Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves [140]-165). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves [140]-165). Also available on the Internet.

Thesis (M.S.)--Western Washington University, 2010. / Includes bibliographical references (leaves 70-73). Also issued online.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Ulrich G. Mueller. Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

OLIVEIRA, Francisca Andréa da Silva. Estudo da diversidade dos micro-organismos associados a ascídias coloniais (Tunicata, Ascidiacea). 2010. 73 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia de Pesca, Fortaleza-CE, 2010 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-14T13:33:32Z No. of bitstreams: 1 2010_dis_fasoliveira.pdf: 963916 bytes, checksum: 735a98015e0ab25bc85042267026ab3a (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-14T13:33:51Z (GMT) No. of bitstreams: 1 2010_dis_fasoliveira.pdf: 963916 bytes, checksum: 735a98015e0ab25bc85042267026ab3a (MD5) / Made available in DSpace on 2016-07-14T13:33:51Z (GMT). No. of bitstreams: 1 2010_dis_fasoliveira.pdf: 963916 bytes, checksum: 735a98015e0ab25bc85042267026ab3a (MD5) Previous issue date: 2010 / The symbiosis with microorganisms is well known for many marine invertebrate taxa. Despite that, information about these interactions along the Brazilian coast are scanty or even nonexistent. Microorganisms have also recognized as the real producers of interesting natural compounds extracted from marine invertebrates, such as ascidians. With that in mind, the goal of the present study was to evaluate the microbiota associated to colonial ascidians, focusing on symbiotic cyanobacterias, then classifying, estimating the community diversity, and identifying specific interactions between the microbiota and its hosts. This study assessed two ascidians species Didemnum galacteum and Cystodytes sp. collected in the west coast of Ceara state (Brazil), at Dois Coqueiros beach and port of Pecém, respectively. The microbiota was analyzed initially through optical microscopy and subsequently by molecular techniques such as denaturing gradient gel electrophoresis (DGGE) and 16S rRNA library. The microscopic analysis showed a community comprising cyanobacteria and diatoms. DGGE results presented the community profile in terms of Operational Taxonomic Units (OTUs), pointing out Didemnum galacteum as the most diverse. The microbiota in the seawater where specimens were collected was compared to that from the ascidians’ tunic surfaces, and results showed higher number of OTUs in the water, and a more specific microbiota in ascidians. The microbiota community studied by 16S rRNA library revealed dominance of bacteria in both libraries assessed, in which Proteobacteria taxon prevailed with either Alphaproteobaccteria in Didemnum galacteum, and Gammaproteobacteria in Cystodytes sp. Others, such as Bacteroidetes, Planctomycetes, Actinobacteria, Cyanobacteria and uncultured bacteria were evident in Didemnum galacteum, but in a lesser proportion / A simbiose com micro-organismos é bem conhecida em diversos táxons de invertebrados marinhos. No entanto, pouca ou quase nenhuma informação há sobre essa interação para os animais do litoral brasileiro. Micro-organismos tem sido apontados ainda como os responsáveis pela produção de compostos com atividades biológicas interessantes presentes em animais como as ascídias. Diante disso, o objetivo da presente pesquisa foi o de estudar a microbiota associada a superfície externa de ascídias coloniais, com ênfase em cianobactérias simbiontes, classificando, conhecendo o perfil de diversidade da comunidade e identificando associações específicas entre componentes da microbiota e ascídias hospedeiras. O estudo foi realizado com duas espécies de ascídias: Didemnum galacteum e Cystodytes sp., coletadas na região oeste do Estado do Ceará (Brasil), na praia dos Dois Coqueiros e Porto do Pecém, respectivamente. A microbiota foi analisada inicialmente por meio da microscopia ótica e posteriormente por técnicas moleculares como: eletroforese em gel de gradiente desnaturante (DGGE) e biblioteca do 16S rRNA. A análise microscópica evidenciou uma comunidade composta por cianobactérias e diatomáceas. Os resultados do DGGE mostraram o perfil da comunidade em termos de Unidades Taxonômicas Operacionais (UTOs), com a maior diversidade de UTOs apontada na ascídia Didemnum galacteum. A microbiota presente na água do mar onde os espécimes foram coletados foi comparada com a microbiota da superfície da túnica da ascídia, e os resultados evidenciaram que o número de UTOs é maior na água do mar e que a ascídia apresenta uma microbiota específica. A comunidade microbiana analisada pela biblioteca do 16S rRNA revelou a dominância de bactérias nas duas bibliotecas analisadas. Dentre as bactérias o táxon dominante em todos os casos foi Proteobacteria, com Alphaproteobacteria para a ascídia Didemnum galacteum e Gammaproteobacteria para a ascídia Cystodytes sp. Outros representantes como Bacteroidetes, Planctomycetes, Actinobacteria, Cyanobacteria e Bactérias não cultiváveis foram evidenciadas na microbiota de Didemnum galacteum, porém em menor proporção

The history of life has involved several major evolutionary transitions that have each led to the emergence of a new individual. Examples of major transitions in individuality include the evolution of the eukaryotic cell, multicellular organisms and eusocial societies. In each of these events, previously independently replicating units (cells, individuals etc.) cooperate to form a new individual, which can then only replicate as a whole. For this to occur, conflict between individuals needs to be minimised, to allow maximising their inclusive fitness to be roughly equivalent to maximising group fitness. It has been predicted that the way in which social groups form should be key for eliminating conflict between individuals and promoting cooperation. In this thesis, I have focused on two major evolutionary transitions; the evolution of multicellularity and the evolution of symbiosis, and show that the mode of group formation (whether groups are parentoffspring associations or not) is crucial for understanding when and why major transitions occur. Firstly, I show that the major transition to obligate multicellularity has only occurred with clonal group formation (where cells remain together after division). Secondly, I use an experimental system to show that predation pressure may be key in promoting the formation of multicellular groups in algae. Finally, I show that the mode of group formation is also important in between-species transitions. I use the evolution of symbiosis to show that transmission route of symbionts and environmental factors, determine how cooperative symbionts will be towards their hosts.

vii, 75 leaves : ill. ; 28 cm Typescript. (Another copy on microfilm is located in Archives) Thesis (M.S.) -- University of Oregon Includes vita and abstract Bibliography: leaves 68-75 University of Oregon theses, Dept. of Biology, M.S., 1980

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A simbiose com micro-organismos à bem conhecida em diversos tÃxons de invertebrados marinhos. No entanto, pouca ou quase nenhuma informaÃÃo hà sobre essa interaÃÃo para os animais do litoral brasileiro. Micro-organismos tem sido apontados ainda como os responsÃveis pela produÃÃo de compostos com atividades biolÃgicas interessantes presentes em animais como as ascÃdias. Diante disso, o objetivo da presente pesquisa foi o de estudar a microbiota associada a superfÃcie externa de ascÃdias coloniais, com Ãnfase em cianobactÃrias simbiontes, classificando, conhecendo o perfil de diversidade da comunidade e identificando associaÃÃes especÃficas entre componentes da microbiota e ascÃdias hospedeiras. O estudo foi realizado com duas espÃcies de ascÃdias: Didemnum galacteum e Cystodytes sp., coletadas na regiÃo oeste do Estado do Cearà (Brasil), na praia dos Dois Coqueiros e Porto do PecÃm, respectivamente. A microbiota foi analisada inicialmente por meio da microscopia Ãtica e posteriormente por tÃcnicas moleculares como: eletroforese em gel de gradiente desnaturante (DGGE) e biblioteca do 16S rRNA. A anÃlise microscÃpica evidenciou uma comunidade composta por cianobactÃrias e diatomÃceas. Os resultados do DGGE mostraram o perfil da comunidade em termos de Unidades TaxonÃmicas Operacionais (UTOs), com a maior diversidade de UTOs apontada na ascÃdia Didemnum galacteum. A microbiota presente na Ãgua do mar onde os espÃcimes foram coletados foi comparada com a microbiota da superfÃcie da tÃnica da ascÃdia, e os resultados evidenciaram que o nÃmero de UTOs à maior na Ãgua do mar e que a ascÃdia apresenta uma microbiota especÃfica. A comunidade microbiana analisada pela biblioteca do 16S rRNA revelou a dominÃncia de bactÃrias nas duas bibliotecas analisadas. Dentre as bactÃrias o tÃxon dominante em todos os casos foi Proteobacteria, com Alphaproteobacteria para a ascÃdia Didemnum galacteum e Gammaproteobacteria para a ascÃdia Cystodytes sp. Outros representantes como Bacteroidetes, Planctomycetes, Actinobacteria, Cyanobacteria e BactÃrias nÃo cultivÃveis foram evidenciadas na microbiota de Didemnum galacteum, porÃm em menor proporÃÃo / The symbiosis with microorganisms is well known for many marine invertebrate taxa. Despite that, information about these interactions along the Brazilian coast are scanty or even nonexistent. Microorganisms have also recognized as the real producers of interesting natural compounds extracted from marine invertebrates, such as ascidians. With that in mind, the goal of the present study was to evaluate the microbiota associated to colonial ascidians, focusing on symbiotic cyanobacterias, then classifying, estimating the community diversity, and identifying specific interactions between the microbiota and its hosts. This study assessed two ascidians species Didemnum galacteum and Cystodytes sp. collected in the west coast of Ceara state (Brazil), at Dois Coqueiros beach and port of PecÃm, respectively. The microbiota was analyzed initially through optical microscopy and subsequently by molecular techniques such as denaturing gradient gel electrophoresis (DGGE) and 16S rRNA library. The microscopic analysis showed a community comprising cyanobacteria and diatoms. DGGE results presented the community profile in terms of Operational Taxonomic Units (OTUs), pointing out Didemnum galacteum as the most diverse. The microbiota in the seawater where specimens were collected was compared to that from the ascidiansâ tunic surfaces, and results showed higher number of OTUs in the water, and a more specific microbiota in ascidians. The microbiota community studied by 16S rRNA library revealed dominance of bacteria in both libraries assessed, in which Proteobacteria taxon prevailed with either Alphaproteobaccteria in Didemnum galacteum, and Gammaproteobacteria in Cystodytes sp. Others, such as Bacteroidetes, Planctomycetes, Actinobacteria, Cyanobacteria and uncultured bacteria were evident in Didemnum galacteum, but in a lesser proportion

Most eukaryotes harbor a diverse community of parasitic, mutualistic, and commensal microbial symbionts. Although the diversity of these microbial symbiotic communities has recently drawn considerable attention, theory regarding the evolution of interactions among symbionts and with the host is still in its nascent stages. Here we evaluate the role of interactions among coinfecting symbionts in the evolution of symbiont virulence toward the host. To do so, we place the virulence-transmission trade-off into a community context and model the evolution of symbiont trophic modes along the continuum from parasitism (virulence) to mutualism (negative virulence). We establish a framework for studying multiple infections of a host by the same symbiont species and coinfection by multiple species, using a concept of shared costs, wherein the negative consequences of virulence (or harm) toward the host are shared among symbionts. Our results show that mutualism can be maintained under infection by multiple symbionts when shared costs are sufficiently low, while greater virulence and parasitism toward the host are more likely when shared costs are high. Last, for coinfection by more than one species, we show that if the presence of a mutualist ameliorates some of the costs of pathogen virulence, then the symbiotic community may more often evolve to a more commensal state and maintain mutualisms.