Genetic variation is the difference in DNA among individuals[1] or the differences between populations among the same species.[2] The multiple sources of genetic variation include mutation and genetic recombination.[3] Mutations are the ultimate sources of genetic variation, but other mechanisms, such as genetic drift, contribute to it, as well.[2]
Darwin's finches or Galapagos finches[4]Parents have similar gene coding in this specific situation where they reproduce and variation in the offspring is seen. Offspring containing the variation also reproduce and passes down traits to their offspring.
^Levinson, Gene (2020). Rethinking evolution: the revolution that's hiding in plain sight. World Scientific. ISBN9781786347268.
^Darwin, 1845. Journal of researches into the natural history and geology of the countries visited during the voyage of H.M.S. Beagle round the world, under the Command of Capt. Fitz Roy, R.N. 2d edition.