Without doubt, bias will determine how we view Galapagos, no less than anything else we see. But, what we see on Galapagos is not evidence for evolution. Nor is it fixity of the species. Rather, it seems to be better explained by selective inbreeding and line breeding. Assured by physical isolation on these oceanic peaks, these are just as effectively accomplished as in a dog fancier's kennel.
Genetic anomalies abound in the quest for coveted characteristics.
Plaguing the industry are hip dysplasia, congenital skin disorders, cataracts, and so on. As genetic characteristics diverge, it becomes impossible for cross breeding between such different examples as great danes and poodles. Yet none denies that both are dogs. In much the same manner, isolation and circumstantial selective breeding of species on the Galapagos similarly cause these to breed true to type, but diverging markedly from their South American relatives. The resultant celebrated Darwin's Finches are an example.