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Allelic heterogeneity is the phenomenon in which different mutations at the same locus lead to the same or very similar phenotypes.These allelic variations can arise as a result of natural selection processes, as a result of exogenous mutagens, genetic drift, or genetic migration.
The quasispecies model is a description of the process of the Darwinian evolution of certain self-replicating entities within the framework of physical chemistry.A quasispecies is a large group or "cloud" of related genotypes that exist in an environment of high mutation rate (at stationary state [1]), where a large fraction of offspring are expected to contain one or more mutations relative ...
Genetic mutations – contribute to the genetic variability within a population and can have positive, negative, or neutral effects on a fitness. [7] This variability can be easily propagated throughout a population by natural selection if the mutation increases the affected individual's fitness and its effects will be minimized/hidden if the ...
In comparison, an evolutionarily stable state describes a population that returns as a whole to its previous composition even after being disturbed. [1] In short: the ESS refers to the strategy itself, uninterrupted and supported through natural selection, while the evolutionarily stable state refers more broadly to a population-wide balance of ...
Mutational robustness (also called mutation tolerance) describes the extent to which an organism's phenotype remains constant in spite of mutation. [9] Robustness can be empirically measured for several genomes [10] [11] and individual genes [12] by inducing mutations and measuring what proportion of mutants retain the same phenotype, function or fitness.
Mutation will have a very subtle effect on allele frequencies through the introduction of new allele into a population. Mutation rates are of the order 10 −4 to 10 −8, and the change in allele frequency will be, at most, the same order. Recurrent mutation will maintain alleles in the population, even if there is strong selection against them.
Thus the observed substitutions (by point mutations) are considered to be accepted by natural selection. One PAM unit is defined as 1% of the amino acid positions that have been changed. To create a PAM1 substitution matrix, a group of very closely related sequences with mutation frequencies corresponding to one PAM unit is chosen.
This is an example of balancing selection between the fierce selection against homozygous sickle-cell sufferers, and the selection against the standard HgbA homozygotes by malaria. The heterozygote has a permanent advantage (a higher fitness) wherever malaria exists.