Mutational Meltdown in Large Sexual Populations

(Received 12 July 1995, accepted 31 July 1995)

Abstract
When a new individual is formed (independently of the reproduction process) it inherits harmful mutations. Moreover, new mutations are acquired 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 population 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 showing 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 genetically inspired model that allows to observe the time evolution of the population mean fitness.