Final answer:
Accumulated microevolutionary changes over extensive time periods can result in macroevolution, leading to the formation of new species.
Step-by-step explanation:
An accumulation of microevolutionary changes over time can lead to macroevolution, which is the emergence of new species.
Microevolution refers to changes within a species, such as shifts in allele frequencies due to factors like migration, nonrandom mating, and natural selection. Over considerable periods, these small-scale changes contribute to significant evolutionary transformations, such as anatomical, physiological, or behavioral differences that are serious enough to mark the creation of a new species. This process, which unfolds over geologic time, is evidenced by the fossil record.
When microevolution continues unabated for many generations, the cumulative effect could lead to a population becoming so genetically distinct from its ancestral population that it constitutes a separate species. This can also occur rapidly under pressure from major environmental changes, like volcanic eruptions or asteroid impacts, prompting accelerated changes due to intense selective pressures. The modern synthesis, which combines Darwinian selection with genetics, explains the link between microevolution and macroevolution as part of evolutionary biology.