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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

The role of polyandry in sexual selection among dance flies

Herridge, Elizabeth J. January 2016 (has links)
Elaborate sexual ornaments evolve because mate choice exerts strong sexual selection favouring individuals with high levels of ornament expression. Consequently, even at evolutionary equilibrium, life history theory predicts that ornamental traits should be under directional sexual selection that opposes contrasting selection to reduce the costs associated with their maintenance. Otherwise, the resources used to maintain ornaments should be used to improve other life history functions. Elaborate female ornaments have only evolved in a few species, despite females commonly experiencing strong sexual selection. One explanation for this rarity is that male preferences for female ornaments may be self-limiting: females with higher mating success become less attractive because of the lower paternity share they provide to mates with every additional sperm competitor. The unusual species in which female ornaments do occur can provide rare insight into how selection can favour the expression of expensive characters in females despite their costs. The main goal of my thesis was to determine how sexual selection acts on exaggerated sexual ornaments, and give new insight into how these ornaments may have evolved, in spite of the self-limiting nature of selection on male preferences. To determine the strength of sexual selection acting on female ornamentation in dance flies, we developed new microsatellite markers to assess polyandry rates by genotyping stored sperm in wild female dance flies. We first used polyandry rates to determine whether ornament expression was associated with higher mating success in female Rhamphomyia longicauda, a species that has evolved two distinct and exaggerated female ornaments. Contrary to our predictions, we found no evidence that females with larger ornaments enjoy higher mating success. We then compared polyandry rates in R. longicauda to those of two other species of dance fly, one (Empis aestiva) that has i independently evolved female ornaments on its legs, and another (E. tessellata) that does not possess any discernable female ornaments. We also estimated the opportunity for sexual selection, which we found to be similar and relatively low in all three species. Moreover, the standardized sexual selection gradients for ornaments were weak and non-significant in all three species. Females with more elaborate ornaments, in both within- and cross-species comparisons, therefore did not enjoy higher mating success. Overall, these results suggested that sexual selection operates rather differently in females compared to males, potentially explaining the general rarity of female ornaments. Our amplifications of stored sperm were able to reveal more than just mate numbers. We developed new methods to study patterns of sperm storage in wild female dance flies. We investigated how the skew in sperm genotypes from mixed sperm stores changed with varying levels of polyandry. Our data suggested that sperm stores were dominated by a single male in R. longicauda, and that the proportion of sperm contributed by this dominant male was largely independent of the number of rival males’ sperm present in the spermatheca. These results were consistent with the expectation of males using sperm ‘offence strategies’ in sperm competition and that the most successful male is likely to be the female’s last partner before oviposition. As a whole, my thesis contributed new molecular resources for an understudied and fascinating group of organisms. It exploited these new resources to provide the first estimates of lifetime mating success in several related species, and suggested that the general prediction that ornament expression should covary with sexual selection intensity does not seem to hold in this group. Instead, both the unusual prevalence of ii ornaments and the inconsistent evidence for sexual selection that sustains them in dance flies may owe their existence to the confluence of two important factors. First, the conditions under which sperm competition occurs: as last male precedence is likely, males are selected to prefer the most gravid females to secure a high fraction of her offspring’s paternity as they are unlikely to mate again before oviposition. Second, potent sexually antagonistic coevolution between hungry females and discerning males: females have evolved ornaments to disguise their stage of egg maturity to receive the benefits of nuptial gifts, while males face the challenge of distinguishing between gravidity and ornamentation in females.
12

A Path Toward Equality in George Sand's <i> Horace</i>, <i> Mauprat</i>, and “Lavinia”

Miller, Katarina 19 July 2012 (has links)
No description available.
13

The Role of Androgens in Male Pregnancy and Female Competitive Behavior in a Sex Role Reversed Pipefish

Scobell, Sunny Kay 2011 December 1900 (has links)
The sex-role reversal and male pregnancy found in syngnathids are highly unusual traits in vertebrates. Reproductive hormones likely influence development and regulation of these traits. However, very few studies have examined the underlying hormonal mechanisms that mediate female competitive behavior and male pregnancy. New methodologies and better husbandry practices have made such studies more feasible in recent years. Research on a relatively small number of species has suggested that androgens are likely regulators of spermatogenesis and the development of the male brood pouch prior to pregnancy. Androgens are also potential candidates for mediating sex-role reversed behavior in female syngnathids. The goal of this dissertation was to examine the role of androgens in the male reproductive cycle and female intrasexual competitive behavior in the sex-role reversed Gulf pipefish, Syngnathus scovelli. From review of the literature, I developed a model for the hormonal regulation of the male reproductive cycle in seahorses. I predicted that androgens would be low during the early stages of pregnancy and increase during the end of pregnancy as males go through another cycle of spermatogenesis in preparation for the next mating event. My study of 11-ketotestosterone and testis mass across the reproductive cycle in male S. scovelli supported this model. I also conducted several studies on the role of androgens in female competitive behavior. I determined that treatment with 11-ketotestosterone the evening prior to an intrasexual interaction resulted in an increase in competitive behavior in large over small test females. Conversely, treatment with 11-ketotestosterone one hour prior to an intrasexual interaction resulted in a decrease in competitive behavior in large over small females when stimulus female behavior was controlled. A comparative study of competitive and courtship behavior in S. scovelli and the closely related S. floridae suggested that sexual selection has affected competitive and courtship behavior in both males and females of these species. The diversity of reproductive patterns exhibited by syngnathids suggests that they will provide a unique opportunity to assess how hormonal regulation of reproductive behavior and function has evolved within this lineage.
14

Adults Before Their Time: Parentification During Adolescence In Divorcing And Married Families

Rogers, Carla Maree Unknown Date (has links)
In broad terms, parentification can be defined as a child taking on the role of parent to his or her own parents; though in reality the construct is more complex. Although related constructs (e.g. boundary transgressions, role reversal, ‘hurried child’) have been discussed in the literature for many years, the term ‘parentification’ per se is a relatively new one within the field of psychological research and empirical studies are still limited. When researching in the field of parentification, an issue that is apparent is the lack of adequate measures of parentification available for children and adolescents. The few measures of parentification that exist have been (a) retrospective (asking adults to recall levels of responsibility within their families of origin as adolescents) and/or (b) uni-dimensional (measuring parentification as a single score rather than taking into account different facets such as confidant to one’s own parents, mediator between conflicting parents, ‘pseudo-parents’ to siblings, or excessive household responsibilities). The first aim of the current research was to develop a reliable and valid multidimensional measure of parentification that was appropriate for completion by children and adolescents. The series of studies that follow utilise this newly developed parentification scale to examine parentification of adolescents aged 10-16 years from families undergoing parental divorce. A comparison group of children from two-parent continuously married (not remarried) families were included. A previously validated uni-dimensional measure of parentification, the Parentification Questionnaire – Youth (PQ-Y: Godsall & Jurkovic, 1995) was also used throughout the studies (although in the current sample, this measure was multidimensional, yielding two factors labelled Alienation and Tangible Tasks). Broad research goals of the studies are: 1. to examine parentification (and its association with family functioning and sibling relationship quality) from the perspective of multiple family members, 2. to explore parentification differences between families on variables of age, sex, birth order, family size and parental marital status, and 3. to assess the extent to which parentification affects adolescent psychological adjustment, and how burden of parentification may mediate the relationship between parentification and psychological adjustment. Parents and children aged 10-16 years from 304 families (127 divorcing; 177 married) were invited to participate in a 12-month study of parentification that included questions about demographics, family responsibilities, family functioning, adolescent adjustment, and sibling relationships. In addition, in divorcing families, both parents and one child (target child) were invited to be interviewed regarding their experiences surrounding the separation and divorce. The measure of parentification designed for the current research adapted the multidimensional, retrospective measure written by Mika, Bergner and Baum (1987). This new measure was labelled the Youth Parentification Scale (YPS), and findings suggest that it is a reliable measure of parentification in the current sample of married and divorcing families. Results revealed that children from divorcing families and girls reported higher levels of parentification (across various factors). Results on multiple perspectives within the family were mixed. In general, children were more likely than their parents to report higher levels of parentification within the family, although this effect differed slightly dependent upon parental marital status. Siblings who reported offering support to other members of the family also rated their relationship with their sibling as warmer: this result held true for both firstand second-born children. Additionally, both first- and second-born children agreed that parentification may affect the relative status/power between siblings. While few direct associations between parentification and adjustment existed, negative adjustment outcomes (higher anxiety, higher depression and lower self-esteem) were evident when the burden associated with increased responsibility was taken into account. Taking on the role of confidant to one’s parents, playing ‘pseudo-parent’ to one’s siblings, or feeling alienated within one’s family of origin was associated with higher levels of burden, which in turn led children to report higher depression and anxiety and lower self-esteem. Additionally, taking on a parentified role was associated with higher levels of burden, which in turn was associated with reports of lower levels of family functioning (i.e. lower intimacy, higher conflict, and a more controlling parenting style). The current research has implications for the development and refinement of future measures of parentification for use in empirical studies. The Youth Parentification Scale showed that different facets of parentification do seem to exist, and that offering comfort and support to mothers or fathers seems to have an association with various aspects of adjustment, sibling relationships and general family functioning. Alienation (a factor emerging from the PQ-Y), while not actually associated with increased responsibility or parentification per se, showed associations with parentification that indicate that this may be an important construct to include in future attempts at developing a comprehensive measure of parentification. Additionally, the current research unveiled findings that may have clinical importance. Findings revealed that while children from divorcing families did exhibit higher scores on various scales of parentification, outcomes were not necessarily worse for these children than for children within married families who were similarly parentified. Adolescence is a time of emotional growth when some age-appropriate adoption of adult responsibility is warranted; and in fact for children undergoing the transition of parental separation and divorce, adoption of extra responsibilities may be adaptive, perhaps even protective inasmuch as it may bring the child closer to parents during a time when anxiety about family dissolution is high. Further studies (preferably longitudinal) exploring the adaptive facets of parentification are warranted.
15

When Mom has a Serious Mental Illness: The Mother-Young Adult Relationship, Caregiving, and Psychosocial Adjustment

Abraham, Kristen M. 10 November 2010 (has links)
No description available.
16

Men and the Movies: Labor, Masculinity, and Shifting Gender Relations in Contemporary Hollywood Cinema

Carrier, Michael B. 17 September 2015 (has links)
No description available.
17

Reported Affect Mediates the Relationship Between Parent-Child Boundary Dissolution and Emerging Adult Functioning Across Cultures

Lin, Kathy Lee 11 April 2017 (has links)
No description available.
18

One Hundred and Fifty Percent Elasticity

Kessler, Eli Mikael 01 January 2008 (has links)
The sculptural environments I create immerse the viewer in a decrepit vaudevillian past. The sculptures allude to narratives within Community Theater as well as the Drag Show. Making becomes an act; manipulating materials such as synthetic hair and paint are associated with the guise of the makeup artist. Frantic rehearsal logic prevails as a dress is repurposed into a male giant's costume and window blinds are used to construct a boat's deck. This collusion asks the viewer to transgress the boundary of the stage, becoming a voyeur privileged to the world of exiled props and role reversal.
19

Mocenská nerovnováha v pečujících rodinách / Power imbalance in caring families

Neubauerová, Eva January 2015 (has links)
Diploma thesis The power imbalance in caring families deals with power dynamics in the caregiving situation, where mother is a care receiver and her own daughter is caregiver. The theoretical part conceptualizes terms such as the power, the power imbalance, role reversal, caregiver, care receiver and ambivalence. The practical part is presented with its own qualitative survey with caregivers. The work confirms that the factors that significantly affect the success of care are (by caring daughter) options for care giving and degree of caring tie, and (by care receiving mother) ability to give up part of their autonomy, to assess properly the subjective and objective assistance needs and satisfaction with quality and quantity of social ties. The work also reveals some of the mechanisms of power dynamics within families; for example, the ways in which the phase of role reversal is reflected in mutual negotiation, persuasion in dimension, feelings of interaction, advocacy and conflict resolution. It turned out that a higher intergenerational power has actor with incomplete role reversal. Phase of role reversal showed to be a key factor in sorting manifestations of power dynamics in caregiving families. The main outcome of this work is the typology of strategies for power influence of caregivers and...
20

Using role reversal in the treatment of learners with performance anxiety in the school environment

Crous, Charleen 10 1900 (has links)
In this study the technique of role reversal for the treatment of performance anxiety, experienced by learners in the school environment, was investigated. Performance anxiety sometimes presents as part of a larger pattern of social phobia and negatively impacts on an individual’s tasks performance due to the fear of negative evaluation. My qualitative study involved a collective, instrumental case study. Role reversal was implemented as part of a group-therapeutic intervention which continued for approximately three months, and involved participants acting as peer tutors. Data analysis focused on the participant’s personal experiences of the technique as well as therapeutic gains and the usefulness of the technique from a school-based counsellor’s perspective. The research findings revealed that although the helping role held certain challenges for the participants, it seemed to generally impact positively on their social and academic confidence and functioning. Additionally their levels of performance anxiety appeared to decrease. / Psychology of Education / M. Ed. (Guidance and Counselling)

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