Final answer:
Macroevolutionary changes are significant evolutionary events that can lead to the emergence of new species and are the result of an accumulation of smaller, microevolutionary changes within a population's genetics over a prolonged period.
Step-by-step explanation:
The statement that 'macroevolutionary changes result from an accumulation of microevolutionary changes over time' means that large-scale evolutions, such as the development of a new species (macroevolution), occur as a consequence of numerous, smaller changes in the genetic makeup of a population (microevolution).
Microevolution involves changes within a species or a population's genetic structure. This includes factors such as mutation, selection, gene flow, and genetic drift which influence allele frequencies. Over extensive periods, these minute changes can accumulate and lead to significant evolutionary changes, such as those observed in the fossil record or during major environmental shifts that influence natural selection.
These macroevolutionary events happen over geologic time and can result in the emergence of new species, major shifts in biodiversity, and the evolution of complex biological structures. The Modern Synthesis is the current scientific consensus that describes this cumulative process of evolution.