the phylogeographic challenge to creationism

Faith, sorry to continue the dog/cat ness argument, but you did bring it up and some people are just like a dog with a bone with these creationists kinds of generalisations (all puns intended).If there was such a creature as a common ancestor to both cats and dogs then would this be seen by creationists to be evidence of macroevolution (whatever that may be - I don't accept it as a scientific term in the way that creationists bandy it about myself). If this common ancestor produced some other creature that was commonly thought of as a dog but actually had more genetic similarity to a cat (a cat with dogness), what would it be, a dog kind ,or a cat kind?. As this would show a gradation between catness and dogness kinds, would this persuade creationists that this elusive macroevolution did actually happen?I doubt it, but the creature may laugh at our attempts to classify it as either a dog or a cat.Maybe someone can guess what creature I am thinking of?

Sorry that you are not following me, but put simply - if there was a creature that was part way between two kinds would you agree that this showed a gradation between these two kinds?I could not agree more that the whole idea of macroevolution is wrong, it's just that small changes build up to greater ones over time (it's all micro).The hard thing to understand about your concept of built in and limited variation is what is the mechanism of this limit. Many others have asked what this might be, there is even a whole thread on that one on this forum.As others have pointed out selection and bottle necks etc. that are required mechanisms of evolution are reductions in the currently available variations of a large population, however they need variations to work on, and these variations do tend to build up over time and yes, this is due to mutation. I just don't see why anyone should find it difficult to conceive that over time these small genetic variations cannot build up to allow further selection to operate on them.I understand that Darwin himself had similar worries about the trend toward less genetic potential that his natural selection theory proposed, so you are in good company there, however that was before genetic variability was understood.Got to sleep now, I may look in again soon, bye.

A small population can have a smaller genetic diversity than a larger population because of the lower frequency of mutation because of the smaller number of offspring within that population to have these differences from their parents. So yes selection for a trait within a population, foundation of a new geographically isolated population, or a reduction in the total population leading to a bottleneck - all of these things starting off with a small number of individuals can reduce genetic diversity compared to the original population. (I don't think that anyone is arguing against this.) Although this does not have to be the case as per others posts i.e. the alleles do not have to be eliminated or significantly reduced, just not expressed.However, there is nothing, no mechanism, to stop this new population from diverging from the original population due to the continuation of the natural process of mutation, whether these mutations are beneficial or neutral. Also of course any totaly harmful mutations always get selected against, so saying that any proportion of mutations are harmful does nothing for the argument.I know you want to separate mutation from other evolutionary processes, but you just can not do that, big surprise - evolution does not get very far without mutation. What I think that you are trying to show is that life on earth shows a trend towards the reduction of genetic diversity by refusing to acknowledge that mutation, over time, produces more diversity than is reduced by the other methods that you insist on discussing to the exclusion of mutation.What the OP was showing you was that the same evolutionary mechanisms are working on populations to produce diversity between various taxonomic levels as the genetic structure between these levels is observed to be similar.
In what way does this show your perceived trend towards reduction of genetic diversity? Or what is your reasoning that the OP does not show increase of genetic diversity?Is there any evidence that you can provide that overall life on earth trends towards reduction of genetic diversity?
It would seem to be the opposite to me and most of the other posters on this thread, so it would be helpful if you could provide your reasoning on this.(sorry that was so long but I am trying to understand your reasoning and just can't get the hang of it)Oh wait I think that I have just got it

quote:

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What a Kind is cannot be determined because it was established 6000 years ago
  —Faith

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So any ancestor that existed more than 6000 years ago did not, by your chronology, exist. Therefore any extrapolation beyond this time scale can not have happened. (oh, and BTW Faith you got the cigar (took the worm ) - for mentioning the hyena, and classifying it as a dog kind. )This message has been edited by halucigenia, 04-12-2005 09:10 PM