Biology · Evolution

Mutations are the ultimate source of genetic variation because they introduce new genetic material into a population. This is crucial for evolution because, without new mutations, there would be no new traits for natural selection and other evolutionary processes to act upon. Migration, genetic drift, and selection all play vital roles in shaping the genetic structure of populations over time, but they rely on existing genetic material and do not create new genetic variants. Therefore, only mutations can be considered the ultimate source of all genetic variation and evolutionary change.

Migration, or gene flow, involves the movement of individuals and their genetic material between populations. While it can introduce new alleles into a population, it does not create new genetic material. Therefore, migration is not the ultimate source of genetic variation.

Mutations are changes in the DNA sequence that can lead to new genetic variants. They are the only process that creates new genetic material, making them the ultimate source of all genetic variation and evolutionary change. This is why mutation is the correct answer.

Genetic drift refers to random changes in allele frequencies within a population, especially in small populations. It can lead to evolutionary change but does not introduce new genetic material. Hence, it is not the ultimate source of genetic variation.

Selection, including natural and artificial selection, acts on existing genetic variation by favoring certain traits over others. While it influences the prevalence of traits, it does not generate new genetic material, thus it is not the ultimate source of genetic variation.