The Effect of Recurrent Mutations on Genetic Diversity in a Large Population of Varying Size

Recurrent mutations are a common phenomenon in population genetics. They may be at the origin of the fixation of a new genotype, if they give a phenotypic advantage to the carriers of the new mutation. In this paper, we are interested in the genetic signature left by a selective sweep induced by recurrent mutations at a given locus from an allele \(A\) to an allele \(a\), depending on the mutation frequency. We distinguish three possible scales for the mutation probability per reproductive event, which entail distinct genetic signatures. Besides, we study the hydrodynamic limit of the \(A\)- and \(a\)-population size dynamics when mutations are frequent, and find non trivial equilibria leading to several possible patterns of polymorphism.