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25 September

Amélie Peres Evolutionary history of genes in vertebrate genomes

14h à 15h30

La soutenance de thèse d’Amélie Peres aura lieu dans la salle Favard, IBENS 46 rue d’Ulm 75005 Paris

Two categories of evolutionary processes can disrupt the gene organization in eukaryotic genomes: changes in the content of genomes by gene duplications or gene deletions, and changes in the order of the genes by rearrangements. Functional and selective impacts of these processes on genomes are poorly understood.
This thesis covers three different projects about duplication and deletion events that change the number of gene copies. We were interested in these events from phylogenetic trees reconstructed at the scale of whole genomes. In the first part we examined the case where these events would be under negative selection, by studying phylogenetic gene trees where no duplication or deletion was fixed. We found that these genes have special properties and propose hypotheses to explain them. In the second part we looked at gene duplications and correlated these events with the evolution of biological functions. Finally in the last part we have studied in detail the ROBO genes family in which one copy has acquired a different function in the developing nervous system of mammals under the influence of positive selection.
Taken together these results provide new elements to measure and understand the global impact of constraints or advantages that gene duplications in particular, and the change of genes copy number in general, can have on a vertebrate genome.