The dodo bird (Raphus cucullatus) lived on the Mauritius...

Question

The dodo bird (Raphus cucullatus) lived on the Mauritius Islands until the arrival of European sailors, who quickly hunted the large, placid, flightless bird to extinction. Rapid morphological evolution such as often accompanies island isolation had caused the bird's huge size and obscured its physical resemblance to any near relatives. However, sequencing of mitochondrial DNA from dodo bones reveals that they were pigeons, closely related to the Nicobar pigeon from other islands in the Indian Ocean. Why was mitochondrial DNA suited to the study of this extinct species?

Accepted Answer

Hi, everyone. Welcome back. Here's our next question. What is the main limitation of using mitochondrial DNA and forensic science? Well, before we walk through our answer choices here and look at them all, let's just think about what DNA is used for in forensic science. And of course, its main use is to be able to identify or rule out victims or suspects from DNA samples. So with that in mind, let's look through our answer choices thinking about what would be the main limitation of using mitochondrial DNA. And of course, we recall the mitochondrial DNA is inherited only from the mother. So with that in mind, let's read through our answer choices and think about them choice. A says it cannot be used to establish an individual's gender. Well, this is correct. You can't see the difference uh between males and females. Looking at mitochondrial DNA. You'd need the sex chromosomes to determine that. But that would only rule out suspects and or only tell you about suspects or victims that the sample was given by a male or a female. That's not super informative, doesn't rule out many people or doesn't specify people. So that definitely wouldn't be the main limitation of using mitochondrial DNA. So we're going to go ahead and eliminate choice. A choice B says it is not as specific as nuclear DNA. Well, this is definitely correct and definitely would come under the term main limitation, mitochondrial DNA is shared by all maternal line relatives. Mitochondrial DNA doesn't recombine with paternal DNA and it doesn't change over time as quickly as nuclear DNA does. And therefore, it tends to be transmitted almost exactly the same from mother to child. And so you cannot eliminate quite so many suspects or victims. Whereas nuclear DNA acts as a DNA fingerprint in a sense, it's very specific to individuals. But mitochondrial DNA, you would have the same DNA by anyone that shares a direct maternal ancestry. So that would be the main limitation. So we'll circle that but just to be thorough, keep on going here. Choice C would say says it is readily polluted and damaged. Well, this is not correct of mitochondrial DNA. Uh mitochondrial DNA is not readily polluted and damaged. So that makes it gives it an advantage compared to nuclear DNA. It's more stable, less susceptible to environmental factors. So it's actually better for retrieving samples from uh area where the DNA has been exposed to the elements or has been there for a long time. So that's actually an advantage of mitochondrial DNA. So definitely not what we're looking for. And then choice D says it is more expensive to examine the nuclear DNA. Well, this is also not correct of mitochondrial DNA and therefore not our answer. Mitochondrial DNA is actually easily, easier to amplify from small sample amounts. So that makes it less expensive to examine the nuclear DNA. So what is the main limitation of using mitochondrial DNA in forensic science? And that's choice B it is not as specific as nuclear DNA. See you in the next video.

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