Genetic drift refers to the change in a type of genes in a population because of the random nature of reproduction. In other words, when people who have the gene causing a specific genetic trait reproduce with people who do not have the gene, the gene can become more popular or totally disappear from the population.
Occurrences of Genetic Drift
Genetic drift can be seen in these examples:
- Of the two pink monkeys in the world – one male, one female – the female dies, ensuring that there will never be a pure-bred pink monkey again.
- A random succession of births results in all other hair colors going extinct within a village full of redheaded people.
- The freckled dazzle-flower exchanges genetic material with a small population of un-freckled dazzle-flowers. After a few seasons, there are no un-freckled dazzle-flowers left.
- The last green-eyed person in a small town dies, leaving only brown-eyed and blue-eyed people.
- An airplane crash introduces the white heron, which loves spotted mackerel, into a population of spotted and unspotted mackerel. Over time, fewer mackerel are born with spots.
- A man steps on a group of beetles, randomly killing most of the green ones but leaving most of the brown ones alive, resulting in fewer green beetles being produced in the population.
- A wildflower population consisting of blue, purple, and pink flowers is subjected to a mudslide that kills most of the blue ones. As time progresses, blue flowers eventually die out, leaving only purple and pink wildflowers.
- Due to random successions of births, a town has an unusually high population of people with strawberry blonde hair, a trait that increases over time and leaves very few people with different hair colors.
- A large population of marmots, about half of which have spots, becomes very ill. More spotted marmots than un-spotted marmots are left; as a result, un-spotted marmots become very rare as time progresses.
- The very last red-billed mallard dies, leaving only orange-billed mallard populations behind.
- A large group of red poppies exchanges genetic material with white poppies. Over time, white poppies become rarer and rarer while red poppies thrive.
With these examples, you probably now have a better idea of what genetic drift is, how it works in the real world and what type of impact genetic drift can have on a species or on a population.