Ok, Farmerman, I think what you're saying is that the primary component of variation, against which selection works, is not mutation events, but combinations of alleles in a population which have (active or inactive) mutations riding in them.
Ultimately, mutation is the root cause of all the component pieces of the genome (going all the way back to self replicative mollecules), but it's the combination of, and activation of these genes which comprise the majority of the differentiation which leads to different species. The implication is that there is tremendous potential for variation built in the genetic structure of every mammal, *without* having to rely on new mutation for new structures (which is what I was assuming before).
In the case of sabre teeth, the root gene (or genes) for this are buried deep in mammalian history (thus the spread through through the various Genus, such as marsupial to feline), and become expressed when they happen to converge by chance due to mixing. These chance expressions are then honed by selection to cause an increase in allele frequency in a population (which is the definition of evloution), and within that new population, there is now an even greater chance that associated genes for even larger teeth will arise in the remaining combinations.
If this is the case, it would explain why mice and chimps and humans are so similar genetically, because it's the combinations and activation of genes which matter, not the simple presence of the genes themselves.
It might also explain the growth curve (replicative mollecule, single cell, multi-cell, plant, animal, etc) which the history of life on Earth shows, because as the genome gets larger, it carries with it all the tools (past mutations) for generating lots of variation (with natural selection waiting for it)
Does this make sense? Am I on the right track to what you were talking about? Or did I miss the point and come up with something else?
Best Regards,
