Cyborg
mutation alone cannot account for all the diversity
No one said it did. You can have variation in a species without mutation. Some will simply be better at reproducing offspring that in turn survive to reproduce than others, just as some horses win races and others don't simply on the basis of natural variation (or un-natural variation) as selected for by envronmental factors.
This means "beneficial" characteristics (to survival in an environment) are strengthened and refined. Some individuals in a population will have environmental selection pressure that is different to the same population elsewhere. The population will eventually split as different characteristics are being favoured on the basis of the environmental pressure of a sub-population's habitat. Those populations would at first be interfertile but eventually drift will take place between sub-populations that are not in contact with each other to the extent that breeding either does not take place (for behavioural reasons) even if creatures from two populations do meet each other, or cannot take place and result in a fertile pairing.
Mutation is grist to the mill as occasionally one will occur that has a net benfit.
The herring gull example given above is a beautiful one of geographical speciation as it goes from interbreeding but distinct populations to non-interbreeding distinct populations. No mutation, just geographical variation building to an extent there is a speciation event.
A good example of a mutation occuring with net benefits is that of sickle-cell trait, which whilst very bad for those with two sets of the gene is beneficial for anyone with one set of the gene who lives in an area where Malaria is rife, as it makes infection of the bloodcells harder (if I'm explaining that right). This mutation is not selected for outside of such areas. Another one with humans is lactose tolerance. It appears that those populations that utilised dairy products had an awful lot of selection pressure favouring those with the mutation, to the extent that now entire populations of humans usually have the gene. In populations where dairy products were not utilised for food the presense of lactose tolerance is not selcetd for and is uncommon as there's no benefit to it.
Cyborg, I appreciate your POV; it was what I had before studying biology, which I only did after exiting the Dubbies. That doesn't mean I am right, but I changed my opinions for reasons, and the counter arguments you use against evolution are ones I once used and then discarded as I came to understood evolutionary biology better.
Your comments about TV sets and amobeas are nicely handled here. http://www.talkorigins.org/faqs/abioprob/abioprob.html
No evolutionary biologist would ever claim smallness is equal to simplicity so I don't know why you try to disprove a statement that hasn't been made.
Of course all science makes assumptions; something which it shares in common with theism. Physics is built on constants that are in certain cases assumptions, albeit educated ones. But science operates by a set of rules regarding evidence. This does not make it infallable, but I just want to make clear that evolutionary biology does not use different rules to other areas of scienece. It is prevented (just as with geology and cosmology) from providing proof in the way someone working with, say, organic chemistry could provide proof of a theory, but that is not neccesarily due to a weakness or error of theory but is a reasonable concquence of the timescales involved.
One sees evolution occuring around us at the rate one would expect. We can't 'put on' the development of a new phylum or kingdom in the way that you can play with chemicals when you want to show your theory is right. But the theory really holds out well; look at the parrallel sets of evidence from evolution in a mammalian dominated environment when compared to a marcupial dominated environment (AUstralia) or an avian dominated environment (New Zealand). It all fits the same theory.
Of course, one might say, rather than "can we completely discount intelligent design?", "Is intelligent design a plausable theory?"
The first phrasing carries a presuppositon or assumption that there is something to discount. That is not scientific as there is no evidence pointing directly to intelligent design, only inferences based upon and opinions about evolutionary processes. It's th difference between "can we competely discount Santa Claus as a mechanism for Christmas present delivery?" and "is Santa Claus a plausable theory of Christmas present delivery?"
If one asks if ID is a plausable theory, and goes to the base concept of the theory, that complexity requires intelligent design, one is immediately lost in a never-ending circular question that can only be escaped from by using non-sceinfic claims.
If complexity requires an intelligent designer, who made the designer, and who made the designer's designer, and who made the designer's designer's designer, ad nausium?
One can claim the designer is non-complex. One can claim that the designer pre-existed and is timeless.
Both claims are huger assumptions than any evolutionary scientist has ever made. Even when they stuck a dinosaur's horns in the wrong place, they knew there were there. ID doesn't know if there were "horns" let alone where they went but bases its entire theory on the presuppositon there were "horns".
