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How do beneficial mutations become common in a population?

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Diagram of a DNA double helix showing its twisted ladder structure, with a close-up of the sugar-phosphate backbone, paired nitrogenous bases (adenine, thymine, cytosine, guanine), and labeled nucleotides and hydrogen bonds. — human genome The human genome is made up of approximately three billion base pairs of deoxyribonucleic acid (DNA). The bases of DNA are adenine (A), thymine (T), guanine (G), and cytosine (C).

Beneficial mutations become common in a population primarily through the process of natural selection.12

When a mutation occurs that provides a hereditary advantage—such as improving an organism's ability to survive, find food, or reproduce in its specific environment—the individuals carrying that variant are more likely to leave behind more descendants than those who lack it. Because these genotypes are passed from parent to child in a stable manner, the beneficial mutation is preserved and multiplied across successive generations.1234

While other random processes like genetic drift and gene flow can alter gene frequencies, they do so without regard to an organism's fitness. Natural selection acts as a critical filter, moderating these random effects by consistently favoring and increasing the frequency of beneficial variations while eliminating harmful ones. Over time, this accumulation of advantageous traits allows populations to become better adapted to their physical and biological conditions.12