Describe three ways that evolution can occur via genetic drift.

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Accepted Answer

Welcome back. Let's look at our next question. Genetic drift can occur as a result of all of these except so we're looking for the one thing that doesn't cause genetic drift. So let's recall from our content video, What is genetic drift? While genetic drift is when you have a variation in the frequency of a given genotype in a small population caused by chance. So we're not talking about natural selection, the favoring of one trait over another, but a chance happening that causes a change of frequency of a given genotype in a small restricted population. So let's look through the answer choices here. Choice A says the bottleneck effect. Well, bottleneck effect is when you have a small number of survivors of some sort of disaster. And in this small number, do you have an unrepresentative sample of your original population. So say for example in the original population, one in 1000 people had red hair, plague comes through. There's only 100 people left. One of them has red hair. So now your frequency of the gene for red hair has gone from one in 1000 to 1 in 100 in your new population after this bottleneck. So that definitely can cause genetic drift. And it's a chance event plague came through a plague killed some people and not others. As long as you don't, as long as red hair doesn't give you an advantage in the plague. Um You're talking about it's caused by chance. So choice A. We're gonna eliminate that because it can cause genetic drift. Choice B. Is the founder effect. Well, the founder effect is when you have a small um group, leave, just leave and start a new population. And just like in bottleneck this new population is an unrepresentative sample. So if now instead of a plague now we have 100 people decided to leave their village and migrate to the new world. And of those 100 people, one had red hair. And um so now the population in the new world, you have one in 100 with red hair. But back at home he was one in 1000. So same thing the small group broke off starts a new population. The new population is an unrepresentative sample in terms of gene frequency. So founder effect definitely cause of genetic drift. So not our answer. Choice C. Says migration while migration is a cause of gene flow, jeans moving from one place to another. If someone that has jean moves to another place where that gene isn't present, um you have a gene flow but it doesn't involve small populations. Um leading to unrepresentative samples. So it's just gene movement along with the movements of individuals. So we're gonna say that choice C. Is our correct answer here. But to be through we'll look on at choice D. Choice D. Says chance, loss of khalil's so there we have that important element of chance. And if we're looking at a small population and just randomly by chance, a person with a trait um or multiple. People with that trait do not reproduce. For whatever reason, it doesn't have anything to do with the desirability of the trait that happens by random that can affect that can be lost in the population, affecting the frequency with which it occurs. So chance, loss of volatiles definitely can be a cause of genetic drift, so not our answer. So once again, genetic drift can occur as a result of all of these except choice C migration. Thanks for watching.

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