The evolutionary life cycle of genes is powered by the process of gene birth and death. Although this mechanism directly impacts the genome content by generating the gain and loss of genes its dynamics within the phylogeny of eukaryotes is still unclear. The gain and loss of entire gene families is another level of the evolutionary turnover in genomes which is rather frequent but often ignored phenomena. To trace gene family gain and loss one can in principle use phylostratigraphic approach.In this project, we propose to get a comprehensive and synchronized estimate of gene family gain and loss across phylogeny of eukaryotes using hundreds of eukaryotic genomes within the phylostratigraphic framework. This knowledge will allow us to estimate rates of gene family gain and loss relate over evolutionary time, and to reconstruct the ancestral genomes. To achieve these goals we will develop novel algorithms and implement a new computational strategy within the phylostratigraphic framework which will be available as a publicly accessible web resource. Once the catalogue of gene family gain and loss is complete, we aim to link the gene-and-loss patterns to the evolution of phenotypes. Beside evolutionary biology, our gene gain and loss collection that cover wide range of eukaryotes will provide valuable information for many fields including comparative genomics, developmental biology and translational medicine. For instance it will allow us to look for the organisms that are ‘evolutionary knockouts’ for genes related to human pathologies and to find new candidate genes for diseases. Beyond the immediate benefits of high impact scientific publications and scientific collaboration we believe that this project will have a profound impact in training young experts that we aim to hire on the project and enabling them to lead the research at the interface between evolutionary and computational biology.