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This study addressed aggressive interactions, and some of the behaviors associated with them, in House Sparrow flocks. The evidence suggests that females are the consistently dominant sex, which does not concur with the current idea of alternating dominance in House Sparrows. Another purpose of this study was to determine if predictions concerning the type of interaction and level of aggression displayed could be made for interacting House Sparrows. I feel that accurate predictions can be made when several factors are taken into account: time of year, sex, and the age of birds at the food resource. In this study adult female House Sparrows dominated males from fall through spring, even when males increased their rate of initiating interactions during winter. Across all interaction types, mid-level aggression was used most often and only in male intrasexual interactions was high-level aggression more common than expected. Juvenile birds, mainly males, change flock dynamics in the fall by eliciting aggressive interactions. / Department of Biology

Call number: LD2668 .T4 1937 H63 / Master of Science

Feeding ecology of breeding House sparrows was studied in a rural settlement in the Czech Republic. Area of home range and feeding habitat selection in relation to farming practices and vegetation management in the study area was examined.

Aging is an underlying risk factor for many major diseases including cancer, cardiovascular disease, and neurodegeneration. Yet we still do not know the full extent of how our bodies age and what determines our lifespan. One mechanism that may play an important role are telomeres, which are protective caps at the end of chromosomes. Telomeres are directly linked to longevity and can be lengthened by the enzyme telomerase. Early life telomere length is critical for lifespan, but we do not know how telomerase performs during this period. Whether variation in telomerase levels can influence telomere length and loss during development with consequences to longevity is still unknown. This thesis focuses on the role of telomerase during post-natal development and its response to stressors and activators with effects on telomeres. Taken together this research enhances our understanding of how telomerase acts and influences telomere during post-natal development.

Badges of status are supposed to have insignificant production costs, so use costs are thought to be most important in ensuring signal reliability. Use costs arise from the use of the status signal in social interactions. Social experiences that arise from the use of inappropriate signals in social interactions may drive mechanisms that result in reduced fitness for inappropriate signalers. The role of social control, probing and familiarity in producing use costs was explored. There was no evidence that social control by dominants produced a cost for cheaters and no evidence that social control by subordinates produced a cost for inappropriate signaling by Trojans. Probing produced a cost for cheating when resource value was high but not when resource value was low. Familiarity had some effect on the cost and benefit of cheating but in patterns that were not predicted. Familiarity both eliminated a benefit of cheating and reduced a cost of cheating; therefore it is uncertain how familiarity affects honest signaling. The status signal of the receiver had no effect on the cost or benefits of cheating, and there was no evidence of punishment. Social experiences have the potential to affect signal development to produce a correspondence between signal and status. The effects of social experience on signal production were examined and there was little evidence that social experience influenced bib development. Neither aggression expressed nor aggression received was not predictive of bib size. Additionally, tests on the different measures of winning experience produced conflicting conclusions regarding the relationship between winning experience and bib development.

Behavioral traits can be remarkably flexible depending on the conditions in which they are expressed, yet, in spite of this flexibility, persistent differences between individuals appear to limit the potential expression of behaviors. For example, despite evidence that parents provide variable amounts of parental care in response to changing environmental conditions, they also differ in the overall level of care they provide. I used a behavioral reaction norm approach to study individual variation in parental care behavior in free-living house sparrows (Passer domesticus). I investigated the nature of this variation by studying the relationship between different forms of parental care, the biological basis of individual variation in care, and the effect of this variation in care on offspring. First, I found a positive covariance between nestling provisioning and nest defense. Parents that provided high levels of care in one context provided high levels of care in the other context, even after accounting for measures of offspring value. Second, I sought to identify the biological sources that create and maintain consistent individual differences in the level of care a parent provides. I found that the likelihood of feeding nestlings large food items was positively associated with genetic heterozygosity, but did not find evidence that nestling provisioning was influenced by additive genetic variation in this population. Parents hatched from larger eggs provisioned offspring at a higher rate than parents hatched from smaller eggs, but there was no effect of other conditions experienced in the nest on the level of care expressed as an adult. I also tested if differences in problem-solving ability were related to differences in parental care behavior. Although I found that problem-solving parents fledged more offspring than parents that could not solve the problem, parental care was not associated with any measure of problem-solving ability. Finally, I found that individual variation in parental care reaction norms predicted the growth rate, size, and immune response of nestlings, which in turn positively affected offspring survival and recruitment. My findings reveal factors maintaining individual differences in parental care behavior and offer new insights into the causes and consequences of individual variation.

abstract: In wild birds, the stress response can inhibit the activity of the innate immune system, which serves as the first line of defense against pathogens. By elucidating the mechanisms which regulate the interaction between stress and innate immunity, researchers may be able to predict when birds experience increased susceptibility to infections and can target specific mediators to mitigate stress-induced suppression of innate immune activity. Such elucidation is especially important for urban birds, such as the House Sparrow (Passer domesticus), because these birds experience higher pathogen prevalence and transmission when compared to birds in rural regions. I investigated the role of corticosterone (CORT) in stress-induced suppression of two measures of innate immune activity (complement- and natural antibody-mediated activity) in male House Sparrows. Corticosterone, the primary avian glucocorticoid, is elevated during the stress response and high levels of this hormone induce effects through the activation of cytosolic and membrane-bound glucocorticoid receptors (GR). My results demonstrate that CORT is necessary and sufficient for stress-induced suppression of complement-mediated activity, and that this relationship is consistent between years. Corticosterone, however, does not inhibit complement-mediated activity through cytosolic GR, and additional research is needed to confirm the involvement of membrane-bound GR. The role of CORT in stress-induced inhibition of natural antibody-mediated activity, however, remains puzzling. Stress-induced elevation of CORT can suppress natural antibody-mediated activity through the activation of cytosolic GR, but the necessity of this mechanism varies inter-annually. In other words, both CORT-dependent and CORT-independent mechanisms may inhibit natural antibody-mediated activity during stress in certain years, but the causes of this inter-annual variation are not known. Previous studies have indicated that changes in the pathogen environment or food availability can alter regulation of innate immunity, but further research is needed to test these hypotheses. Overall, my dissertation demonstrates that stress inhibits innate immunity through several mechanisms, but environmental pressures may influence this inhibitory relationship. / Dissertation/Thesis / Doctoral Dissertation Biology 2017

DNA methylation patterns are sex and tissue specific in many species, yet many studies useblood samples, due to its accessibility, to establish links between the DNA methylation anddifferent phenotypes. This raises the question of whether DNA methylation in blood samplesreflect the DNA methylation pattern in other tissues that are more relevant to the phenotypebeing studied. In this research, samples were collected from the brain, blood, liver and gonadof 16 house sparrow (Passer domesticus), half of them were female, while the others weremale. Reduced representation bisulfite sequencing (RRBS) was performed to get themethylation profile in each sample. The result showed a tissue specific methylation profile inthe four investigated tissues, a strong and positive correlation between 0.74 – 0.85 was foundbetween tissues, in which a weaker correlation was found between blood and other tissue. Indifferential methylation analysis, most of the differently methylated sites between sexes werefound in gonads, while the fewest was found in blood, and Z chromosome wasoverrepresented place in all four tissues where the majority of the differently methylated sitesbetween sexes were found. Comparison with the house sparrow genome annotation foundabout half of the differentially methylated sites between sexes were within genes and about 20 % of them were in the exon or coding region of a gene. The result suggested that bloodcould be useful in reflecting the general DNA methylation level in other tissues, but it was nota reliable bioindicator for further detailed study in DNA methylation pattern or in geneontology enrichment pathway analysis.

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