for-an-intriguing-hypothesis-about-how-genetic-drift-might-lead-to-the-evolution-of-fundamental-diff

Name: for an intriguing hypothesis about how genetic drift might lead to the evolution of fundamental diff
Uploaded: 2020-05-19
Duration: 5 min 53 s
Channel: Numerade
Description: For an intriguing hypothesis about how genetic drift might lead to the evolution of fundamental differences in the molecular machinery of different kinds of organisms, see:

Question

For an intriguing hypothesis about how genetic drift might lead to the evolution of fundamental differences in the molecular machinery of different kinds of organisms, see:

Breanna Kloczkowski · Accepted Answer

other guys. So through this question he asks us to talk about why and how. Um Also species convergent lee evolved to not have eyes and the species all happen to live in caves. So, basically, in order for this to have happened, one a certain subgroup of these populations had to have ha genetic mutation or something that caused them to not have eyes. It could start off with one singular organism that just didn&#x27;t have eyes, and they had to have survived better and at the heart your rate, man, those with eyes in order about to become the predominant tree. So one reason this could have happened is because eyes are openings on your body. They can make you more vulnerable to viruses and bacteria getting into your body. And normally, that&#x27;s okay for us as humans, because seeing outweighs being more vulnerable of are some bacteria as far a survival goes. But for these animals that lived in Thorne caves, it didn&#x27;t really use their eyes anyway. It was it was actually more beneficial Teoh not have them. In this case. It could be because it made them less vulnerable to those kinds of diseases and things, or it could have just been for a different reason that we can&#x27;t really know of for sure right now. So that is why they would have evolved without, um, eyes and for the survival of a convergent Lee with, like, more sort of our species, they would have had to have experienced the same thing. So within see, there&#x27;s like five different she. She&#x27;s where it was going, only purpose of the more shapes. So they all would have had Teoh have a ball from having eyes, and then one like organism within their population would have hut you generically, just been born with our eyes, and that would have could have been advantageous for them. And so then they could have passed those genes on to offspring a higher rate and with higher local survival and everything, so that so that what about that happen? And again, it would have happened in full of those Fiji&#x27;s um so there&#x27;s something about living in a cave that makes it&#x27;s more advantageous and higher or easier to survive. If you don&#x27;t have eyes and then moving on to the second part of this question, they ask about limericks theory of evolution and how this or what this would have said about the animals lives in caves. So the most common explanation for his theory of evolution is the giraffe. And so basically, he said, that there waas this original short backdraft and the drop cooked stretching to reach higher leaves, and thus he stretched in church and church. Is that became longer. And then the drop was able to pass luxury on Teoh its offspring. So essentially, we re saying, is the species couple traits not just based on something that is inherent within them, but based on things that can change throughout one&#x27;s own life. So with the animals that organism cell phone without eyes, they could pin that. You don&#x27;t believe that all these animals organisms always with their eyes closed and so eventually their island just gonna like sealed shut. They pass that on, um Teoh their offspring. So it had to do with something so essentially he would have said something that these organisms were doing throughout their life, made their eyes somehow like a less useful or wherever such that, um, they passed on progressively a lack of I trait. And so this could have been done slowly, like maybe it was at first. They were passing on weaker eyes and weaker islands and eyes that were you wanted to stay close, Mr Time. In that somehow, was Prasong finally to know eyes. Or you could have just suggested that it wasn&#x27;t like one generation. These organisms just passed on. No eyes. So hysteria Who is essentially that? Because of whatever these organisms organisms were doing during our lifetime, they passed on a trait that eventually became collectivized and that that would have had to have happened with all of those same species that were living in caves.

Alexander Clippinger · Answer

in a single gene of a person coding gene. They&#x27;re so different. Racing mutation, depending on what part of the gene we&#x27;re talking about on this is really important. And it highlights of important Stephen Biology, which I&#x27;ll say at the end of the video, that kind of give us the reason why this is happening. But I drew little anatomy of a person coding Jean just a basic one energy in particular. Um, we&#x27;ve got enhancer upstream and then a promoter close to the Exxon and then uninterested at the end, which is gonna gets placed out. And I basically told, um, where the likely places where mutation is abundant and then where the places where it&#x27;s not as frequent. And then we&#x27;ll see at the end what themes happened, what patterns in marriage. So the first is that, uh, actually, before we start, I&#x27;m gonna make a caveat. This is important. Um, this is a general thing we can keep in mind when we, um I think about mutations that could pretty coding genes is that the number of mutations that are silent so is never silent. Mutations is a lot higher, and the number of mutations that actually impact things. So a number of miss institutions. So again, the number of purty the number of mutations that are a nuclear tight change. But they don&#x27;t impact any FINA type is a lot higher than the ones that actually do it back to videotape. So now we get into Gene, actually, so we&#x27;ll start the enhancer. The promoter. These were usually conserved sequences of and they&#x27;re important for binding protein factors are in a prelim. A recent all of those conglomerates of proteins that help translation and transcription occurs. So these are gonna be sites of low mutation, the Exxon. It&#x27;s also gonna be a site of levitation because this displaced and catch for the actual purty the N Tron is going to be a site of relatively high mutation. It&#x27;s gonna gets placed out. And then it&#x27;s important to note that at the beginning and the end of in Charlyne splice sites, these air also places a relatively low mutation. So what&#x27;s the theme? What&#x27;s the pattern? Why are the places with limitations have low where they have in common? There was enjoying a high mutation. Um, well, the driving force is that, um it&#x27;s important to maintain the function of a protein anti protein function. And that&#x27;s why you don&#x27;t see a lot of mutations in the Exxon, which actually codes for the protein in its functions. You might see some scattered around in here, but especially low is the mutation prevalence in the active site or any important domains or anything like that. That&#x27;s going to be key for the hurting to function normally, because that was decreased fitness. If you saw a lot of mutations here and same along the same lines, the enhancer and promoter regions are important for kick starting transcription. So that&#x27;s why you tasted so low there because it wouldn&#x27;t get expressed. It moves where it conserved. An interim doesn&#x27;t really matter cause it&#x27;s gonna gets placed out anyway. So these proteins so have a huge these mutations that here don&#x27;t have a huge impact of her teeth. Books

April Townson · Answer

In order to answer this question, we have to first understand what a molecular clock is. So let&#x27;s just review the definition real quick. A molecular clock is defined as the average rate. A gene or an amino acid or basically a section of a genetic code mutates over generational time. For instance, we might have these two genes or gene segments. It could even be like individual bases along each path that mutates, say, five times each generation. And these mutations could be silence of just substitution. Zor they could be non synonymous. Substitution. So, yeah, there&#x27;s no real way of knowing exactly just yet. This is just a general example. In comparison, though, we might have these other genes or gene components that mutate 15 times each generation. And so there&#x27;s. That&#x27;s why we&#x27;re only looking at certain proteins or certain genetic code, not the GM as a whole, because different sections might mutate a different rates, depending on different factors. And I know you might now be thinking OK, well, now that we have this down, what are those factors? Well, as we can see, sometimes there are internal factors or inherent factors that just means certain sections of a Gino mutate more certain proteins or more tended to certain mutations or changes, perhaps based on certain biochemical interactions or the type of DNA, polymerase cetera. But there are also a lot of external factors, and by external factors. I&#x27;m talking about things beyond the biochemical, genome and proteins themselves. And this question in particular, mentions two important things. It mentions population size and generation time. So now that we have two examples of factors that might affect molecular clocks and why we might not be able to, you know, use this data in order to make certain assumptions about, uh, how often genetic changes happen over time and how we can use that to make file a genetic trees, we first have to address these things that can cause differences in the rates and why they might not be comparable in certain circumstances. And so, first, let&#x27;s address the most a parent factor, which is generation time and note how on the first flight, I mentioned that this is the average rate a gene or me too acid or protein mutates over generations. This is because genetic mutations can be passed down through a population not just as a function of time like year to year, but as a function of how often those genes will get passed down, which is a measure of the generation time, or how often a new generation arises. And this changes depending on the organism. So some species like humans. We live an average of 70 to 80 years, and because of our longer development time, usually about every 20 to 30 years, we might have a new generation of. And so every 20 to 30 years. That means that this is the time line of when these mutations might take hold in a population when we can actually see changes in the molecular clock. Basically, in comparison, some species of Drosophila can have 10 to 20 generations per year. And so dress awful. Uh, species obviously live on a much shorter timeline than humans do, and so they have to reproduce ah lot more often in order to maintain their population sides. And so because of this, if we were to compare, say, let&#x27;s say we wanted to compare genes that were shared incoming between humans and just awful oh, flies. This might be important developmental genes or something that&#x27;s been in our lineages for a very long time and can be traced back to a common ancestor. If we were to do that, then we would have to note that the amount of time that this particular original ancestral green might have mutated along our lineage would be much less often then, along the just awful a lineage, because every year there would be 10 or 20 times that this gene or this protein might have mutated, whereas for the humans every 20 or 30 years it would mutate. And so that&#x27;s why we have to consider these differences and generation time. If we wanted to compare the molecular clocks of these two genes and trace it back to AnAnd Cess, Tral gene or a most recent common ancestor and so that takes care of generation time. But how much population size? Uh, excuse me. Not population time. Population size effect. Uh, these genes are these military clocks. Excuse me. So let&#x27;s take an example where we have a large population and a dill. It eerie ISS gene mutation springs up in some members of the opposition in one generation. And this is this event Asians, to this population. And so, over the course of many generations, let&#x27;s say 10. It is completely wiped out. It&#x27;s removed from the population. Maybe it springs up again in, like, one or two, just because mutations are goingto happen anyway. But they will again be bread out of the population because it&#x27;s large enough that these organisms won&#x27;t find mates usually and are. They&#x27;re much less likely to be able to reproduce and spread that mutation. And so you&#x27;re less likely to see fixation of certain genes. And as a result, you&#x27;re more likely to see a lot of mutations happening in this particular section of the Gina, where this military issue Haitian occur. So let&#x27;s compare what would happen in a small population. We would. We have a much smaller population size and but the same number of organisms that become affected with this deal. It eeriest vacation over the same amount of generations because there are much fewer organisms to make with. It&#x27;s much more likely that these organisms here are going to spread this rotation, and you would expect to see this gene proliferate among larger and larger segments of the population, and maybe over time it would become fixated. And in that case, if every or most of the organisms in this population have this bad copy of this gene, yes, it is likely to mutate, but you&#x27;re not going to see as many variations in it at all. And there are also from just outside, like a pure numbers perspective. You&#x27;re not going to have as many chances for it to mutate because there were fewer organisms in the first place. Like, let&#x27;s say, let&#x27;s return to our human and fly example in a case where we&#x27;re looking at the same gene or a homologous gene between the two. If a human population on Lee has 10 people would say it&#x27;s on a remote island off somewhere, far from the rest of like people and on the same island you have, I don&#x27;t know, maybe 50 or something just awful. A species get very hypothetical. Um, in this case, you would have many more copies of the just awful lodging than the human gene. In order to that, would a be able to be mutated and be be present at all for data collection. And so this is how population size can effect molecular clocks and why we also need to take a look at

Bryan Lynn · Answer

This is a throwback to a few chapters ago and recall at the molecular clock technique says that if we have the DNA son ancestral gene, then there oclock sort of measures time in mutations, so there would be some degree of time that passes. And we would get mostly the ancestral gene. Ah, but with potentially a modification. So maybe one of them went to an aquatic environment. And some some mutations happen there that we&#x27;ve been official. The other one did up some other mutations. Okay, then time was on again. These red arrows air time, and we see, maybe this 1st 1 stays mostly the same. But then we get, uh, two more mutations in that the in this other branch here, so we&#x27;re really doing is comparing DNA and seen where these mutations occur. So there&#x27;s two things that we expect to see. One is we expect to see a lot of similar DNA who are identical. What are you better? Um, say many of those and then if it&#x27;s just having started to be going to evolve in a separate species, were probably at this first stage, so we would expect to see just a few a mutations or differences. And so the evidence we would be looking at would be this, uh, genetic evidence success exactly what we&#x27;re looking at with, um, the molecular clocks technique requires looking at DNA, but likely if they&#x27;re developing a different species. These mutations are something observable, like some sort of FINA type. So there should be something that we could observe that may have led us to wanting to tested and a maybe one of them got stripes now are one seems to have thicker branches and the other does&#x27;nt. Um, so not only would we be looking for the DNA, but probably there&#x27;s a trait that pairs with it.

Kendrick Buford · Answer

All right. So we&#x27;re thinking about the interplay of natural selection and Jeanette Drew and we talked about natural age if you don&#x27;t chapter. But I want you guys to know that you need drooped is just basically the variation of our of the frequency of a deal. Type in a small population oh, into the chance of a particular gene disappearing because individual die. So basically, you have a small population and you don&#x27;t pass on your genes. You have greater die out of jeans because, I mean, you know where to get their gene from you die out and your population is too small, you don&#x27;t actually have as much of a chance to share. So Michael Lynch had our pots. Is that mutation rates are determined by interplay between natural selection and genetic groups. So both needs to get played their part. So what kind of experiment could you have to which will be designed? Have you keep me different types of E. Coli each of different effective population sizes? 1000 generations using that type of experiment? How Lynch&#x27;s hypothesis predict that mutation rates will evolve, so you just have different sizes of E. Coli small colony enable small a tiny bit colony Hughes, Kaufman and banks. So you just let these colonies do what they do and reproduce 2000 generations. So let&#x27;s hypothesis is correct if you have a large population sides So this guy right here, he would have lower of mutation, res and small loans. Who? This guy right here. We have higher population mutation rates and this is because the small populations are affected. Maura Maginn. It droops. So it&#x27;s not quite a mutation itself, Janet Group. But Jeanette Drip does help expedite the elimination and change of the total genetics of a population.

Problem

In animals, the rate of sequence change appears t…

Problem 22 Easy Difficulty

For an intriguing hypothesis about how genetic drift might lead to the evolution of fundamental differences in the molecular machinery of different kinds of organisms, see:

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