The structure and dynamics of complex microbe-host interaction networks
Microbes form intricate and intimate relationships with most animals and plants, many of which are crucial for host development, health and functioning. Microbe--host symbiotic associations are poorly explored in comparison with other species interaction networks. The current paradigm on symbiosis r...
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| Formato: | tesis doctoral |
| Fecha de publicación: | 2016 |
| País: | España |
| Recursos: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/96369 |
| Acesso em linha: | https://hdl.handle.net/2117/96369 https://dx.doi.org/10.5821/dissertation-2117-96369 |
| Access Level: | acceso abierto |
| Palavra-chave: | Microbiologia Microorganismes Àrees temàtiques de la UPC::Enginyeria civil |
| Resumo: | Microbes form intricate and intimate relationships with most animals and plants, many of which are crucial for host development, health and functioning. Microbe--host symbiotic associations are poorly explored in comparison with other species interaction networks. The current paradigm on symbiosis research stems from species-poor systems where pairwise and reciprocally specialised interactions between a single microbe and host that coevolve are the norm. These symbioses involving just a few species are fascinating in their own right, but more diverse and complex host-associated microbial communities, so-called microbiomes, are increasingly found, with new emerging questions that require new paradigms and approaches. In this thesis, I investigate the structure and dynamics of complex microbe-host systems, focusing on the specialisation of their ecological interactions and on identifying fingerprints of coevolution in multispecies communities. I take a holistic approach to study interactions between complex assemblages of microbes associated to multiple host species through time and space. My overreaching objective is twofold. First, to determine the structure and dynamics of host-associated cores--a set of highly specialised and complementary microbial symbionts with a disproportionately large influence on the dynamics and stability of the assemblage as a whole. Second, to increase our understanding of the underlying ecological and evolutionary processes that determine the structure and dynamics of core microbiomes, which ultimately influence the functional relationship between symbionts and hosts. In my thesis, I use marine sponges and their associated bacteria as a study system. Marine sponges are one of the invertebrate phyla harbouring the largest abundance and diversity of microbes, and it is the phylogenetically oldest, still extant metazoan phyla with the hypothesized oldest microbe-host symbiotic interactions. I show that sponge-associated microbial communities emerge as one of the most specialised, yet highly diverse ecological networks ever analysed. I show that hosts harbour a core microbiome not only common to most individuals of the same species, but that cores often consist of abundant, temporally stable microbes that persistently associate to hosts over periods of years and probably even longer, and that some hosts preserve subsets of their specialised interactions by vertically transmitting microbes to the next generation. I find that the presence of high-density core microbiomes confers hosts a resistance against the increase in abundance of the many occasional microbes that pass through the sponge due to its filter-feeding activities. I show that intraspecific interactions through density-dependent dynamics together with weak interspecific interactions are likely key determinants of microbiome stability and fingerprints of coevolved interactions. |
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