Amoeba Sisters Video Recap: Genetic Drift Populations can have variety, despite being made up of the same species. If a population has different expressed traits, this can be due to different inherited alleles. Genetic drift can cause a change in allele frequency in a population. What if you had to explain genetic drift to a friend who has not watched the video? Use the comics below in your narration of genetic drift. Refer to Comic A, Comic B, and Comic C in your narrative. You can use the comics in any order you choose!
The Correct Answer and Explanation is:
Genetic drift refers to a random change in the frequency of alleles within a population over time. This concept is especially noticeable in small populations, where chance events can have a greater impact on which traits get passed down to future generations. Unlike natural selection, which favors traits that improve survival or reproduction, genetic drift is driven by luck rather than advantage.
Comic A shows a group of beetles with both green and brown colors. These color differences represent different alleles inherited from parent beetles. Initially, both colors are present in the population, which illustrates genetic diversity. Over time, a random event—like a few beetles being stepped on by hikers—can remove individuals regardless of their color. The loss happens by chance, not because one color is better than the other.
Comic B demonstrates a bottleneck effect. A disaster, such as a natural catastrophe, drastically reduces the size of the beetle population. Only a few survive by luck, not because of superior traits. The surviving beetles happen to be mostly brown. In this case, the gene pool has shrunk, and the allele frequency has changed randomly. Future generations will mostly inherit brown coloration, not because it is more beneficial, but because of chance survival.
Comic C explains the founder effect. A small group of beetles leaves the original population to start a new colony. If the founding beetles happen to carry only brown alleles, then the new population will likely consist only of brown beetles. Again, this is a random sampling, and not based on any adaptive advantage.
Genetic drift highlights how randomness can influence evolution. Even traits with no advantage or disadvantage can become more or less common purely by chance events, especially in small populations. This randomness makes genetic drift a powerful force in shaping the genetic makeup of populations.
