Mutations would eventually lead to the extinction of a species

If Pro does not have the full text of the article, then it is impossible to know whether or not Kondrashov actually did answer his own question. For that matter, it may also be that someone else has answered Kondrashov's question. And, of course, humans are a special case, given that we put a great deal of effort into making sure as many members of our species survive if at all possible, even if they ordinarily wouldn't. C1: The two are quite related. Negative mutations, even if they have no effect on the organism itself, can have an effect on the offspring. For instance, if I develop a mutation that leads to trait X, but it does not manifest because it is recessive, my offspring are at risk for having trait X. Now, Pro says that any mutation 'degrades the information'. False. Whether or not the information is degraded depends on the mutation. If it is beneficial, it is 'upgraded'. If it is neutral/environment-dependent, it is simply 'replaced' with something that works in different circumstances or is little different. If it is harmful, it is 'downgraded'. Pro's argument that linkage blocks prohibit selection against harmful traits is mistaken. Firstly, any given linkage block has a probability of forming, rather than being a certainty. Therefore, the presence of a specific block can be selected against. Two adjacent loci are very likely to be inherited together, but since it isn’t certain, members of the species with the beneficial mutation but not the negative one would be selected for. Secondly, Pro’s argument assumes that positive mutations will necessarily form linkage blocks with negative ones with a high enough frequency to cause such an accumulation of negative mutations as to render the population unviable. C2: Yes, but the information is conserved in DNA for humans. Furthermore, RNA viruses mutate very quickly: they evolve six times faster than human DNA[1]. In any event, I didn’t say that DNA viruses would be acceptable but RNA viruses would not. I said that the fact that 40% of mutations in RNA viruses in a single experiment were lethal does not tell us very much about the frequency of lethal mutations in humans. C3: Hey, sterilization’s a lot better than termination or dooming millions to live with severe congenital illnesses. I would, by the way, like both a source and an explanation by Pro for how, exactly, a fast reproductive cycle is supposed to delay this, rather than simply speeding it up. Pro’s source talks about body mass, and the resultant effects on population size—namely, species with large body mass have fewer members, thus leading to increased risk of mutational meltdown. C4: Because you can’t add zero and zero and get one. If a mutation affects part of the genome that has no function, then the mutation is meaningless. Not ‘very slightly deleterious’. Not ‘causes trait X in conjunction with gene Y’. Disregarding nonfunctional DNA, if the effect is so slight that only in conjunction with other traits it can be selected against, these ‘groups’ of mutations will be weeded out. C5: There’s a great deal of support for three. Loewe mentioned that in his paper. Pro says there is no experimental support for three, but is wrong here as well, albeit indirectly. We know from a great deal of evidence that species are very, very old, at least compared to the time in which various sources Pro has cited say they should have gone extinct. We know that Muller’s ratchet and mutational meltdown can apply to populations (this is why genetic diversity is so important in endangered species[2]). Now, here Pro says that you can’t slow down the ratchet enough to stave off extinction indefinitely. False. It’s quite easy, because Muller’s ratchet relies on irreversibility—it isn’t a true ratchet in organisms with sexual reproduction. The whole point of Muller’s ratchet is that when you have asexual organisms reproducing, and they do not undergo recombination, you can never have offspring with fewer mutations, but in sexual reproduction you can—you can put together non-mutated areas of the genome. This isn’t always enough to avert Muller’s ratchet, because if the ratchet is turning at two ‘clicks’ each generation and turning back only one ‘click’, that’s still one net ‘click’. But if it turns back a number of ‘clicks’ equal or greater to the number of ‘clicks’ forward, Muller’s ratchet can be avoided. Thus preventing extinction. http://www.actionbioscience.org... http://darwin.eeb.uconn.edu...