Observing it in *micro-evolution* is not enough evidence to say that it can happen in *macro*. It can imply it, and people can deduce it, but that's speculation and conjecture.
So-called "micro-evolution" is EVOLUTION. The observed changes of an organism, as a result of better suitability for survival due to a specific trait, IS THE VERY MECHANISM postulated by Darwin, and since confirmed by generations of scientists.
You can see it happening, folks. It isn't speculation and conjecture; it's observed fact. It is happening in the very short terms in the case of bacteria; drug-resistant strains have evolved in response to the use of antibiotics, as an example.