Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

<p>Although we often study mutualisms (interactions in which both species benefit) at the level of the individual partners, mutualistic interactions take place in the context of populations and communities. Sharing mutualists with others in a population could result in indirect interactions in the form of mutualist-mediated competition or facilitation. In my dissertation work I asked whether intraspecific competition or facilitation for ants might occur in an extrafloral nectary-bearing (EFN) plant, and what the consequences would be for long-term population dynamics of the plant. My focal species was <italic>Colubrina spinosa</italic> (Rhamnaceae), a neotropical treelet on which I observed 69 ant species at La Selva Biological Station, Costa Rica. </p><p> Demonstrating intraspecific competition for mutualists requires that 1) neighbor densities affect mutualist visits to an individual, and 2) change in mutualist visits results in reduced benefit. To determine how mutualist density affects plant benefit, I experimentally manipulated ant abundances on plants over two years and measured growth and survival. To assess competition for mutualists, I excluded ants from conspecific neighbors and followed ant abundance on focal plants. To consider long-term facilitation, in which greater local nectar resources increase local ant abundance, I manipulated nectar resources in a two-year field experiment and estimated ant abundance on <italic>C. spinosa</italic> plants and on baits. </p><p> Considering local neighbor density both within a 1m radius and in 5x5 m plots, ant densities on <italic>C. spinosa</italic> plants showed evidence for a small-scale competition effect and a contrasting plot-level facilitation effect. The small-scale competition was sized-based; smaller plants lost ants to larger plants. Ant benefit to plants also depended on plant size. For larger plants, those with greater size-adjusted ant density had higher growth and survival than those with fewer ants than expected for their size. </p><p> To determine whether these contrasting competition and facilitation effects could impact population growth or densities, I modeled population dynamics with an integral projection model (IPM). Growth and survival were functions of ant density, which in turn depended on conspecific neighbors, plant size, and mean background ants. Results suggest that larger-scale facilitation of mutualists impacts long-term population growth more than small-scale competition. Population growth rate increased with increasing background ant density, which depended on facilitation at the 5x5m plot scale. In contrast, small-scale competition caused a redistribution of mutualist ants among plants of different sizes, but had very little effect on long-term population growth. </p><p> I thus conclude that on the scale of individuals there is evidence of intraspecific competition for ants as well as facilitation in the EFN plant <italic>C. spinosa</italic>, but only facilitation effects lead to appreciable changes in population dynamics. If mutualist-mediated facilitation effects tend to occur over long time scales in other systems as well, facilitation might prove to be more important than competition in other mutualisms.</p> / Dissertation

Esta pesquisa tem como objetivo testar os critérios da técnica de Análise de Conteúdo Baseada em Critérios (Criteria-Based Content Analysis – CBCA) em relatos comuns de adultos, visando verificar quais critérios são mais frequentes em relatos verdadeiros. Trata-se de um estudo preliminar para futura elaboração de técnica de avaliação da credibilidade do testemunho, a ser utilizada para auxiliar as avaliações psicológicas das entrevistas realizadas nas perícias com adultos. Foram realizadas 46 entrevistas com relato livre e perguntas abertas com adultos a partir de 18 anos e escolaridade mínima de ensino médio, propondo-se 3 tarefas: 2 relatos (um verdadeiro e um falso) e a aplicação da Escala Fatorial de Neuroticismo - EFN. Na análise das entrevistas, obteve-se como resultados que os critérios “5: Descrições de interações” e “8: Detalhes não-usuais” são significativamente mais presentes nos relatos verdadeiros. Os resultados da EFN não mostraram diferenças significativas entre os participantes em função do nível de ansiedade. Os itens significativos para a verificação da credibilidade do testemunho poderão ser futuramente utilizados em novas pesquisas que explorem a análise das versões apresentadas à perícia criminal oficial durante a reprodução simulada dos fatos, após serem testados, em novas pesquisas específicas frente à veracidade na técnica pericial. / This research aimed to test the criteria of the Criteria-Based Content Analysis - CBCA technique in common reports of adults to ascertain which are the most frequent in true reports. It is a preliminary study to allow future elaboration of technical assessment of witness credibility to be used to assist psychological assessments in forensic interviews with adults. For this purpose, 46 free reports and open questions interviews with adults with minimum age of 18 years and at least high school education were made. Three tasks were proposed: to tell two stories (one true and one false) and to answer the Factorial Scale of Neuroticism - EFN. The analysis of the interviews showed that criteria “5: description of interactions” and “8: non-usual details” were significantly more frequent in true reports. The results of the EFN did not show significant differences among the participants based on the level of anxiety The significant items for checking the credibility of the testimony can be further explored in new research to explore the analysis of the versions presented to the crime scene investigators during reconstruction, after being tested in specific new research on expert technical veracity.

Esta pesquisa tem como objetivo testar os critérios da técnica de Análise de Conteúdo Baseada em Critérios (Criteria-Based Content Analysis – CBCA) em relatos comuns de adultos, visando verificar quais critérios são mais frequentes em relatos verdadeiros. Trata-se de um estudo preliminar para futura elaboração de técnica de avaliação da credibilidade do testemunho, a ser utilizada para auxiliar as avaliações psicológicas das entrevistas realizadas nas perícias com adultos. Foram realizadas 46 entrevistas com relato livre e perguntas abertas com adultos a partir de 18 anos e escolaridade mínima de ensino médio, propondo-se 3 tarefas: 2 relatos (um verdadeiro e um falso) e a aplicação da Escala Fatorial de Neuroticismo - EFN. Na análise das entrevistas, obteve-se como resultados que os critérios “5: Descrições de interações” e “8: Detalhes não-usuais” são significativamente mais presentes nos relatos verdadeiros. Os resultados da EFN não mostraram diferenças significativas entre os participantes em função do nível de ansiedade. Os itens significativos para a verificação da credibilidade do testemunho poderão ser futuramente utilizados em novas pesquisas que explorem a análise das versões apresentadas à perícia criminal oficial durante a reprodução simulada dos fatos, após serem testados, em novas pesquisas específicas frente à veracidade na técnica pericial. / This research aimed to test the criteria of the Criteria-Based Content Analysis - CBCA technique in common reports of adults to ascertain which are the most frequent in true reports. It is a preliminary study to allow future elaboration of technical assessment of witness credibility to be used to assist psychological assessments in forensic interviews with adults. For this purpose, 46 free reports and open questions interviews with adults with minimum age of 18 years and at least high school education were made. Three tasks were proposed: to tell two stories (one true and one false) and to answer the Factorial Scale of Neuroticism - EFN. The analysis of the interviews showed that criteria “5: description of interactions” and “8: non-usual details” were significantly more frequent in true reports. The results of the EFN did not show significant differences among the participants based on the level of anxiety The significant items for checking the credibility of the testimony can be further explored in new research to explore the analysis of the versions presented to the crime scene investigators during reconstruction, after being tested in specific new research on expert technical veracity.

Esta pesquisa tem como objetivo testar os critérios da técnica de Análise de Conteúdo Baseada em Critérios (Criteria-Based Content Analysis – CBCA) em relatos comuns de adultos, visando verificar quais critérios são mais frequentes em relatos verdadeiros. Trata-se de um estudo preliminar para futura elaboração de técnica de avaliação da credibilidade do testemunho, a ser utilizada para auxiliar as avaliações psicológicas das entrevistas realizadas nas perícias com adultos. Foram realizadas 46 entrevistas com relato livre e perguntas abertas com adultos a partir de 18 anos e escolaridade mínima de ensino médio, propondo-se 3 tarefas: 2 relatos (um verdadeiro e um falso) e a aplicação da Escala Fatorial de Neuroticismo - EFN. Na análise das entrevistas, obteve-se como resultados que os critérios “5: Descrições de interações” e “8: Detalhes não-usuais” são significativamente mais presentes nos relatos verdadeiros. Os resultados da EFN não mostraram diferenças significativas entre os participantes em função do nível de ansiedade. Os itens significativos para a verificação da credibilidade do testemunho poderão ser futuramente utilizados em novas pesquisas que explorem a análise das versões apresentadas à perícia criminal oficial durante a reprodução simulada dos fatos, após serem testados, em novas pesquisas específicas frente à veracidade na técnica pericial. / This research aimed to test the criteria of the Criteria-Based Content Analysis - CBCA technique in common reports of adults to ascertain which are the most frequent in true reports. It is a preliminary study to allow future elaboration of technical assessment of witness credibility to be used to assist psychological assessments in forensic interviews with adults. For this purpose, 46 free reports and open questions interviews with adults with minimum age of 18 years and at least high school education were made. Three tasks were proposed: to tell two stories (one true and one false) and to answer the Factorial Scale of Neuroticism - EFN. The analysis of the interviews showed that criteria “5: description of interactions” and “8: non-usual details” were significantly more frequent in true reports. The results of the EFN did not show significant differences among the participants based on the level of anxiety The significant items for checking the credibility of the testimony can be further explored in new research to explore the analysis of the versions presented to the crime scene investigators during reconstruction, after being tested in specific new research on expert technical veracity.

Bourse de maîtrise du Groupe de recherche sur le système nerveux central GRSNC, (2009,2010) Bourse d’études supérieures du Canada Frederick Banting et Charles Best, IRSC Instituts de recherche en santé du Canada, (2011) / EphA7 est un membre de la famille des récepteurs à tyrosine kinase Eph, qui régulent l’adhérence et la motilité cellulaires. EphA7 est hautement conservé chez les vertébrés et largement exprimé durant l'embryogenèse, en particulier pendant le développement du SNC. Dans le cerveau adulte, EphA7 est transcrit principalement dans l'hippocampe, avec de faibles niveaux d'expression ailleurs. Nous avons cartographié sa distribution dans le cerveau du rat et de la souris adultes, par hybridation in situ et immunohistochimie en microscopie photonique et électronique. Les deux méthodes montrent une distribution de marquage très cohérente. Le signal le plus fort a été observé dans l’hippocampe, avec des niveaux moins élevés dans l’habénula, le striatum, l’amygdale, les cortex cingulaire, piriforme et entorhinal, ainsi que le cervelet. Au niveau ultrastructural, dans l’hippocampe, l’immunoréactivité d’EphA7 a été localisée dans le cytoplasme des cellules granulaires (gyrus dentelé) et pyramidales (CA1 et CA3) en ordre décroissant d’intensité. Dans le neuropile de CA1, des épines dendritiques et des prolongements astrocytaires, souvent périsynaptiques, ont été les éléments le plus fréquemment marqués. Plus rarement, nous avons aussi rencontré des dendrites et des terminaisons axonales immunopositives. La localisation préférentielle d’EphA7 dans les épines dendritiques et les prolongements astrocytaires périsynaptiques est conséquente avec un rôle de ce récepteur dans la plasticité synaptique / Abstract: EphA7 is a member of the family of Eph receptor tyrosine kinases, which regulate cell adhesion and motility. EphA7 is highly conserved in vertebrates and widely expressed during embryogenesis, especially during the development of the CNS. In the adult brain, EphA7 is transcribed mainly in the hippocampus, with low expression levels elsewhere. We have mapped its distribution in the adult brain of rat and mice by in situ hybridization and by immunohistochemistry in light and electron microscopy. Both methods show very consistent labelling distribution. The strongest signal was observed in the hippocampus, but modest levels were detected in the habenula, striatum, amygdala, the cingulate, piriform and entorhinal cortex, and the cerebellum. At the ultrastructural level, in the hippocampus, EphA7 immunoreactivity was localized in the cytoplasm of granule (dentate gyrus) and pyramidal cells (CA1 and CA3) in descending order of intensity. In the neuropil of CA1, dendritic spines and astrocytic processes, often perisynaptic were the most frequently labelled. More rarely, we also observed immunopositive dendrites and axon terminals. The preferential localization of EphA7 in dendritic spines and perisynaptic astrocytic processes is consistent with a role of this receptor in synaptic plasticity

EphA7 est un membre de la famille des récepteurs à tyrosine kinase Eph, qui régulent l’adhérence et la motilité cellulaires. EphA7 est hautement conservé chez les vertébrés et largement exprimé durant l'embryogenèse, en particulier pendant le développement du SNC. Dans le cerveau adulte, EphA7 est transcrit principalement dans l'hippocampe, avec de faibles niveaux d'expression ailleurs. Nous avons cartographié sa distribution dans le cerveau du rat et de la souris adultes, par hybridation in situ et immunohistochimie en microscopie photonique et électronique. Les deux méthodes montrent une distribution de marquage très cohérente. Le signal le plus fort a été observé dans l’hippocampe, avec des niveaux moins élevés dans l’habénula, le striatum, l’amygdale, les cortex cingulaire, piriforme et entorhinal, ainsi que le cervelet. Au niveau ultrastructural, dans l’hippocampe, l’immunoréactivité d’EphA7 a été localisée dans le cytoplasme des cellules granulaires (gyrus dentelé) et pyramidales (CA1 et CA3) en ordre décroissant d’intensité. Dans le neuropile de CA1, des épines dendritiques et des prolongements astrocytaires, souvent périsynaptiques, ont été les éléments le plus fréquemment marqués. Plus rarement, nous avons aussi rencontré des dendrites et des terminaisons axonales immunopositives. La localisation préférentielle d’EphA7 dans les épines dendritiques et les prolongements astrocytaires périsynaptiques est conséquente avec un rôle de ce récepteur dans la plasticité synaptique / Abstract: EphA7 is a member of the family of Eph receptor tyrosine kinases, which regulate cell adhesion and motility. EphA7 is highly conserved in vertebrates and widely expressed during embryogenesis, especially during the development of the CNS. In the adult brain, EphA7 is transcribed mainly in the hippocampus, with low expression levels elsewhere. We have mapped its distribution in the adult brain of rat and mice by in situ hybridization and by immunohistochemistry in light and electron microscopy. Both methods show very consistent labelling distribution. The strongest signal was observed in the hippocampus, but modest levels were detected in the habenula, striatum, amygdala, the cingulate, piriform and entorhinal cortex, and the cerebellum. At the ultrastructural level, in the hippocampus, EphA7 immunoreactivity was localized in the cytoplasm of granule (dentate gyrus) and pyramidal cells (CA1 and CA3) in descending order of intensity. In the neuropil of CA1, dendritic spines and astrocytic processes, often perisynaptic were the most frequently labelled. More rarely, we also observed immunopositive dendrites and axon terminals. The preferential localization of EphA7 in dendritic spines and perisynaptic astrocytic processes is consistent with a role of this receptor in synaptic plasticity / Bourse de maîtrise du Groupe de recherche sur le système nerveux central GRSNC, (2009,2010) Bourse d’études supérieures du Canada Frederick Banting et Charles Best, IRSC Instituts de recherche en santé du Canada, (2011)

The purpose of this study was to explore the incentives and barriers perceived by low-income women of child-bearing age related to their participation in nutrition education programs. The specific programs of concern in this study are the Expanded Food and Nutrition Education Program (EFNEP) and the Food Stamp Nutrition Education (FSNE) program. This qualitative study sought to hear the voices of the women so that nutrition programs can be made more successful in reaching this population. Personal interviews were conducted with 23 women in their homes or appropriate local sites, and transcripts were analyzed to identify categories and themes. People of low socioeconomic status and those with the least education have higher rates of obesity and overweight and suffer disproportionately from poor health. Women receiving Temporary Assistance to Needy Families (TANF) also receive Medicaid. Medicaid costs have escalated due to the obesity rate, which is currently estimated at 64% of the adult population. In addition, 30% of American children are experiencing obesity or are overweight. It is important for parents to understand the causes of obesity and the effects of the chronic diseases related to obesity. Prevention programs are more cost effective than medical treatment of the diseases associated with obesity, and proper nutrition can reduce the incidence of chronic diseases. Findings of this study suggest that isolation is the main impediment to participating in nutrition education programs. Missing from the interviewed women's circumstances are social capital, human capital, and economic capital. Social capital relates to the connections and relationships that are important in life. Human capital involves the knowledge and skills acquired through life experiences. Economic capital refers to individual wealth or economic resources available to an individual or community. Nutrition education programs should be refined to incorporate opportunities for socialization that will develop trust and reciprocity, as well as nutrition knowledge. Based on the results of this study, Virginia Cooperative Extension programs will be adapted to incorporate weight control and cooking classes with nutritious recipes. The learning environment will be safe, learner-centered, and fun. New marketing tools that are more appealing to the prospective clients will be developed. / Ed. D.