Mutasjonsakkumulation

Mutasjonsakkumulation, often translated as mutation accumulation, is a concept in evolutionary biology that describes the process where deleterious mutations can build up in the genomes of organisms over time, particularly in asexual populations or under specific selective pressures. This accumulation occurs because mutations arise randomly. In asexual reproduction, offspring are genetically identical to the parent, barring new mutations. If a mutation is slightly harmful, it might not be efficiently removed by natural selection, especially if the population size is small or if the organism experiences relaxed selection.

Over many generations, a significant number of these slightly deleterious mutations can gather in an individual's genome. This phenomenon is a key driver of Muller's ratchet, a model explaining the degradation of genomes in asexual lineages. The ratchet refers to the irreversible accumulation of mutations, where even if a beneficial mutation arises, it cannot "rescue" a genome that has accumulated multiple deleterious ones because recombination, which could separate the beneficial from the deleterious, is absent or limited.

The rate of mutation accumulation is influenced by factors such as mutation rate, population size, and the strength of selection. In small populations, genetic drift is a stronger force, allowing slightly harmful mutations to become fixed more easily than in large populations where selection is more effective. Understanding mutation accumulation is crucial for comprehending the evolution of aging, the maintenance of sexual reproduction, and the long-term viability of populations.