7.3 Artificial Selection

Learning objectives

7.3A—Explain how humans can affect diversity within a populationExplain how humans can affect diversity within a population.• Through artificial selection, humans affect variation in other species.

Artificial selection occurs when humans choose which individuals reproduce based on a desired heritable phenotype. This choice changes which variants are passed to the next generation.

Population contains heritable variation → humans select breeders with a preferred phenotype → those individuals contribute more offspring → the associated variation becomes more common across generations.

For example, if humans repeatedly breed only plants with a heritable early-flowering phenotype, early flowering can become more common in later generations while alternative flowering-time variants become less represented.

Artificial selection therefore changes diversity within a population by shifting the relative representation of variants. When breeding is restricted to a narrow subset, variation not chosen by humans may decline.

Humans do not cause an individual to acquire the desired inherited trait through use or training. They alter population variation by controlling differential reproduction over generations.

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—7.4 Population GeneticsRead