Matching Items (15)

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The evolution of addiction: a case study of nicotine dependence

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A variety of studies have shown that the tendency toward nicotine dependence has a genetic component. The work described in this thesis addresses three separate questions: i) are there unidentified

A variety of studies have shown that the tendency toward nicotine dependence has a genetic component. The work described in this thesis addresses three separate questions: i) are there unidentified SNPs in the nicotinic receptors or other genes that contribute to the risk for nicotine dependence; ii) is there evidence of ongoing selection at nicotinic receptor loci; and, iii) since nicotine dependence is unlikely to be the phenotype undergoing selection, is a positive effect on memory or cognition the selected phenotype. I first undertook a genome –wide association scan of imputed data using samples from the Collaborative Study of the Genetics of Nicotine Dependence (COGEND). A novel association was found between nicotine dependence and SNPs at 13q31. The genes at this newly associated locus on chromosome 13 encode a group of micro-RNAs and a member of the glypican gene family. These are among the first findings to implicate a non-candidate gene in risk for nicotine dependence. I applied several complimentary methods to sequence data from the 1000 Genomes Project to test for evidence of selection at the nicotinic receptor loci. I found strong evidence for selection for alleles in the nicotinic receptor cluster on chromosome 8 that confer risk of nicotine dependence. I then used the dataset from the Collaborative Studies on the Genetics of Alcoholism (COGA) and looked for an association between neuropsychological phenotypes and SNPs conferring risk of nicotine dependence. One SNP passed multiple test correction for association with WAIS digit symbol score. This SNP is not itself associated with nicotine dependence but is in reasonable (r 2 = 0.75) LD with SNPs that are associated with nicotine dependence. These data suggest at best, a weak correlation between nicotine dependence and any of the tested cognitive phenotypes. Given the reproducible finding of an inverse relationship between SNPs associated with risk for nicotine dependence and cocaine dependence, I hypothesize that the apparently detrimental phenotype of nicotine dependence may confer decreased risk for cocaine dependence. As cocaine use impairs the positive rewards associated with social interactions, reducing the risk of cocaine addiction may be beneficial to both the individual and the group.

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  • 2014

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Definitely directed evolution (1890-1926): the importance of variation in major evolutionary works by Theodor Eimer, Edward Drinker Cope, and Leo Berg

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This dissertation shows that the central conceptual feature and explanatory motivation of theories of evolutionary directionality between 1890 and 1926 was as follows: morphological variation in the developing organism limits

This dissertation shows that the central conceptual feature and explanatory motivation of theories of evolutionary directionality between 1890 and 1926 was as follows: morphological variation in the developing organism limits the possible outcomes of evolution in definite directions. Put broadly, these theories maintained a conceptual connection between development and evolution as inextricably associated phenomena. This project develops three case studies. The first addresses the Swiss-German zoologist Theodor Eimer's book Organic Evolution (1890), which sought to undermine the work of noted evolutionist August Weismann. Second, the American paleontologist Edward Drinker Cope's Primary Factors (1896) developed a sophisticated system of inheritance that included the material of heredity and the energy needed to induce and modify ontogenetic phenomena. Third, the Russian biogeographer Leo Berg's Nomogenesis (1926) argued that the biological world is deeply structured in a way that prevents changes to morphology taking place in more than one or a few directions. These authors based their ideas on extensive empirical evidence of long-term evolutionary trajectories. They also sought to synthesize knowledge from a wide range of studies and proposed causes of evolution and development within a unified causal framework based on laws of evolution. While being mindful of the variation between these three theories, this project advances "Definitely Directed Evolution" as a term to designate these shared features. The conceptual coherence and reception of these theories shows that Definitely Directed Evolution from 1890 to 1926 is an important piece in reconstructing the wider history of theories of evolutionary directionality.

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Date Created
  • 2014

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Development of an artificial genetic system capable of Darwinian evolution

Description

The principle of Darwinian evolution has been applied in the laboratory to nucleic acid molecules since 1990, and led to the emergence of in vitro evolution technique. The methodology of

The principle of Darwinian evolution has been applied in the laboratory to nucleic acid molecules since 1990, and led to the emergence of in vitro evolution technique. The methodology of in vitro evolution surveys a large number of different molecules simultaneously for a pre-defined chemical property, and enrich for molecules with the particular property. DNA and RNA sequences with versatile functions have been identified by in vitro selection experiments, but many basic questions remain to be answered about how these molecules achieve their functions. This dissertation first focuses on addressing a fundamental question regarding the molecular recognition properties of in vitro selected DNA sequences, namely whether negatively charged DNA sequences can be evolved to bind alkaline proteins with high specificity. We showed that DNA binders could be made, through carefully designed stringent in vitro selection, to discriminate different alkaline proteins. The focus of this dissertation is then shifted to in vitro evolution of an artificial genetic polymer called threose nucleic acid (TNA). TNA has been considered a potential RNA progenitor during early evolution of life on Earth. However, further experimental evidence to support TNA as a primordial genetic material is lacking. In this dissertation we demonstrated the capacity of TNA to form stable tertiary structure with specific ligand binding property, which suggests a possible role of TNA as a pre-RNA genetic polymer. Additionally, we discussed the challenges in in vitro evolution for TNA enzymes and developed the necessary methodology for future TNA enzyme evolution.

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Date Created
  • 2013

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Genomic diversity and abundance of LINE retrotransposons in 4 anole lizards

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Vertebrate genomes demonstrate a remarkable range of sizes from 0.3 to 133 gigabase pairs. The proliferation of repeat elements are a major genomic expansion. In particular, long interspersed nuclear elements

Vertebrate genomes demonstrate a remarkable range of sizes from 0.3 to 133 gigabase pairs. The proliferation of repeat elements are a major genomic expansion. In particular, long interspersed nuclear elements (LINES) are autonomous retrotransposons that have the ability to "cut and paste" themselves into a host genome through a mechanism called target-primed reverse transcription. LINES have been called "junk DNA," "viral DNA," and "selfish" DNA, and were once thought to be parasitic elements. However, LINES, which diversified before the emergence of many early vertebrates, has strongly shaped the evolution of eukaryotic genomes. This thesis will evaluate LINE abundance, diversity and activity in four anole lizards. An intrageneric analysis will be conducted using comparative phylogenetics and bioinformatics. Comparisons within the Anolis genus, which derives from a single lineage of an adaptive radiation, will be conducted to explore the relationship between LINE retrotransposon activity and causal changes in genomic size and composition.

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Date Created
  • 2013

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Where did you come from? Where will you go?: human evolutionary biology education and American students' academic interests and achievements, professional goals, and socioscientific decision-making

Description

In the United States, there is a national agenda to increase the number of qualified science, technology, engineering, and maths (STEM) professionals and a movement to promote science literacy among

In the United States, there is a national agenda to increase the number of qualified science, technology, engineering, and maths (STEM) professionals and a movement to promote science literacy among the general public. This project explores the association between formal human evolutionary biology education (HEB) and high school science class enrollment, academic achievement, interest in a STEM degree program, motivation to pursue a STEM career, and socioscientific decision–making for a sample of students enrolled full–time at Arizona State University. Given a lack of a priori knowledge of these relationships, the Grounded Theory Method was used and was the foundation for a mixed–methods analysis involving qualitative and quantitative data from one–on–one interviews, focus groups, questionnaires, and an online survey. Theory development and hypothesis generation were based on data from 44 students. The survey instrument, developed to test the hypotheses, was completed by 486 undergraduates, age 18–22, who graduated from U.S. public high schools. The results showed that higher exposure to HEB was correlated with greater high school science class enrollment, particularly for advanced biological science classes, and that, for some students, HEB exposure may have influenced their enrollment, because the students found the content interesting and relevant. The results also suggested that students with higher K–12 HEB exposure felt more prepared for undergraduate science coursework. There was a positive correlation between HEB exposure and interest in a STEM degree and an indirect relationship between higher HEB exposure and motivation to pursue a STEM career. Regarding a number of socioscientific issues, including but not limited to climate change, homosexuality, and stem cell research, students' behaviors and decision–making more closely reflected a scientific viewpoint—or less–closely aligned to a religion–based perspective—when students had greater HEB exposure, but this was sometimes contingent on students' lifetime exposure to religious doctrine and acceptance of general evolution or human evolution. This study has implications for K–12 and higher education and justifies a paradigm shift in evolution education research, such that more emphasis is placed on students' interests, perceived preparation for continued learning, professional goals and potential contributions to society rather than just their knowledge and acceptance.

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Date Created
  • 2014

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Three perspectives on multilevel selection: an experimental, historical, and synthetic analysis of group-level selection

Description

During the 1960s, the long-standing idea that traits or behaviors could be

explained by natural selection acting on traits that persisted "for the good of the group" prompted a series of

During the 1960s, the long-standing idea that traits or behaviors could be

explained by natural selection acting on traits that persisted "for the good of the group" prompted a series of debates about group-level selection and the effectiveness with which natural selection could act at or across multiple levels of biological organization. For some this topic remains contentious, while others consider the debate settled, even while disagreeing about when and how resolution occurred, raising the question: "Why have these debates continued?"

Here I explore the biology, history, and philosophy of the possibility of natural selection operating at levels of biological organization other than the organism by focusing on debates about group-level selection that have occurred since the 1960s. In particular, I use experimental, historical, and synthetic methods to review how the debates have changed, and whether different uses of the same words and concepts can lead to different interpretations of the same experimental data.

I begin with the results of a group-selection experiment I conducted using the parasitoid wasp Nasonia, and discuss how the interpretation depends on how one conceives of and defines a "group." Then I review the history of the group selection controversy and argue that this history is best interpreted as multiple, interrelated debates rather than a single continuous debate. Furthermore, I show how the aspects of these debates that have changed the most are related to theoretical content and empirical data, while disputes related to methods remain largely unchanged. Synthesizing this material, I distinguish four different "approaches" to the study of multilevel selection based on the questions and methods used by researchers, and I use the results of the Nasonia experiment to discuss how each approach can lead to different interpretations of the same experimental data. I argue that this realization can help to explain why debates about group and multilevel selection have persisted for nearly sixty years. Finally, the conclusions of this dissertation apply beyond evolutionary biology by providing an illustration of how key concepts can change over time, and how failing to appreciate this fact can lead to ongoing controversy within a scientific field.

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  • 2014

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Evolution under our feet: Anthony David Bradshaw (1926-2008) and the rise of ecological genetics

Description

How fast is evolution? In this dissertation I document a profound change that occurred around the middle of the 20th century in the way that ecologists conceptualized the temporal and

How fast is evolution? In this dissertation I document a profound change that occurred around the middle of the 20th century in the way that ecologists conceptualized the temporal and spatial scales of adaptive evolution, through the lens of British plant ecologist Anthony David Bradshaw (1926–2008). In the early 1960s, one prominent ecologist distinguished what he called “ecological time”—around ten generations—from “evolutionary time”— around half of a million years. For most ecologists working in the first half of the 20th century, evolution by natural selection was indeed a slow and plodding process, tangible in its products but not in its processes, and inconsequential for explaining most ecological phenomena. During the 1960s, however, many ecologists began to see evolution as potentially rapid and observable. Natural selection moved from the distant past—a remote explanans for both extant biological diversity and paleontological phenomena—to a measurable, quantifiable mechanism molding populations in real time.

The idea that adaptive evolution could be rapid and highly localized was a significant enabling condition for the emergence of ecological genetics in the second half of the 20th century. Most of what historians know about that conceptual shift and the rise of ecological genetics centers on the work of Oxford zoologist E. B. Ford and his students on polymorphism in Lepidotera, especially industrial melanism in Biston betularia. I argue that ecological genetics in Britain was not the brainchild of an infamous patriarch (Ford), but rather the outgrowth of a long tradition of pastureland research at plant breeding stations in Scotland and Wales, part of a discipline known as “genecology” or “experimental taxonomy.” Bradshaw’s investigative activities between 1948 and 1968 were an outgrowth of the specific brand of plant genecology practiced at the Welsh and Scottish Plant Breeding stations. Bradshaw generated evidence that plant populations with negligible reproductive isolation—separated by just a few meters—could diverge and adapt to contrasting environmental conditions in just a few generations. In Bradshaw’s research one can observe the crystallization of a new concept of rapid adaptive evolution, and the methodological and conceptual transformation of genecology into ecological genetics.

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Date Created
  • 2015

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From conflict to common ground: establishing Religious Cultural Competence in Evolution Education (ReCCEE)

Description

Evolution is the foundation of biology, yet it remains controversial even among college biology students. Acceptance of evolution is important for students if we want them to incorporate evolution into

Evolution is the foundation of biology, yet it remains controversial even among college biology students. Acceptance of evolution is important for students if we want them to incorporate evolution into their scientific thinking. However, students’ religious beliefs are a consistent barrier to their acceptance of evolution due to a perceived conflict between religion and evolution. Using pre-post instructional surveys of students in introductory college biology, Study 1 establishes instructional strategies that can be effective for reducing students' perceived conflict between religion and evolution. Through interviews and qualitative analyses, Study 2 documents how instructors teaching evolution at public universities may be resistant towards implementing strategies that can reduce students' perceived conflict, perhaps because of their own lack of religious beliefs and lack of training and awareness about students' conflict with evolution. Interviews with religious students in Study 3 reveals that religious college biology students can perceive their instructors as unfriendly towards religion which can negatively impact these students' perceived conflict between religion and evolution. Study 4 explores how instructors at Christian universities, who share the same Christian backgrounds as their students, do not struggle with implementing strategies that reduce students' perceived conflict between religion and evolution. Cumulatively, these studies reveal a need for a new instructional framework for evolution education that takes into account the religious cultural difference between instructors who are teaching evolution and students who are learning evolution. As such, a new instructional framework is then described, Religious Cultural Competence in Evolution Education (ReCCEE), that can help instructors teach evolution in a way that can reduce students' perceived conflict between religion and evolution, increase student acceptance of evolution, and create more inclusive college biology classrooms for religious students.

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Date Created
  • 2018

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Advancing the causal theory of natural selection

Description

The Modern Synthesis embodies a theory of natural selection where selection is to be fundamentally understood in terms of measures of fitness and the covariance of reproductive success and trait

The Modern Synthesis embodies a theory of natural selection where selection is to be fundamentally understood in terms of measures of fitness and the covariance of reproductive success and trait or character variables. Whether made explicit or left implicit, the notion that selection requires that some trait variable cause reproductive success has been deemphasized in our modern understanding of exactly what selection amounts to. The dissertation seeks to advance a theory of natural selection that is fundamentally causal. By focusing on the causal nature of natural selection (rather than on fitness or statistical formulae), certain conceptual and methodological problems are seen in a new, clarifying light and avenues toward new, interesting solutions to those problems are illustrated. First, the dissertation offers an update to explicitly causal theories of when exactly a trait counts as an adaptation upon fixation in a population and draws out theoretical and practical implications for evolutionary biology. Second, I examine a case of a novel character that evolves by niche construction and argue that it evolves by selection for it and consider implications for understanding adaptations and drift. The third contribution of the dissertation is an argument for the importance of defining group selection causally and an argument against model pluralism in the levels of selection debate. Fourth, the dissertation makes a methodological contribution. I offer the first steps toward an explicitly causal methodology for inferring the causes of selection—something often required in addition to inferring the causes of reproductive success. The concluding chapter summarizes the work and discusses potential paths for future work.

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Date Created
  • 2016

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Professor attitudes and beliefs about teaching evolution

Description

Teaching evolution has been shown to be a challenge for faculty, in both K-12 and postsecondary education. Many of these challenges stem from perceived conflicts not only between religion and

Teaching evolution has been shown to be a challenge for faculty, in both K-12 and postsecondary education. Many of these challenges stem from perceived conflicts not only between religion and evolution, but also faculty beliefs about religion, it's compatibility with evolutionary theory, and it's proper role in classroom curriculum. Studies suggest that if educators engage with students' religious beliefs and identity, this may help students have positive attitudes towards evolution. The aim of this study was to reveal attitudes and beliefs professors have about addressing religion and providing religious scientist role models to students when teaching evolution. 15 semi-structured interviews of tenured biology professors were conducted at a large Midwestern universiy regarding their beliefs, experiences, and strategies teaching evolution and particularly, their willingness to address religion in a class section on evolution. Following a qualitative analysis of transcripts, professors did not agree on whether or not it is their job to help students accept evolution (although the majority said it is not), nor did they agree on a definition of "acceptance of evolution". Professors are willing to engage in students' religious beliefs, if this would help their students accept evolution. Finally, professors perceived many challenges to engaging students' religious beliefs in a science classroom such as the appropriateness of the material for a science class, large class sizes, and time constraints. Given the results of this study, the author concludes that instructors must come to a consensus about their goals as biology educators as well as what "acceptance of evolution" means, before they can realistically apply the engagement of student's religious beliefs and identity as an educational strategy.

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Date Created
  • 2014