Has natural selection really been tested and verified?

You are assuming that this exact mutation has to arise for there to be a protective effect. In fact there may be a number of other mutations with similar functional effects. But once such a trait has appeared in a population where there is a strong selective pressure to promote its spread then other protective mutations would be redundant. We don't know this is the only mutation to have this effect, only that it was the first to spread through the affected population. Dear Mr Bolder-dash,The ethics committee has decided to decline your request for approval to subject living human beings to dioxin poisoning in order to test for heritable resistance traits.Yours, The ethics committee.The problem with your suggestion is that a lot of these are very sporadic environmental factors. You are unlikely to find a population which is consistently being bitten by rabid dogs, or hopefully exposed to dangerous levels of dioxin. In almost all the cases of identified protective mutations in humans they are for factors which are endemic to the population in which they are identified.There may well be mutations which could confer some degree of resistance to dioxin arising, but there is going to be very little selective pressure to maintain such a trait unless the population is consistently being exposed to dangerous levels of dioxin, but low enough to allow the maintenance of a breeding population.We just can't know what these mutations are until they have somehow been identified, there are just too many possible mutations and we know too little to be able to predict the effect of most of them. I think the number of factors needed to make accurate probability assessments too great for it to really be tenable, one of those factors would be all of the other possible mutations conferring a similar degree of protection. If we could do it it would certainly be interesting but I'm not sure it would really tell us anything important about natural selection or evolution in general.TTFN,WK

I know that short responses are frowned upon but I can't think of any sensible response to this post other than - WTF?Not only do you not seem to want to discuss natural selection you don't even seem to want to discuss evolution as any evolutionary biologist would understand it.TTFN,WK

One does not need to be an evolutionary biologist to understand what has been written on the subject in published research.There were no logical questions. You asked essentially the same thing I had already answered with regard to the frequency of mutations and then went into an incoherent ramble about evolving a hole in the head to allow one to sense the vibration of cosmic strings. To re-iterate, the frequency of any specific mutation that produces a protective effect against kuru does not tell us the frequency of all possible mutations producing such a protective effect. So while we could, given enough funding and time, sequence a large enough population to estimate a general rate of occurence that specific protective SNP in populations not exposed to Kuru, it would give us little in the way of worthwhile information. And it certainly isn't neccessary to demonstrate natural selection is in operation.TTFN,WKEdited by Wounded King, : No reason given.

You continue to ignore my point that the specific mutation is less important than the actual trait, and we can't know all the possible mutations that will give rise to the trait. It isn't as if the G127V mutant is the only protective allele that has been identified (Mead et al., 2003). Without knowing how many othe possible pretctive alles there are your probability value will be meaningless, just like those tornado in a junkyard calculations that IDists/creationists love to throw around for whole functional amino acid sequences like modern proteins assembling themselves de novo. You are looking at the wrong organisms. These sort of traits didn't initially arise in large metazoans like zebras or octopi. What we would need to be looking for would be such mutations in primitive metazoans like Amphioxus or ascidians.You are also assuming that the time scales on which such studies could be conducted is the same as that for the kuru mutant, but while we may have a narrow window for the origin of the G127V allele we have no such window for the evolution of the eye and therefore no reasonable expectation of what any particular frequency would tell us about evolution. Finding no such mutations in an entire population of primitive chordates would not show us that such a mutation was impossible or even prohibitively unlikely.I'm not even convinced it would be practical to look for such a trait. One paper on a theoretical model for eye evolution was based on steps involving only a 1% change in concavity for the sensitive patch, surely too small for us to reasonably be able to screen a population for (Nilsson and Pelger, 1994)? It is also erroneous to assume that the origin of the depression is a simple coincidence independent of the rest of the structure. If it is rather that tensions generated from the development of the nerve fibres, prefiguring the optic nerve, and the sensitive region affect the morphological development of the region then we might expect the two traits to occur togther much more frequently.You are making way too many assumptions about how things must have occurred.I fear that even if your approach is theoretically sound, which I would dispute, it is totally impractical.TTFN,WK

Because a lot of 'species' classifications are based on old fashioned morphological or even simply geographic criteris, they aren't base on the actual establishment of reproductive isolation. Therefore what have been identified by taditional methods as distinct 'species' may still be considered to form part of one breeding population due to gene flow between different populations at hybridisation zones.The Grant's research has identified instances of cross 'species' breeding in only a small number of instances, around 2% of breeding pairs, as such a hybrdisation 'zone'. The reproductive barriers between the species are caused by pre-mating isolation through song type (Grant and Grant, 2008).This level of hybridisation is put forward by the Grant's as a potential medium for transfer of genetic variation between populations.TTFN,WK

Because one common definition of 'evolutionary change' is the changing frequencies of alleles within a population over generations. This encompasses both changes in pre-existing alleles and also the creation of new alleles by mutation.In terms of the sort of long term complex gross morphological changes you are talking about, i.e. evolution of the eye, obviously both of these things must come into play. In terms of a simple demonstration of natural selection all we need is a population with allelic variation producing differential survival/reproductive success in a particular environment. Obviously the original source of this variation is likely to be due to mutation of some form but having observed that original mutation doesn't change the natural selection we can observe operating in the population subsequently. As an example we can observe selection in action on an assorted population of melanic or wild-type peppered moths without having identified the first melanic moth to appear in the population, or even knowing exactly what the genetic basis of the melanism is.Obviously when changes in allelic frequency are considered evolution then genetic drift is also seen as a mechanism for evolutionary change, though not adaptive evolutionary change.TTFN,WK

Wow, you're right, its almost as if somebody stopped us from presenting the masses of data that has been accumulated showing natural selection in microorganism, Oh wait! It was you.Showing natural selection on populations in the wild is hard. It may seem easy to you in your armchair drinking your brandy and smoking that cigar, but for field biologists it is a massive investment of time and effort, not to mention not being as easy to attract funding for as sexy new technologies like bacterial whole genome resequencing which can pinpoint the genetic basis of specific bacterial traits. Shockingly the experiments that can be done in a lab with a flask full of E. coli predominate, because scientists are pragmatists and don't arrange their research based on the pre-concieved notions of creationist/IDists/whatever stripe of evolution denial you adhere to. As I believe someone pointed out, when you talk about choice in a sexual species, as you did in the OP, you seem rather to be talking about sexual selection.Also, I can't imagine why no one has posted more examples given the way you thoroughly discredited the ones that were given. No, wait! That didn't happen at all. You just made it clear that in fact your thread about natural selection was actually about random mutation and whether mutation rates were sufficient to generate the neccessary variation, something completely unclear from your OP about natural selection.The idea that having failed to show a clear origin for 30-100 million species is a blow for evolution seems patently absurd. It is a science essentially only 150 years old and for the modern synthesis the age is closer to 50 years. Even if every scientist on the planet had been working round the clock for those 50 years on such a project I doubt we could have provided a clear origin for even a fraction of those species, in many cases the divergences may be so far back that such a reconstruction is impossible in anything approaching the sort of detail you seem to demand.Once again an armchair 'creationist' tell us how trivially easy it should be for scientists to do all sorts of things, were evolution to be true, and if that doesn't convince you evolutionists out there, well, then I guess nothing will TTFN,WK

Except it couldn't because genetic drift isn't a source of novel variation.TTFN,WK

No I didn't, I pointed ou that there is plenty of research but because scientists aren't idiots they do that resarch on the sort of subjects where it is practical, i.e. all the microbiological research and short genertaion organism research such as on Drosophila that you just handwave away.There is plenty of research 'in support of natural selection playing a vital role in the process of evolution' but you decided right from the start to disbar the vast majority of it and you have continued to reject all the examples you have been given without giving any coherent reason why. No, there are 8 people insulting you because you came in with a question, when it was answered you blew off the answers and said that in fact you were looking for another question to be answered and then blew off all the answers on that as well, not to mention insisting that it was the question you were asking all along, and you're still doing it! You didn't mention mutation in your OP, you specifically focused on natural selection both in the OP and your title.No one has a problem with bringing mutation into the debate, provided you actually realise that it is something distinct from Natural Selection, at the moment you just keep on insisting you are right in lumping mutation in with natural-selection, and you aren't.Did you ever wonder if the reason you run into so many people telling you you are wrong because you don't know a damn thing about the biology you are trying to discuss is in fact because you are wrong because you don't know a damn thing about the biology you are trying to discuss? You say you are 'here in an attempt to gain enlightenment from others who may have another intelligent or interesting point of view', but you don't seem interested in our points of view, or the reserach that has been published, only on asking why people haven't observed this thing you think they should have or why they haven't yet got round to sequencing the whole genomes of the entire population of the western world to look for the natural prevalence of one specific mutation with a protective effect against kuru.Maybe you should look at Olivia Judson's excellent recent article in the NY Times and then you can come back and tell us more about the wonderful way that mutations just magically appear in a population when they are needed. Apparently you didn't get my answer, it is almosy trivial to show in the sort of short generation microbial experiments that can be readily performed in a lab. It is much harder in wild populations of organisms with much longer generation spans in the order of months or years because you ideally need to follow a population over multiple generations to be able to account for random factors. You chose to artificially restrict where examples could be drawn and then go on about how few examples were presented? There are also plenty of other examples but it was pretty clear after only the first few responses, like to RAZD's initial one that in fact examples of studies showing natural selection in action weren't actually what you wanted, which is probably why no one bothered to present any more. To now act as if only being presented 4-5 examples was because of a lack of them is disingenuous in the extreme.TTFN,WK

It is correct in theory that new mutations are not required for one initial interbreeding population to become two populations that cannot interbreed.Let us assume there is one initial population with a wide genetic variety, there may be some individuals within that population that are for some reason genetically incompatible. These incompatible organisms produce only sterile or non-viable offspring. These individuals still form part of the same population as they can still interbreed with other members of the population who do not have the specific genetic features associated with the incompatibility so there is still considerable capacity for gene flow between the sub populations of organisms with these incompatibilities in the whole population over the generations.If for some reason the population becomes divided then genetic drift may cause these incompatible genetic traits to become fixed in different populations. In that case if they consolidated into one region again we would expect to see little if any successful breeding between the populations and we would consider them to have become distinct species.This can also result from traits being selected for but genetic drift is a perfectly suitable source of fixation in this case. Indeed there is much debate as whether it is selection or drift that is more likely to give rise to such incompatibilities. I would suspect that true genetic post-mating incompatibility is likely to be due to drift more often than pre-mating behavioural isolation, which seems like a prime target for sexual selection.Obviously the source of the initial variation in the population is going to be mostly due to mutations, but no new mutations are required for the two reproductively isolated populations to arise.I suspect that this may not be 'new species. (ie macroevolution)' as you were thinking of it.TTFN,WK

All of those explanations have made things as clear as mud to me. I think too many people are using 'change' and evolution in too many different contexts. So to add to the confusion I'll pitch in with my own opinions.In my view there are ~3 things that are being variously conflated here.Facts of evolutionWe can observe heritable change in populations. Either directly by seeing how genetic variations spread between generations and what new mutations arise or indirectly by studying changes in phenotypes and from that genotypes and determining their heritability across generations. These can be observed independent of our understanding of the source of the mutations or of the factors leading to the changes in the proportions of each variant. This is a way to produce a purely descriptive set of data on the evolution of a population, it will capture both adaptive and neutral evolutionary changes.Theories of EvolutionThe main one espoused on this site is a slightly updated form of the modern synthesis. This is the marriage of traditional Darwinian theory, population genetics and the molecular genetic principles that were elucidated in the middle of last century when DNA was first being manipulated. More recently comparative developmental biology has become a key factor in our understanding of how genetic changes can give rise to morphological variation. Most of these theories are based around the primary source of genetic variation being genetic mutation, essentially random in terms of the effects on fitness of the organism but not random as in equiprobable. This variation introduces new allelic variants into the population which then change in proportion due to both selective factors and non-selective random factors. Some of the factors Bolder-dash described, such as a bomb going off, are essentially non-selective and would contribute to genetic drift rather than selection. Even really robust people will tend be killed by a bomb going off.Genetic drift is considered the main source of neutral evolution, essentially random changes in genetic frequencies from one generation to the next, while Natural selection is credited with adaptive evolution when genetic variants which improve an organisms reproductive success, normally also survival, will increase in frequency amongst the population.The Evolutionary history of life on EarthThe third element that often comes up is our ability to accurate describe or infer the actual evolutionary history of life on Earth, or any specific organism. This is the fundamental basis of arguments from design. We observe an organ/system is well adapted to its task and ask how it got there. In line with evolutionary theory the biologist proposes it is the result of a succession of genetic mutations in the organisms ancestors which have been propagated throughout the population due to improving the organisms fitness. The IDer says that is all very well but where are all these ancestors? What are the genetic mutations that gave rise to this system?And this is where the principle disconnect arises because all of our best answers are mostly going to be inferences from the available evidence, such as conserved patterns of expression of homologous genes producing homologous structures in developing embryos and the ways those patterns can be affected by genetic changes, or the patterns of variation we see in organisms within and between species.There is now an increasing body of research where actual specific genetic bases are being identified for selected traits in populations, but this is still a young field dependent on advance in sequencing technology.Similarly we can infer periods of selection on specific genes/genetic sequences in populations by looking at wide samples of genetic material both within and between specific populations and within and between different species.But we are never going to be able to go back in time and get DNA samples from actual organisms ancestral to any modern lineage, with the possible exception of very recent common ancestors. We might get some Neanderthal DNA but we aren't going to get any DNA from the latest common ancestor of humans and chimps. We also aren't ever going to effectively prove the 'out of Africa' theory to someone who doesn't accept that comparative genetics can tell us anything about ancestral populations. It is frequently going to be impossible to provide the level of detail demanded by a skeptic, because the level required is frequently unrealistic.TTFN,wK

Possibly, there are certainly many couples which have fertility problems so I would imagine the necessary genetic variability is there in the population. However I think that human population size is too large and gene flow between geographically distant populations too frequent for this to realistically happen except perhaps in the even to some cataclysmic environmental change producing some seriously long term isolation, and even then it would probably be a matter of chance if such incompatibilities became fixed. No as far as I know. I don't know if there has been any specific research into inter-population fertility. Its another one of those things where ethics precludes doing the straightforward experiments we might in an animal model and instead we need to rely on whatever mating partners people happen to have chosen, we can't force a Maori to mate with an Inuit. Certainly it hasn't happened to the extent that there are clearly segregating breeding populations.The possible exception is in the form of pre-mating isolation in behavioral rather than genetic terms since some insular ethnic groups prefer to keep marriages within their own populations. But this is a social rather than a biological barrier.TTFN,WK

I have to say that 30 somatic mutations in a lifetime sounds implausibly low to me. I think historically such estimates have been based on techniques where phenotypic changes have been identified and used as a proxy for somatic mutation rather than actual measurements of change at the genetic level. These changes are often based on 1 or 2 marker proteins which may or may not be representative of mutation rate throughout the genome. One recent paper that looked at actual sequence level changes suggests that somatic mutation rates are actually 10-1000 times as high as traditional methods have estimated and their distibution is affected by factors such as the expression level of gene (Sylva et al., 2009). I'm afraid your guesswork is wrong, probably due in part to the very low level of somatic mutation you are using as a base line. There is plenty of research suggesting that the total number of new mutations per diploid human genome per generation is ~100 (Kondrashov, 2002). These estimates are based both on cross species comparisons between humans and chimps and on the spontaneous rate of de novo mutations causing heritable Mendelian diseases.TTFN,WK

Hi Herebedragons,You ask some good questions but I think this thread is already quite fragmented enough. Perhaps you could repost your questions in the existing Understanding the Genetics of Speciation thread?TTFN,WK

They do do this Peg, it is called 'adaptive evolution'. This distinguishes it from evolutionary changes which are simply the result of random factors, which are 'neutral evolution'. I would suggest that most de novo mutations should be considered 'neutral evolution' when they first arise, it is the following spread of specific mutations through the population by natural selection that constitutes adaptive evolution.So these distinctions do exist, as do distinctions between genetic/ molecular evolution and gross morphological evolution, i.e. the distinction between the evolution of genotypes and phenotypes.But if you don't make the effort to actually read about evolutionary research you probably aren't going to pick up this sort of detail. You won't get these distinctions made in most science reporting.TTFN,WK