What is the definition of evolution in a biological context?

In a biological context, evolution is defined as the gradual development or change of heritable traits in populations over generations. This definition emphasizes the importance of genetic variation and the mechanisms through which traits are passed from one generation to the next. It is a slow, continuous process driven by natural selection, genetic drift, mutations, and gene flow, which ultimately leads to adaptations that enhance the survival and reproduction of organisms in given environments.

This definition is crucial because it captures the essence of how species evolve over long periods. Evolution is not just about the appearance of new traits or immediate reactions to environmental stimuli; instead, it involves changes in the genetic makeup of populations, leading to adaptations that may eventually result in new species forming.

Understanding evolution as a gradual process also helps clarify why immediate changes or rapid adaptations are not considered evolution in the strict sense. Instead, they may reflect acclimatization or phenotypic plasticity, which are responses to environmental pressures but do not involve genetic changes over generations. Hence, the definition centers on heritable traits and population dynamics over extended time frames.