"How does observing macroevolution in the lab discredit the idea that species on earth were intelligently created?"
Think about it. Try to imagine what Richard Dawkins would say if macroevolution were observed in the lab. I'm sure that would abundant enough evidence for him -- given that he is already convinced *before* such an occurrence was ever observed!
I need to get to work, so please do not interpret any lack of reply on my part as a tacit agreement with any posts that follow here.
I don't believe ID officially denies macroevolution which is evolution above the species level. For example one species of beetle evolving into another species of beetle would not disprove ID in the eyes of its advocates. Even bigger observed changes would not disprove the ID explaination that specific biological systems (ie flagellum) could only be designed by intelligence.