Describe three ways that evolution can occur via genetic drift.

Video transcript

Welcome back. Let's look at our next problem. It says genetic drift can occur as a result of all of these except so among our four answer choices, three of them will be something they can cause genetic drift and the one that does not is the answer we're looking for. So let's just recall from our content videos, what is genetic drift? And genetic drift? Is that variation in the relative frequency of different Jenna types in a small population due to chance. So that's kind of two very important parameters there. It's when you have a small population, um, and the variation of this genotype frequencies as a result of chance. So let's look through our answer choices, choice A says bottleneck effect. The bottleneck effect occurs when you have a small number of survivors of some sort of disaster. So you now have you got an original population, some sort of disaster. You have a small number of survivors and that small number of survivors has a variation in the relative frequency of Jenna types compared to its original population Just due to chance. So an example would be a plague comes through in a population that in which 1% of the people have red hair. And in only 10 people survive this plague, including one person with red hair. That has nothing to do with the red hair has nothing to do with survival from the plague. But you now have this bottleneck effect. You've got a tiny population of only 10 people that now has a red haired frequency of 10%. So that is definitely an example of genetic drift. Um Changing those genotype frequency due to chance. So not our answer choice B says founder effect. The founder effect is when you have a small population that moves away So you have original source population and then you have a small group that moved a large distance away. So just like in our bottleneck effect, we have say a source population with a frequency of red hair occurring in 1% of the population, 10 people leave their country and move to the new world. One of those people has red hair. So now that small population that has moved away Shows the founder effect because in the the small population that moved away, 10% of the people have red hair. Just due to chance, the red hair has nothing to do with the fact that they moved. So that does cause genetic drift. And is not our answer here. Choice C. Is natural selection. Natural selection causes a variation and genotype frequency. But due to those genes being either advantageous or disadvantageous in a given environment. So that genotype frequency is not varying due to chance. So natural selection does not cause genetic drift since the variation and genetic drift is caused by chance. So that would not be natural selection. And finally, choice, decent chance, loss of alleles. So this would be something like I've got eight plants, four have red flowers, four have white flowers and three plants with white flowers just happened to die. Nothing to do with their flower color. Just by chance. Well, I've now lost, my original population was half and half my surviving population, only three, only one has white flowers. I've lost those white flower alleles just by chance. So that is a cause of genetic drift, and not our answer. So genetic drift can occur as a result of all these except choice. C natural selection. See you in the next video.