"The origins of eukaryotes and mitochondria are among the most fundamental questions in biology and are central to understanding eukaryotic genomic and cellular evolution. It is now accepted that the mitochondrion was ancestrally present in all eukaryotic groups and that it derives from an alpha-proteobacterium, although the precise identity of the original endosymbiont is unknown. In this project the candidate will use sophisticated computational analyses to investigate current hypotheses for the origin of eukaryotes, to identify the closest alpha-proteobacterial relatives of mitochondria, and to determine the root of the eukaryotic tree. Genome-wide computational analysis tools developed by the host lab will be used to identify genes transferred from the mitochondrial endosymbiont to the eukaryotic host nuclear genome during the evolution of the mitochondrion. The cohort of transferred genes will then be used to (i) determine the position of mitochondria among contemporary alpha-proteobacteria and (ii) root the eukaryotic tree. To do this, the candidate will be trained in the most sophisticated probabilistic methods for modeling sequence evolution and for inferring evolutionary relationships. The project is multidisciplinary and will enhance the candidate's analytical, mathematical and computational skills on a series of tightly focused biological problems for which the host laboratory has a strong international reputation. These new skills, and her already extensive international experience and contacts, will provide her with the competencies to develop a leading role as a European evolutionary biologist and bioinformatician. The project will also provide her with generic analytical skills relevant to the FP7 Health theme, ""Multidisciplinary fundamental genomics and molecular biology approaches to study basic biological processes directly relevant to health and diseases"" and ""Coordination and Support Actions in large-scale data gathering and systems biology""."