"we could consider darwins finches.those with the most advantagious beak for the food source are most likely to survive and pass on that characteristic to progeny.we had finches-we still have finches.
i really cant see how this is evidence for darwinism-other than his borrowing from earlier creationists writings."

Have you heard or read anyone saying that the development of one species leads to the demise of another? I have not.

The idea is that specific species of finches developed to meet local conditions. Obviously if the parent species of finch is thriving in another place then there is no environmental pressure on the species to evolve. In a place ideal for finches the most finch-like will tend to pass on their genes.