What does it typically mean when selection is described as "strong"?

When selection is described as "strong," it signifies that it significantly alters the population’s genetic structure. In the context of evolution, strong selection indicates that certain traits provide a substantial advantage or disadvantage to individuals possessing them, leading to notable changes in allele frequencies within a population over time. This can result in rapid evolutionary changes, as individuals with advantageous traits are more likely to survive and reproduce, thereby passing those traits on to future generations.

The process of strong selection emphasizes the impact of environmental pressures and the importance of natural selection in shaping the genetic make-up of a population, allowing for a more efficient response to selection pressures. Strong selection can lead to decreased genetic diversity if only a small set of alleles becomes favored, which can push a population quickly toward adaptive peaks.