Microevolution refers to the small-scale changes in gene frequencies within a single population, while macroevolution describes larger evolutionary changes that transcend species boundaries and result in the origin of new types of organisms. These grand transformations, such as the development of mammals and flowering plants, fall under the category of macroevolution. In contrast, microevolution typically occurs within a species and brings about changes at the species level. This change in gene frequencies over time is driven by processes like mutation, genetic drift, gene flow, and natural selection. From a population genetics perspective, microevolution can be observed in just a few generations.