Genetic variation

There is usually extensive genetic variation within a population of a species. Even when individuals look rather similar, their genomes can contain many different versions of DNA sequences.

Different combinations of inherited versions of genes, called alleles, mean offspring are genetically different from one another and from their parents. This creates genetic variation within a population—a group of organisms of the same species. The cell division that produces genetically different gametes is covered in the next lesson.

The main advantage of sexual reproduction is the genetic variation produced by combining genetic information. If a disease appears or conditions change, some individuals may already have inherited features that help them survive and reproduce. Variation therefore gives a population a better chance of persisting; it does not guarantee that any particular offspring will survive.

Within a population, individuals usually carry many differences in their genetic material. This is called genetic variation, and OCR describes it as usually extensive: there are normally many genetic differences spread throughout the population, rather than just one or two.