Final answer:
Microevolution refers to changes in allele frequencies within a population, while macroevolution is the term used for broader scale evolutionary changes that lead to the formation of new species. They overlap when microevolutionary changes accumulate to result in speciation, and both involve changes in genetic structure.
Step-by-step explanation:
Difference between Microevolution and Macroevolution
Microevolution is the change in allele frequencies that occurs over time within a population. This is the evolution that happens on a small scale among individuals within a species and is influenced by factors like mutation, genetic drift, gene flow (migration), and natural selection. Macroevolution, on the other hand, is evolution on a scale of separated gene pools. Macroevolution refers to broader scale evolutionary changes that scientists see over paleontological time, often resulting in the formation of new species—a process known as speciation.
Overlapping between microevolution and macroevolution can occur when numerous instances of microevolutionary changes accumulate over a long period and lead to speciation. This is in line with phyletic gradualism, a theory suggesting that species evolve through a large number of small changes over long time periods. However, punctuated equilibrium posits that most evolutionary changes occur in short bursts, associated with speciation events, instead of gradual changes.
While they happen at different scales, both microevolution and macroevolution show changes in a population's genetic structure. However, microevolution deals with changes within a species, and macroevolution deals with changes that are significant enough to result in new species over time, potentially due to events like environmental catastrophes or isolation.