What does evolution refer to in a biological context?

In a biological context, evolution is defined as a permanent genetic change in a population over time. This process encompasses the alterations in allele frequencies within a gene pool, which can occur through mechanisms such as natural selection, genetic drift, mutation, and gene flow. Over generations, these genetic changes can lead to variations that either affirm the fitness of a population in its environment or contribute to speciation, where new species emerge.

The emphasis on "permanent genetic change" highlights that evolution is not just about immediate adaptations or responses to environmental pressures but involves a sustained change that is inheritable through generations. This foundational concept is crucial for understanding how species evolve and adapt over the long term, leading to biodiversity.

The other options, while relevant to evolution in broader discussions, do not encapsulate the essence of evolution as biological change over time. For instance, the formation of new species can occur as a result of evolutionary processes but is a specific outcome rather than a definition of evolution itself. Similarly, while biodiversity increase can be a consequence of evolutionary processes, it does not define evolution. Adaptation pertains to specific traits that enhance survival in current environments and may not account for the overarching changes in genetic makeup over time.