Cambridge O Level Biology · Syllabus 5090 · Inheritance
Artificial Selection
What is Artificial Selection?
The process in which humans choose which individuals of a species will breed, in order to increase the frequency of a desired inherited feature in later generations. Individuals showing the desired feature are selected and bred together, their offspring are assessed, those showing the feature most strongly are selected as the next parents, and the process is repeated over many generations. Artificial selection is used to produce crop varieties with higher yield or disease resistance and livestock with desired characteristics. Because it repeatedly breeds from a small number of chosen individuals it tends to reduce genetic diversity, which can leave the variety vulnerable to a new disease or a change in conditions. It is distinct from genetic modification, which changes an organism's genetic material directly.
This definition is part of the Inheritance chapter in Cambridge O Level Biology.
Artificial Selection in context
Inheritance is the transmission of genetic information from one generation to the next. A gene is a length of DNA that codes for a protein; an allele is one of the alternative forms that gene can take. The order of the bases A, T, C and G along a strand of DNA sets the order of amino acids in a protein, which sets the protein’s shape, which sets what the protein can do — and that is how a molecule you cannot see decides a feature you can. Because gametes carry one allele of each gene, a cross between two known genotypes has a predictable outcome: Tt × Tt is expected to give 3 tall : 1 short, and Tt × tt is expected to give 1 tall : 1 short. Those are probabilities, not guarantees. Mutation makes new alleles at random, meiosis and fertilisation shuffle them into new combinations, and selection — by the environment in natural selection, by people in artificial selection — changes how common each allele becomes over generations. That change is evolution.
Common mistakes with Artificial Selection
- “Artificial selection is genetic modification.” Artificial selection chooses which existing organisms breed. Genetic modification changes genetic material directly. Write “Artificial selection selects parents; it does not alter their genes.”
Questions students ask about Artificial Selection
Is artificial selection the same as genetic modification?
No. Artificial selection chooses which existing individuals are allowed to breed, and relies entirely on normal inheritance of alleles that are already present in the species. Genetic modification changes an organism’s genetic material directly and can introduce a gene from a different species. Artificial selection is Topic 17; genetic modification belongs to Chapter 18.