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A beneficial, or advantageous mutation increases the fitness of the organism. Examples are mutations that lead to antibiotic resistance in bacteria (which are beneficial for bacteria but usually not for humans). A neutral mutation has no harmful or beneficial effect on the organism.
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with artificial selection, which is ...
Genetic diversity. A graphical representation of the typical human karyotype. Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. [ 1 ]
In genetics, a selective sweep is the process through which a new beneficial mutation that increases its frequency and becomes fixed (i.e., reaches a frequency of 1) in the population leads to the reduction or elimination of genetic variation among nucleotide sequences that are near the mutation. In selective sweep, positive selection causes ...
The neutral theory assumes that most mutations that are not deleterious are neutral rather than beneficial. Because only a fraction of gametes are sampled in each generation of a species, the neutral theory suggests that a mutant allele can arise within a population and reach fixation by chance, rather than by selective advantage. [1]
This mutation provides some protection against drought and enables people to drink milk without diarrhea, which causes dehydration. [15] Lactase persistence is a rare ability among mammals. [75] Because it involves a single gene, it is a simple example of convergent evolution in humans.
A heterozygote advantage describes the case in which the heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotype. Loci exhibiting heterozygote advantage are a small minority of loci. [ 1 ] The specific case of heterozygote advantage due to a single locus is known as overdominance ...
Silent mutation. Point substitution mutations of a codon, classified by their impact on protein sequence. Silent mutations, also called synonymous or samesense mutations, are mutations in DNA that do not have an observable effect on the organism's phenotype. The phrase silent mutation is often used interchangeably with the phrase synonymous ...