MUTATIONAL MELTDOWN IN LARGE SEXUAL POPULATIONS

When a new individual is formed (independently of the reproduction pro cess) it inherits harmful mutations. Moreover, new mutations are acqui red even in the genetic code formation, most of them deleterious ones. This might lead to a time decay in the mean fitness of the whole popu lation that, for long enough time, would produce the extinction of the species. This process is called Mutational Meltdown and such question used to be considered in the biological literature as a problem that only occurs in small populations. In contrast with earlier biological assumptions, here we present results obtained in different models show ing that the mutational meltdown can occur in large populations, even in sexual reproductive ones. We used a bit-string model introduced to study the time evolution of age-structured populations and a genetical ly inspired model that allows to observe the time evolution of the pop ulation mean fitness.