How is evolution defined in a biological context?

In a biological context, evolution is defined as the change in the genetic composition of a population over successive generations. This definition emphasizes that evolution operates at the population level rather than the individual level. Over time, variations that arise through mutations, genetic drift, migration, and natural selection can lead to changes in alleles and genetic traits within a population, contributing to its evolution.

While adaptations of individual organisms to their environment can occur, this process does not equate to evolution, which requires population-level genetic change. Similarly, the emergence of new species is a possible outcome of evolutionary processes but is not the complete definition of evolution itself. The stabilization of genetic traits suggests a lack of change, which contrasts with the dynamic nature of evolution as it encompasses continuous genetic shifts within a population. Thus, the correct choice captures the essence of evolution as a gradual change in genetic makeup across generations.