Mutation Pressure

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Mutation Pressure

a factor that tends to decrease the average fitness of populations because of the continuous appearance of injurious hereditary changes. The mutation pressure contributes to the general genetic load of deleterious genes in a population. Besides being influenced by the mutation pressure, the fitness of populations is affected by immigration from neighboring populations of individuals with genotypes less suited to the new conditions than the indigenous inhabitants, dissimilar fitness of homozygotes and heterozygotes, and other factors.

REFERENCE

Muller, H. J. “Our Load of Mutations.” American Journal of Human Genetics, 1950, vol. 2, p. 111.

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From these theoretical arguments, it appears that a theory involving deleterious mutation pressure alone as the cause for senescence is not consistent with mortality plateaus far below 100%.

Further, classic ideas about mutation pressure (Mukai et al.

Further, female early-age mortality increased nearly 2% per generation under mutation pressure (Pletcher et al.

They do not imply that the mortality curve will no longer change under mutation pressure, but when mutational effects are small it will always tend to converge on these values.

Thus, the decline of early age mortality results in a net mutation pressure in favor of increasing mortality rates at older ages.

Mortality plateaus and the evolution of senescence: why are old-age mortality rates so low?

If codon usage is selected, then mutation pressure will not be the sole determinate of base composition in third positions, and the story told by Osawa becomes more complicated.

Evolution of the Genetic Code

Mutation pressure is not the only force that could maintain variation in viability, and we do not discount the possibility of temporal or spatial variation in selection pressures.

The evolution of mate preferences for multiple sexual ornaments

Following the logic in previous paragraphs, it is clear that deleterious mutation pressure in the origin of replication could produce such a situation, because the relationship between