The role of variance in natural selection is crucial, as it provides the genetic diversity necessary for populations to adapt to changing environments. Variance within a population means there are different traits among individuals, some of which may be more advantageous under specific environmental conditions. When selective pressures are exerted, individuals with beneficial traits are more likely to survive and reproduce, passing those traits to future generations. This process ultimately leads to evolutionary changes over time, allowing populations to better fit their habitats and respond to ecological shifts while maintaining biodiversity.