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Genetic diversity, meiosis and adaptations GapFill
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are changes to the genetic material of an individual, which may occur spontaneously due to a fault in DNA replication. If the wrong base is incorporated into a sequence it is known as a ; however, because many amino acids are coded for by more than one triplet, this does not always result in a change in the final amino acid sequence. If a base deletion occurs, it usually has a more profound effect on the resulting polypeptide due to the introduction of a .
is another method which can increase genetic diversity. Independent segregation of means that daughter cells contain different combinations of maternal and paternal genes, and can also result in recombination of alleles to produce non-identical daughter cells. of gametes then restores the correct number of chromosomes to a cell, while introducing further variation.
Natural selection relies on the generation of new alleles by these processes. If an allele provides a selective in a certain environment, it is more likely to be passed on to the next generation and increase in within a population. For example, a new allele for antibiotic resistance in bacteria is likely to spread throughout a population through the process of . If natural selection favours the average phenotype and selects against extremes, e.g. in human birth weight, this is known as .
Through natural selection, species become more adapted to their environments. This may be through: