Resumen de Evolutionary dynamics of populations with genotype-phenotype map
Esther Ibáñez Marcelo
In this thesis we develop a multi-scale model of the evolutionary dynamics of a population of cells, which accounts for the mapping between genotype and phenotype as determined by a model of the gene regulatory network. We study topological properties of genotype-phenotype networks obtained from the multi-scale model. Moreover, we study the problem of evolutionary escape and survival taking into account a genotype-phenotype map. An outstanding feature of populations with genotype-phenotype map is that selective pressures are determined by the phenotype, rather than genotypes. Our multi-scale model generates the evolution of a genotype-phenotype network represented by a pseudo-bipartite graph, that allows formulate a topological definition of the concepts of robustness and evolvability. We further study the problem of evolutionary escape for cell populations with genotype-phenotype map, based on a multi-type branching process. We present a comparative analysis between genotype-phenotype networks obtained from the multi-scale model and networks constructed assuming that the genotype space is a regular hypercube. We compare the effects on the probability of escape and the escape rate associated to the evolutionary dynamics between both classes of graphs. We further the study of evolutionary escape by analysing the long term survival conditioned to escape. Traditional approaches to the study of escape assume that the reproduction number of the escape genotype approaches infinity, and, therefore, survival is a surrogate of escape. Here, we analyse the process of survival upon escape by taking advantage of the fact that the natural setting of the escape problem endows the system with a separation of time scales: an initial, fast-decaying regime where escape actually occurs, is followed by a much slower dynamics within the (neutral network of) the escape phenotype. The probability of survival is analysed in terms of topological features of the neutral network of the escape phenotype.
