Résumé
Global changes impose an unprecedented challenge on biologists, particularly because of the urgency to develop strategies that optimize the trade-off between the conservation of biodiversity and growing resource needs. A key step consists of developing fundamental knowledge for a better understanding and better prediction of how these changes modify biodiversity at each organizational level of life. By combining conceptual reflections and empirical approaches, I study the ecology and evolution of interactions at different levels of organization of life from molecules to ecosystems.My work falls within two main eco-evolutionary contexts. 1. Host-pathogen-environment relationships and more particularly the factors that influence the transmission of pathogens. 2. The response of organisms to global changes with corals as the main model. A summary of my completed work is presented in this section. This synthesis does not follow a chronological order but is structured according to the different organizational levels in which my research work takes place, from molecules to ecosystems, in order to best anchor the questions that animate me today.