A 9-bp deletion in the mitochondrial genome between the gene for cytochrome oxidase subunit II and the gene for tRNAᴸʸˢ is a common polymorphism among Polynesians and also in a population of Taiwanese natives. The frequency of the polymorphism varies between populations: The highest frequency is seen in the Maoris of New Zealand (98%), lower levels are seen in eastern Polynesia (80%) and western Polynesia (89%), and the lowest level is seen in the Taiwanese population. What do these frequencies tell us about the settlement of the Pacific by the ancestors of the present-day Polynesians?

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Welcome back. Let's look at our next problem. It says a study was conducted to appreciate mutations in MT DNA in certain populations. Which of the following statements is correct. Regarding the higher rate of mutations in MT DNA in a particular population choice. A the population is less susceptible to mitochondrial disorders, choice B, the population has a lower risk of developing genetic diseases. Choice. C the population has a decreased likelihood of passing on mutations to future generations or choice. D the population shows greater genetic diversity in their mitochondrial genomes. So we recall that MT DNA means mitochondrial DNA. And there's two key things to remember about it. One, it's inherited only from the mother. So none from the father and of increased importance to this question, as our question says about higher rate of mutations, it has a greater rate of mutation then nuclear DNA. So with that in mind, let's go through our answer choices. Cho says the population is less susceptible to mitochondrial disorders. Well, this answer doesn't really make sense. We just know that mutations occur at a greater rate, but this doesn't mean this doesn't tell us anything about whether or not the population is more susceptible to disorders. That really depends on what kind of mutations accumulate. There can be beneficial mutations, there can be neutral mutations. So this answer is not correct choice. B the population has a lower risk of developing genetic diseases. Again, just like in choice A, we'll say same as a, it depends on the kind of mutations that occur. So we don't have information to say whether they have a lower or higher risk of developing diseases. Choi says the population has a decreased likelihood of passing on mutations to future generations. Well, this also cannot be our answer. Mitochondrial DNA is always passed um on only from the mother, always inherited in the same way and therefore, rate of mutation won't affect how likely it is that mutations will be passed on. So we're left with choice D the population shows shows greater genetic diversity in our mitochondrial genomes. Well, this is correct. That's the one thing you can say when there's more mutations occurring, you have greater genetic diversity since there are more changes that can occur to the DNA. So the statement that is correct regarding a higher rate of mutations in mitochondrial DNA is choice D the population shows greater genetic diversity in their mitochondrial genomes. See you in the next video.

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Key Concepts

Mitochondrial DNA and Maternal Inheritance

Population Genetics and Polymorphism Frequency

Human Migration and Settlement Patterns in the Pacific