My dissertation focuses on the evolutionary forces that have shaped the chemical signaling system of plethodontid salamanders. Pheromones mediate two phases of plethodontid reproduction: mate attraction prior to courtship and female persuasion during courtship. Substrate-borne chemical signals are believed to play an important role in mate attraction for these animals. A behavioral assay of sex- and species-specific odor preferences in closely related species of Plethodon indicates that: (1) there is asymmetry on the receiver side of the system, wherein male salamanders invest more energy searching for mating partners than do females; (2) substrate-borne chemical signals are sexually dimorphic and male preference strongly favors the female odor versus the male odor; (3) females of allopatric salamander species have evolved distinctive chemical cues; and (4) female chemical signals of sympatric species are divergent and may play a role in sexual isolation. Sexual persuasion is another phase of plethodontid reproduction that is mediated by chemical signals. Plethodontid Receptivity Factor (PRF) is a proteinaceous pheromone that is produced by the male and delivered to the female during courtship. Female receptivity increases following application of this pheromone. PRF is a recent innovation of the male courtship signal, originating in eastern Plethodon (~27 MYA). Codon-substitution models indicate that several amino acid sites along the PRF protein have experienced positive selection. Structural modeling suggests that many of these selected residues are important for receptor binding. Adaptive change in this pheromone is likely driven via a coevolutionary association with female receptors. The male plethodontid courtship signal, however, is comprised of multiple chemical components. I investigate micro- and macro-evolutionary divergence in plethodontid chemical communication by surveying two additional pheromone component genes, PMF and SPL. Like PRF, regions of the PMF and SPL genes have experienced adaptive change. At least one of these components (SPL) has been retained in the signaling system for ~100 MY. However, significant differences in the composition of the courtship pheromone are evident in some plethodontid lineages. It appears as if at least two lineages (Desmognathus and eastern Plethodon) use different major pheromone components and yet achieve the same behavioral response in the female (increased receptivity). / Graduation date: 2005

In animals, reproductive behaviors serve to attract individuals together during the breeding season and to coordinate the behavioral and physiological states of individuals so that mating can successfully occur. In snakes, the various reproductive behaviors including courtship, mating, courtship inhibition, male combat and trailing are mediated primarily by pheromones. Pheromones are naturally produced chemical signals that influence the physiology or behavior of a conspecific when released by one individual into the environment. The research included in this study was designed to characterize the role pheromones play in the mediation of reproductive behaviors of the brown tree snake (Boiga irregularis) a rear-fanged, arboreal colubrid native to Australia, Papua-New Guinea and the Solomon Islands. Much attention has been paid to this species as it is an introduced pest species on the Pacific island of Guam where it has caused considerable economic and ecological damage. In order to create behavioral bioassays designed to experimentally determine the role pheromones play in the mediation of brown tree snake reproductive behavior, the complete repertoire of courtship, mating and male combat behaviors were described. Male brown tree snakes display combat and courtship behaviors similar to other colubrid species while female brown tree snakes take a very active role in courtship, displaying behaviors that both release and inhibit male courtship. These data represent the first description of any reproductive behaviors in this species and one of only a few studies examining the reproductive behaviors of a tropical species. A behavioral bioassay measuring the release of male courtship behavior was utilized to isolate and characterize the female sex pheromone of this species as a suite of non-polar, non-volatile skin lipid molecules. Using another bioassay, the pheromonal inhibition of male courtship behavior by a volatile pheromone originating from female cloacal secretions was characterized. Lastly, pheromone mediated mate attraction was examined by determining the abilities of male brown tree snakes to follow conspecific pheromone trails during the breeding season. Male brown tree snakes possess the ability to follow both male and female pheromone trails but did not, however, discriminate between male and female pheromones trails when given a choice. / Graduation date: 1999

Identifying factors related to adolescent sexual activity is an important issue for health care, education, and public policy. This research explores the idea that sexual identity relates to adolescent sexual activity and the riskiness of the behavior. Sexual identity is composed of many factors, including self-esteem, sexual self-efficacy, body image, and social isolation. As well, the development of sexual identity is related to age and familial relations. From a symbolic interaction perspective, the formation of sexual identity occurs through the creation of highly subjective symbols or meanings assigned to sexuality. Riskier sexual behaviors seem to occur predominantly in adolescence, and understanding the meanings associated with sexual identity may help to explain why. It was hypothesized that adolescent sexual identity would be related to whether or not adolescents had participated in sexual activity and if they had, whether such activity was safer or riskier. The data, collected from 2,373 7th through 12th graders, were part of a community-based program in a rural northwest community. Participants were divided into three groups based upon their sexual activity status of abstaining behavior, safer behavior, or riskier behavior. Group membership was determined utilizing measures of birth control use, sexually transmitted disease history, and pregnancy experience. Discriminating variables included self-esteem, sexual self-efficacy, body image, social isolation, parental monitoring, and age. Analysis revealed significant sex differences on all six discriminating variables. Stepwise discriminant function analysis found age, parental monitoring, and sexual self-efficacy to be significant contributors to the model for both sexes. The discriminant function classification, utilizing all six variables, correctly classified 93% of both females and males, illuminating the significance of sexual identity in discriminating among the groups. Older adolescents with an increased sense of sexual identity and parents who monitor their behavior, may be more inclined to participate in safer sexual behaviors. The development of sexual identity is a culmination of cognitive, affective, and behavioral processes that together help the individual see her/himself as a sexual person. The research presented here provides insight into the sexual identity of adolescents. Such knowledge may be beneficial in designing sexuality education programs designed to facilitate positive, well-developed sexual identity. / Graduation date: 1995

This study is intended to explore how physicians can best help their older patients attain a better quality of life through sexual healthcare by eliciting older patients perceptions and experiences regarding their sexual health needs and what role their physician should play in meeting those needs. Participants consisted of individuals and couples over the age of 65 recruited from a continuing care retirement community and from a VA Geriatric Clinic. Twenty in-depth, one-on-one interviews were conducted, and transcripts were analyzed using qualitative methodology. Analysis of transcripts revealed a broad range of findings including seniors perceptions of: the definitions of sexual activity and sexual health, their own sexual status, their own sexual health needs, the barriers to meeting their sexual health needs, and the ageist beliefs of others and themselves. This study exposed older patients self-perceived sexual health needs and the barriers to having those needs met; this knowledge should help physicians improve the quality of life for their senior patients through improved sexual health care.

Thesis (M. Sc.)--York University, 1998. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 31-40). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL:http://wwwlib.umi.com/cr/yorku/fullcit?pMQ27371.

published_or_final_version / Social Work and Social Administration / Doctoral / Doctor of Philosophy

This present research aimed (1) to examine the level of sexual health knowledge, patterns of sexual attitudes and prevalence of sex-related behaviours among college students in contemporary China; (2) to explore factors predicting knowledge, attitude and behavior regarding sexuality; and (3) to assess gender differences in both characteristics and correlates. Based on data collected from 274 college students (167 male and 107 female) by the way of convenience sampling, in Hefei, China, Phase 1 of the study first selected, examined and modified (if necessary) three instruments (Sexual Health Knowledge Scale, SHKS; Sexual Attitude Scale, SAS; Sex-Related Behaviour Questionnaire, SRBQ), which was used in Phase 2 of the Study. It was found that the examined and (if necessary) modified SHKS, SAS and SRBQ showed good psychometric properties and internal consistencies, which could be useful questionnaires for the measurement of Chinese college students’ sexuality regarding knowledge, attitude and behaviour. Phase 2 of the Study including Section 1, 2 and 3 explored characteristics and correlates of sexual health knowledge, sexual attitudes and sex-related behaviors among an convenience sample of 1398 college students (828 male and 570 female) in Hefei, China. The results in Section 1 demonstrated college students had very limited sexual health knowledge and boys were likely to be much more knowledgeable than girls. Subscales and global score of sexual health knowledge correlated with received sexuality education, romantic relationship experience and coming from urban area, but the overall impact of the factors studied was not strong. The results in Section 2 indicated males had neutral attitudes about sexuality and females had relatively conservative attitudes. Although the overall impact of the factors studied was not strong, several variables (i.e., relationship experience, time spent online, parents’ education, family income, urbanity and sexual health knowledge,) were statistically significantly associated with subscales and global score of sexual attitude. Age was a positive predictor of permissiveness for males and a negative predictor for females. It was found in Section 3 that specific sex-related behaviours in the last one year varied in frequency. Prevalence of some sex-related behaviors (i.e., heterosexual intercourse, oral sex) remained low, while prevalence of other sexual behaviours (i.e., masturbation, pornography use) was high. The magnitude of gender differences in some sex-related behaviors (i.e., oral sex) was relatively small while there was the big gender gap in other sexual behaviours (i.e., masturbation). Moreover, students who had romantic relationship experience, lower educational aspiration or had received sexuality education reported more sexual behaviors involvement. Interestingly, males, but not females, were significantly influenced by time spent online. The thesis suggested significance at theoretical, empirical and practical level, limitations (i.e., gender-related reporting bias, limitation of generalization) and possible directions (i.e., safe sex, sexual and gender monitories, qualitative, cross-cultural and longitudinal study) for future research by reflecting on the findings of this research. Finally, the research was evaluated in terms of practical implications for sexuality education and broader public health policy in aspects of the role of schools and families, students’ participation, Internet utilization, teaching strategies and resources recommendation. / published_or_final_version / Education / Doctoral / Doctor of Philosophy

The current study used multi-wave data from the National Longitudinal Study of Adolescent to Adult Health to examine the existence of typologies of readiness for sexual intercourse and contraception among a nationally representative sample of adolescents aged 15-18. Grounded in the theory of planned behavior, the current study used latent profile analyses to establish five profiles of sexual readiness based on adolescents' attitudes, subjective norms, and perceived behavioral control for sexual intercourse and contraception. Analyses were conducted cross-sectionally and longitudinally, and five classes were confirmed at each of two waves. The current study established and characterized four profiles of readiness for sexual behavior at both waves: “impulsive adolescents,” “precarious adolescents,” “well-controlled adolescents,” and “conservatively-reared adolescents.” Two separate fifth profiles also emerged: “hasty adolescents” at wave 1, and “unrestrained adolescents” at wave 2. Logistic regression of longitudinal data indicated that compared to “impulsive adolescents” at wave 1, “precarious” and “conservatively-reared” adolescents were significantly less likely to engage in sexual intercourse at wave 2, and “well-controlled” adolescents were significantly less likely to engage in casual sex. Wave 1 cross-sectional data indicated that “precarious” adolescents were less likely to have used contraception either at their first time or most recent time of sex, and all other profiles were more likely to have employed contraception than “impulsive” adolescents. Wave 2 cross-sectional analyses indicated that two profiles (“precarious” and “conservatively-reared”) were less likely to engage in sexual intercourse, and two profiles (“well-controlled” and “unrestrained”) were more likely to engage in sexual intercourse than “impulsive” adolescents. / text

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published_or_final_version / abstract / toc / Clinical Psychology / Master / Master of Social Sciences