What does genetic variation refer to?

Genetic variation refers to the differences in DNA among individuals within a population. This variation is crucial for evolution and adaptation, as it provides the raw material for natural selection. Variations can arise from mutations, gene flow, and sexual reproduction, leading to different traits being expressed among individuals. Understanding genetic variation is fundamental in fields like genetics, evolutionary biology, and conservation, as it influences how populations respond to environmental changes.

The other options do not accurately capture the essence of genetic variation. Common sequences of alleles indicate a lack of differentiation, not variation. The effect of gene expression is related to how genes are utilized but does not address the differences in DNA sequences themselves. Environmental influences on genes pertain to epigenetics and how the environment can affect gene expression without altering the underlying DNA sequence, which again is distinct from genetic variation.