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付記する学位プログラム名: 霊長類学・ワイルドライフサイエンス・リーディング大学院 / 京都大学 / 新制・課程博士 / 博士(理学) / 甲第24466号 / 理博第4965号 / 新制||理||1709(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 古市 剛史, 准教授 Huffman Michael Alan, 教授 今井 啓雄 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Sibling aggression is one of the most frequently occurring forms of aggression within the family and has been associated with socioemotional problems. Guided by the cultural context perspective and family systems theory, a conceptual model depicting the direct and indirect effects of cultural orientation values, traditional gender role attitudes, parental differential treatment, and parent-child conflict on sibling aggression and psychosocial functioning (i.e., psychological distress and interpersonal difficulties) was developed. It was hypothesized that perceptions of cultural values and gender role attitudes endorsed by primary caregivers would be associated with family dynamics factors (i.e., parental differential treatment and parent-child conflict) that contributed to sibling aggression and resulting impaired psychosocial functioning. A total of 272 participants completed the online questionnaire that measured the variables of interest. Structural equation modeling (SEM) methods were used to analyze the data. Findings of the final models lent clear support to the indirect effects of cultural values and gender role attitudes on sibling aggression and resulting psychosocial functioning through differential treatment and parent-child conflict although the results also yielded some unexpected nuances regarding the indirect effect paths. Specifically, lower levels of independent cultural values contributed to greater levels of sibling aggression and impaired psychosocial functioning through more differential treatment and parent-child conflict, while higher levels of traditional gender role attitudes contributed to the outcome variables only through differential treatment. Findings are discussed from the cultural context and family systems framework. Limitations, future directions, and clinical implications are also discussed.

Recently, models of aggressive behavior have begun to appreciate the influence of both psychological and biological predictors of maladaptive behavior. The aim of the current project was to clarify the roles that the noradrenergic system (i.e., norepinephrine metabolite, 3-methoxy-4-hydroxyphenyglycol [MHPG]) and characteristics of the rearing environment play in different expressions of aggression (i.e., hostile and instrumental). It was predicted that higher concentrations of MHPG would be related to increased self-reports of aggressive behavior, especially hostile forms, while expressing aggression during an analog aggression task would lead to decreases in MHPG. It was also predicted that concentrations of MHPG would interact with childhood environment characteristics to predict aggressive behavior in youth. A sample of 68 male youth, aged 7 to 17, were recruited from two agencies in southwest Virginia serving disadvantaged youth. They completed self-report measures on their childhood environment, aggressive and delinquent behaviors, as well as exposure to community violence and negative life events. In addition, youth played a challenging computer game with an alleged "opponent" and lost. Half of the participants were able to retaliate after the game against their "opponent." Salivary MHPG was measured once before and three times after the game. A series of ANOVAs and hierarchical regressions were conducted in order to test the main and interactive effects of punitive childhood experiences and baseline MHPG on aggressive behavior. Findings failed to support the primary predictions; however, results of supplemental analyses showed significant associations of aggression with negative mood, negative family atmosphere, and increased baseline MHPG after controlling for negative family atmosphere. Also, parental punishment and rejection significantly predicted delinquency, and a significant interaction effect indicated that higher recovery concentrations of MHPG placed rejected youth more at risk for engaging in delinquent behavior. Results of the present study help to enhance understanding of the differences in biological and psychological correlates of aggression and delinquency in at-risk youth, and inform prevention and intervention efforts. / Ph. D.

The majority of vertebrates are tropical, existing in an environment with low temperature seasonality. However, there is a strong research bias towards temperate-zone studies of seasonality. I investigated the timing of life history stages and trade-offs in tropical rufous-collared sparrows (Zonotrichia capensis) in the humid Andes of Ecuador, then compared my data to temperate-zone Zonotrichia. In Chapter II, I investigated the function of male territorial aggression. Males had peak territorial aggression scores during pre-breeding and nesting, suggesting that paternity protection and food resource defense are the primary selective forces shaping male territorial behavior. Territorial aggression responses depended on the life history stage of males, which were not synchronized within the general population. In Chapter III, I tested for a trade-off between male territorial aggression scores and paternal provisioning rate. Males with higher provisioning rates had nestlings with larger body size, but contrary to the findings of previous studies, there was no direct relationship between aggression and paternal provisioning. In Chapter IV, I investigated how Z. capensis allocated supplemental food. Previous studies (mainly in temperate-zone breeding birds) found food supplements were allocated to reproduction. We supplemented fed birds in both non-breeding and feeding fledglings life history stages; both groups molted (replaced feathers) in response to supplementation, thus invested in their own maintenance over immediate reproduction. In Chapter V, I tested whether latitude and/or altitude are good predictors of reproductive synchrony in Zonotrichia. Reproductive synchrony indices overlapped among tropical and temperate populations. The high altitude, temperate-zone Zonotrichia population had the highest synchrony index, but there was only a weak relationship of altitude in a comparison of tropical populations. Cumulatively I found that tropical humid-forest resident Z. capensis time life history stages according to individual condition and history and not by overarching climatic cues. / Ph. D.

Despite considerable advances in the development and implementation of school-based interventions, aggressive behavior in schools remains a significant problem for both educators and the community as a whole. The present study was designed to examine possible contextual influences on the course and treatment of aggression in schools, in an effort to inform future intervention development. The aim of the present study was to examine possible influences on teachers' response to reactive and proactive aggression in the classroom, and test the applicability of Weiner's attributional model of motivation and emotion. A sample of 121 middle school teachers completed self-report measures of teaching characteristics, efficacy, stress, and burnout. They also responded to four vignettes of student aggression with measurements of proposed attributions, affective reactions, and interventions. A series of ANOVAs showed that teacher's proposed responses differed as a function of child aggression subtype, teacher stress, burnout, efficacy, and training. Multiple regression analyses were used to test Weiner's theoretical model, as well as consider the moderating influence of teacher characteristics. Findings failed to support the application of Weiner's model to the current sample. Alternative patterns of moderation and mediation were significant, however. Implications of study findings were discussed as they relate to relevant theoretical models and recent advances in clinical and educational research. / Ph. D.

As urbanization spreads, understanding its impact on wildlife is increasingly urgent. By comparing the traits and fitness of individuals within the same species found in both urban and rural habitats (urban adapters), we can better understand the behavioral and physiological coping mechanisms wild birds employ in the face of rapid environmental change. For my dissertation, I investigated the physiological, behavioral, and fitness differences between urban and rural living song sparrows (Melospiza melodia) to explore how song sparrows are adjusting to urban environments. In my first chapter, I investigated urban birds' termination of the glucocorticoid stress response by looking at their ability to reduce circulating levels of glucocorticoid 'stress' hormones and the relative abundance of receptors that provide negative feedback in the hippocampus and hypothalamus. I found that urban males have a lower relative abundance of glucocorticoid receptors and the enzyme 11β-HSD2 in the hippocampus compered too rural, though we found no difference in negative feedback at the periphery, as both urban and rural song sparrows responded similarly to a challenge with synthetic glucocorticoid (dexamethasone). In chapter 2, I asked if increased aggression, which has been rigorously documented in urban males, is also expressed by females, and whether this aggressive signaling is constraining other reproductive behaviors such as maternal care. Indeed, female song sparrows, like males, expressed increased aggressive signaling compared to rural, suggesting urban habitats may favor a more aggressive phenotype. Finally, in Chapter 3, I investigated the consequences of increased male aggression on their social partners and offspring by measuring parental care and nestling outcomes across urban and rural habits. I was unable to establish a trade-off between parental care and aggression in either sex, suggesting this increased aggression is not constraining other reproductive behaviors. In fact, the more aggressive urban males visited the nest significantly more frequently, a trend also seen in urban females during the daylight hours, though the relationship was not significant over a 24-hour period. Additionally, urban birds had significantly higher reproductive metrics compared to rural, though they also had the added cost of increase brood parasitism by brown-headed cowbirds (Molothrus ater) compared to rural. Overall increased urban aggression was associated with higher reproductive success without any reduction in paternal care. Additionally, we found physiological differences in the glucocorticoid stress response system associated with the differences in habitat but whether theses differences represent mechanisms of acclimation or potential costs of living in urban habitats is not yet clear. / Doctor of Philosophy / As urbanization spreads, understanding its impacts on wild bird conservation is increasingly urgent. By comparing the behaviors and reproductive success of animals living in urban and rural habitats (urban adapters), we can better understand the coping mechanisms wild birds' employ in the face of this form of rapid environmental change. In my dissertation, I compared the physiology, behavior, and reproductive success of urban and rural song sparrows (Melospiza melodia) to explore the changes song sparrows make to survive and reproduce in urban environments. In my first chapter, I investigated how urban birds terminate their stress response by looking at their ability to reduce circulating levels of stress hormones and the relative abundance of "shut down" targets in the brain. In chapter 2, I asked if increased aggression, regularly document in urban males, is also expressed by females, and whether this aggression is constraining other reproductive behaviors. Finally, in Chapter 3, I investigated the consequences of increased male aggression on their social partners and offspring by measuring parental care and nestling outcomes across urban and rural habits. I found that urban males have a lower relative abundance of one type of "shut down" target, and a lower abundance of a potentially protective enzyme in the hippocampus, though we found no difference in how quickly urban and rural birds cleared stress hormone from their blood. Female song sparrows, like males, expressed increased aggressive signaling compared to rural, suggesting urban habitats may favor a more aggressive pattern of behavior. However, I was unable to establish a trade-off between parental care and aggression in either sex, suggesting increased aggression is not constraining other reproductive behaviors. In fact, the more aggressive urban males visited the nest significantly more often, a trend also seen in urban females during the daylight hours, though the relationship was not significant over a 24-hour period. Additionally, urban birds had significantly higher reproductive metrics compared to rural, though they also had the added energetic cost of increased brood parasitism by brown-headed cowbirds (Molothrus ater), compared to rural. Collectively, my results suggest that individuals of this species, the song sparrow, may benefit from livening in low intensity urban habitats and that living in such altered environments favors or permits higher aggression.

Urban areas are a unique and growing habitat type. Animals living in this novel habitat are faced with new challenges, but may also encounter novel opportunities. Though urban animals have been observed to differ from their rural counterparts in a variety of behavioral and physiological traits, little is known about the specific features of urban areas that drive these differences and whether they are adaptive. Understanding this process is important from a conservation perspective and also to gain insight into how animals colonize novel habitats more generally. Using song sparrows (Melospiza melodia), a native songbird commonly found in urban areas, I explored responses to urbanization and the drivers and consequences of these responses with an eye toward understanding whether song sparrows had successfully adapted to urban habitats (Chapter I). I began by comparing body condition and levels of corticosterone, a hormone associated with energy management and the stress response in birds, between urban and rural populations (Chapter II). There was more variation across years than between habitats, suggesting that a variable environmental factor common to both habitats is the primary driver of these traits. I then compared territorial aggression levels and tested the effect of food availability on aggression (Chapter III). Fed rural birds and all urban birds had higher aggression levels than unfed rural birds, indicating that territorial aggression is related to resource availability in this species and that urban habitats may be perceived as more desirable. Finally, I looked for differences in reproductive timing and success and for relationships between reproductive success and aggression (Chapter IV). Higher reproductive success in urban populations, coupled with differences in the timing of successful nests between habitats, suggest differences in predation risk and predator community structure between habitats. In Chapter V, I synthesize my major findings and suggest directions for future research building on these results. I conclude that urban song sparrows differ from rural birds, that these differences are influenced by resource availability, and that urban habitats can potentially support stable song sparrow populations, though more research is necessary to determine the fitness impacts of specific traits that change with urbanization. / Ph. D.