Which process involves gradual changes in an allele frequency in a population over generations?

The process that involves gradual changes in allele frequency in a population over generations is microevolution. This concept refers specifically to small-scale evolutionary changes that occur within a population, such as shifts in allele frequencies due to mechanisms like natural selection, genetic drift, mutation, and gene flow. Over time, these changes can lead to significant variations and adaptations within a population, reflecting the ongoing process of evolution at the population level.

In contrast, macro-evolution describes larger-scale evolutionary changes that can result in the emergence of new species or groups from common ancestors, often over longer time frames. Uniformitarianism is a principle in geology that posits that the processes we see today, such as erosion and sedimentation, also operated in the past, but it is not directly related to changes in allele frequency. Survival of the fittest refers to the mechanism of natural selection, which drives microevolution but does not define the gradual changes in allele frequencies by itself. Thus, microevolution is the most accurate term for the gradual changes in allele frequency over generations within a population.