DNA methylation (DNAm) is the covalent modification of DNA by addition of a methyl group primarily at the cytosine directly upstream of a guanine. DNAm level plays a central role in transcriptional regulation and is linked to disease. Therefore, understanding genetic and environmental influences on DNAm level in healthy tissue is an important step in the elucidation of trait and disease etiology. However, at present only a minority of easy to access human tissues and ethnicities have been investigated. Therefore, we studied DNAm level measured in five human tissues: cerebellum, frontal cortex, pons, temporal cortex and colon in either North American or South American samples. We applied a novel statistical approach to estimate the heritability attributable to genomic regions (regional heritability, ĥ²/r,g ) for DNAm level at thousands of individual DNAm sites genome-wide. In all five tissues, DNAm level was significantly associated with the local genomic region for more DNAm sites than expected by chance. Moreover, DNAm level could be predicted from the local sequence variants with an accuracy that scaled with the estimated ĥ²/r,g . Our results inform on molecular mechanisms regulating DNAm level and trait etiology in several ways. Firstly, DNAm level at DNAm sites located in genomic risk regions and measured in a tissue relevant to the disease can be influenced by the local genetic variants. Specifically, we found that genetic variation within a region associated with Fluid Intelligence was also associated with local DNAm level at the proline-rich coiled-coil 1 (PRRC1) gene in healthy temporal cortex tissue. Additionally, we replicated the finding of a Colorectal Cancer risk variant (rs4925386) associated with two DNAm sites in healthy colon tissue. More generally, we showed that DNAm sites located within a susceptibility region and measured in a relevant tissue exhibit a similar overall pattern of estimated ĥ²/r,g to DNAm sites outwith a susceptibility region. Secondly, the propensity for DNAm level to be associated with the local sequence variation differs with respect to CpG dinucleotide density and genic location. Most notably, DNAm sites located in CpG dense regions of the genome are less likely to be heritable than DNAm sites located in CpG sparse regions of the genome. Additionally, within both CpG dense and CpG sparse regions of the genome intergenic DNAm sites are more likely to be heritable than intragenic DNAm sites. Overall, our study suggests that variation in DNAm level at some DNAm sites is at least partially controlled by nuclear genetic variation. Moreover, DNAm level in healthy tissue has the potential to act as an intermediary in trait variation and etiology.

No description available.

This thesis was conducted to empirically examine and compare the different conceptualizations of the integrity test construct identified in previous research. The conceptualizations assert that integrity tests measure a major trait (i.e., Conscientiousness or Honesty-Humility), a combination of major traits, or a combination of minor traits (personality facets). The general fit and predictive validity (of counterproductive work behavior, or CWB) of each conceptualization was tested. Psychology undergraduates (N = 436) participated via online surveys containing two personality scales, two integrity tests, and a CWB scale. The results most support the conceptualizations of integrity as either solely the broad trait Conscientiousness or a combination of Conscientiousness, Agreeableness, and Neuroticism. Statistical issues were encountered with the models of several conceptualizations due to the number of predictors used and high multicollinearity between them. A closer examination revealed that integrity tests mostly encompass behaviors typically associated with the traits Conscientiousness and Agreeableness.

M.A. (Clinical Psychology) / Sportsmen and –women, professional and amateur alike, are faced with multiple pressures that often poses an ultimate hindrance on their performance. Some of these pressures include performance anxiety, fatigue and burnout, and negative physiological arousal resultant of performance and perfectionism. The latter, is often a construct that is misunderstood by athletes, coaches, sport managers and spectators, to have a purely negative consequence on an athlete’s performance and sports career. Theory (Flett & Hewitt, 2005; Gotwals, Stoeber, Dunn & Stoll, 2012; Hamachek, 1978) suggests, however, that perfectionism does not only have a negative consequence, but very often, it has a positive influence on a sporting performance. Thus, it is assumed that in the sporting society, perfectionism holds a false ideology. The constructs of perfectionism and personality often correlates with one another, particularly because of the theoretical link between the personality trait Neuroticism, and perfectionism. This ideology is no different among athletes. Sportsmen and -women often strive for perfection within their performance, which is known to most as a debilitating phenomenon in which they need to understand and reduce. However, Gotwals et al. (2012) have found this ideology to be a controversial issue as they have found that in sport, perfectionism is less of a debilitating phenomenon and more of an adaptive phenomenon. In order to better understand the entire construct of perfectionism, it becomes necessary to analyse the relationship it has with personality.

M.A. / Using the concept of resilience, this study investigates mechanisms and strategies used by young men in Zola, Soweto to cope in adverse circumstances. The study breaks with the preoccupation of social science research with 'youth as trouble' issues and resonates with the United Nations' objective to drive forward notions of human development which aim at sustaining support and collaboration in assisting people to develop their full potential. In specific, the study asks the question “What are the mechanisms and strategies that young men in Soweto use to cope in adverse circumstances?” The study, contrary to most resilience studies worldwide, employed a qualitative methodology and relies strongly on data collected in 2007 through in-depth interviews and participant observation among young men of 18-24 years of age in Zola, Soweto, just outside of Johannesburg. The findings highlight how notions of masculinity contribute to the legitimisation of crime and the high uptake of criminal responses to adversity in a context of poverty and inequality – a process I discuss in light of Michael Ungar's notion of 'hidden resilience'. The project's contributions to research are threefold: Firstly, the study contributes to the international body of resilience literature by providing a context-specific account of risk and adaptation among young men in an urban township environment in South Africa. Secondly, it adds to recent discussions on the appropriateness of different methods in studying resilience by reflecting on some of the most common approaches to researching resilience among children and youths. Lastly, the project takes a glance at potential fields of interest for policy and programme development that emanate from the study's innovative perspective on 'youth at risk' in Zola.

D. Litt. et Phil. / In the past, psychology has typically focused on identifying and treating mental illness, psychological deficits and disabilities, and research was often concerned with the respective roles of nature and nurture in behavioural problems. A number of psychologists and researchers have initiated a paradigm shift to one of positive psychology which emphasises enhancing personal strengths, developing and maintaining well-being, and encouraging positive emotions. Little research however has thus far been done to investigate the role of nature and nurture in psychological wellness. The current study addressed this dearth in the scientific literature by investigating the possible relationships between temperament and psychological well-being, specifically character strengths and resilience. The study was based on the assumption that positive emotionality and psychological well-being may have biological roots, just as psychopathology has been found to have biological underpinnings. The biologically-based construct of temperament refers to the innate and stable aspect of an individual that impacts thoughts, feelings and behaviours. Psychological wellbeing, for the purposes of the current study, incorporated two elements, namely character strengths and resilience. Character strengths may be defined as positive characteristics within individuals. Resilience refers to coping with, and perhaps even thriving, when faced with challenging life situations.

With close to 2100 species, the flowering plant genus Carex (Cyperaceae; sedges) is an example of an evolutionary radiation. Despite its potential for use as a model taxon in evolutionary studies, the diversification of sedges remains largely unexplored. This thesis realizes the potential of Carex as an evolutionary model group by using it to ask questions about species richness patterns. More specifically, it seeks to determine the relationship, if any, between rates of trait evolution and species richness. This tests the hypothesis that organisms with increased abilities to evolve new traits, speciate more rapidly. Morphological and ecological (habitat and climatic niche) traits are modelled on a nearly complete regional (North America north of Mexico) phylogeny and rates of trait evolution are compared among non-nested sister groups. However, before trait evolution is modelled, this work evaluates the sensitivity of climatic niche estimates to underlying distribution datasets. It tests the agreement of niche estimates derived from the commonly used online repository GBIF (the Global Biodiversity Information Facility) and county-level distributions via BONAP (the Biota of North America Program). Results showed that in the context of phylogenetic comparative analyses, it is not vital to obtain highly accurate climatic niche estimates. The second study found significant positive correlations between the rates of climatic niche, habitat and reproductive morphological evolution and species richness. This result supports the role of high trait lability in generating species richness and more generally, the idea that high trait disparity through evolutionary time leads to species success.

Trait mindfulness refers to the tendency of being mindful in everyday life. Individuals characterized with high trait mindfulness have reported high subjective wellbeing and are less prone to depression and stress. The aim with this systematic review was to investigate the neural correlates of trait mindfulness. Also, to compare the neural correlates underlying trait mindfulness with those related to mindfulness practices. A systematic search, screening and selection was conducted, resulting in twelve articles included for data extraction and discussion. All studies investigated resting state brain activity or brain structure, measured by fMRI or MRI, in relation to individual scores in trait mindfulness measures. Trait mindfulness was characterized by reduced connectivity within the DMN (between the PCC, the medial PFC, the STG and the thalamus e.g.) and increased functional connectivity between the insula and the ACC within the SN. Further, decreased functional connectivity between the DMN and the SN was observed. No consistent structural correlates characterizing trait mindfulness were reported. Reduced connectivity within the DMN is thought to associate with reduced vulnerability to rumination and depression. Increased connectivity within the SN has been linked to enhanced body awareness and interoception. Decreased functional connectivity between the DMN and the SN has been suggested to facilitate enhanced attention. Trait mindfulness appears to share some neural characteristics with those linked to mindfulness practices: weaker functional connectivity within the DMN, increased involvement of the insula and the ACC within the SN, and weaker connectivity between the DMN and the SN.

Obesity, diabetes, hypertension, and heart disease are highly heritable conditions that in aggregate are the major causes of morbidity and mortality in the developed world and are growing problems in developing countries. To map the causal genes, we conducted a population screen for these conditions on the Pacific Island of Kosrae. Family history and genetic data were used to construct a pedigree for the island. Analysis of the pedigree showed highly significant heritability for the metabolic traits under study. DNA samples from 2,188 participants were genotyped with 405 microsatellite markers with an average intermarker distance of 11 cM. A protocol using LOKI, a Markov chain Monte Carlo sampling method, was developed to analyze the Kosraen pedigree for height, a model quantitative trait. Robust quantitative trait loci for height were found on 10q21 and 1p31. This protocol was used to map a set of metabolic traits, including plasma leptin to chromosome region 5q35; systolic blood pressure to 20p12; total cholesterol to 19p13, 12q24, and 16qter; hip circumference to 10q25 and 4q23; body mass index to 18p11 and 20q13; apolipoprotein B to 2p24-25; weight to 18q21; and fasting blood sugar to 1q31-1q43. Several of these same chromosomal regions have been identified in previous studies validating the use of LOKI. These studies add information about the genetics of the metabolic syndrome and establish an analytical approach for linkage analysis of complex pedigrees. These results also lay the foundation for whole genome scans with dense sets of SNPs aimed to identifying causal genes.

No description available.