A Guide to the tactics of Evolutionists

If.... ... was supposed to describe hermaphroditism then we have appear to have found yet another scientific concept you have misunderstood.TTFN,WKEdited by Wounded King, : No reason given.

You claimed to have already 'predicted' NWR's argument, I assumed you meant you had done so in this thread, did you only mean you had predicted it in your head?If you [b]did[/i] mean in the thread then I am at a loss to see where you think you made any such prediction unless it is in the sentence I quoted which described the organism mating with itself. If there arises in a population of sexually reproducing hermaphroditic organisms a lineage which has lost one set of sex organs. Since hermaphroditic systems can sometimes results in self fertilisation not having both sets of organs would both reduce the neccessary metabolic cost of building and maintaining both and also make sexual reproduction obligate thereby reducing the risk of selfing. One sex could easily arise before the other in such a system.TTFN,WK

Maybe this would be a suitable topic for a thread of its own rather than distracting this one from discussing evolutionist debabting tactics. I'd certainly be happy to go into more detail on proposed origins of sexual reproduction and sexes.TTFN,WK

Care to provide some evidence that a 6 fingered hand is beneficial?TTFN,WK

You assume that the degree of isolation and population reduction seen in this drastic example of a targeted reduction in the wolf population is representative of what would be required for speciation to occur, I see no evidence of that. Is there a reason you assume we should treat them as equivalent?Vila gives a figure of 380,000 as an estimate for the historical population and the current Mexican wolf population is ~310 while that of the Canadian grey wolf is between 60-80,000. I don't know if a 50% reduction in genetic diversity is really surprising when you eradicate ~80% of the population especially if, as Vila suggests, the large remaining alaskan population would have already had a lower genetic diversity than the ancestral mexican and central US populations. There is ongoing further reduction in diversity due to the small nature of the isolated populations. However there is no reason to suppose that the reason for the reduction in diversity is mostly due to the small isolated populations rather than due to the initial massive extermination of the wolves. Care to provide some rationale for this?Every single genetic mutation, no matter what its outcome, increases genetic diversity. Every single offspring, even from an asexual parent, is likely to represent some increase in genetic diversity, however small. It may not all be functionally relevant diversity, and it certainly may not consist substantially of beneficial mutations but it is increasing diversity none the less.What Vila says in your article is that it takes thousands of years to build up the level of diversity seen in the pre-extermination wolf population, but this is an arbitrary amount of variation it doesn't represent any requisite level of diversity it is simply the level that happened to be extant in that particular population, a population which would certainly have had 1000s of years of extensive range and large population size in which that variation could develop.why should it take thousands of years for any genetic diversity to develop?The paper your article was based on 'Legacy lost: genetic variability and population size of extirpated US grey wolves (Canis lupus)' is most interesting but I don't think it really supports the contentions you are making.TTFN,WKEdited by Wounded King, : No reason given.

Probably, but the extent of the reduction need not be as drastic as the 50% in the Vila study. If the extermination had been of the less genetically diverse historical Canadian population and the more genetically diverse central population of C.l.nubilus had survived they might have only seen the loss of ~4 haplotypes.It certainly isn't guaranteed that the loss of diversity would ensure a failure to thrive of the population and subsequent further reductions in diversity, nor that regaining an equivalent amount of diversity would require thousands of years. Only if you insist on sympatric speciation (speciation within a single population) rather than allopatric (two populations are geographically isolated) or parapatric (Populations are contiguous but with restricted gene flow due to differential success in differing environments). If you look at the diversification of Cichlid's in lake Victoria you will see that rather than all fighting for the same niche they have diversified to fill many different niches, this diversification probably encompasses more than one of the categories above (Kocher, 2004; Won et al., 2005). Not at all, but that isn't what you said. You went from the specific case of wolves to making a general argument that 'it takes thousands of years presumably for mutations to increase genetic diversity'. If you are only talking about the current wolf population in North America that is fine, but you seemed to be applying it more broadly.TTFN,WK

Care to define thrive for me? Because a population of 12,500 doesn't sound thriving to me especially for a population described as showing 'remarkable physiologic impairments including increased spermatozoa abnormalities, decreased fecundity, high infant mortality, and increased sensitivity to disease agents' (Menotti-Raymond and O'Brien, 1993).If you can tell us about the historical genetic diversity of Cheetahs in a similar way to the study of wolves I am keen to hear it, but the present studies are on populations which have been through recent severe reductions as well as further back historical reductions.Never mind, cheetahs are rather beside the point. And the other point is that there is more than one process at work.If you feel that there is a sufficient body of work to show that genetic variability cannot show a net increase in a population then it is rather up to you to provide it. So far your 2 examples, wolves and cheetahs are at the extreme edge of extinction. Do you have any examples from a more successful, numerous and wide ranging species?I doubt anyone would even dispute a contention that there is a strong tendency in the history of life towards the reduction of genetic diversity, as represented by the fact that 99%, or whatever the number is, of species that have existed are now extinct.This does not however mean that genetic diversity in a population cannot increase at a faster rate than decrease in that population. For a really accurate study we really need a number of genetic samples from a well supported ancestral species so we could do a study similar to that done for the wolves.I also think you should allow that near extinction is not the same as small populations being isolated. While the genetic diversity of the isolated population may be reduced in comparison to the original population the original population may still retain all of its diversity. So the real question in such a situation would be if considering both populations there was an overall increase or decrease in genetic diversity over time.At them moment I am not aware of any such studies having been done.TTFN,WK

Well then why not put up a specific targetted level of change, otherwise all we have are the automated creationist shifting goalposts.If you think you think you have a simple general formula for the level of reduction in genetic diversity then why no let us have it?I doubt any such formula exists different populations under different environmetal conditions will develop in different ways, and some will fail to develop further and become extinct.If you there taht a barrier exists then why is the onus not on you to prove it ratherthan on us to disprove it? We can show you hundreds of studies showing various different types of mutation rates all of which contribute to genetic variation. We can also find lots of studies of different populations undergoing different trends in terms of population genetics.If you really think there is a scientific case to be made then why not continue as you were with th wolf studies rather than retreating to the typical demands that we satisfy your fanciful objectives to prove that such a barrier doesn't exist.Can you point to a single genetic sequence that could not arise through mutation?If you think such genetic systems exist surely the burden is on you to demonstrate their existence?There are still worthwhile arguments to be made that the mechanisms of macroevolution need not merely be those of microevolution writ large (Penny and Phillips, 2004), but you don't seem to be in a position to make them.TTFN,WK

But there is no such claim. You are saying that we should see mutation providing sufficient additional genetic variation to a population to overcome the effects of drift and selection in terms of reducing variation. And you have been specifically wanting to talk about small isolated populations. OK, how small? How isolated?Just saying 'small' and 'isolated' is vague. What might be true for a population of several hundred may not be for one of several thousand. Similarly if there is even a very small amount of gene flow with related populations it can change the population dramatically. going back to the wolves the same authors had a paper showing that the introduction of one outsider to a highly inbred population, one starting from only 2 wolves, was sufficient to hugely increase heterozygosity and lead to a large population expansion (Vila et al., 2003).You also now seem to be conflating these measurements of variation with macroevolution and for the life of me I can't see how that is supposed to work. To say macroevolution cannot be a result of microevolutionary processes because in small isolated populations genetic variation tends to reduce seems like almost a classic example of bait and switch, one does not follow from the other.TTFN,WK

Actually another interesting corrollary of this is that you do not need any single 'larger' population as such, several partially isolated small populations are sufficient. While each small population may tend towards homozygosity due to drift the stochastic nature of the process means that they will different alleles will run to fixation. So while any one population may lose considerable diversity the larger metapopulation of populations, as it were, is likely to retain a good deal of the variance from the ancestral population and infrequent gene flow will allow the sporadic reintroduction of diversity from such distinct gene pools. A loss of genetic diversity need not, as you yourself pointed out, lead to poor health. In extreme cases and with long term inbreeding it very likely would but again why extrapolate from populations on the edge of extinction to any population potentially undergoing speciation from its progenitor population?There is a dynamic balance between the effects of drift, mutation and selection which depending on a number of the variable we have touched on briefly, i.e. population size and gene flow amongst others, can lead to a number of different outcomes including extinction and the acumulation of detrimental mutations, but also to a higher rate of fixation of beneficial mutations and even, according to some research, to the so called fitness reversal of detrimental mutations to beneficial.I have a list of references touching on several aspects of the balance between mutation, selection and drift. I am going to be away for the next few days but I'll see if I can put together a short overview of some of the recent research when I get back.TTFN,WK