Evolution, religion, and ignorance.

[Angrboda]

I would have to disagree with the supposition that once you've demonstrated microevolution you've thereby demonstrated macroevolution because macroevolution is "just more of the same." ... We don't know enough about the mechanics of genetics to say that there are no limits to variability at the biological level "based solely on observation of microevolution in existing genetic populations." The conclusion that macroevolution occurs is one based on a pattern of evidence, it's an inference from a lot of evidence. In that respect, it is categorically different from microevolution...

Ring species, by exhibiting the entire process of speciation - ie "macro"evolution - simulataneously across space, rather than sequentially across time, provides independent demonstration that there is no binding genetic limitations of variability at biological level that would preclude speciation, whether we might otherwise be said to know enough about genetics to have been able to make this determination a priori or not.

I knew that sentence was going to be problematic. What I was aiming for is that we don't know enough about the mechanics of genetics, the molecular basis, to conclude that there are not barriers to speciation at that level. I don't think there are, but as the general point of my post explained, demonstrating that there are no such molecular level barriers to speciation depends on inference from a pattern of evidence, which includes ring species, not from either our knowledge of the chemistry and physiology of genetics, nor from making a uniformitarian assumption that microevolution leads to macroevolution on the basis of trend. Since it's not known what the null hypothesis is based on a causal understanding of speciation, the proof that there is no barrier to speciation lies elsewhere, in less direct inferences. Evolution is no different from any other science, if you don't have explicit demonstration of the mechanism, whether acupuncture or macroevolution, you have to resort to indirect proof. Evidence like ring species, ERVs, and molecular phylogeny provide that proof. An assumption of uniformitarianism about genetic processes is not itself evidence; the molecular chemistry of genetics is too complex for such assumptions themselves to bear the weight of the inference to macroevolution. That requires actual evidence, not mere assumptions.