Final answer:
Mutation and gene flow are the evolutionary processes that generally increase genetic diversity in a population, with mutation introducing new genomic variations and gene flow happening through migration.
Step-by-step explanation:
The evolutionary process that generally increases genetic diversity in a population is mutation. Mutation refers to changes in the organism's DNA and is a crucial factor in driving diversity within populations. These random changes can introduce new genetic variations, which can lead to phenotypic differences that may be potentially advantageous, neutral, or detrimental. Another critical process is gene flow, often a result of migration. When individuals from one population move to another, they bring with them different genetic material that can increase the genetic diversity in the receiving population.
Although natural selection and genetic drift are essential evolutionary forces, they do not inherently increase genetic diversity. Natural selection often reduces diversity by favoring specific alleles over others, while genetic drift randomly changes allele frequencies in small populations, which can lead to a loss of genetic variation.