Browsing by Subject "Selection"

Now showing 1 - 8 of 8
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    Data for "Towards Stewardship of Wild Species and Their Domesticated Counterparts: A Case Study in Northern Wild Rice (Zizania palustris L.)"
    (2024-08-08) McGilp, Lillian; Haas, Matthew W; Shao, Mingqin; Millas, Reneth; Castell-Miller, Claudia; Kern, Anthony J; Shannon, Laura M; Kimball, Jennifer A; jkimball@umn.edu; Kimball, Jennifer, A.; University of Minnesota Cultivated Wild Rice Research Lab
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    Evaluation of phenotypic and physiologic characteristics of selected sources of white spruce, Picea glauca (Moench) Voss
    (2013-12) Pike, Carolyn C.
    White spruce is highly valued for its wood pulp in commercial forestry in Minnesota. Seed orchards have been developed using genotypes selected for increased volume production. I conducted three different experiments to study the variation of ecophysiologic traits among genotypes selected from the Minnesota Tree Improvement Cooperative's program to better characterize the phenotype of selected genotypes. In chapter 1, I analyzed wood specific gravity, tree volume, and leaf traits on 25-year old trees in a white spruce progeny test. Wood specific gravity was negatively correlated with tree volume. Needle traits, primarily specific leaf area (SLA), leaf area ratio (LAR) and leaf mass ratio (LMR), were positively correlated with wood volume. In chapter 2, I planted seedlings from four genotypes selected for superior volume growth and two wild sources in a common garden. I harvested ten trees from each genotype, each year for three years. I examined biomass allocation, tree allometry and assessed genetic correlations among allocation of biomass to major organs. The largest differences in biomass were found between the two wild sources that represented two different seed zones in Minnesota. Selected sources more closely resembled the southern, than the northern, wild source. The northern wild sources had slightly higher allocation to roots but otherwise no significant differences in allometry were found. In chapter 3, I set up an outdoor experiment by planting five selected- and two wild- seed sources into 1-gallon containers to test the effects of mid-winter warming on phenology and growth of white spruce. Bud-break time was delayed in plots that were warmed in February, and advanced in those warmed in March. Overall controls had the highest height growth and intermediate bud-break time. Climatic warming that takes place during winter months may delay or advance bud-break depending on the timing. Growth of white spruce is expected to decline with increased episodes of winter warming. Selected sources should be favored in reforestation across Minnesota because of the higher productivity and adaptability to local conditions.
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    Haplotype-Based Selection Signature Analysis Using University Of Minnesota And Us Contemporary Holstein Cattle
    (2015-11) Yang, Jing
    Artificial selection in dairy cattle since 1964 has achieved steady increase in milk production that was accompanied by unintended declines in fertility. We conducted selection signature analysis to identify genome changes due to the forty years of selection using direct comparison of 45,878 SNPs between Holstein cattle unselected since 1964 and contemporary Holsteins. The Holstein genome had a landscape change from the unselected to the elite contemporary Holsteins. About 31% of the genome was affected by the forty years of selection, and 230 regions had highly significant changes in long-range allele frequencies and genotypic heterozygosity. From these 230 regions, 197 genes with documented fertility functions mostly in mice and humans were identified, leading to the hypothesis that the unintended declines in fertility since 1964 was due to hitchhiking of selection by negative effects of fertility genes. The female-male ratio of the 197 fertility genes is approximately 5:4, indicating that the fertility problems in the contemporary Holstein population likely was due to decreased fertility in both females and males. The elite Holsteins were more heterozygous than their contemporaries in all thirty regions where the elite cows and their contemporaries had significant heterozygosity differences, including seven regions in or near large clusters of olfactory receptors, zinc fingers, cationic amino acid transporters, sialic acid-binding Ig-like genes, vomeronasal receptors, keratin genes, EMR2 receptors, and transfer RNA’s.
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    On the Quantification and Generalizability of Differential Prediction in Selection Systems
    (2019-05) Dahlke, Jeffrey
    Differential prediction analyses are important for personnel psychologists to determine whether the regression lines linking a predictor variable to a criterion/performance variable are comparable between a referent group and a legally protected focal group. Although many decades of research on cognitive tests has indicated that differential prediction does occur for racial/ethnic minority groups in the U.S. relative to Whites, the bulk of evidence has indicated that these differences result into the overprediction of Black and Hispanic individuals’ performance from cognitive test scores, which does not indicate predictive bias against these groups. However, research published over the past decade by Aguinis Culpepper, and Pierce (2010; 2016) has questioned the accuracy and generalizability of past findings, arguing that the historic trends could have been caused by statistical artifacts. In a series of four studies, I present methodological advancements in the quantification of differential prediction and supply substantive analyses that refute the findings reported by Aguinis et al. (2010; 2016). Specifically, I (1) offer derivations of simplified effect-size estimation procedures for differential prediction analyses with accompanying standard-error estimators, (2) illustrate the effects of composite predictors on differential prediction effects, (3) demonstrate the generalizability of White-minority and male-female differential prediction in the post-secondary education admissions domain, and (4) present findings from a simulation study designed to identify which features of selection systems could cause statistical artifacts to bias the results of differential prediction analyses conducted on cognitive test scores.
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    Pavement Rehabilitation Selection
    (Minnesota Department of Transportation, 2008-01) Dai, Shongtao; Skok, Eugene; Westover, Thomas; Labuz, Joseph; Lukanen, Erland
    The objective of the project was to outline best practices for the selection of asphalt pavement recycling techniques from the many choices that are available. The report specifically examines cold-in-place recycling (CIR), plain full depth reclamation (FDR), and mill & overlay (M&O). Interviews, surveys, and site visits were conducted at both Mn/DOT districts and counties, where relevant rehabilitation information was supplied on over 120 projects. A database was constructed to organize the details of these projects, and the parameters in the database included (1) cracking, (2) ride, (3) rutting, (4) age, and (5) traffic volume. From studying the existing rehabilitation projects in the State, Ride Quality Index (RQI) and Surface Rating (SR) were selected as the descriptors of pavement surface condition. A decision procedure based on the analysis of all available projects was developed. The decision procedure included (1) consideration of road geometrics; (2) pavement condition survey; and (3) structural adequacy evaluation. Furthermore, a step-by-step checklist was developed to provide local engineers with a simple and useful tool to follow the decision procedures. The procedure includes selection of rehabilitation method, pavement thickness design, materials mixture design, and construction.
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    Population genomics of the legume symbionts Sinorhizobium meliloti and S. medicae
    (2013-11) Epstein, Brendan
    The nitrogen-fixing mutualism between legumes and rhizobia is ecologically and agriculturally important and is a model for the molecular genetics of plant microbe interactions and the evolution of mutualism. The goal of this research was to investigate the evolutionary forces shaping genetic diversity in two species of rhizobia, Sinorhizobium meliloti and S. medicae by integrating population genetic tools, experimental evolution, and whole-genome sequencing. In Chapter 1, I characterize the diversity and divergence of S. meliloti and S. medicae and ask how selection and horizontal gene transfer (HGT) have shaped nucleotide variation. I find limited evidence for HGT between S. meliloti and S. medicae, indicating that recombination with closely related species does not have much impact on nucleotide diversity in Sinorhizobium spp. and does not prevent species from diverging. I also find that the targets of strong positive selection are different in the two species, suggesting that S. meliloti and S. medicae may be subject to different selective pressures in nature. The goal of Chapter 2 was to examine gene content and copy number variation. While I find that S. meliloti and S. medicae both have extensive variation in content and copy number, most of this variation seems to be deleterious. This suggests that the large size of bacterial pangenomes is due, in part, to many short-lived, deleterious gains and losses of genes rather than adaptation. Finally, in Chapter 3, I use experimental evolution to tests for costs of mutualism. I do not find clear evidence of costs, but I do identify a mutation in the purM gene that may affect host range. Overall, this contributes to our understanding of both the evolution of rhizobia, and the evolutionary forces shaping variation in prokaryotes.
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    Reactions Toward Anonymized Reviews in Selection
    (2023) Banuelos, Sebastian
    Race, gender, and age biases are prevalent when decision-making processes in the workplace are subjective and lack job-relevant criteria. Decision-maker reactions can influence decision quality, willingness to support, confidence in, and preference to use selection tools. The anonymized review (AR) is a hiring process that minimizes bias in selection by redacting identifying information (e.g., name, age, gender) from applicant materials (e.g., applications, resumes, etc.). This study was a two-part investigation that examined decision-maker reactions toward ARs. Justification for using ARs was expected to positively influence decision-maker reactions toward ARs. Additionally, diversity attitudes were expected to have a moderating effect on the relationship between justification and decision-maker reactions. Results from Study 1 showed insignificant main effects for ARs and justification. Study 1 results also showed that individuals with low diversity attitudes will react negatively to ARs when justification is not provided. Lastly, qualitative responses from Study 2 revealed perceptions of accuracy and practicality toward ARs as significant themes. Practical implications of the study are discussed and recommendations provided.
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    The validity of judgment : can the assessor learn to outperform the equation?
    (2010-09) Klieger, David M.
    When judgments (i.e., predictions of outcomes) are incorrect, the negative consequences for individuals, organizations, and society can be serious. For various kinds of outcomes, meta-analyses and literature reviews reveal, time and again, that the predictive validity of information combined in the mind of the assessor ("clinical data combination") is smaller than the predictive validity when the information is combined using an equation or actuarial table ("mechanical data combination"). Therefore, using mechanical approaches instead of clinical ones would seem prudent. However, judgment validity encompasses consequential validity as well as predictive accuracy. Furthermore, even some of the scholars who have emphasized the superior accuracy of mechanical methods admit that it may be possible for a judge to systematically out-predict a mechanical method. One such possible approach is configural reasoning, an assessor's use of a functional form (e.g. an interaction) absent from the mechanical method and yet predictive of the outcome. As indicated by the aforementioned studies indicating the superior accuracy of mechanical combination, judges do not productively employ such techniques in general. Nevertheless, it remains an empirical question whether assessors can be taught to utilize configural reasoning to outperform an equation. In addition, it is important to determine the traits of those individuals who predict and learn to predict most accurately, because identifying such people can minimize the costs of error and training. This dissertation tries to be comprehensive in scope. It employs experimental designs and methods of assessing individual differences to answer questions about the degree (if any) to which people can be taught to outperform a mechanical equation, the degree (if any) to which assessors can learn to improve the accuracy of their judgments, the degree (if any) to which judges can be made less overconfident in their judgment strategies, the relationship of any changes in accuracy to any changes in confidence, the individual differences that define those who predict and learn to predict most accurately, and the timing of and extent to which (if any) assessors gain insight about the most accurate predictive approach. Prior to addressing these issues, this dissertation lays certain groundwork. It clarifies the nomological networks for clinical and mechanical combination. It enumerates much of the vast research that reveals the human cognitive limitations and informational barriers that are thought to contribute to a vicious cycle of lesser clinical accuracy and overconfidence in judgment strategies. Furthermore, it discusses why one should even care about clinical combination if mechanical procedures are generally more accurate. The most extensive background information provided prior to discussion of the studies conducted by this author concerns the Lens Model as a toolkit for measuring accuracy as well as the determinants of accuracy. Although this portion of the dissertation is somewhat detailed and intricate, it is necessary. First, understanding the Lens Model leads to understanding the determinants of judgment accuracy. Second, understanding the Lens Model leads to understanding how the judge can and cannot outperform the mechanical approach. Third, understanding the Lens Model leads to understanding the limitations of prior research. Fourth, understanding the Lens Model is essential if the reader is to fully understand results, discussion, and conclusions of the author's experiments. Also reviewed are the "skill score" as an alternative to the Lens Model for measuring accuracy as well as the major considerations involved when teaching people to improve their accuracy and lessen in confidence. The "skill score" provides information about elevation and scatter that is not available from the Lens Model. Final preliminaries focus on experimental design, namely how and why use of a disordinal interaction is central to the experiments conducted by the author, as well as issues concerning the number of experimental cues (predictors) employed, cue redundancy (intercorrelation), the importance of representative design in the experiments, the conduciveness of various types of experimental feedback to learning, and the impact of incentives on judgment accuracy in the experiments. The author conducted two studies - one in Fall 2009 and another in Spring 2010. Although some of the experimental design details of the studies differed in important ways, their general blueprints were quite similar. Using mostly undergraduate subjects at the University of Minnesota, both studies collected information about individual differences (cognitive ability, gender, personality, interests, and experience). In the experimental portions of the studies, subjects were asked to make predictions of job performance for hypothetical job candidates based on the cognitive ability test score for each candidate as well as how interesting or boring the candidate was expected to find the job. The most accurate clinical prediction strategy would involve applying knowledge that the correlation between cognitive ability and job performance was positive when the applicant was expected to find the job interesting but negative when the applicant was expected to find the job boring (i.e. a disordinal interaction). The competing mechanical model was a linear version of a model that incorporated the disordinal interaction. Subjects were asked about their confidence in how accurately they were making predictions, and in order to assess insight, subjects were asked to narratively self-report the nature of their judgment strategies. Data were analyzed using longitudinal hierarchical linear modeling (for within-person change over time in accuracy, the determinants of accuracy, and confidence), correlation (for between-person differences), and frequencies (mainly for evaluating insight). Results were fascinating, although many were inconclusive (often due to lack of statistical significance). Although subjects could outperform the mechanical model under certain experimental conditions, this superiority was not statistically significant. Some of the individuals, experimental groups, and/or subject pool means increased or declined in accuracy, the determinants of accuracy, and confidence over time as expected, but often these results were not statistically significant. Nevertheless, there was some evidence that criterion-related feedback about the disordinal interaction led to improved accuracy and decreased confidence while lack of it had the opposite effects. Several individual differences were significantly associated with accuracy, with cognitive ability being the difference most pervasively related to accuracy to a statistically significant degree. Findings for insight were complicated by the inconsistent nature of subjects' narratives. Nevertheless, there was relatively high agreement between raters of subjects' insight, and ratings of insight often had statistically significant correlations with objective measures of accuracy. Moreover, insight as variously measured was often achieved, and if achieved was usually achieved early.