchmarking, other worldwide performance measurement models and benchmarking models were reviewed and discussed. Through these findings, a modified version of the current CCS was developed. A test was performed on the financial assessment portion of the developed model using 5,751 contractors who were classified at the time of this study. The results showed that only 14% of the 5,751 contractors are financially capable in their respective CCS grades. The proposed new CCS model which is outlined in this study includes two major modifications. The first modification is on existing components, which will improve the transparency, simplicity, and speed of the CCS process. The second modification is the addition of a new component, which will continually track contractor performance over time and motivate contractors to improve their performance.
ContributorsAlmutairi, Saud (Author) / Kashiwagi, Dean (Thesis advisor) / Kashiwagi, Jacob (Committee member) / Sullivan, Kenneth (Committee member) / Arizona State University (Publisher)
Created2017