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DC Field | Value | Language |
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dc.contributor.advisor | López Legentil, Susanna | - |
dc.contributor.advisor | Erwin, Patrick M. | - |
dc.contributor.author | Pita Galán, Lucía | - |
dc.contributor.other | Universitat de Barcelona. Departament de Biologia Animal | - |
dc.date.accessioned | 2014-06-13T10:03:59Z | - |
dc.date.available | 2014-06-13T10:03:59Z | - |
dc.date.issued | 2014-05-26 | - |
dc.identifier.uri | http://hdl.handle.net/2445/54978 | - |
dc.description.abstract | [spa] Las esponjas de mar son determinantes en el bentos debido a su diversidad, abundancia, a que son refugio para otros organismos y a su influencia en los ciclos biogeoquímicos. Además, cuentan con defensas químicas cuya actividad citotóxica tiene potencial farmacéutico. Estas funciones que hacen relevante a las esponjas derivan en parte de su simbiosis con una compleja microbiota dominada por bacterias y específica de la especie de esponja considerada. Pero, hasta ahora, la mayoría de estudios se basan en muestras recogidas en un punto concreto en el tiempo y el espacio, por lo que desconocemos el potencial dinamismo de la interacción. En esta tesis tomamos como modelo esponjas simpátricas del género Ircinia para distinguir el efecto relativo de las condiciones externas y de la especie de esponja sobre la estructura de su comunidad bacteriana a escalas espaciales y temporales. En concreto, evaluamos el efecto de las corrientes y heterogeneidad espacial del ambiente (escala de cientos de kilómetros) sobre las comunidades bacterianas en esponjas de Las Bahamas (Ircinia felix e I. strobilina) (capítulo 1), y confirmamos si el mismo patrón ocurre también en las especies mediterráneas (I. fasciculata, I. variabilis e I. oros) (capítulo 2). Dado que el Mediterráneo Occidental se caracteriza por una marcada estacionalidad en las condiciones del agua también investigamos las comunidades bacterianas de estas especies en distintas estaciones del año (capítulo 3). Finalmente, considerando las recientes mortalidades masivas de esponjas en esta zona, testamos en experimentos de acuario si cambios anormales del ambiente (incremento de temperatura o disminución de la densidad de partículas en el agua) influyen en las comunidades simbiontes (capítulo 4). Para caracterizar las comunidades bacterianas combinamos microscopía electrónica y herramientas moleculares (librerías de clones y huella molecular de secuencias del gen ARNr 16S). Nuestros resultados demuestran que procesos específicos de la esponja, y no factores biogeográficos, son los principales responsables de estructurar las comunidades bacterianas simbiontes. La especificidad de las comunidades bacterianas respecto a la especie de esponja se mantuvo a las escalas espaciotemporales analizadas. Los experimentos de estrés no causaron ningún cambio significativo en la comunidad bacteriana. Proponemos que esta asociación, íntima y estable, ha resultado en un sistema cooperativo en el que la actividad de la propia comunidad, junto con la homeostasis del animal, contribuyen a la persistencia de la interacción frente a distintas condiciones ambientales. | spa |
dc.description.abstract | [eng] Marine sponges are a key component of benthic ecosystems in oceans all around the world, from shallow to deep waters, due to their diversity, abundance and influence in the cycle of nutrients. Moreover, the chemical defenses of the sponge against competitors, predators and fouling make the sponge a rich source of novel antitumoral drugs. But the relevance of sponge partially relies on their association with a complex microbial community that expands the metabolism of the host (e.g., via photosynthesis or nitrogen fixation) and takes part of metabolite synthesis. The symbiotic community is dominated by bacteria. One sponge specimen can host hundreds of bacterial taxa that are closely related with other sponge-derived bacteria but rare or absent in the surrounding environment (i.e., seawater and sediments). The sponge-associated bacterial communities are species-specific, but most of the studies are based on samplings at a particular point in time and space; thus, we ignore the potential dynamism of this interaction. The main objective of this PhD thesis was to identify the specificity and persistence of sponge-bacteria symbiosis through spatial and temporal scales. In particular, we used sympatric sponges of the genus Ircinia as a model to distinguish the relative role of environmental-related and host-related factors on the structure of their bacterial communities. In particular, we aimed to assess the effect of currents and spatial heterogeneity of the environment on the bacterial communities associated with sponges from the Bahamas (Ircinia felis and I. strobilina) at a scale of hundreds of kilometers (chapter 1) and confirm if the same pattern is applied to Mediterranean species (I. fasciculata, I. variabilis and I. oros) (chapter 2). Considering the marked seasonality in seawater conditions (i.e., temperature, irradiance, nutrient levels) in the Western Mediterranean Sea, we also investigated the bacterial communities in these sponges through different seasons (chapter 3). Recently, sponges and other filter-feeding invertebrates in the Mediterranean Sea have overcome mass mortality events; thus, we tested in aquaria experiments the potential influence of abnormal environmental changes (drastic increase of temperature and food shortage) in the symbiotic bacterial communities in I. fasciculata and I. oros. Bacterial communities were characterized by transmission electron microscopy and molecular tools (i.e., clone libraries and DNA fingerprinting of 16S rRNA gene sequences). The results derived from this thesis show that host-specific rather than biogeographic factors play a major role in structuring and maintaining sponge-associated bacterial communities. The bacterial communities in Ircinia spp. were species-specific and this specificity were maintained through hundreds of kilometers (chapters 1 and 2) and despite seasonality in seawater conditions (chapter 3). Moreover, stress conditions in aquaria experiments did not significantly affect the symbiotic bacterial communities (chapter 4). These results suggest a tight and stable link between the sponges and their bacterial communities. We proposed that this symbiosis have resulted in a cooperative system where the activity of the bacterial community, together with the homeostasis of the animal host, contribute to the persistence of the interaction under different environmental conditions. | eng |
dc.format.extent | 258 p. | - |
dc.format.mimetype | application/pdf | - |
dc.language.iso | eng | - |
dc.publisher | Universitat de Barcelona | - |
dc.rights | cc-by-nc-nd, (c) Pita, 2014 | - |
dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/3.0/ | - |
dc.source | Tesis Doctorals - Departament - Biologia Animal | - |
dc.subject.classification | Esponges | - |
dc.subject.classification | Biogeografia | - |
dc.subject.classification | Microbiologia marina | - |
dc.subject.classification | Bacteris | - |
dc.subject.classification | Ecologia marina | - |
dc.subject.other | Sponges | - |
dc.subject.other | Biogeography | - |
dc.subject.other | Marine microbiology | - |
dc.subject.other | Bacteria | - |
dc.subject.other | Marine ecology | - |
dc.title | Biogeography of sponge-associated bacterial communities and resilence to anthropogenic perturbations = Biogeografía de las comunidades bacterianas asociadas a esponjas y su resiliencia frente a perturbaciones antropogénicas | - |
dc.type | info:eu-repo/semantics/doctoralThesis | - |
dc.type | info:eu-repo/semantics/publishedVersion | - |
dc.identifier.dl | B 14948-2014 | - |
dc.date.updated | 2014-06-13T10:03:59Z | - |
dc.rights.accessRights | info:eu-repo/semantics/openAccess | - |
dc.identifier.tdx | http://hdl.handle.net/10803/145031 | - |
Appears in Collections: | Tesis Doctorals - Departament - Biologia Animal |
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File | Description | Size | Format | |
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LPG_PhD_THESIS.pdf | 16.38 MB | Adobe PDF | View/Open |
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