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Non Darwininion Evolution Summary: Most molecular biologists simply assume that evolution and natural selection are the same thing. And so there's other ways that we can evolverit. The title is sort of an homage to a controversial and classic paper that appeared in 19 69, authered by king and a jukes. Transcript: Speaker 2 evolution and natural selection on the molecular level? And what you mean by that? Speaker 1 Sure so i think that generally, people simply assume that evolution and natural selection are the same thing. But in actural fact, they're not really the same thing. Evolution simply, i mean, there's a lot of definitions out there, but i'm going to make it supersimple here. Evolution just means change over time. And natural selection is one way in which change can occur. It's a mechanism through which a evolution is enacted. But actually, it's not the only mechanism. And that's one of the sort of mis standings that a lot of the lay public have. And to be quite honest, most molecular biologists have, right? Most molecular biologists simply assume that evolution and natural selection are the same thing. And that's where a lot of problems arise. And so there's other ways that we can evolverit. Speaker 2 Ye. Speaker 1 This is where, this is where sor of the title comes in. I'll also point out that the title is sort of an homage, a to a very, a controversial and classic paper that appeared a, you know, in i believe, 19 69, authered by king and a jukes. (Time 0:01:28)
Genetic fixation Summary: Yelamem: There was waight too much fixation for naturalf to be compatible with natural selection. And in fact, if you actually look at how different alils fix and how they tend to spread, well, the smaller the population is, the more drastic of an effect the alil has to have on whether it gets fixed or not. So this is the origin of neutral theory. Transcript: Speaker 1 And what he put forward is, when you actually look at the rate of a fixation of variation in populations, m there was waight too much fixation for naturalf to be compatible with natural selection. And in fact, if you actually look at how different alils fix and how they tend to spread, well, the smaller the population is, the more drastic of an effect the alil has to have on the fitness for natural selection to even have a say as to whether it gets fixed. And so this is the origin of neutral theory. And that is a very important idea, that there's a fundamental association between the power of natural selection to have even a saying whether an alil gets fixed. And ultimately, the population size. And it's not just the population size, but thisa concept called the effect ov population size. Speaker 2 Yelamem, really quickly, you're talking about fixation. And just to make it clear for the listener, i think you can figure it out from the context, but fixation is you havein alel it's almost zero %. It's a new mutation, and you know, eventually it goes to 100 %. And once it goes to 100 %, if you have a random walk process, like jon drift, now it's going t to go up and up and down, up and down, but at some point it's either going to fix or it's going to go extinct. (Time 0:17:57)
Genetic drift - Bias mutation Summary: Molecular biologists are uncovering new features, a sort of information content mornas that distinguish them from the non information content. The different parts of the genum are experiencing subtle changes in mutation. It turns out that the act of transcribing a danan arne helps to more efficiently, a, repair those parts of the dana. There was a big paper, i think, i in nature that kind of went all over the blog people are still talking about. Transcript: Speaker 1 I were uncovering new features, a sort of information content mornas that distinguish them from the non information content. So we're really, like, looking at really the nuts and bolts of how you soard information at the molecular level. I mean, that that's the sort of, the science really drives me a and, you know, there's some sing things in there. One of the things that we can see is that some of the information, a and, and i don't know if we have time to get into this, appears to be creative, in a non adaptive manner. That's, i think, one of the fundamental surprises that we can see, a and that's coming out of of fa. What we think is happening is that there's a, and this goes back to actually the nuts and bolts of how evolution works, where we talked about mutation and we talked about the rolels of selection and drift. So mutation is creating variation, selection and drift a is shaping genom in that it allows certain mutations to either reach fixation or not. But it turns out that the generation of mutations is not strictly random. And what i mean by that is that certain parts of the genom experience different types of mutation than other parts of the genu. And it appears, i mean, our work is kind of indicating that a parts of the genu that are functional experience different types of mutations than other parts of the genum that are not functional. And that actually subtly shapes, actually, how jeans look and, ah, and actually, ah, that is sort of imparting information into the geno. So so we've been very interested in a process ed bias mutation. And what i mean by bias mutation is not this idea that there's any forethought that mutationisit is kind of directing evolution, because a mutation kind of can foresee the future. But rather that a just just the idea that functional parts of the gen because they are functional, they will acquire different types of mutations than non functional parts of the geno, right? So for examplea parts of the genom that are transcribed into arne, because they are being transcribed rit actually te the machinery that transcribes the d an ato r and a subtly affects how those parts of the d an a are mutated. Because, for example, a d an a replication machinery can collide with with the r an a transcriptional machinery, and that generates a whole host of different mutations that you would find in that part of the genum and other parts of the geno. It turns out that the act of transcribing a danan arne helps to more efficiently, a, repair those parts of the dana. And there's a lot of data. There was a big paper, i think, i in nature that kind of went all over the blog people are still talking about but we've had, we've had inklings that this a has been happening for a while, that a, a mutation is actually not random. The different parts of the genum are experiencing subtle changes in mutation. And if you accumulate that overtime, sort of those marks, right of mutational bias can be, in a sense, coopted by the cell to identify functional parts of the geno over non functional parts of the geno. Speaker 2 E, wo it sounds like a, it sounds like you're going to have a an exciting decade. A and a, you know, charles darwin would be proud. I think, you know, where his theory has, has gone where no victorian hasa gone before. Obviously, because they didn't understand molecular biology, and didn't know anything about dana. But, i mean, thats ta sem. That's the beauty of it, you know, volution as an analytic theory a, you know, i mean, it's not dependent on whatever substraitit it, you know, was down there. But (Time 1:17:44)