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Ring species are a fascinating example of how geographic isolation and inbreeding can force the expression of dormant or recessive genetic traits in an organism, and cause loss of genetic information to the point where the ability to interbreed is lost. We've reproduced this effect several times in history with dogs, parakeets, tropical fish, corn, etc. In some cases, our efforts at selective breeding have made it impossible for our "domesticated" plant or animal to breed with the original parent plant or animal.

It would appear that a ring species is an example of the same principle at work in kind of a stretched out way due to a unique type of geographic isolation.

The real issue here is information. Has information been added to the salamander populations, or has information been removed? "Uphill" evolution, the kind that goes from eukayrote to human being requires the uphill kind. Information must be added. Evolution that produces ring species can work with loss of information.

This may demonstrate how salamanders can split into salamandar species, but does not explain how Dinosaurs, for example, can become birds.

Now, if you supposed that the original life on planet Earth contained all the genetic information for all the species we find on the planet, then evolution can easily explain what we see today.

However, information theory makes a pretty strong argument, mathematically, that evolution cannot add information to a system. The main argument is that information is independent of the storage mechanism, so that damaging the mechanism (mutation in the DNA) always causes loss of information. The mathematical arguments are pretty sound, and the empirical evidence seems to lean that way, too. Specifically, the fact that randomly induced changes in DNA do not produce random mutations in the organism. For example, bombarding fruit flies with radiation creates a PATTERN of mutations, usually some form of multiple limbs or organs, or the loss of limbs or organs. The mutations are not random.